Case Report: Improved Oxygenation after One Lung Ventilation in Severe Cardiomegaly due to Cor Pulmonale; analysis with Heart-Lung Interaction Approach

Bambang Pujo Semedi; Willy Kurniawan; Arinanda Lalita Hayu; Yoppie Prim Avidar; Suryanti Chan

doi:10.12688/f1000research.171612.2

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Case Report

Revised

Case Report: Improved Oxygenation after One Lung Ventilation in Severe Cardiomegaly due to Cor Pulmonale; analysis with Heart-Lung Interaction Approach

[version 2; peer review: 2 approved with reservations]

Bambang Pujo Semedi ^1,2, Willy Kurniawan^1,2, Arinanda Lalita Hayu^1,2, Yoppie Prim Avidar^1,2, Suryanti Chan ³

Bambang Pujo Semedi ^1,2, Willy Kurniawan^1,2, [...] Arinanda Lalita Hayu^1,2, Yoppie Prim Avidar^1,2, Suryanti Chan ³

PUBLISHED 20 Feb 2026

Author details Author details

¹ Department of Anesthesiology and Reanimation, Airlangga University, Surabaya, East Java, Indonesia
² Department of Anesthesiology and Reanimation, Dr. Soetomo General Academic Hospital, Surabaya, East Java, Indonesia
³ Universitas Dian Nuswantoro, Semarang, Central Java, Indonesia

Bambang Pujo Semedi
Roles: Conceptualization, Supervision, Writing – Original Draft Preparation, Writing – Review & Editing

Willy Kurniawan
Roles: Investigation, Methodology, Project Administration, Writing – Original Draft Preparation

Arinanda Lalita Hayu
Roles: Resources, Software

Yoppie Prim Avidar
Roles: Resources, Validation

Suryanti Chan
Roles: Writing – Review & Editing

OPEN PEER REVIEW

REVIEWER STATUS

Abstract

Introduction

One-lung ventilation (OLV) is used to isolate one lung during thoracic surgery, but manipulation and positioning can affect heart-lung interaction. Cardiomegaly may exacerbate these changes, especially in the left lateral decubitus (LLD) position.

Objectives

To investigate the effect of cardiomegaly on heart-lung interaction during OLV, particularly in the LLD position.

Case presentation

A 20-year-old male with recurrent spontaneous pneumothorax was scheduled for right-sided bronchopleural fistula repair via thoracotomy. The patient presented with cardiomegaly (cardiothoracic ratio 75%) and echocardiographic evidence of right ventricular and atrial dilation. In the LLD position, OLV led to desaturation when both lungs were ventilated, but oxygenation improved when only the left lung was ventilated.

Results

Cardiomegaly alters heart-lung interaction during OLV, particularly in the LLD position. The enlarged heart exerts pressure on the left lung, impairing ventilation. When both lungs are ventilated in this position, ventilation is directed toward the right lung, reducing oxygenation and causing desaturation. However, restricting ventilation to the left lung improved oxygenation due to better lung compliance and less interference from the enlarged heart.

Conclusions

Cardiomegaly affects heart-lung interaction during OLV in the LLD position. Oxygenation improves when only the left lung is ventilated, likely due to less compression of the left lung. The supine position may further enhance oxygenation even with bilateral ventilation. This case highlights the importance of considering cardiomegaly in OLV management. This section should be written as per the CARE checklist item 3.

Keywords

one-lung ventilation, cardiomegaly, thoracotomy.

Corresponding authors: Bambang Pujo Semedi, Suryanti Chan

Competing interests: No competing interests were disclosed.

Grant information: The author(s) declared that no grants were involved in supporting this work.

Copyright: © 2026 Semedi BP et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

How to cite: Semedi BP, Kurniawan W, Hayu AL et al. Case Report: Improved Oxygenation after One Lung Ventilation in Severe Cardiomegaly due to Cor Pulmonale; analysis with Heart-Lung Interaction Approach [version 2; peer review: 2 approved with reservations]. F1000Research 2026, 15:2 (https://doi.org/10.12688/f1000research.171612.2) First published: 05 Jan 2026, 15:2 (https://doi.org/10.12688/f1000research.171612.1) Latest published: 19 Apr 2026, 15:2 (https://doi.org/10.12688/f1000research.171612.4)

Revised Amendments from Version 1

In this revised version, we have substantially expanded the case description to improve clarity and clinical relevance in response to peer-review comments. The intraoperative timeline has been clarified with a more detailed chronological account of positioning, initiation of one-lung ventilation, hemodynamic changes, and ventilatory adjustments. The preoperative cardiopulmonary status has been described in greater detail to better contextualize the patient’s baseline condition.
The Discussion section has been extensively revised to provide a more structured differential analysis of intraoperative desaturation, including consideration of alternative causes such as device malposition, shunt physiology, and right ventricular dysfunction. We have strengthened the physiological reasoning based on heart–lung interaction principles and added clearer clinical implications to enhance the educational value of the case. A dedicated limitations paragraph has also been included to acknowledge the absence of detailed serial intraoperative physiological measurements.
These revisions aim to improve transparency, scientific rigor, and practical applicability for clinicians managing similar cases.

See the authors' detailed response to the review by Zhiyao Wang
See the authors' detailed response to the review by Praveen Kumar Neema

Introduction

One-lung ventilation (OLV) is a technique used during thoracotomy to selectively ventilate one lung while collapsing the other. This can be achieved using a double-lumen tube (DLT), a single-lumen tube with a bronchial blocker, or an endotracheal tube positioned endobronchially (Butterworth et al., 2013). The procedure involves both manipulation of the lungs and changes in body positioning, which can affect heart-lung interaction. Non-ventilated but perfused lungs may result in a right-to-left shunt, a condition that can be partly mitigated by hypoxic pulmonary vasoconstriction and gravity, which redistributes blood flow to the lower lung (Marongiu et al., 2020). However, OLV also affects cardiac function. Positive pressure ventilation can decrease venous return and systemic vascular resistance, while alveolar hypoxia may induce pulmonary vasoconstriction, increasing the workload on the right ventricle (Slinger et al., 2019). These interactions between the heart and lungs are critical, as changes in one component often affect the other. In this case, we present a patient with cardiomegaly who experienced significant changes in oxygenation during OLV. The patient exhibited desaturation when both lungs were ventilated, but oxygenation improved when only the diseased lung was ventilated.

Case report

Patient information: A 20-year-old male, weighing 45 kg with a height of 165 cm (BMI 16.5 kg/m²), presented in March 2022 with sudden onset shortness of breath. He had no prior chronic illness until one year earlier, when he experienced moderate COVID-19 pneumonia. Since then, he reported reduced exercise tolerance and recurrent shortness of breath but had not sought medical care.

Clinical findings: On initial evaluation, he was alert, with blood pressure 100/70 mmHg, heart rate 110 bpm, respiratory rate 26–28 breaths per minute, oxygen saturation 95–96% on 2 L/min oxygen via nasal cannula, and temperature 36.7°C. Physical examination revealed decreased breath sounds on the right hemithorax with a thoracic drain in situ after recurrence.

Timeline

Timeline of patient is presented by Table 1.

Table 1. Timeline of patient.

Date/Period	Event	Findings/Intervention	Outcome
March 2022	Sudden onset shortness of breath	Diagnosed with right spontaneous pneumothorax	Thoracic drain inserted
Day 8	Follow-up	Improvement on chest X-ray	Drain removed
Day 9	Recurrence of dyspnea	Repeat thoracic drain insertion	Symptom relief
Following days	Diagnostic imaging	CT scan → bronchopleural fistula (posterior segment, RUL)	Planned thoracotomy
Pre-op	Preoperative evaluation	Stable vitals; ABG: pH 7.37, PaO₂ 80 mmHg, PaO₂/FiO₂ 200; Echo: RA/RV dilatation, pulmonary & tricuspid regurgitation	Intermediate probability of pulmonary hypertension
Intra-op	Induction & maintenance	Fentanyl, propofol, rocuronium; sevoflurane; double-lumen tube; VC ventilation	Stable at start
Intra-op (LLD, OLV)	Complication	Hypotension (75/45 mmHg), SpO₂ ↓ to 88%	Norepinephrine & milrinone started; ventilator adjusted (TV 300 mL, RR 20, PEEP 8, FiO₂ 100%) → SpO₂ ↑ to 92%
Post-op	Supine, two-lung ventilation	Stable oxygenation	No further desaturation

Diagnostic assessment: The working diagnosis was a right bronchopleural fistula complicating spontaneous pneumothorax. The diagnosis was confirmed by thoracic computed tomography, while transthoracic echocardiography demonstrated right atrial and right ventricular dilatation with evidence of impaired cardiopulmonary reserve. Differential diagnoses, including persistent pneumothorax without fistula and interstitial lung disease, were considered but excluded based on clinical evaluation and imaging findings.

Therapeutic intervention: The patient was transferred to the operating room with standard ASA monitoring. Prior to induction, an arterial line was inserted for continuous blood pressure monitoring. Baseline measurements showed blood pressure 105/55 mmHg, heart rate 110 bpm, and oxygen saturation 95% on 3 L/min oxygen via nasal cannula.

Anesthesia was induced with fentanyl, propofol, and rocuronium. After adequate muscle relaxation, a 37 Fr left-sided double-lumen tube (DLT) was inserted. Correct placement was confirmed clinically by auscultation and selective lung ventilation assessment. Following intubation, mechanical ventilation was initiated in volume-controlled mode with a tidal volume of 360 mL, respiratory rate 18 breaths per minute, PEEP 5 cmH₂O, and FiO₂ 0.5. Oxygen saturation improved to 99%, and hemodynamics remained stable.

After surgical preparation, the patient was positioned in the left lateral decubitus (LLD) position. Two-lung ventilation was initially maintained during positioning, and no immediate desaturation occurred.

One-lung ventilation (OLV) of the left lung was then initiated to facilitate right thoracotomy. Shortly after initiation of OLV in the LLD position, the patient developed progressive hypotension (blood pressure decreased to 75/45 mmHg) accompanied by oxygen desaturation to 88%. At this time, ventilatory parameters were reassessed and adjusted. Tidal volume was reduced to 300 mL, respiratory rate increased to 20 breaths per minute, PEEP increased to 8 cmH₂O, and FiO₂ increased to 1.0.

Vasopressor and inotropic support were initiated with norepinephrine (50 ng/kg/min) and milrinone (0.3 μg/kg/min) to address suspected right ventricular strain and reduced systemic vascular resistance. Following these interventions, oxygen saturation improved gradually to 92%, and blood pressure stabilized.

No major surgical traction or compression events were noted at the time of desaturation. The remainder of the procedure proceeded under careful hemodynamic and ventilatory monitoring.

At the end of surgery, the patient was returned to the supine position and two-lung ventilation was resumed. Oxygenation stabilized, and no further desaturation episodes were observed.

Follow-up and outcomes: At the end of surgery, the patient was returned to the supine position with two-lung ventilation, after which oxygenation stabilized and no further desaturation occurred. Postoperative follow-up revealed stable respiratory function without recurrence of pneumothorax or desaturation events.

Discussion

In this case, intraoperative desaturation occurred shortly after initiation of one-lung ventilation (OLV) in the left lateral decubitus (LLD) position, accompanied by hypotension. Several potential mechanisms were considered, including double-lumen tube (DLT) malposition, increased right-to-left intrapulmonary shunt during OLV, atelectasis of the dependent lung, acute right ventricular dysfunction, and mechanical compression of the lung due to severe cardiomegaly.

DLT malposition was considered unlikely based on clinical reassessment and selective ventilation findings. The close temporal relationship between positioning, initiation of OLV, hemodynamic instability, and oxygen desaturation suggested a combined cardiopulmonary interaction rather than an isolated ventilatory issue.

The incidence of hypoxemia during OLV has decreased significantly over time, from approximately 25% in the 1970s to less than 10% in modern practice (Semedi et al., 2021). Under normal circumstances, hypoxemia during OLV is primarily caused by right-to-left intrapulmonary shunting from the non-ventilated lung. Hypoxic pulmonary vasoconstriction (HPV) helps mitigate this effect by reducing perfusion to the collapsed lung and redistributing blood flow to the ventilated lung (Marongiu et al., 2020). However, if atelectasis affects the dependent lung, oxygenation may worsen due to ventilation–perfusion (V/Q) mismatch (Rehatta et al., 2019). Typically, oxygenation improves with two-lung ventilation.

The present case deviated from this classical pattern. The patient had severe cardiomegaly (cardiothoracic ratio 75%) with right atrial (RA) and right ventricular (RV) dilation and suspected pulmonary hypertension. Pulmonary hypertension, which may develop in patients with chronic lung disease or post-COVID-19 pulmonary sequelae, increases RV afterload and reduces cardiopulmonary reserve (Taha et al., 2023). Elevated pulmonary vascular resistance (PVR) increases RV workload and may impair cardiac output, especially under stress conditions.

Positive pressure ventilation during OLV can further exacerbate these hemodynamic alterations. Increased intrathoracic pressure may reduce venous return and elevate right atrial pressure, thereby compromising RV preload. In addition, excessive alveolar distension may compress pulmonary capillaries and increase PVR, potentially worsening RV afterload and decreasing cardiac output (Guia et al., 2020). The observed intraoperative hypotension supports the possibility of transient RV compromise in this setting. Administration of norepinephrine and milrinone was therefore aimed at increasing systemic vascular resistance and reducing RV afterload.

A distinctive feature of this case was the improvement in oxygenation when only the dependent left lung was ventilated in the LLD position. We hypothesize that severe cardiomegaly altered the usual distribution of ventilation. In the LLD position, gravitational displacement of the mediastinum combined with marked cardiac enlargement may have exerted compressive forces on the dependent left lung, reducing its compliance during two-lung ventilation. This could have redirected ventilation preferentially toward the non-dependent right lung, which was diseased, thereby worsening V/Q mismatch despite ongoing perfusion of the dependent lung.

When OLV was instituted and ventilation was restricted to the left lung, positive pressure ventilation may have been more effectively distributed within the dependent lung despite mechanical compression. In this situation, ventilation–perfusion matching may have improved compared with two-lung ventilation in the same position. Although inferential, this explanation is physiologically consistent with known heart–lung interaction principles (Marongiu et al., 2020).

After returning the patient to the supine position and resuming two-lung ventilation, oxygenation stabilized. In the supine position, posterior displacement of the enlarged heart may reduce its compressive effect on lung parenchyma, thereby improving regional ventilation. Nonetheless, cardiomegaly may still influence lower-lobe ventilation distribution even in the supine position.

This case suggests that in patients with severe cardiomegaly and suspected pulmonary hypertension, oxygenation behavior during OLV may not follow classical physiological expectations. Unexpected hypoxemia in such patients should prompt evaluation not only of airway devices and ventilatory settings, but also of positional and mediastinal effects on lung mechanics. Awareness of altered heart–lung interaction may help guide intraoperative decision-making and prevent unnecessary escalation of interventions.

Limitations

This case report has several limitations. Detailed serial intraoperative physiological parameters such as dynamic lung compliance, airway pressure trends, serial ABG values, and comprehensive echocardiographic indices were not systematically documented, as this case was not initially managed as a prospective physiological study. Therefore, the proposed mechanisms remain inferential and based on available clinical data combined with established heart–lung interaction principles. Future prospective studies incorporating advanced hemodynamic and respiratory monitoring would be valuable to confirm these observations.

Conclusion

Severe cardiomegaly may significantly alter heart–lung interaction during one-lung ventilation, particularly in the left lateral decubitus position. In this case, oxygenation unexpectedly improved with single-lung ventilation, suggesting that mediastinal compression and positional effects can modify ventilation–perfusion dynamics. Clinicians should be aware that oxygenation patterns during OLV may deviate from classical expectations in patients with marked cardiac enlargement and suspected pulmonary hypertension. Careful evaluation of positioning, ventilatory strategy, and hemodynamic status is essential when managing such cases.

Consent

Written informed consent for the publication of this case report and any associated images has been obtained from the patient. The patient has given permission for their medical information to be published in this case report. All identifying information has been removed to ensure confidentiality, in accordance with ethical standards and privacy regulations.

Data availability

All data underlying the results are available as part of the article and no additional source data are required.

Reporting guidelines

The CARE checklist for this case report is available in the Zenodo repository, DOI: https://doi.org/10.5281/zenodo.18042365 (Willy, K., 2025).

Data are available under the terms of the Creative Commons Attribution 4.0 International license (CC-BY 4.0).

Acknowledgements

The authors extend their deepest gratitude to the staff of the Department of Anesthesiology and Reanimation, Faculty of Medicine, Universitas Airlangga and Dr. Soetomo General Academic Hospital for their invaluable assistance and continuous support in writing and publishing this case report.

References

Butterworth JF, Mackey DC, Wasnick JD, et al.: Morgan and Mikhail’s clinical anesthesiology. 5th ed.McGrew Hill Education; 2013.
Guia MF, Paula F, Pinto P, et al.: Respiratory failure in pulmonary hypertension patients. Rev. Port. Cardiol. 2020; 39(9): 551–552. Publisher Full Text
Marongiu I, Spinelli E, Mauri T: Cardio-respiratory physiology during one-lung ventilation: complex interactions in need of advanced monitoring. Ann. Transl. Med. 2020; 8(8): 524–524. PubMed Abstract | Publisher Full Text | Free Full Text
Rehatta NM, Hanindito E, Tantri A, et al.: Anestesiologi dan Terapi Intensif Buku Teks KATI-PERDATIN.2019.
Semedi BP, Airlangga PS, Hidayati HB, et al.: Lung recruitment maneuver: is it really safe? Anaesth. Pain Intensive Care. 2021; 25(3). Publisher Full Text
Slinger P, Blank RS, Campos J, et al.: Principles and Practice of Anesthesia for Thoracic Surgery. 2nd ed.2019. Publisher Full Text
Taha HA, Elshafey BI, Abdullah TM, et al.: Study of pulmonary hypertension in post-COVID-19 patients by transthoracic echocardiography. Egypt. J. Bronchol. 2023; 17(1). Publisher Full Text
Willy K: CARE Checklist Willy. [Data set]. Zenodo. 2025. Publisher Full Text

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Version 4

VERSION 4 PUBLISHED 05 Jan 2026

Author details Author details

Bambang Pujo Semedi
Roles: Conceptualization, Supervision, Writing – Original Draft Preparation, Writing – Review & Editing

Willy Kurniawan
Roles: Investigation, Methodology, Project Administration, Writing – Original Draft Preparation

Arinanda Lalita Hayu
Roles: Resources, Software

Yoppie Prim Avidar
Roles: Resources, Validation

Suryanti Chan
Roles: Writing – Review & Editing

Competing interests

No competing interests were disclosed.

Grant information

The author(s) declared that no grants were involved in supporting this work.

Article Versions (4)

version 4

Revised

Published: 19 Apr 2026, 15:2

https://doi.org/10.12688/f1000research.171612.4

version 3

Revised

Published: 26 Mar 2026, 15:2

https://doi.org/10.12688/f1000research.171612.3

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Published: 05 Jan 2026, 15:2

https://doi.org/10.12688/f1000research.171612.1

© 2026 Semedi BP et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Semedi BP, Kurniawan W, Hayu AL et al. Case Report: Improved Oxygenation after One Lung Ventilation in Severe Cardiomegaly due to Cor Pulmonale; analysis with Heart-Lung Interaction Approach [version 2; peer review: 2 approved with reservations]. F1000Research 2026, 15:2 (https://doi.org/10.12688/f1000research.171612.2)

NOTE: If applicable, it is important to ensure the information in square brackets after the title is included in all citations of this article.

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Open Peer Review

Version 2

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PUBLISHED 20 Feb 2026

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Reviewer Report 12 Mar 2026

Praveen Kumar Neema, Amrita Institute of Medical Sciences, Kochi, Kerala, India

Approved with Reservations

https://doi.org/10.5256/f1000research.196561.r461303

The sentence, “The procedure involves both manipulation of the lungs and changes in body positioning, which can affect heart-lung interaction” is not clear, do the authors mean ‘surgical procedure’ please rephrase
In view of continuous oxygen requirement, did you measure peripheral oxygen saturation (SpO2) on room air?
However, OLV also affects cardiac function. Positive pressure ventilation can decrease venous return and systemic vascular resistance. How do you explain a decrease in systemic vascular resistance with positive pressure ventilation? please expand and provide reference.
The patient exhibited desaturation when both lungs were ventilated, but oxygenation improved when only the diseased lung was ventilated. The timeline described in the case report and the sentence do not match; as per the case report, the saturation was normal when both the lungs were ventilated and the patient developed desaturation after the initiation of one lung ventilation.
Transthoracic echocardiography demonstrated right atrial and right ventricular dilatation with evidence of impaired cardiopulmonary reserve, what was the right ventricular systolic pressure (RVSP) measured by TR jet?
Following intubation, mechanical ventilation was initiated in volume-controlled mode with a tidal volume of 360 mL, respiratory rate 18 breaths per minute, PEEP 5cmH2O, and FiO2 0.5. Oxygen saturation improved to 99%, and hemodynamics remained stable. Do you mean two lung ventilation? How did you manage loss of tidal volume through bronchopleural fistula?
Table 1: comment on right ventricular systolic pressure
Timeline-Intraop: describe ventilation parameters in detail. From the timeline it is not clear when the patient deteriorated and developed desaturation and hypotension. In the case report it is mentioned that initially two-lung ventilation was maintained and there was no desaturation. Does it mean that patient developed complications after initiating one lung ventilation?
Tidal volume was reduced to 300 mL, respiratory rate increased to 20 breaths per minute, PEEP increased to 8cmH2O, and FiO2 increased to 1.0. what was the rationale?
The close temporal relationship between positioning, initiation of OLV, hemodynamic instability, and oxygen desaturation suggested a combined cardiopulmonary interaction rather than an isolated ventilatory issue, please expand. What were the possible mechanisms and how did you assess them and finally what was the responsible mechanism?
The hypothesis, ‘The present case deviated from this classical pattern. The patient had severe cardiomegaly…and increase PVR, potentially worsening RV afterload and decreasing cardiac output (Guia et al., 2020). The observed intraoperative hypotension supports the possibility of transient RV compromise in this setting. You should discuss the role of bronchopleural fistula during two lung ventilation, I believe, during two lung ventilation, the bronchopleural fistula prevented excessive increase in intrathoracic pressure and pulmonary vascular resistance. With the initiation of OLV, the pulmonary vascular resistance severely, which increased tricuspid and pulmonary regurgitation and severely compromised right ventricular cardiac output. Consequently, decreasing left ventricular cardiac output and precipitating severe hypotension and desaturation. The vicious cycle was interrupted once tidal volume was decreased. The decrease in right ventricular cardiac output is expected to be pronounced in presence of right ventricular dysfunction.
We hypothesize…thereby worsening V/Q mismatch despite ongoing perfusion of the dependent lung; this is possible, if there is no bronchopleural fistula; however, the effect is expected to be mild in presence of bronchopleural fistula.
When OLV was instituted…explanation is physiologically consistent with known heart–lung interaction principles (Marongiu et al., 2020). This paragraph can be removed
This case suggests that in patients with severe cardiomegaly and suspected pulmonary hypertension, oxygenation behavior during OLV may not follow classical physiological expectations, I do not agree with the statement. The deterioration of hemodynamic and saturation should be anticipated and, perhaps, appropriate adjustments of ventilation parameters would have prevented the deterioration.

Is the background of the case’s history and progression described in sufficient detail?

Partly
Are enough details provided of any physical examination and diagnostic tests, treatment given and outcomes?

Yes
Is sufficient discussion included of the importance of the findings and their relevance to future understanding of disease processes, diagnosis or treatment?

No
Is the case presented with sufficient detail to be useful for other practitioners?

Partly

Competing Interests: No competing interests were disclosed.

Reviewer Expertise: Cardiovascular physiology; cardiopulmonary bypass, adult and pediatric cardiac anesthesia, thoracic anesthesia,

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.

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Author Response 26 Mar 2026

Suryanti Suryanti, Universitas Dian Nuswantoro, Semarang, Indonesia

26 Mar 2026

Author Response
We sincerely thank the reviewer for the insightful and constructive comments. We have carefully revised the manuscript to address all concerns. Detailed responses to each comment are provided below, and ... Continue reading
We sincerely thank the reviewer for the insightful and constructive comments. We have carefully revised the manuscript to address all concerns. Detailed responses to each comment are provided below, and the corresponding revisions have been incorporated into the manuscript.
1. Comment 1: The sentence, “The procedure involves both manipulation of the lungs and changes in body positioning, which can affect heart-lung interaction” is not clear, do the authors mean ‘surgical procedure’ please rephrase.
Response: Thank you for this suggestion. The sentence referred to the thoracic surgical procedure requiring one-lung ventilation and lateral positioning. We have revised the sentence to clarify this meaning. Revision in manuscript: The sentence has been revised as follows: “Thoracic surgical procedures requiring lung isolation and lateral decubitus positioning may significantly influence heart–lung interactions.”
2. Comment 2: In view of continuous oxygen requirement, did you measure peripheral oxygen saturation (SpO₂) on room air?
Response: Thank you for this important question. Unfortunately, the exact SpO₂ value on room air was not documented in the medical record because the patient was already receiving supplemental oxygen due to respiratory symptoms at the time of evaluation. Baseline oxygenation was assessed using arterial blood gas analysis, which showed PaO₂ 80 mmHg with a PaO₂/FiO₂ ratio of approximately 200. We have clarified this point in the revised manuscript.
Revision in manuscript: A clarifying sentence has been added in the case presentation section indicating that baseline oxygenation was assessed using arterial blood gas analysis.
3. Comment 3: However, OLV also affects cardiac function. Positive pressure ventilation can decrease venous return and systemic vascular resistance. How do you explain a decrease in systemic vascular resistance with positive pressure ventilation? Please expand and provide reference.
Response: Thank you for this important comment. We have expanded the discussion to clarify the hemodynamic effects of positive pressure ventilation. Positive pressure ventilation increases intrathoracic pressure, which reduces venous return and may decrease left ventricular preload. Additionally, reduced preload and cardiac output may lead to reflex vasodilation or altered autonomic tone, contributing to decreased systemic vascular resistance in some clinical settings. Relevant references have been added to support this explanation. Revision in manuscript: The discussion section has been expanded to explain the hemodynamic effects of positive pressure ventilation on venous return, cardiac output, and systemic vascular resistance, with additional references.
4. Comment 4: The patient exhibited desaturation when both lungs were ventilated, but oxygenation improved when only the diseased lung was ventilated. The timeline described in the case report and the sentence do not match.
Response: We appreciate the reviewer’s careful observation. The reviewer is correct that the description was inconsistent with the timeline. The sentence has been corrected to reflect the actual sequence of events. Revision in manuscript: The corrected sentence is: “Oxygen saturation remained stable during two-lung ventilation but decreased after the initiation of one-lung ventilation.”
5. Comment 5: Transthoracic echocardiography demonstrated right atrial and right ventricular dilatation… what was the right ventricular systolic pressure (RVSP) measured by TR jet?
Response: Thank you for this important comment. Unfortunately, the exact right ventricular systolic pressure (RVSP) derived from the tricuspid regurgitation jet was not documented in the available echocardiography report in the medical record. However, transthoracic echocardiography demonstrated right atrial and right ventricular dilatation with moderate tricuspid regurgitation, suggesting impaired right heart function and possible elevation of right-sided pressures. We have clarified this point in the revised manuscript. Revision in manuscript: A clarifying sentence has been added in the echocardiography findings section indicating that the RVSP value was not available in the echocardiography report.
6. Comment 6: Do you mean two lung ventilation? How did you manage loss of tidal volume through bronchopleural fistula?
Response: Yes, the reviewer is correct that the ventilation described refers to two-lung ventilation following intubation. This has been clarified in the revised manuscript. Regarding tidal volume loss through the bronchopleural fistula, ventilation was carefully monitored and adjusted to minimize air leakage while maintaining adequate oxygenation. Lung isolation and ventilator parameter adjustments were used to reduce leakage and optimize ventilation. Revision in manuscript: The text has been revised to clarify that two-lung ventilation was initially used and to briefly describe the strategy for managing tidal volume loss due to the bronchopleural fistula.
7. Comment 7: Table 1: comment on right ventricular systolic pressure.
Response: Thank you for this suggestion. Unfortunately, the right ventricular systolic pressure (RVSP) derived from the tricuspid regurgitation jet was not documented in the available echocardiography report in the medical record. Therefore, the RVSP value could not be included in Table 1. We have clarified this limitation in the revised manuscript. Revision in manuscript: A clarifying note has been added in the echocardiography findings section indicating that the RVSP value was not available in the echocardiography report.
8. Comment 8: Timeline – intraoperative events are unclear.
Response: Thank you for pointing this out. The intraoperative timeline has been revised to clarify the sequence of ventilation strategies, oxygen desaturation, and hemodynamic changes.
Revision in manuscript: The timeline figure and corresponding text have been updated to clearly indicate:

initiation of two-lung ventilation

transition to one-lung ventilation

onset of desaturation and hypotension

subsequent ventilatory adjustment

9. Comment 9: Tidal volume was reduced to 300 mL… what was the rationale?
Response: The rationale was to reduce airway pressure and minimize air leakage through the bronchopleural fistula while maintaining adequate ventilation. Lower tidal volume with increased respiratory rate was used to maintain minute ventilation and reduce intrathoracic pressure.
Revision in manuscript: This rationale has been added to the intraoperative management section.
10. Comment 10: Please expand possible mechanisms explaining the cardiopulmonary interaction.
Response:
We thank the reviewer for this important suggestion. The discussion has been expanded to describe possible mechanisms including:

increased pulmonary vascular resistance during OLV

right ventricular afterload elevation

impaired right ventricular output in the presence of cardiomegaly

altered ventilation-perfusion relationships

These mechanisms were considered in explaining the observed intraoperative hemodynamic instability.
Revision in manuscript: Additional discussion has been included in the Discussion section.
11. Comment 11: hypothesis regarding bronchopleural fistula and RV failure
Response: We appreciate this insightful physiological interpretation. We agree that the bronchopleural fistula may have influenced intrathoracic pressure dynamics during two-lung ventilation. We have incorporated this explanation into the discussion and acknowledged that increased pulmonary vascular resistance during OLV may have contributed to right ventricular compromise in this patient.
Revision in manuscript: The discussion now includes a paragraph discussing the potential role of bronchopleural fistula in modulating intrathoracic pressure and pulmonary vascular resistance during ventilation.
12. Comment 12: Paragraph beginning “When OLV was instituted…” can be removed.
Response: Thank you for this suggestion. As recommended, the paragraph has been removed to improve clarity and avoid redundancy.
13. Comment 13: “I do not agree with the statement…”
Response: We appreciate the reviewer’s perspective. We have revised the conclusion to avoid overstating the finding and to emphasize that careful anticipation and adjustment of ventilatory parameters are important in patients with cardiomegaly undergoing OLV. Revision in manuscript:
The conclusion has been modified to reflect a more cautious interpretation of the findings.
We sincerely thank the reviewer for the insightful and constructive comments. We have carefully revised the manuscript to address all concerns. Detailed responses to each comment are provided below, and the corresponding revisions have been incorporated into the manuscript.
1. Comment 1: The sentence, “The procedure involves both manipulation of the lungs and changes in body positioning, which can affect heart-lung interaction” is not clear, do the authors mean ‘surgical procedure’ please rephrase.
Response: Thank you for this suggestion. The sentence referred to the thoracic surgical procedure requiring one-lung ventilation and lateral positioning. We have revised the sentence to clarify this meaning. Revision in manuscript: The sentence has been revised as follows: “Thoracic surgical procedures requiring lung isolation and lateral decubitus positioning may significantly influence heart–lung interactions.”
2. Comment 2: In view of continuous oxygen requirement, did you measure peripheral oxygen saturation (SpO₂) on room air?
Response: Thank you for this important question. Unfortunately, the exact SpO₂ value on room air was not documented in the medical record because the patient was already receiving supplemental oxygen due to respiratory symptoms at the time of evaluation. Baseline oxygenation was assessed using arterial blood gas analysis, which showed PaO₂ 80 mmHg with a PaO₂/FiO₂ ratio of approximately 200. We have clarified this point in the revised manuscript.
Revision in manuscript: A clarifying sentence has been added in the case presentation section indicating that baseline oxygenation was assessed using arterial blood gas analysis.
3. Comment 3: However, OLV also affects cardiac function. Positive pressure ventilation can decrease venous return and systemic vascular resistance. How do you explain a decrease in systemic vascular resistance with positive pressure ventilation? Please expand and provide reference.
Response: Thank you for this important comment. We have expanded the discussion to clarify the hemodynamic effects of positive pressure ventilation. Positive pressure ventilation increases intrathoracic pressure, which reduces venous return and may decrease left ventricular preload. Additionally, reduced preload and cardiac output may lead to reflex vasodilation or altered autonomic tone, contributing to decreased systemic vascular resistance in some clinical settings. Relevant references have been added to support this explanation. Revision in manuscript: The discussion section has been expanded to explain the hemodynamic effects of positive pressure ventilation on venous return, cardiac output, and systemic vascular resistance, with additional references.
4. Comment 4: The patient exhibited desaturation when both lungs were ventilated, but oxygenation improved when only the diseased lung was ventilated. The timeline described in the case report and the sentence do not match.
Response: We appreciate the reviewer’s careful observation. The reviewer is correct that the description was inconsistent with the timeline. The sentence has been corrected to reflect the actual sequence of events. Revision in manuscript: The corrected sentence is: “Oxygen saturation remained stable during two-lung ventilation but decreased after the initiation of one-lung ventilation.”
5. Comment 5: Transthoracic echocardiography demonstrated right atrial and right ventricular dilatation… what was the right ventricular systolic pressure (RVSP) measured by TR jet?
Response: Thank you for this important comment. Unfortunately, the exact right ventricular systolic pressure (RVSP) derived from the tricuspid regurgitation jet was not documented in the available echocardiography report in the medical record. However, transthoracic echocardiography demonstrated right atrial and right ventricular dilatation with moderate tricuspid regurgitation, suggesting impaired right heart function and possible elevation of right-sided pressures. We have clarified this point in the revised manuscript. Revision in manuscript: A clarifying sentence has been added in the echocardiography findings section indicating that the RVSP value was not available in the echocardiography report.
6. Comment 6: Do you mean two lung ventilation? How did you manage loss of tidal volume through bronchopleural fistula?
Response: Yes, the reviewer is correct that the ventilation described refers to two-lung ventilation following intubation. This has been clarified in the revised manuscript. Regarding tidal volume loss through the bronchopleural fistula, ventilation was carefully monitored and adjusted to minimize air leakage while maintaining adequate oxygenation. Lung isolation and ventilator parameter adjustments were used to reduce leakage and optimize ventilation. Revision in manuscript: The text has been revised to clarify that two-lung ventilation was initially used and to briefly describe the strategy for managing tidal volume loss due to the bronchopleural fistula.
7. Comment 7: Table 1: comment on right ventricular systolic pressure.
Response: Thank you for this suggestion. Unfortunately, the right ventricular systolic pressure (RVSP) derived from the tricuspid regurgitation jet was not documented in the available echocardiography report in the medical record. Therefore, the RVSP value could not be included in Table 1. We have clarified this limitation in the revised manuscript. Revision in manuscript: A clarifying note has been added in the echocardiography findings section indicating that the RVSP value was not available in the echocardiography report.
8. Comment 8: Timeline – intraoperative events are unclear.
Response: Thank you for pointing this out. The intraoperative timeline has been revised to clarify the sequence of ventilation strategies, oxygen desaturation, and hemodynamic changes.
Revision in manuscript: The timeline figure and corresponding text have been updated to clearly indicate:

initiation of two-lung ventilation

transition to one-lung ventilation

onset of desaturation and hypotension

subsequent ventilatory adjustment

9. Comment 9: Tidal volume was reduced to 300 mL… what was the rationale?
Response: The rationale was to reduce airway pressure and minimize air leakage through the bronchopleural fistula while maintaining adequate ventilation. Lower tidal volume with increased respiratory rate was used to maintain minute ventilation and reduce intrathoracic pressure.
Revision in manuscript: This rationale has been added to the intraoperative management section.
10. Comment 10: Please expand possible mechanisms explaining the cardiopulmonary interaction.
Response:
We thank the reviewer for this important suggestion. The discussion has been expanded to describe possible mechanisms including:

increased pulmonary vascular resistance during OLV

right ventricular afterload elevation

impaired right ventricular output in the presence of cardiomegaly

altered ventilation-perfusion relationships

These mechanisms were considered in explaining the observed intraoperative hemodynamic instability.
Revision in manuscript: Additional discussion has been included in the Discussion section.
11. Comment 11: hypothesis regarding bronchopleural fistula and RV failure
Response: We appreciate this insightful physiological interpretation. We agree that the bronchopleural fistula may have influenced intrathoracic pressure dynamics during two-lung ventilation. We have incorporated this explanation into the discussion and acknowledged that increased pulmonary vascular resistance during OLV may have contributed to right ventricular compromise in this patient.
Revision in manuscript: The discussion now includes a paragraph discussing the potential role of bronchopleural fistula in modulating intrathoracic pressure and pulmonary vascular resistance during ventilation.
12. Comment 12: Paragraph beginning “When OLV was instituted…” can be removed.
Response: Thank you for this suggestion. As recommended, the paragraph has been removed to improve clarity and avoid redundancy.
13. Comment 13: “I do not agree with the statement…”
Response: We appreciate the reviewer’s perspective. We have revised the conclusion to avoid overstating the finding and to emphasize that careful anticipation and adjustment of ventilatory parameters are important in patients with cardiomegaly undergoing OLV. Revision in manuscript:
The conclusion has been modified to reflect a more cautious interpretation of the findings.
Competing Interests: The authors declare that they have no competing interests. Close
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Respond or Comment

COMMENTS ON THIS REPORT

Author Response 26 Mar 2026

Suryanti Suryanti, Universitas Dian Nuswantoro, Semarang, Indonesia

26 Mar 2026

Author Response
We sincerely thank the reviewer for the insightful and constructive comments. We have carefully revised the manuscript to address all concerns. Detailed responses to each comment are provided below, and ... Continue reading
We sincerely thank the reviewer for the insightful and constructive comments. We have carefully revised the manuscript to address all concerns. Detailed responses to each comment are provided below, and the corresponding revisions have been incorporated into the manuscript.
1. Comment 1: The sentence, “The procedure involves both manipulation of the lungs and changes in body positioning, which can affect heart-lung interaction” is not clear, do the authors mean ‘surgical procedure’ please rephrase.
Response: Thank you for this suggestion. The sentence referred to the thoracic surgical procedure requiring one-lung ventilation and lateral positioning. We have revised the sentence to clarify this meaning. Revision in manuscript: The sentence has been revised as follows: “Thoracic surgical procedures requiring lung isolation and lateral decubitus positioning may significantly influence heart–lung interactions.”
2. Comment 2: In view of continuous oxygen requirement, did you measure peripheral oxygen saturation (SpO₂) on room air?
Response: Thank you for this important question. Unfortunately, the exact SpO₂ value on room air was not documented in the medical record because the patient was already receiving supplemental oxygen due to respiratory symptoms at the time of evaluation. Baseline oxygenation was assessed using arterial blood gas analysis, which showed PaO₂ 80 mmHg with a PaO₂/FiO₂ ratio of approximately 200. We have clarified this point in the revised manuscript.
Revision in manuscript: A clarifying sentence has been added in the case presentation section indicating that baseline oxygenation was assessed using arterial blood gas analysis.
3. Comment 3: However, OLV also affects cardiac function. Positive pressure ventilation can decrease venous return and systemic vascular resistance. How do you explain a decrease in systemic vascular resistance with positive pressure ventilation? Please expand and provide reference.
Response: Thank you for this important comment. We have expanded the discussion to clarify the hemodynamic effects of positive pressure ventilation. Positive pressure ventilation increases intrathoracic pressure, which reduces venous return and may decrease left ventricular preload. Additionally, reduced preload and cardiac output may lead to reflex vasodilation or altered autonomic tone, contributing to decreased systemic vascular resistance in some clinical settings. Relevant references have been added to support this explanation. Revision in manuscript: The discussion section has been expanded to explain the hemodynamic effects of positive pressure ventilation on venous return, cardiac output, and systemic vascular resistance, with additional references.
4. Comment 4: The patient exhibited desaturation when both lungs were ventilated, but oxygenation improved when only the diseased lung was ventilated. The timeline described in the case report and the sentence do not match.
Response: We appreciate the reviewer’s careful observation. The reviewer is correct that the description was inconsistent with the timeline. The sentence has been corrected to reflect the actual sequence of events. Revision in manuscript: The corrected sentence is: “Oxygen saturation remained stable during two-lung ventilation but decreased after the initiation of one-lung ventilation.”
5. Comment 5: Transthoracic echocardiography demonstrated right atrial and right ventricular dilatation… what was the right ventricular systolic pressure (RVSP) measured by TR jet?
Response: Thank you for this important comment. Unfortunately, the exact right ventricular systolic pressure (RVSP) derived from the tricuspid regurgitation jet was not documented in the available echocardiography report in the medical record. However, transthoracic echocardiography demonstrated right atrial and right ventricular dilatation with moderate tricuspid regurgitation, suggesting impaired right heart function and possible elevation of right-sided pressures. We have clarified this point in the revised manuscript. Revision in manuscript: A clarifying sentence has been added in the echocardiography findings section indicating that the RVSP value was not available in the echocardiography report.
6. Comment 6: Do you mean two lung ventilation? How did you manage loss of tidal volume through bronchopleural fistula?
Response: Yes, the reviewer is correct that the ventilation described refers to two-lung ventilation following intubation. This has been clarified in the revised manuscript. Regarding tidal volume loss through the bronchopleural fistula, ventilation was carefully monitored and adjusted to minimize air leakage while maintaining adequate oxygenation. Lung isolation and ventilator parameter adjustments were used to reduce leakage and optimize ventilation. Revision in manuscript: The text has been revised to clarify that two-lung ventilation was initially used and to briefly describe the strategy for managing tidal volume loss due to the bronchopleural fistula.
7. Comment 7: Table 1: comment on right ventricular systolic pressure.
Response: Thank you for this suggestion. Unfortunately, the right ventricular systolic pressure (RVSP) derived from the tricuspid regurgitation jet was not documented in the available echocardiography report in the medical record. Therefore, the RVSP value could not be included in Table 1. We have clarified this limitation in the revised manuscript. Revision in manuscript: A clarifying note has been added in the echocardiography findings section indicating that the RVSP value was not available in the echocardiography report.
8. Comment 8: Timeline – intraoperative events are unclear.
Response: Thank you for pointing this out. The intraoperative timeline has been revised to clarify the sequence of ventilation strategies, oxygen desaturation, and hemodynamic changes.
Revision in manuscript: The timeline figure and corresponding text have been updated to clearly indicate:

initiation of two-lung ventilation

transition to one-lung ventilation

onset of desaturation and hypotension

subsequent ventilatory adjustment

9. Comment 9: Tidal volume was reduced to 300 mL… what was the rationale?
Response: The rationale was to reduce airway pressure and minimize air leakage through the bronchopleural fistula while maintaining adequate ventilation. Lower tidal volume with increased respiratory rate was used to maintain minute ventilation and reduce intrathoracic pressure.
Revision in manuscript: This rationale has been added to the intraoperative management section.
10. Comment 10: Please expand possible mechanisms explaining the cardiopulmonary interaction.
Response:
We thank the reviewer for this important suggestion. The discussion has been expanded to describe possible mechanisms including:

increased pulmonary vascular resistance during OLV

right ventricular afterload elevation

impaired right ventricular output in the presence of cardiomegaly

altered ventilation-perfusion relationships

These mechanisms were considered in explaining the observed intraoperative hemodynamic instability.
Revision in manuscript: Additional discussion has been included in the Discussion section.
11. Comment 11: hypothesis regarding bronchopleural fistula and RV failure
Response: We appreciate this insightful physiological interpretation. We agree that the bronchopleural fistula may have influenced intrathoracic pressure dynamics during two-lung ventilation. We have incorporated this explanation into the discussion and acknowledged that increased pulmonary vascular resistance during OLV may have contributed to right ventricular compromise in this patient.
Revision in manuscript: The discussion now includes a paragraph discussing the potential role of bronchopleural fistula in modulating intrathoracic pressure and pulmonary vascular resistance during ventilation.
12. Comment 12: Paragraph beginning “When OLV was instituted…” can be removed.
Response: Thank you for this suggestion. As recommended, the paragraph has been removed to improve clarity and avoid redundancy.
13. Comment 13: “I do not agree with the statement…”
Response: We appreciate the reviewer’s perspective. We have revised the conclusion to avoid overstating the finding and to emphasize that careful anticipation and adjustment of ventilatory parameters are important in patients with cardiomegaly undergoing OLV. Revision in manuscript:
The conclusion has been modified to reflect a more cautious interpretation of the findings.
We sincerely thank the reviewer for the insightful and constructive comments. We have carefully revised the manuscript to address all concerns. Detailed responses to each comment are provided below, and the corresponding revisions have been incorporated into the manuscript.
1. Comment 1: The sentence, “The procedure involves both manipulation of the lungs and changes in body positioning, which can affect heart-lung interaction” is not clear, do the authors mean ‘surgical procedure’ please rephrase.
Response: Thank you for this suggestion. The sentence referred to the thoracic surgical procedure requiring one-lung ventilation and lateral positioning. We have revised the sentence to clarify this meaning. Revision in manuscript: The sentence has been revised as follows: “Thoracic surgical procedures requiring lung isolation and lateral decubitus positioning may significantly influence heart–lung interactions.”
2. Comment 2: In view of continuous oxygen requirement, did you measure peripheral oxygen saturation (SpO₂) on room air?
Response: Thank you for this important question. Unfortunately, the exact SpO₂ value on room air was not documented in the medical record because the patient was already receiving supplemental oxygen due to respiratory symptoms at the time of evaluation. Baseline oxygenation was assessed using arterial blood gas analysis, which showed PaO₂ 80 mmHg with a PaO₂/FiO₂ ratio of approximately 200. We have clarified this point in the revised manuscript.
Revision in manuscript: A clarifying sentence has been added in the case presentation section indicating that baseline oxygenation was assessed using arterial blood gas analysis.
3. Comment 3: However, OLV also affects cardiac function. Positive pressure ventilation can decrease venous return and systemic vascular resistance. How do you explain a decrease in systemic vascular resistance with positive pressure ventilation? Please expand and provide reference.
Response: Thank you for this important comment. We have expanded the discussion to clarify the hemodynamic effects of positive pressure ventilation. Positive pressure ventilation increases intrathoracic pressure, which reduces venous return and may decrease left ventricular preload. Additionally, reduced preload and cardiac output may lead to reflex vasodilation or altered autonomic tone, contributing to decreased systemic vascular resistance in some clinical settings. Relevant references have been added to support this explanation. Revision in manuscript: The discussion section has been expanded to explain the hemodynamic effects of positive pressure ventilation on venous return, cardiac output, and systemic vascular resistance, with additional references.
4. Comment 4: The patient exhibited desaturation when both lungs were ventilated, but oxygenation improved when only the diseased lung was ventilated. The timeline described in the case report and the sentence do not match.
Response: We appreciate the reviewer’s careful observation. The reviewer is correct that the description was inconsistent with the timeline. The sentence has been corrected to reflect the actual sequence of events. Revision in manuscript: The corrected sentence is: “Oxygen saturation remained stable during two-lung ventilation but decreased after the initiation of one-lung ventilation.”
5. Comment 5: Transthoracic echocardiography demonstrated right atrial and right ventricular dilatation… what was the right ventricular systolic pressure (RVSP) measured by TR jet?
Response: Thank you for this important comment. Unfortunately, the exact right ventricular systolic pressure (RVSP) derived from the tricuspid regurgitation jet was not documented in the available echocardiography report in the medical record. However, transthoracic echocardiography demonstrated right atrial and right ventricular dilatation with moderate tricuspid regurgitation, suggesting impaired right heart function and possible elevation of right-sided pressures. We have clarified this point in the revised manuscript. Revision in manuscript: A clarifying sentence has been added in the echocardiography findings section indicating that the RVSP value was not available in the echocardiography report.
6. Comment 6: Do you mean two lung ventilation? How did you manage loss of tidal volume through bronchopleural fistula?
Response: Yes, the reviewer is correct that the ventilation described refers to two-lung ventilation following intubation. This has been clarified in the revised manuscript. Regarding tidal volume loss through the bronchopleural fistula, ventilation was carefully monitored and adjusted to minimize air leakage while maintaining adequate oxygenation. Lung isolation and ventilator parameter adjustments were used to reduce leakage and optimize ventilation. Revision in manuscript: The text has been revised to clarify that two-lung ventilation was initially used and to briefly describe the strategy for managing tidal volume loss due to the bronchopleural fistula.
7. Comment 7: Table 1: comment on right ventricular systolic pressure.
Response: Thank you for this suggestion. Unfortunately, the right ventricular systolic pressure (RVSP) derived from the tricuspid regurgitation jet was not documented in the available echocardiography report in the medical record. Therefore, the RVSP value could not be included in Table 1. We have clarified this limitation in the revised manuscript. Revision in manuscript: A clarifying note has been added in the echocardiography findings section indicating that the RVSP value was not available in the echocardiography report.
8. Comment 8: Timeline – intraoperative events are unclear.
Response: Thank you for pointing this out. The intraoperative timeline has been revised to clarify the sequence of ventilation strategies, oxygen desaturation, and hemodynamic changes.
Revision in manuscript: The timeline figure and corresponding text have been updated to clearly indicate:

initiation of two-lung ventilation

transition to one-lung ventilation

onset of desaturation and hypotension

subsequent ventilatory adjustment

9. Comment 9: Tidal volume was reduced to 300 mL… what was the rationale?
Response: The rationale was to reduce airway pressure and minimize air leakage through the bronchopleural fistula while maintaining adequate ventilation. Lower tidal volume with increased respiratory rate was used to maintain minute ventilation and reduce intrathoracic pressure.
Revision in manuscript: This rationale has been added to the intraoperative management section.
10. Comment 10: Please expand possible mechanisms explaining the cardiopulmonary interaction.
Response:
We thank the reviewer for this important suggestion. The discussion has been expanded to describe possible mechanisms including:

increased pulmonary vascular resistance during OLV

right ventricular afterload elevation

impaired right ventricular output in the presence of cardiomegaly

altered ventilation-perfusion relationships

These mechanisms were considered in explaining the observed intraoperative hemodynamic instability.
Revision in manuscript: Additional discussion has been included in the Discussion section.
11. Comment 11: hypothesis regarding bronchopleural fistula and RV failure
Response: We appreciate this insightful physiological interpretation. We agree that the bronchopleural fistula may have influenced intrathoracic pressure dynamics during two-lung ventilation. We have incorporated this explanation into the discussion and acknowledged that increased pulmonary vascular resistance during OLV may have contributed to right ventricular compromise in this patient.
Revision in manuscript: The discussion now includes a paragraph discussing the potential role of bronchopleural fistula in modulating intrathoracic pressure and pulmonary vascular resistance during ventilation.
12. Comment 12: Paragraph beginning “When OLV was instituted…” can be removed.
Response: Thank you for this suggestion. As recommended, the paragraph has been removed to improve clarity and avoid redundancy.
13. Comment 13: “I do not agree with the statement…”
Response: We appreciate the reviewer’s perspective. We have revised the conclusion to avoid overstating the finding and to emphasize that careful anticipation and adjustment of ventilatory parameters are important in patients with cardiomegaly undergoing OLV. Revision in manuscript:
The conclusion has been modified to reflect a more cautious interpretation of the findings.
Competing Interests: The authors declare that they have no competing interests. Close
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Version 1

VERSION 1

PUBLISHED 05 Jan 2026

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Reviewer Report 12 Feb 2026

Zhiyao Wang, Fudan University, Shanghai, China

Approved with Reservations

https://doi.org/10.5256/f1000research.189236.r452227

The background and progress are described to some extent, but not sufficiently:

1) The overall timeline is unclear;
2) There is a lack of description of the preoperative respiratory status;
3) Descriptions of key events are still lacking, such as the specific timing of changes in body position, when one-lung ventilation was started, how the DLT position was confirmed, whether there was surgical traction/compression, re-expansion procedures, changes in ABG, changes in airway pressure/compliance, etc. The text lacks physical examination-related content such as dynamic changes in vital signs, respiratory examination, signs of respiratory distress, and cardiac examination; in terms of diagnostic examinations, it lacks indicators reflecting the severity of cardiopulmonary function, such as key echocardiographic parameters (TR Vmax, estimated PASP, TAPSE), right ventricular function, estimated pulmonary artery pressure, baseline hemodynamics, and exercise tolerance; follow-up is too brief, lacking details on objective endpoints such as postoperative imaging re-examination, ABG/echocardiography, chest tube indwelling time, whether the condition relapsed, and length of hospital stay. The discussion section still has shortcomings.

First, the hypotheses should be discussed based on key objective physiological data (vital signs, ABG, airway pressure/compliance, EtCO₂ trends, etc.). Second, it is recommended to discuss the reasons for the intraoperative oxygen saturation decrease and the basis for exclusion. Finally, it is recommended to elaborate on the clinical significance of this case. Due to the insufficient detail in the case description, it is currently not sufficient to provide guidance for other clinicians in real-world clinical scenarios.

Is the background of the case’s history and progression described in sufficient detail?

Partly
Are enough details provided of any physical examination and diagnostic tests, treatment given and outcomes?

Partly
Is sufficient discussion included of the importance of the findings and their relevance to future understanding of disease processes, diagnosis or treatment?

Partly
Is the case presented with sufficient detail to be useful for other practitioners?

Partly

Competing Interests: No competing interests were disclosed.

Reviewer Expertise: clinical anesthesia; acute pain; chronic pain

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Author Response 20 Feb 2026

Suryanti Suryanti, Universitas Dian Nuswantoro, Semarang, Indonesia

20 Feb 2026

Author Response
We sincerely thank the reviewer for the detailed and insightful comments. We fully agree that additional physiological parameters such as serial ABG measurements, detailed airway pressure/compliance trends, comprehensive echocardiographic indices, ... Continue reading
We sincerely thank the reviewer for the detailed and insightful comments. We fully agree that additional physiological parameters such as serial ABG measurements, detailed airway pressure/compliance trends, comprehensive echocardiographic indices, and extended follow-up data would strengthen the scientific rigor of this report.
However, as this case was retrospectively prepared from routine clinical practice rather than a prospectively designed physiological study, certain detailed intraoperative parameters were not systematically recorded or are no longer retrievable from the medical record.
Nevertheless, we have carefully revised the manuscript to:

Clarify the intraoperative timeline and sequence of events.

Expand the description of preoperative cardiopulmonary status based on available data.

Provide a more structured physiological interpretation based on the documented vital signs and clinical course.

Include a dedicated “Limitations” paragraph in the Discussion acknowledging the absence of detailed serial physiological data.

Emphasize that this report is hypothesis-generating and aims to highlight a potentially under-recognized heart–lung interaction phenomenon in patients with severe cardiomegaly undergoing OLV.

We agree that future prospective studies with comprehensive hemodynamic and respiratory monitoring would be necessary to validate the proposed mechanisms.
We sincerely appreciate the reviewer’s comments, which have helped us improve the clarity and transparency of our report.
We sincerely thank the reviewer for the detailed and insightful comments. We fully agree that additional physiological parameters such as serial ABG measurements, detailed airway pressure/compliance trends, comprehensive echocardiographic indices, and extended follow-up data would strengthen the scientific rigor of this report.
However, as this case was retrospectively prepared from routine clinical practice rather than a prospectively designed physiological study, certain detailed intraoperative parameters were not systematically recorded or are no longer retrievable from the medical record.
Nevertheless, we have carefully revised the manuscript to:

Clarify the intraoperative timeline and sequence of events.

Expand the description of preoperative cardiopulmonary status based on available data.

Provide a more structured physiological interpretation based on the documented vital signs and clinical course.

Include a dedicated “Limitations” paragraph in the Discussion acknowledging the absence of detailed serial physiological data.

Emphasize that this report is hypothesis-generating and aims to highlight a potentially under-recognized heart–lung interaction phenomenon in patients with severe cardiomegaly undergoing OLV.

We agree that future prospective studies with comprehensive hemodynamic and respiratory monitoring would be necessary to validate the proposed mechanisms.
We sincerely appreciate the reviewer’s comments, which have helped us improve the clarity and transparency of our report.
Competing Interests: Authors declare there are no any competing interest. Close
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COMMENTS ON THIS REPORT

Author Response 20 Feb 2026

Suryanti Suryanti, Universitas Dian Nuswantoro, Semarang, Indonesia

20 Feb 2026

Author Response
We sincerely thank the reviewer for the detailed and insightful comments. We fully agree that additional physiological parameters such as serial ABG measurements, detailed airway pressure/compliance trends, comprehensive echocardiographic indices, ... Continue reading
We sincerely thank the reviewer for the detailed and insightful comments. We fully agree that additional physiological parameters such as serial ABG measurements, detailed airway pressure/compliance trends, comprehensive echocardiographic indices, and extended follow-up data would strengthen the scientific rigor of this report.
However, as this case was retrospectively prepared from routine clinical practice rather than a prospectively designed physiological study, certain detailed intraoperative parameters were not systematically recorded or are no longer retrievable from the medical record.
Nevertheless, we have carefully revised the manuscript to:

Clarify the intraoperative timeline and sequence of events.

Expand the description of preoperative cardiopulmonary status based on available data.

Provide a more structured physiological interpretation based on the documented vital signs and clinical course.

Include a dedicated “Limitations” paragraph in the Discussion acknowledging the absence of detailed serial physiological data.

Emphasize that this report is hypothesis-generating and aims to highlight a potentially under-recognized heart–lung interaction phenomenon in patients with severe cardiomegaly undergoing OLV.

We agree that future prospective studies with comprehensive hemodynamic and respiratory monitoring would be necessary to validate the proposed mechanisms.
We sincerely appreciate the reviewer’s comments, which have helped us improve the clarity and transparency of our report.
We sincerely thank the reviewer for the detailed and insightful comments. We fully agree that additional physiological parameters such as serial ABG measurements, detailed airway pressure/compliance trends, comprehensive echocardiographic indices, and extended follow-up data would strengthen the scientific rigor of this report.
However, as this case was retrospectively prepared from routine clinical practice rather than a prospectively designed physiological study, certain detailed intraoperative parameters were not systematically recorded or are no longer retrievable from the medical record.
Nevertheless, we have carefully revised the manuscript to:

Clarify the intraoperative timeline and sequence of events.

Expand the description of preoperative cardiopulmonary status based on available data.

Provide a more structured physiological interpretation based on the documented vital signs and clinical course.

Include a dedicated “Limitations” paragraph in the Discussion acknowledging the absence of detailed serial physiological data.

Emphasize that this report is hypothesis-generating and aims to highlight a potentially under-recognized heart–lung interaction phenomenon in patients with severe cardiomegaly undergoing OLV.

We agree that future prospective studies with comprehensive hemodynamic and respiratory monitoring would be necessary to validate the proposed mechanisms.
We sincerely appreciate the reviewer’s comments, which have helped us improve the clarity and transparency of our report.
Competing Interests: Authors declare there are no any competing interest. Close
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Version 4

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Zhiyao Wang, Fudan University, Shanghai, China
Praveen Kumar Neema, Amrita Institute of Medical Sciences, Kochi, India

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28 Apr 2026 | for Version 4

Zhiyao Wang, Fudan University, Shanghai, China

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Approved

The authors have sufficiently addressed all comments and concerns.

Competing Interests

No competing interests were disclosed.

Reviewer Expertise

Anesthesiology; perioperative analgesia; pain neuroscience; neuroimmune mechanisms;

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.

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22 Apr 2026 | for Version 4

Praveen Kumar Neema, Amrita Institute of Medical Sciences, Kochi, Kerala, India

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Approved

The authors have revised the manuscript and is now acceptable.

Competing Interests

No competing interests were disclosed.

Reviewer Expertise

Cardiovascular physiology; cardiopulmonary bypass, adult and pediatric cardiac anesthesia, thoracic anesthesia,

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08 Apr 2026 | for Version 3

Praveen Kumar Neema, Amrita Institute of Medical Sciences, Kochi, Kerala, India

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Approved With Reservations

2nd revision

Introduction
Change 'lungs' to lung

Paragraph
After surgical preparation, the patient was positioned in the left lateral decubitus (LLD) position. Two-lung ventilation
was initially maintained during positioning, and no immediate desaturation occurred.
To the above paragraph add the sentence
During two-lung ventilation, an unknown portion of tidal volume was leaking through the bronchopleural fistula.

One-lung ventilation (OLV) of the left lung was then initiated to facilitate right thoracotomy. Shortly after initiation of OLV in the LLD position, the patient developed progressive hypotension (blood pressure decreased to 75/45 mmHg) accompanied by oxygen desaturation to 88%. At this time, ventilatory parameters were reassessed and adjusted. Tidal volume was reduced to 300 mL, respiratory rate increased to 20 breaths per minute, PEEP increased to 8 cmH2O, and
FiO2 increased to 1.0. Tidal volume was reduced to decrease airway pressure and minimize air leakage through the
bronchopleural fistula. To maintain adequate minute ventilation, the respiratory rate was increased. This strategy also helped limit excessive intrathoracic pressure that could worsen hemodynamic compromise.

Modify the paragraph as
One-lung ventilation (OLV) of the left lung was then initiated to facilitate right thoracotomy. Shortly after initiation of
OLV in the LLD position, the patient developed progressive hypotension (blood pressure decreased to 75/45 mmHg)
accompanied by oxygen desaturation to 88%. At this time, the volume loss through the bronchopleural fistula stopped; therefore, the ventilatory parameters were reassessed and adjusted. Tidal volume was reduced to 300 mL, respiratory rate increased to 20 breaths per minute, PEEP increased to 8 cmH2O, and FiO2 increased to 1.0. Tidal volume was reduced to decrease airway pressure. This strategy helped limit excessive intrathoracic pressure that could worsen hemodynamic compromise.

Rewrite the paragraph
A distinctive feature of this case was the improvement in oxygenation when only the dependent left lung was ventilated in the LLD position. We hypothesize that severe cardiomegaly altered the usual distribution of ventilation. In the LLD position, gravitational displacement of the mediastinum combined with marked cardiac enlargement may have exerted compressive forces on the dependent left lung, reducing its compliance during two-lung ventilation. This could have redirected ventilation preferentially toward the non-dependent right lung, which was diseased, thereby worsening V/Q mismatch despite ongoing perfusion of the dependent lung.

A distinctive feature of this case was better oxygenation when both the lungs were ventilated in the LLD position. We hypothesize that during one lung ventilation, severe cardiomegaly and increased intrathoracic pressure increased the compression of pulmonary vasculature and aggravated right ventricular dysfunction. This could have
redirected perfusion toward the non-dependent right lung, which was diseased, thereby worsening V/Q mismatch. Conceivably, reduced tidal volume, milrinone and nor-epinephrine combined together improved RV performance, increased the systemic arterial pressure and arterial saturation.

Competing Interests

No competing interests were disclosed.

Reviewer Expertise

Cardiovascular physiology; cardiopulmonary bypass, adult and pediatric cardiac anesthesia, thoracic anesthesia,

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Author Response

19 Apr 2026

Suryanti Suryanti, Universitas Dian Nuswantoro, Semarang, Indonesia

Dear Reviewer,
Thank you very much for your careful review and valuable comments on our manuscript. We have revised the manuscript accordingly and addressed each point as follows:

Introduction
- Comment: Change “lungs” to “lung”
- Response: Revised as suggested.
Paragraph on patient positioning and two-lung ventilation
- Comment: Add the sentence regarding tidal volume leakage through the bronchopleural fistula
- Response: The sentence “During two-lung ventilation, an unknown portion of tidal volume was leaking through the bronchopleural fistula.” has been added to clarify the presence of air leakage during two-lung ventilation.
Paragraph on one-lung ventilation (OLV) and ventilatory adjustments
- Comment: Modify the paragraph as suggested
- Response: The paragraph has been revised accordingly. We have clarified that volume loss through the bronchopleural fistula ceased after initiation of OLV and adjusted the explanation of ventilatory management to focus on reduction of airway pressure and limitation of intrathoracic pressure to mitigate hemodynamic compromise.
Discussion paragraph (physiological interpretation)
- Comment: Rewrite the paragraph
- Response: The paragraph has been substantially revised as suggested. We have corrected the interpretation to reflect improved oxygenation during two-lung ventilation rather than OLV. The discussion now emphasizes the role of severe cardiomegaly, increased intrathoracic pressure, pulmonary vascular compression, and right ventricular dysfunction in worsening ventilation–perfusion mismatch. We also incorporated the contribution of reduced tidal volume, milrinone, and norepinephrine in improving right ventricular performance and systemic oxygenation.

We believe these revisions have significantly improved the clarity and physiological consistency of the manuscript. We sincerely appreciate your insightful comments.
Kind regards,

On behalf of all authors,
Suryanti Chan

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Competing Interests

No competing interests were disclosed.

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Reviewer Report

10 Views

12 Mar 2026 | for Version 2

Praveen Kumar Neema, Amrita Institute of Medical Sciences, Kochi, Kerala, India

10 Views Cite this report Responses(1)

Approved With Reservations

Is the background of the case’s history and progression described in sufficient detail?

Partly
Are enough details provided of any physical examination and diagnostic tests, treatment given and outcomes?

Yes
Is sufficient discussion included of the importance of the findings and their relevance to future understanding of disease processes, diagnosis or treatment?

No
Is the case presented with sufficient detail to be useful for other practitioners?

Partly

Competing Interests

No competing interests were disclosed.

Reviewer Expertise

Cardiovascular physiology; cardiopulmonary bypass, adult and pediatric cardiac anesthesia, thoracic anesthesia,

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Responses (1)

Author Response

26 Mar 2026

Suryanti Suryanti, Universitas Dian Nuswantoro, Semarang, Indonesia

We sincerely thank the reviewer for the insightful and constructive comments. We have carefully revised the manuscript to address all concerns. Detailed responses to each comment are provided below, and the corresponding revisions have been incorporated into the manuscript.
1. Comment 1: The sentence, “The procedure involves both manipulation of the lungs and changes in body positioning, which can affect heart-lung interaction” is not clear, do the authors mean ‘surgical procedure’ please rephrase.
Response: Thank you for this suggestion. The sentence referred to the thoracic surgical procedure requiring one-lung ventilation and lateral positioning. We have revised the sentence to clarify this meaning. Revision in manuscript: The sentence has been revised as follows: “Thoracic surgical procedures requiring lung isolation and lateral decubitus positioning may significantly influence heart–lung interactions.”
2. Comment 2: In view of continuous oxygen requirement, did you measure peripheral oxygen saturation (SpO₂) on room air?
Response: Thank you for this important question. Unfortunately, the exact SpO₂ value on room air was not documented in the medical record because the patient was already receiving supplemental oxygen due to respiratory symptoms at the time of evaluation. Baseline oxygenation was assessed using arterial blood gas analysis, which showed PaO₂ 80 mmHg with a PaO₂/FiO₂ ratio of approximately 200. We have clarified this point in the revised manuscript.
Revision in manuscript: A clarifying sentence has been added in the case presentation section indicating that baseline oxygenation was assessed using arterial blood gas analysis.
3. Comment 3: However, OLV also affects cardiac function. Positive pressure ventilation can decrease venous return and systemic vascular resistance. How do you explain a decrease in systemic vascular resistance with positive pressure ventilation? Please expand and provide reference.
Response: Thank you for this important comment. We have expanded the discussion to clarify the hemodynamic effects of positive pressure ventilation. Positive pressure ventilation increases intrathoracic pressure, which reduces venous return and may decrease left ventricular preload. Additionally, reduced preload and cardiac output may lead to reflex vasodilation or altered autonomic tone, contributing to decreased systemic vascular resistance in some clinical settings. Relevant references have been added to support this explanation. Revision in manuscript: The discussion section has been expanded to explain the hemodynamic effects of positive pressure ventilation on venous return, cardiac output, and systemic vascular resistance, with additional references.
4. Comment 4: The patient exhibited desaturation when both lungs were ventilated, but oxygenation improved when only the diseased lung was ventilated. The timeline described in the case report and the sentence do not match.
Response: We appreciate the reviewer’s careful observation. The reviewer is correct that the description was inconsistent with the timeline. The sentence has been corrected to reflect the actual sequence of events. Revision in manuscript: The corrected sentence is: “Oxygen saturation remained stable during two-lung ventilation but decreased after the initiation of one-lung ventilation.”
5. Comment 5: Transthoracic echocardiography demonstrated right atrial and right ventricular dilatation… what was the right ventricular systolic pressure (RVSP) measured by TR jet?
Response: Thank you for this important comment. Unfortunately, the exact right ventricular systolic pressure (RVSP) derived from the tricuspid regurgitation jet was not documented in the available echocardiography report in the medical record. However, transthoracic echocardiography demonstrated right atrial and right ventricular dilatation with moderate tricuspid regurgitation, suggesting impaired right heart function and possible elevation of right-sided pressures. We have clarified this point in the revised manuscript. Revision in manuscript: A clarifying sentence has been added in the echocardiography findings section indicating that the RVSP value was not available in the echocardiography report.
6. Comment 6: Do you mean two lung ventilation? How did you manage loss of tidal volume through bronchopleural fistula?
Response: Yes, the reviewer is correct that the ventilation described refers to two-lung ventilation following intubation. This has been clarified in the revised manuscript. Regarding tidal volume loss through the bronchopleural fistula, ventilation was carefully monitored and adjusted to minimize air leakage while maintaining adequate oxygenation. Lung isolation and ventilator parameter adjustments were used to reduce leakage and optimize ventilation. Revision in manuscript: The text has been revised to clarify that two-lung ventilation was initially used and to briefly describe the strategy for managing tidal volume loss due to the bronchopleural fistula.
7. Comment 7: Table 1: comment on right ventricular systolic pressure.
Response: Thank you for this suggestion. Unfortunately, the right ventricular systolic pressure (RVSP) derived from the tricuspid regurgitation jet was not documented in the available echocardiography report in the medical record. Therefore, the RVSP value could not be included in Table 1. We have clarified this limitation in the revised manuscript. Revision in manuscript: A clarifying note has been added in the echocardiography findings section indicating that the RVSP value was not available in the echocardiography report.
8. Comment 8: Timeline – intraoperative events are unclear.
Response: Thank you for pointing this out. The intraoperative timeline has been revised to clarify the sequence of ventilation strategies, oxygen desaturation, and hemodynamic changes.
Revision in manuscript: The timeline figure and corresponding text have been updated to clearly indicate:

initiation of two-lung ventilation
transition to one-lung ventilation
onset of desaturation and hypotension
subsequent ventilatory adjustment

9. Comment 9: Tidal volume was reduced to 300 mL… what was the rationale?
Response: The rationale was to reduce airway pressure and minimize air leakage through the bronchopleural fistula while maintaining adequate ventilation. Lower tidal volume with increased respiratory rate was used to maintain minute ventilation and reduce intrathoracic pressure.
Revision in manuscript: This rationale has been added to the intraoperative management section.
10. Comment 10: Please expand possible mechanisms explaining the cardiopulmonary interaction.
Response:
We thank the reviewer for this important suggestion. The discussion has been expanded to describe possible mechanisms including:

increased pulmonary vascular resistance during OLV
right ventricular afterload elevation
impaired right ventricular output in the presence of cardiomegaly
altered ventilation-perfusion relationships

These mechanisms were considered in explaining the observed intraoperative hemodynamic instability.
Revision in manuscript: Additional discussion has been included in the Discussion section.
11. Comment 11: hypothesis regarding bronchopleural fistula and RV failure
Response: We appreciate this insightful physiological interpretation. We agree that the bronchopleural fistula may have influenced intrathoracic pressure dynamics during two-lung ventilation. We have incorporated this explanation into the discussion and acknowledged that increased pulmonary vascular resistance during OLV may have contributed to right ventricular compromise in this patient.
Revision in manuscript: The discussion now includes a paragraph discussing the potential role of bronchopleural fistula in modulating intrathoracic pressure and pulmonary vascular resistance during ventilation.
12. Comment 12: Paragraph beginning “When OLV was instituted…” can be removed.
Response: Thank you for this suggestion. As recommended, the paragraph has been removed to improve clarity and avoid redundancy.
13. Comment 13: “I do not agree with the statement…”
Response: We appreciate the reviewer’s perspective. We have revised the conclusion to avoid overstating the finding and to emphasize that careful anticipation and adjustment of ventilatory parameters are important in patients with cardiomegaly undergoing OLV. Revision in manuscript:
The conclusion has been modified to reflect a more cautious interpretation of the findings.

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Competing Interests

The authors declare that they have no competing interests.

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Reviewer Report

17 Views

12 Feb 2026 | for Version 1

Zhiyao Wang, Fudan University, Shanghai, China

17 Views Cite this report Responses(1)

Approved With Reservations

Is the background of the case’s history and progression described in sufficient detail?

Partly
Are enough details provided of any physical examination and diagnostic tests, treatment given and outcomes?

Partly
Is sufficient discussion included of the importance of the findings and their relevance to future understanding of disease processes, diagnosis or treatment?

Partly
Is the case presented with sufficient detail to be useful for other practitioners?

Partly

Competing Interests

No competing interests were disclosed.

Reviewer Expertise

clinical anesthesia; acute pain; chronic pain

Respond to this report

Responses (1)

Author Response

20 Feb 2026

Suryanti Suryanti, Universitas Dian Nuswantoro, Semarang, Indonesia

We sincerely thank the reviewer for the detailed and insightful comments. We fully agree that additional physiological parameters such as serial ABG measurements, detailed airway pressure/compliance trends, comprehensive echocardiographic indices, and extended follow-up data would strengthen the scientific rigor of this report.
However, as this case was retrospectively prepared from routine clinical practice rather than a prospectively designed physiological study, certain detailed intraoperative parameters were not systematically recorded or are no longer retrievable from the medical record.
Nevertheless, we have carefully revised the manuscript to:

Clarify the intraoperative timeline and sequence of events.
Expand the description of preoperative cardiopulmonary status based on available data.
Provide a more structured physiological interpretation based on the documented vital signs and clinical course.
Include a dedicated “Limitations” paragraph in the Discussion acknowledging the absence of detailed serial physiological data.
Emphasize that this report is hypothesis-generating and aims to highlight a potentially under-recognized heart–lung interaction phenomenon in patients with severe cardiomegaly undergoing OLV.

We agree that future prospective studies with comprehensive hemodynamic and respiratory monitoring would be necessary to validate the proposed mechanisms.
We sincerely appreciate the reviewer’s comments, which have helped us improve the clarity and transparency of our report.

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Competing Interests

Authors declare there are no any competing interest.

Alongside their report, reviewers assign a status to the article:

Approved - the paper is scientifically sound in its current form and only minor, if any, improvements are suggested

Approved with reservations - A number of small changes, sometimes more significant revisions are required to address specific details and improve the papers academic merit.

Not approved - fundamental flaws in the paper seriously undermine the findings and conclusions

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[3] Marongiu I, Spinelli E, Mauri T: Cardio-respiratory physiology during one-lung ventilation: complex interactions in need of advanced monitoring. Ann. Transl. Med. 2020; 8(8): 524–524. PubMed Abstract | Publisher Full Text | Free Full Text

[4] Rehatta NM, Hanindito E, Tantri A, et al.: Anestesiologi dan Terapi Intensif Buku Teks KATI-PERDATIN.2019.

[5] Semedi BP, Airlangga PS, Hidayati HB, et al.: Lung recruitment maneuver: is it really safe? Anaesth. Pain Intensive Care. 2021; 25(3). Publisher Full Text

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Case Report: Improved Oxygenation after One Lung Ventilation in Severe Cardiomegaly due to Cor Pulmonale; analysis with Heart-Lung Interaction Approach

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Table 1. Timeline of patient.

Discussion

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