ABSTRACT
Background: Respiration is an important contributor to heart rate variability (HRV). It has been well established that decreasing the breathing frequency increases the HRV and the HRV is maximum at a breathing frequency of 0.1 Hz (6 breaths/min). Many studies have investigated the changes in HRV parameters during 0.1 Hz breathing, but only a few studies have explored the persisting effects, if any, of 0.1 Hz breathing after spontaneous breathing is resumed. Aim and Objectives: The aim of this study was to study the immediate effect of 5 min of controlled deep breathing at 0.1 Hz frequency, on short-term HRV. Materials and Methods: Twelve healthy volunteers were made to perform deep slow breathing at the rate of 6 breaths per minute following recorded prompts, for 5 min. Their baseline 5-min short-term HRV parameters before the controlled breathing were compared with the short-term HRV parameters of three 5-min segments of ECG recorded successively after the resumption of spontaneous breathing using repeated measures ANOVA. Results: There was no significant difference in the short-term HRV parameters measured before and after the 5 min of deep breathing. Conclusion: Controlled breathing at 0.1 Hz frequency for 5 min does not produce a significant immediate change in the short-term HRV of healthy individuals.