We studied the effects of positive alveolar pressure (PA) on systemic to pulmonary bronchial blood flow, Q̇(br(s-p)), in humans. The Q̇(br(s-p)) was measured during total cardiopulmonary bypass as the volume of blood accumulating in the left heart. This blood was vented by gravity from the left heart via a cannula introduced in the right upper pulmonary vein and advanced to the lowest portion of the left heart. In group A (n = 10) the Q̇(br(s-p)) was measured for 25 to 95 min with constant PA (4.0 ± 0.2 cm H2O, mean ± SE). In group B (n = 10) Q̇(br(s-p)) was measured for 20 min with PA = 4.1 ± 0.2 cm H2O and for a further 20 min with PA = 14.1 ± 0.4 cm H2O. The Q̇(br(s-p)) ranged between 0.32 and 2.76 percent of cardiac output (pump flow) and remained constant with time (group A). The increase of PA from 4.1 ± 0.2 to 14.1 ± 0.4 cm H2O reduced Q̇(br(s-p)) by ~40 percent (p <0.01, group B). We conclude that positive PA reduces Q̇(br(s-p)) during total cardiopulmonary bypass. Therefore, we advise using low PA during assisted ventilation to preserve bronchial blood flow.
|Number of pages||5|
|Publication status||Published - 1989|
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine