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.
Colebatch
H J
HJ
Department of Medicine, University of New South Wales, Prince Henry Hospital, Australia.
Ng
C K
CK
Maccioni
F J
FJ
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*