Effect of left atrial pressure on bronchial vascular hemodynamics

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Abstract

We studied the bronchial vascular response to downstream pressure elevation by increasing left atrial pressure (Pla) and mean airway pressure (P̄aw) with positive end-expiratory pressure (PEEP). In seven pentobarbital-anesthetized ventilated sheep, we cannulated and perfused the bronchial branch of the bronchoesophageal artery. Steady-state bronchial artery pressure- (Pba) flow (Qba) relationships were obtained as Pla was increased by inflating a balloon catheter in the left atrium. Bronchial vascular resistance (BVR), determined by the inverse slope of the Pba-Qba relationship, increased significantly from 3.2 ± 0.3 (SE) mmHg·ml-1·min-1 at a Pla of 2.9 ± 0.7 mmHg to 5.1 ± 0.5 mmHg·ml-1·min-1 at a Pla of 20.1 ± 2.0 mmHg (P = 0.0007). Under control Qba (23.3 ± 1.2 ml/min), these changes in BVR represent a 3.6 ± 0.7-mmHg increase in Pba per mmHg increase in Pla. The zero-flow pressure increased 1.3 ± 0.2 mmHg/mmHg increase in Pla. After infusion of papaverine, a smooth muscle paralytic agent, directly into the bronchial artery, BVR decreased significantly to 1.3 ± 0.7 mmHg·ml-1·min-1 (P = 0.0004). Under these dilated conditions, BVR was unaltered by increases in Pla. After papaverine administration, Pba increased 0.9 ± 0.1 and 1.2 ± 0.1 mmHg/mmHg increase in Pla during control and zero-flow conditions, respectively. Thus the effect of Pla elevation on BVR appears to be dependent on active smooth muscle responses. P̄aw elevation had similar effects on Pba. Under control Qba, Pba increased 2.2 ± 0.4 mmHg/mmHg increase in P̄aw. However, after papaverine administration, this response was unaltered, with Pba increasing 2.2 ± 0.6 mmHg/mmHg increase in P̄aw. We conclude that Pla elevation results in increases in BVR that are smooth muscle dependent. Although elevation in P̄aw increases BVR, the response is not dependent on vascular smooth muscle but is probably the result of mechanical distortion of airway vessels.

Original languageEnglish (US)
Pages (from-to)837-842
Number of pages6
JournalJournal of applied physiology
Volume69
Issue number3
DOIs
StatePublished - 1990

Keywords

  • bronchial artery
  • mean airway pressure
  • positive end-expiratory pressure
  • pressure-flow curves
  • sheep

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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