Time components of circulatory transport from the lungs to a peripheral artery in humans

Abstract

Blood gas changes occurring in the lung undergo delay and damping on their way to a peripheral artery sampling site. Knowledge of the time components of circulatory transfer is important for the understanding of respiratory control and cardiovascular reflexes in response to blood gas transients. Providing steady state with regard to VA/Q distribution, cardiac output and peripheral blood flow, the relationship between the time courses of small end-tidal and peripheral PO2 changes is determined by the transfer function of the interposed vascular segment. This transfer function, expressed as delay time TD and mean transit time (MTT), was measured in six well-trained subjects, allowing the calculation of arterial time-courses from end-tidal to the reverse. They were studied at rest and during four different dynamic leg exercise intensities in the supine posture. TD and MTT amounted to 15.8 +/- 1.7 (mean +/- SEM) and 18.3 +/- 2.1 s at rest and were shortened to 7.7 +/- 0.6 and 11.5 +/- 1.8 s during exercise at 170 W. The shortening of TD and MTT did not appear to be simply an inverse function of cardiac output, suggesting that the shortening occurs in the central circulatory segment but not in the arm segment.

Retracted: Chest digital dynamic radiography to detect changes in human pulmonary perfusion in response to alveolar hypoxia

“…No complications occurred. Considering the transport delay between the lung capillaries and the sampling site, 18 obtained blood samples were obtained 20 sec after the beginning of imaging. All participants underwent blood gas tests using an ABL 800 FLEX blood gas analyser (Radiometer, Tokyo, Japan).…”

Phase I dynamics of cardiac output, systemic O2 delivery, and lung O2 uptake at exercise onset in men in acute normobaric hypoxia

“…In hypoxia, SaO 2 data were corrected for time delay between lungs and fingertip (30). Continuous recordings of arterial pulse pressure were obtained at a fingertip of the right arm by means of a noninvasive cuff pressure recorder (Portapres; FMS, Amsterdam, The Netherlands).…”

A new interpolation-free procedure for breath-by-breath analysis of oxygen uptake in exercise transients

“…In this study, we did not consider d 2 values lower than 8 s, because d 2 represents the blood transit time from contracting muscles to lungs at exercise start, which is between 7 and 9 s at the present steady state metabolic rate (Barstow and Molé 1987;lindholm et al 2006;Whipp et al 1982). In fact table 2 shows that for none there was no effect of d 2 on the fraction of synthetic noiseless data that deviated from the Exact Parameters by less than the width of the confidence intervals.…”