Coronary artery disease is a major reason for illness and fatality worldwide. In India, every year, around 1,40,000 CABG (Coronary Artery Bypass Graft) surgeries are carried out. It is a revascularization method that involves redirecting blood flow to other arteries to enhance blood supply to the heart muscles. ¹ Despite significant breakthroughs in clinical care and interventional treatments, CABG is the most widely utilized type of cardiac surgery performed globally, and an excellent therapy for reducing symptoms and mortality in individuals with coronary artery disease (CAD). ^{2 , 3} CABG, on the other hand, is a challenging procedure that causes a host of clinical and functional issues. ⁴ Some degree of pulmonary impairment is unavoidable in the immediate postoperative period following CABG. ⁵ These effects may persist, resulting in 25-30% reductions in lung volume, ⁶ maximal inspiratory and expiratory pressure (MIP and MEP) relative to expected values), ⁷ and thoracic mobility. ⁸

The patient has a sternotomy and is then connected to a cardiorespiratory bypass machine during coronary artery bypass grafting (CABG), the usual treatment for CAD. ⁹ However, this form of surgery has a variety of postoperative complications. Two of the most prevalent symptoms are inactivity and pulmonary impairment. ¹⁰ These concerns may be connected with socioeconomic costs such as prolonged hospital stays, substantial treatment expenditures, ICU care for the majority of patients, or even fatality if the patient is not effectively managed. ¹¹ General anesthesia, mechanical ventilation duration, cardiopulmonary bypass, and the sternotomy incision can all have an impact on postoperative pulmonary function following heart surgery. ¹² The use of cardiopulmonary bypass and general anesthesia in cardiac surgery is a crucial factor in patient outcomes. ¹³ PPCs have been connected to various cardiopulmonary bypass-related events, including blood exposure to artificial materials, body temperature fluctuation, organ ischemia-reperfusion, surgical trauma, and endotoxin release; all of these generate an immediate inflammatory response. ^{14 – 16}

Anesthesia may increase the alveolar-arterial oxygen gradient and decrease functional residual capacity and vital capacity, leading to hypoxemia and atelectasis. Anesthetic medications predispose to PPCs by producing immunological dysfunction, which leads to lung damage. Incisional discomfort has been linked to a decrease in postoperative lung function; however, this resolves within a month of surgery. ¹⁷

The POWERbreathe Medic Plus has the lowest initial load of any Plus device, 9 cm H ₂O. This gadget is used for low-load respiratory muscle training. The Powerbreathe Medic Plus is intended for those who have very weak breathing muscles as a result of, for example, illness, hospitalization, or existing respiratory health disorders such as COPD and asthma.

Aim: To study the efficacy of POWERbreathe Medic Plus device on maximal inspiratory pressure, functional capacity, and quality of life in Coronary Artery Bypass Graft Patients.

Study approval from the Ethics Committee of the Datta Meghe Institute of Higher Education and Research, study participants will be selected from the Cardiovascular and Thoracic Surgery Unit of Acharya Vinoba Bhave Rural Hospital, Sawangi (Meghe), Wardha, Maharashtra, based on inclusion and exclusion criteria. Subjects will be contacted and chosen according to the study’s criteria. The sequentially numbered opaque sealed envelope (SNOSE) technique will be employed in a randomised strategy to assign members. This research protocol will examine the impact of the POWERbreathe Medic Plus device on peak inspiratory pressure, functional capacity, and quality of life in transplant patients through an independent two-group study. coronary bypass surgery. There will be 72 individuals in the trial (36 in each traditional group).

Study Design: Randomised control trial.

Study Setting: This study will be carried out in Cardiovascular and Thoracic Surgery Unit, Acharya Vinoba Bhave Rural Hospital, Sawangi (Meghe), Wardha, Maharashtra.

Targeted population: CABG patients from age group of 30-60 years.

Sampling technique: Simple Random Sampling Technique.

Allocation : Sequentially numbered opaque sealed envelope (SNOSE) technique

Sample size calculation.

Formula Using Mean difference n 1 = n 2 = 2 ( Z α + Z β ) 2 σ 2 ( δ ) 2

Z _α = 1.96

α = Type l error at 5% at both sides two tailed

Z _β = 1.645 Power at 95%.

Difference (Mean) result in 6MWT for conventional chest therapy = 125 (As per ref. article).

Considering Std. Dev = 145.8

According to reference articles. N1 = 2 ∗ [ ( 1.96 + 1.645 ) 2 ( 1.96 ) 2 ] / ( 1.65 ) 2 = 32

Total samples required = 36 per Group.

Considering 10% drop out = 4

The total sample size = 72

Ref Article: - Moderate-to-high intensity inspiratory muscle training improves the effects of combined training on exercise capacity in patients after coronary artery bypass graft surgery: A randomized clinical trial. ²⁰

Study duration: The study duration will be one year. The flowchart of consort diagram is shown in Figure 1.

Reduced respiratory muscle tone has been linked with decreased functional capacity in cardiac operations patients, which leads to a protracted period of lung function recovery as well as the commencement of physical deconditioning that can last several weeks. ²¹ Changes in lung sizes and capabilities, alveolar dysfunction, depression of central respiratory stimulation, and mechanical disorders of thoracic function all contribute to RMS changes. ^{22 , 23}

Furthermore, it is well known that the majority of cardiac surgery patients have preoperative bouts of muscular weakness, which is increased after the surgery. ²⁴ However, although the respiratory muscles are similarly passive, they are weaker than the peripheral muscles. ^{24 , 25} Following coronary artery bypass graft (CABG) surgery, patients may experience postoperative pulmonary complications (PPCs) are a significant cause of morbidity and death, as well as an increase in hospital stay and resource utilization. ^{26 , 27}

Adele Cook et al. (2023) studied the effect of Preoperative threshold inspiratory muscle training in adults undergoing cardiac surgery. According to the study, preoperative threshold inspiratory muscle training has the potential to minimize the postoperative duration of hospital stay and pulmonary complications following heart surgery. ²⁸

Xiaoyu Chen et al. (2019) undertook a study to see if short-term rigorous preoperative inspiratory muscle training could reduce the occurrence of postoperative pulmonary problems in patients undergoing heart surgery. The study concluded that a 5-day intense schedule of preoperative inspiratory muscle training reduced the frequency and duration of postoperative hospitalization in patients undergoing heart surgery. ²⁹

Thayse Campos de Menezes et al. (2018) conducted a study to evaluate the effect of respiratory and peripheral muscle strength after cardiac surgery. According to study findings after cardiac surgery, there is a decline in respiratory and peripheral muscle strength. ³⁰

Alquaimi M et al. (2017) conducted a study on pulmonary rehabilitation program (PRP) in ILD patients. This study revealed that IMT in ILD patients improved 6MWD, Fatigue severity scale (FSS) and MIP. ³¹

Kazuki Okura et al. (2016) conducted a study on the efficacy of moderate-intensity, short-duration inspiratory muscle training in COPD patients. According to the study finding it enhances PImax and exercise capacity in older COPD patients. ³²

Bárbara Maria Hermes et al. (2015) studied the effects of a short-term inspiratory muscle training program combined with aerobic and resistance exercise on respiratory muscle strength, functional capacity, and quality of life in patients who had coronary artery bypass surgery. This concludes that inspiratory muscle training used for shorter periods had the potential to improve respiratory muscle strength, and functional capacity in coronary artery bypass surgery. ²¹