Velocity Profiles in the Main Pulmonary Artery of Dogs and Man, Measured with a Thin-Film Resistance Anemometer

Abstract

Instantaneous velocity of pulmonary artery blood was measured using a thin-film resistance anemometer mounted on a hypodermic needle. Studies were performed, at thoracotomy, in five dogs and five patients. Instantaneous blood velocity was recorded at several sites across the transverse axis of the main pulmonary artery to determine the shape of the velocity profile. We found the velocity profile, in both man and dog, to be approximately flat. In dog, the mean velocity, normalized to that at the center line, ranged from 1.18 (SD ± 0.03) to 0.81 (SD ± 0.27). In man, mean velocity of pulmonary artery blood, normalized in a similar fashion, ranged from 1.08 (SD ± 0.03) to 0.84 (SD ±0.07), while the normalized peak systolic velocity ranged from 1.04 (SD ± 0.07) to 0.95 (SD ± 0.16). The results, in dogs, suggest that there is little asymmetry of the velocity profile and therefore these have been taken as evidence that the use of cuff electromagnetic flowmeters on the pulmonary artery of dogs is not subject to significant inaccuracies associated with a nonsymmetrical flow profile. The finding of a relatively flat velocity profile in patients, moreover, will make it easier for catheter-tip flowmeters to measure bulk velocity in the pulmonary artery.