Variability of resting respiratory drive and timing in healthy subjects

• Published in: Journal of applied physiology (1985) Vol. 65; no. 1; p. 309
• Main Authors: Tobin, M J, Mador, M J, Guenther, S M, Lodato, R F, Sackner, M A
• Format: Journal Article
• Language: English
• Published: United States 01.07.1988
• Subjects: Adult; Aging; Female; Humans; Male; Middle Aged; Periodicity; Plethysmography; Reference Values; Respiration; Tidal Volume; Time Factors
• ISSN: 8750-7587
• DOI: 10.1152/jappl.1988.65.1.309

Studies of breathing pattern have focused primarily on changes in the mean values of the breathing pattern components, whereas there has been minimal investigation of breath-to-breath variability, which should provide information on the constancy with which respiration is controlled. In this study we examined the variability of breathing pattern both on a breath-to-breath and day-to-day basis by calculating the coefficient of variation (i.e., the standard deviation expressed as a percentage of the mean). By examining breath-to-breath data, we found that the coefficients of variation of tidal volume (VT) and fractional inspiratory time (TI/TT, an index of timing) obtained with an inductive plethysmograph and spirometer were within 1% of each other. Examination of breath-to-breath variability in breathing pattern over a 15-min period in 65 subjects revealed large coefficients of variation, indicating the need to base calculations on a relatively large number of breaths. Less breath-to-breath variability was observed in respiratory frequency [f, 20.8 +/- 11.5% (SD)] and TI/TT (17.9 +/- 6.5%) than in VT (33 +/- 14.9%) and mean inspiratory flow (VT/TI, an index of drive; 31.6 +/- 12.6%; P less than 0.0001). Older subjects (60-81 yr) displayed greater breath-to-breath variability than young subjects (21-50 yr). Use of a mouthpiece did not affect the degree of variability.