Response of Pulmonary Artery Pressure and Total Pulmonary Resistance of Untrained, Convalescent Man to Prolonged Mild Steady State Exercise1

Abstract

Although many published studies relevant to the effects of exercise on the gross pulmonary hemodynamics of patients with heart disease are available in the literature, few data are to be found which deal with normal man (1-6). There have been conflicting claims that there is no increase, no significant increase, a consistent increase, or an occasional decrease in the pulmonary artery pressure of normal man as the result of exercise loads eventuating in oxygen uptakes up to 400 ml. per M.2 per min. (2) and pulmonary blood flows two to three times the resting basal levels (1, 5). Moreover, comparison among the published data is difficult because of variations in the exercise posture, the duration of exercise, the work loads employed, and the timing of blood and pressure sampling, which often are varied in different subjects within the same body of data.Slonim, Ravin, Balchum, and Dressler (6) alone have systematically studied the continuous pulmonary artery pressure variations in 5 normal subjects in the recumbent position over a 7-minute period of exercise, employing an almost uniform work rate between 784 and 840 foot-pounds per minute. These authors noted immediate increases in pulmonary systolic, diastolic and mean pressures, which usually reached a peak between the first and third minutes of exercise with an overall tendency to a slight secondary decline by the sixth minute. A steady state was not achieved.The present report is intended to extend these findings employing a mild and uniform external work load of 850 foot-pounds per minute sustained over a period of 39 minutes. This mild amount of work was selected in order that steady state be attained in a reasonably uniform period of time, 1 Supported by a grant from United Appeal, Lorain County, Ohio. that it be maintained as long as possible, and that some lower limit of valid, measurable change be established for comparison in subjects with heart disease physically unable to exercise at higher work loads and achieve the steady state (7). MATERIALS AND METHODSStudies were conducted on 12 subj ects with normal cardio-respiratory systems who had convalesced from various illnesses (bronchopneumonia, active peptic ulcer, eczematoid dermatitis), or had been admitted for investigation of minor complaints. None were anemic or febrile. All had been ambulatory for several days before the studies were conducted. On the day prior to the experiment the subjects were exercised in the supine position at a standard work rate of 850-foot pounds per minute for a period of 39 minutes. In all but three instances the steady state, as determined by repetitive determinations of the oxygen consumption (8), was attained within 10 to 12 minutes of exercise; in the remaining three, it was attained at the 12 to 14-minute period. The following morning, at an ambient temperature of 23 degrees C., cardiac catheterization was performed in the post-absorptive state with mild sedation (Pentobarbital Sodium, 0.1 Gm.), employing standard No. 7F Cournand catheters. The supine position was...

Pulmonary vascular distensibility and lung compliance as modified by dextran infusion and subsequent atropine injection in normal subjects.

“…The decline of pressure in our studies appears to follow a time course similar to that reported for MPAP by Sancetta and Rakita during prolonged steady state exercise (57). The decrease of MPAP observed by Widimsky, Berglund, and Malmberg during repeated exercise seems also to have a time constant of the same order (58).…”

Pulmonary vascular resistances during exercise in normal subjects: a systematic review

“…1) [8][9][10][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]. After the exclusion of individuals with prospectively defined implausible data, 222 subjects (147 males, 33 females, 42 sex not available) were analysed.…”

Influence of Age on Pulmonary Haemodynamics at Rest and during Supine Exercise

“…Second, the exercise protocol is important since pressures and flow resistance in the lesser circulation tend to fall after a few minutes of exercise [12,24], or when exercise periods are repeated [25]. Thus the rise in pulmonary artery pressure may not be as much as expected with progressive increments in work load, when exercise periods are prolonged or repeated exercise is used.…”