Inspiratory gas flow induced by cardiac systole.
This study was made to quantify the inspiratory gas flow pulse produced by cardiac systole. Ten adults (9 men, 1 woman; age 24-65 yr) were studied, of whom two had respiratory muscle weakness. The inspiratory flow pulse commenced 50-60 msec after the R wave of the ECG and lasted 106 (SD22) msec. In eight subjects seated and breathing through a mouthpiece, the flow pulse reached a peak of 120 (SD 58) ml sec-1 and displaced a volume of 6.6 (SD 2.3) ml (range 3.6-9.9 ml). Similar results were obtained using a nasal mask. By adding an external airway resistance, the effective intrathoracic pressure responsible for inspiratory flow was estimated to be -0.21 (SD 0.03) cm H2O. Duplicate studies showed little variation in pulse volume. The mechanism of the inspiratory gas flow pulse and its contribution to gas exchange is discussed.
Department of Medicine, University of New South Wales, Prince Henry Hospital, Australia.
H J
HJ
Colebatch
C K
CK
Ng
F J
FJ
Maccioni
D000328:Adult; D000368:Aged; D000403:Airway Resistance / Q000502:physiology; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012119:Respiration / Q000502:physiology*; D012129:Respiratory Function Tests; D015656:Respiratory Mechanics / Q000502:physiology; D013599:Systole / Q000502:physiology*