F1000Research F1000Research 2046-1402 F1000 Research Limited London, UK 10.12688/f1000research.144927.1 Research Article Articles The comparison study on accuracy of peak expiratory flow rate measurement by PRAAN, spirometry, and the mini-Wright peak flow meter

[version 1; peer review: 1 not approved]

 Chaiparnich Sirawich Conceptualization Data Curation Formal Analysis Methodology Project Administration Software Writing – Original Draft Preparation Writing – Review & Editing 1 Poachanukoon Orapan Conceptualization Data Curation Investigation Resources Supervision Writing – Original Draft Preparation Writing – Review & Editing https://orcid.org/0000-0003-0610-8242 a 2 Manasilp Natcha Conceptualization Data Curation Investigation Methodology Writing – Original Draft Preparation Writing – Review & Editing 1 Saiphoklang Narongkorn Conceptualization Data Curation Formal Analysis Investigation Project Administration Supervision Validation Writing – Review & Editing https://orcid.org/0000-0003-2462-9471 3 Tantibundhit Charturong Conceptualization Data Curation Formal Analysis Project Administration Resources Writing – Review & Editing 4 Vatcharavongvan Pasitpon Conceptualization Data Curation Investigation Methodology Visualization Writing – Review & Editing https://orcid.org/0000-0002-8655-7154 5 Kunumpol Pattapol Conceptualization Data Curation Formal Analysis Project Administration Visualization Writing – Review & Editing 4 Plienphanich Phongpan Conceptualization Data Curation Formal Analysis Validation Writing – Review & Editing https://orcid.org/0000-0003-2264-8900 4 Pugongchai Apiwat Conceptualization Data Curation Formal Analysis Methodology Project Administration Software Validation Writing – Review & Editing 6 Leelasittikul Kanyada Conceptualization Data Curation Formal Analysis Project Administration Software Validation Writing – Review & Editing 6 Prompoom Nantavat Conceptualization Data Curation Formal Analysis Methodology Project Administration Resources Software Writing – Review & Editing 7 Faculty of Medicine, Thammasat University, Pathum Thani, 12120, Thailand Department of Pediatrics, Faculty of Medicine, Thammasat University, Pathum Thani, 12120, Thailand Department of Internal Medicine, Faculty of Medicine, Thammasat University, Pathum Thani, 12120, Thailand Department of Electrical and Computer Engineering, Faculty of Engineering, Thammasat School of Engineering, Thammasat University, Pathum Thani, 12120, Thailand Community Medicine and Family Medicine, Faculty of Medicine, Thammasat University, Pathum Thani, 12120, Thailand Medical Diagnostics Unit, Thammasat University Hospital, Pathum Thani, 12120, Thailand Plastic Development and Design Center, Plastics Institute of Thailand, Pathum Thani, 12120, Thailand orapanpoachanukoon@yahoo.com

No competing interests were disclosed.

 9 7 2024 2024 13 782 1 7 2024 Copyright: © 2024 Chaiparnich S et al. 2024 This is an open access article distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background

PRAAN, a digital peak flow meter, was developed to measure peak expiratory flow rate (PEFR) for asthma monitoring. This study aimed to compare PRAAN’s accuracy to that of spirometry and the mini-Wright peak flow meter for PEFR measurement.

 Methods

Two cross-sectional studies were conducted in 106 healthy adult participants. Study A (n=56) compared PRAAN with spirometry, while study B (n=50) compared PRAAN with the mini-Wright peak flow meter. PEFR values were collected using crossover studies. Pearson’s correlation and Bland-Altman plots were used to report the relationship and agreement between two measurements, respectively.

 Results

In study A, 51.8% were female, mean age was 24.3±5.6 years, and PEFR was 480.3±86.8 L/min. PEFR measured by PRAAN had very strongly positive correlation with spirometry (r=0.980, P<0.001). Bland-Altman analysis showed that there was good agreement between them, with a low mean difference of -7.07 liters/minute (95% CI: -40.58 to 26.44 liters/minute) and 92.9%, which were within the limit of agreement (LOA). In study B, 54.0% were female, mean age was 23.5±2.4 years, and PEFR was 495.1±82.7 L/min. PEFR measured by PRAAN and by the mini-Wright peak flow meter showed very strongly positive correlation (r=0.971, P<0.001). Bland-Altman comparison of PEFR between these two measurements showed that there was a very good agreement between them, with a low mean difference of 0.84 liters/minute (95% CI: -38.68 to 40.38 liters/minute) and 94.0%, which were within LOA.

 Conclusions

The accuracy of PRAAN is in the agreement with spirometry and the mini-Wright peak flow meter. The clinical application of PRAAN may potentially lead to a monitoring strategy that healthcare providers can use to improve the management of asthma.

 agreement asthma Bland-Altman plots correlation digital peak flow meter peak expiratory flow rate The author(s) declared that no grants were involved in supporting this work. Introduction

Asthma is a chronic respiratory disease which is characterized by airway inflammation, hyperresponsiveness, and variable expiratory airflow limitation. 1 It is increasingly prevalent, 2 , 3 probably because of factors including air pollution, 4 – 6 sedentary lifestyles, 7 , 8 and genetic predisposition. 9 , 10 Diagnosis of asthma is based on clinical characteristics and lung function assessment such as spirometry with bronchodilator testing. 1 , 11 , 12 However, spirometry results may vary in the same patients and should be carried out by well-trained technicians. In clinical practice, peak expiratory flow rate (PEFR) is measured by peak flow meter to assess airflow limitation of asthmatic patients. It is an indispensable parameter for monitoring airway diseases, particularly asthma, 13 and it is recommended as an alternative tool when spirometry is not available. 14 A frequent application of PEFR is in home monitoring of asthmatic patients because it is easy to do, and it is inexpensive. In Thailand, patients use mechanical mini-Wright peak flow meters and record their PEFR values in peak flow diaries. For physicians, limited accessibility of spirometry and peak flow meters, poor compliance with manual data collection, and data fabrication are longstanding problems. 15

PRAAN ( Precise Reliable Advanced Affordable and Novel), under copyright license number 2201002185 is a digital peak expiratory flow device (D-PEF device) designed to function like a peak flow meter. It has direct electronic power, data storage, and built-in analytical functions, and a complementary mobile application serves as an interface for the device. PRAAN is equipped with light interruption sensors and a detachable blower to measure PEFR. Acknowledging the potential advantages offered by PRAAN, a study was conducted to compare its accuracy to that of the gold standard spirometry and the mini-Wright peak expiratory flow meter. A demonstration of substantial agreement between the results would endorse acceptance from the medical field and promote the broader adoption of PRAAN as a reliable alternative.

This study aimed to compare measurements of PEFR by PRAAN digital peak flow device with measurements by spirometry and by the mini-Wright peak flow meter.

 Methods Study design and participants

Two sets of cross-sectional studies were conducted at Thammasat University Hospital, Thailand between December 2022 and June 2023. Study A (n=56 ) was a comparison of PEFR measured by PRAAN and spirometry, while study B (n=50 ) was a comparison of PEFR measured by PRAAN and the mini-Wright peak flow meter. In both studies, a cross-over method was done, in which participants in each study were divided into two groups. The first group underwent PEFR measurements using PRAAN, followed by measurements using spirometry or the mini-Wright peak flow meter while the second group underwent the measurements in the opposite order ( Figure 1).

Flowchart of the study for the measurement of peak expiratory flow rate.

Heathy subjects aged 18 years or older were included. Subjects with active respiratory infection (e .g ., common cold, COVID-19 ), inability to perform PEFR measurement or spirometry, current or former smoking, or respiratory diseases including asthma, chronic obstructive pulmonary disease, or any obstructive airway disease were excluded.

Ethical approval was obtained from the Human Research Ethics Committee of Thammasat University (Medicine), Thailand (IRB No. MTU-EC-PE-0-154/65, COA No. 254/2022) and the date of approval Decmber 16, 2022. in full compliance with international guidelines such as the Declaration of Helsinki, the Belmont Report, CIOMS Guidelines, and the International Conference on Harmonisation-Good Clinical Practice (ICH-GCP). All methods etwere performed in accordance with these guidelines and regulations. All participants provided written informed consent.

 PRAAN

PRAAN is an ergonomic and portable digital peak flow meter meticulously crafted for precise the measurement of PEFR ( Figure 2). This device features an internal sensor arrangement utilizing light interruptions for accurate PEFR evaluation ( Figure 3). It is comprised of two central elements: a main chassis housing the sensor, display, and controller board, and a detachable blower equipped with perpendicular blades and a mouthpiece holder. The blower’s distinct design enables full immersion, adhering to stringent hospital -grade cleanliness criteria. PRAAN was engineered to endure impacts, chemicals, and thermal fluctuations, and it is made of antibacterial plastic. It can be operated in two distinct modes: standalone mode and mobile application mode, offering real-time PEFR measurements. Additionally, PRAAN considers PEFR factors such as sex, age, and height. A light indicator system of red, yellow, and green lights, signifies lung function levels.

PRAAN is the digital peak expiratory flow device. PRAAN’s built-in system.

Participants performed the test by forcefully exhaling through the mouthpiece, with results promptly displayed on the device screen or mobile application. The displayed light indication offered insights into lung function status. PRAAN mandated three vigorous exhalations with a variance of less than 10% between blows to finalize assessment.

 Spirometry

Participants performed this procedure by exhaling forcefully into a specialized device known as a spirometer. Before testing, participants received instructions and the spirometer was meticulously calibrated to ensure accuracy, allowing the spirometer to record volumetric and flow rate data. Pulmonary function parameters including forced vital capacity (FVC), forced expiratory volume in one second (FEV 1), FEV 1/FVC ratio, and PEFR were recorded. Spirometry was performed according to the American Thoracic Society and European Respiratory Society guidelines 16 – 18 using PC spirometer (Vyntus ® SPIRO, Vyaire Medical, Inc., Mettawa, IL, USA).

 Mini-Wright peak flow meter

The mini-Wright peak flow meter (Clement Clarke International Ltd., UK) is a compact handheld device used for assessment of PEFR in our study. This device facilitated precise measurements of exhaled airflow vigor. 19 Participants were instructed to exhale forcefully through the mouthpiece, prompting the movable marker to traverse the calibrated scale and indicated the highest achieved flow rate. The test was performed with three attempts, with one-minute breaks between attempts. The maximal value of the three efforts was recorded for the final analysis.

 Statistical analysis

Data are presented as number (%) and mean ± standard deviation (SD). Pearson’s correlation was used to determine the relationship of PEFR measured by PRAAN and spirometry or the mini-Wright peak flow meter. Bland-Altman plots were used to determine agreement of PEFR obtained by PRAAN and spirometry or the mini-Wright peak flow meter. In the Bland-Altman plot, the mean difference between the two methods of measurement was calculated and compared among the subjects to make sure that the difference lies within the limit of agreement between the two methods. The 95% limits of agreement, which represent where 95% of the future differences between the two methods would be, was calculated via the use of standard deviation. The proportional bias also calculated by utilizing a linear relationship between the difference for each paired measurement. Two-tailed P-values of less than 0.05 were considered statistically significant. All data analyses were done on SPSS version 26.0 software https://www.ibm.com/products/spss-statistics (IBM Corp., Armonk, NY, USA).

 Results

Data were collected from 56 subjects in study A (51% females, mean age 24.3 years) and 50 subjects in study B (54% females, mean age 23.5 years). PEFR measured by PRAAN was 473.2±85.6 L/minute and 495.9±76.1 L/minute in studies A and B, respectively. PEFR measured by spirometry and the mini-Wright peak flow meter were 480.3±86.8 L/minute and 495.1±82.7 L/minute in studies A and B, respectively ( Table 1).

Demographics and peak expiratory flow rate of healthy subjects.
Variable Study A (n=56) Study B (n=50)
Age, years 24.3±5.6 23.5±2.4
Male/Female 27 (48.2)/29 (51.8) 23 (46.0)/27 (54.0)
Body weight, kg 64.7±12.0 60.4±11.6
Height, m 1.69±0.06 1.68±0.05
Body mass index, kg/m 2 22.7±3.6 21.4±3.5
PEFR by PRAAN, L/minute 473.2±85.6 495.9±76.1
PEFR by spirometry or mini-Wright, L/min 480.3±86.8 495.1±82.7

Data presented as n (%) or mean±SD

L=liters, m=meters, PEFR=peak expiratory flow rate.

There were very strongly positive correlations between PEFR measured by PRAAN and by spirometry (r=0.980, P<0.001), as well as PEFR measured by PRAAN and by the mini-Wright peak flow meter (r=0.971, P<0.001) ( Table 2).

Correlation of peak expiratory flow rate (PEFR) between PRAAN and spirometry or the mini-Wright.
Variable PEFR by PRAAN
Correlation coefficient (r) P-value
PEFR by spirometry 0.980 <0.001
PEFR by mini-Wright 0.971 <0.001

In study A, the comparison between PRAAN and spirometry revealed no statistically significant difference in PEFR values (P>0.05). The comparison of PEFR between PRAAN and spirometry by Bland–Altman analysis (as shown in Figure 4) showed that there was a good agreement between them, with a low mean difference of -7.07 liters/minute (95% CI: -40.58 to 26.44 liters/minute) and only 4 of 56 measurements (7.1%) were outliers ( Figure 4). No proportional bias was detected (B=-0.015, P=0.582).

Bland-Altman plots for PEFR measured by PRAAN and spirometry.

Study B compared PEFR between PRAAN and the mini-Wright peak flow meter. The results indicated no statistically significant difference in the PEFR values obtained from the two devices (P>0.05). The Bland–Altman comparison of PEFR between PRAAN and the mini-Wright peak flow meter (as shown in Figure 5) showed that there was a very good agreement between them, with a low mean difference of 0.84 liters/minute (95% CI: -38.68 to 40.38 liters/minute) and only 3 of 50 measurements (6%) were outliers ( Figure 5). However, a proportional bias was detected (B=-0.084, P=0.020).

Bland-Altman plots for PEFR measured by PRAAN and the mini Wright peak flow meter.

Data presented as n (%) or mean±SD

L=liters, m=meters, PEFR=peak expiratory flow rate

 Discussion

This study is a comparison of PEFR measurement by an innovative digital peak flow meter named PRAAN with measurement by the mini-Wright peak flow meter or by spirometry in healthy adult subjects. Our results showed that the accuracy of PRAAN was similar to the accuracy of spirometry and to the accuracy of the mini-Wright peak flow meter.

PRAAN emerges as a portable and economically viable D-PEF device. It’s light indicator system, comprising red, yellow, and green lights, signifies lung function levels or asthma action plans. This design serves to enhance individuals’ awareness of their lung function status, promoting respiratory health awareness, particularly in Thailand’s healthcare setting.

Through seamless coordination with a companion mobile application, the D-PEF device streamlines daily PEFR collection, enhancing efficiency. The mobile application not only simplifies PEFR measurement but also safeguards against data fabrication, ensuring reliable data acquisition. This integration exemplifies a contemporary approach to PEFR assessment, combining accurate measurement methods with user-friendly technology to enhance respiratory health management.

Spirometry is a foundational technique in pulmonary function assessment. 20 It provides valuable insights into lung function and holds widespread clinical utility for diagnosing and monitoring respiratory conditions, aiding in disease identification, severity assessment, and treatment progress evaluation. 21 , 22 However, potential limitations of spirometry are participant effort, 23 operator dependency and interpretation difficulty, 21 , 22 and equipment calibration for standardizing protocols to ensure accurate results. 24 In the context of our study, spirometry served as a reference method, facilitating the comprehensive evaluation of PEFR.

PEFR is recommended as a crucial parameter for asthma management according to the international guidelines. 1 The mini-Wright peak flow meter is simple to operate, cheap and convenient to assess airflow limitation and variability. 25 , 26 However, it is noteworthy that variations in technique and effort among subjects may influence to PEFR results. 15 , 27 Our study design is similar to a study comparing 11 peak flow meters on the market by Folgering H, et al. 27 A parallel performance of PRAAN and the mini-Wright peak flow meter in PEFR assessment is evident through the lack of statistically significant differences in our study. The robust positive correlation and substantial agreement emphasize their concordance, strengthening PRAAN’s credibility as a measurement tool. These outcomes suggest that PRAAN can serve as a suitable alternative to the mini-Wright device, offering a convenient and reliable option for healthcare professionals in assessing PEFR. Our results showed that the accuracy of PRANN digital peak flow meter is equivalent to the gold standard spirometry and the mini-Write peak flow meter.

PRAAN’s performance is on par with established methods, and its user-friendly design and potential economic benefits reinforce its relevance in respiratory health management. Moreover, the adherence to PEFR monitoring is limited, which is why it is not widely used in clinical practice. A study by Miles JF, et al showed that using electronic media in PEF-based self-management plans may help to improve asthma outcomes. 28 Our digital peak flow meter could increase compliance by using the mobile application.

There are a few limitations in our study. Firstly, the sample size was small, however study results could detect the correlation of two measurements. Secondly, the study population was not generalized distribution due to narrow age ranges. However, we focused on a healthy population in this study. A large study is needed to verify PRAAN accuracy for all age groups of normal subjects and asthmatic patients.

 Conclusions

PRAAN digital peak flow meter is an accurate instrument for assessing PEFR, in agreement with spirometry and the mini-Wright peak flow meter. It demonstrates reliability and potential for wider application with addition to clinical practice, managing respiratory health, including asthma.

 Ethics and consent

Ethic approval was obtained from the Human Research Ethics Committee of Thammasat University (Medicine), Thailand (IRB No. MTU-EC-PE-0-154/65, COA No. 254/2022) and the date of approval December 16 2022, in full compliance with international guidelines such as the Declaration of Helsinki, the Belmont Report, CIOMS Guidelines, and the International Conference on Harmonisation-Good Clinical Practice (ICH-GCP). All methods were performed in accordance with these guidelines and regulations. All participants provided written informed consent.

 Clinical trial registration

thaiclinicaltrials.org with number TCTR20230816002

 Data availability Underlying data

Figshare: The comparison study on accuracy of peak expiratory flow rate measurement by PRAAN, spirometry, and the mini-Wright peak flow meter. DOI: https://doi.org/10.6084/m9.figshare.24511357.v1

Please ensure your data availability statement adheres to the following format:

Study_PEF.xlsx

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

 Acknowledgements

The authors would like to thank Michael Jan Everts, Faculty of Medicine, Thammasat University, for proofreading this manuscript. The location for conducting out the research was provided by Thammasat University Research Unit in Allergy and Respiratory Medicine, and Medical Diagnostics Unit, Thammasat University Hospital, Thailand.

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Competing interests: No competing interests were disclosed.

 27 9 2024 Copyright: © 2024 To Y 2024 This is an open access peer review report distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. recommendation reject

To find out the feasibility of PEFR meter for patients with respiratory diseases, it would be essential to test it with both healthy volunteers and individuals with various respiratory diseases.  Otherwise, it is not possible to identify patients and to evaluate disease severity. The range of PEFR value is broad if you enroll both healthy volunteers and patients.  Analysis using only healthy volunteers would not prove the machine’s potential for patients.

Is there any influence to the machine by temperature, humidity, meteorological changes, or altitude?  As far as the machine is precise one, the authors must describe how these circumstances affect to ability of PEFR-measurement when using this machine.

Is this machine needs AC-power?  If so, it would not be able to use some of the developing countries with a lack of power.  The authors should clarify not only merit but demerit of this machine.

Mini-lite PEFR meter is used worldwide.  If the authors think this machine may be one of the alternatives of Mini-lite, Detailed comparison with Mini-lite must be shown not only good part but also bad part.

Limitations of the device should be shown in discussion section.

Is the work clearly and accurately presented and does it cite the current literature?

Yes

If applicable, is the statistical analysis and its interpretation appropriate?

Not applicable

Are all the source data underlying the results available to ensure full reproducibility?

Partly

Is the study design appropriate and is the work technically sound?

No

Are the conclusions drawn adequately supported by the results?

Yes

Are sufficient details of methods and analysis provided to allow replication by others?

Partly

Reviewer Expertise:

Asthma and Allergy

I confirm that I have read this submission and believe that I have an appropriate level of expertise to state that I do not consider it to be of an acceptable scientific standard, for reasons outlined above.