Effect of paced breathing on ventilatory and cardiovascular variability parameters during short-term investigations of autonomic function

• Published in: American journal of physiology. Heart and circulatory physiology Vol. 290; no. 1; pp. H424 - H433
• Main Authors: Pinna, G. D, Maestri, R, La Rovere, M. T, Gobbi, E, Fanfulla, F
• Format: Journal Article
• Language: English
• Published: United States 01.01.2006
• Subjects: Autonomic Nervous System - physiology; Baroreflex - physiology; Blood Pressure - physiology; Cardiovascular Physiological Phenomena; Female; Heart Rate - physiology; Humans; Lung Volume Measurements; Male; Middle Aged; Oxygen - blood; Respiration
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.00438.2005

Departments of 1 Biomedical Engineering, 2 Cardiology, and 3 Pneumology, Salvatore Maugeri Foundation–Institute of Care and Scientific Research, Scientific Institute of Montescano, Montescano, Pavia, Italy Submitted 2 May 2005 ; accepted in final form 2 September 2005 Paced breathing (PB) around 0.25 Hz has been advocated as a means to avoid confounding and to standardize measurements in short-term investigations of autonomic cardiovascular regulation. Controversy remains, however, as to whether it causes any alteration in autonomic control. We addressed this issue in 40 supine, middle-aged, healthy volunteers by assessing the changes induced by PB (0.25 Hz for 8 min) on 1 ) ventilatory parameters, 2 ) the indexes of autonomic control of cardiovascular function, and 3 ) the spectral indexes of cardiovascular variability. Subjects were grouped into group 1 ( n = 31), if spontaneous breathing was regular and within the high-frequency (HF) band (0.15–0.45 Hz), or group 2 ( n = 9), if it was irregular or slow (<0.15 Hz). In both groups, PB was accompanied by an increase in minute ventilation (both groups, P < 0.01), whereas tidal volume increased only in group 1 ( P = 0.0003). End-tidal CO 2 decreased by [median (lower quartile, upper quartile)] –0.2 (–0.5, –0.1)% ( group 1 , P < 0.0001) and –0.6 (–0.8, –0.5)% ( group 2 , P = 0.008). Mean R-R interval and systolic and diastolic pressure remained remarkably stable (all P 0.13, both groups). No significant changes were observed in spectral indexes of R-R and pressure variability (all P 0.12, measured only in group 1 to avoid confounding), except in the HF power of pressure signals, which significantly increased (all P < 0.05) in association with increased tidal volume. In conclusion, PB at 0.25 Hz causes a slight hyperventilation and does not affect traditional indexes of autonomic control or, in subjects with spontaneous breathing in the HF band, most relevant spectral indexes of cardiovascular variability. These findings support the notion that PB does not alter cardiovascular autonomic regulation compared with spontaneous breathing. heart rate variability; controlled breathing; baroreflex sensitivity; spectral analysis Address for reprint requests and other correspondence: G. D. Pinna, Servizio di Bioingegneria, Fondazione S. Maugeri, IRCCS, Istituto Scientifico di Montescano, 27040 Montescano, Pavia, Italy (e-mail: gdpinna{at}fsm.it )