Effect of device guided slow deep breathing on central sympathetic outflow and arterial baroreflex sensitivity in young healthy individuals (1170.4)

Abstract

We sought to investigate whether device guided slow deep breathing (SDB; RESPeRATE©) influences muscle sympathetic nerve activity (MSNA) and spontaneous baroreflex sensitivity in young healthy individuals. Following a 10 min supine baseline period, 9 men (29±7 years, body mass index 24±2 kg/m2; mean±SD) undertook 10 min of SDB while respiratory frequency (strain gauge pneumobelt), partial pressure of end‐tidal carbon dioxide (PETCO2), blood pressure (BP; finger photoplethymography), heart rate (HR; ECG) and MSNA (microneurography) were continuously monitored. Indices of arterial baroreflex control of the heart (sequence technique) and MSNA burst incidence were calculated. Respiratory rate was reduced from 12±2 to 6.2±0.7 breaths/min (P<0.001) during SDB, while PETCO2 (P=0.50), and mean BP (P=0.40) were unchanged. SDB significantly reduced MSNA burst incidence (i.e., percentage of cardiac cycles associated with a MSNA burst) from 25 (20‐38) to 20 (18‐33) (median and interquartile range; P=0.04). Neither cardiac (systolic BP‐RR interval; P=0.26) or sympathetic (P=0.95) baroreflex sensitivity were changed with SDB. Thus, reductions in MSNA burst incidence with device guided SDB in young healthy individuals appear not to be secondary to a change in baroreflex sensitivity, but may reflect an increase in lung inflation afferent input and/or a reduction in central respiratory‐sympathetic coupling.Grant Funding Source: Supported by British Heart Foundation