Effects of Slow Breathing on Blood Pressure and End Tidal Carbon Dioxide in Hypertension: Randomised Controlled Trial

Introduction: Inhibition of breathing elevates End-tidal Carbon dioxide (EtCO2 ) and contributes to sustained Hypertension (HT). Aim: To find out the immediate efficacy of Slow breathing (SB) in controlling Blood Pressure (BP) and its influence on EtCO2 in patients with hypertension. Materials and Methods: Randomised control parallel group study was undertaken at outpatient department of medicine in Rajah Muthiah Medical College and Hospital, Annamalai University, Chidambaram, Tamil Nadu, India. Forty hypertensive patients were randomly assigned to receive either slow breathing training for half an hour or as controls. For study group, 30 minutes of SB was practised through recorded auditory command. The breathing instruction consists of four seconds of inspiration and 6 seconds of expiration. Main outcome measured BP {Systolic (S) and Diastolic (D)} and EtCO2 . Paired sample t-test and independent sample t-test were the statistical tools used for inferential analysis. Results: The mean drop in SBP and DBP was 12.30±2.79 mmHg and 3.90±4.44 mmHg respectively in study group following training and it was statistically significant. The mean drop in SBP and DBP in controls was 1.05±3.34 and 0.30±2.10, respectively. There was significant reduction in EtCO2 following training in study group, the mean difference was 1.80±2.46. Between group analysis shows that, there was significantly greater reduction in SBP and DBP in study group following training but statistical significance was not achieved for EtCO2. Conclusion: Practice of slow breathing is effective in immediate reduction of systolic and diastolic BP. EtCO2 could play a role in reducing BP, but long-term study is warranted to better evaluate its role in BP reduction.