Bronchial collateral vessel micropuncture pressure in postobstructive pulmonary vasculopathy

Area of Science:

• Cardiovascular Physiology
• Pulmonary Medicine
• Vascular Biology

Background:

• Postobstructive pulmonary vasculopathy significantly increases bronchial blood flow.
• Bronchial collaterals were previously shown to enter the pulmonary circuit distally.
• The pressure within bronchial collaterals (Pbr) in this condition was unknown.

Purpose of the Study:

• To test the hypothesis that bronchial collateral pressure (Pbr) approximates the pressure at the downstream end of the pulmonary arterial segment (Pao).
• To investigate the relationship between bronchial collateral pressure and pulmonary arterial/venous pressures in a canine model of pulmonary artery ligation.

Main Methods:

• Utilized pump-perfused canine left lower lobes 3-15 months after left main pulmonary artery ligation.
• Measured pulmonary arterial and venous pressures, Pao, and Pvo using arterial and venous occlusion.
• Determined Pbr via micropuncture of pleural surface bronchial vessels (201 ± 16 μm diameter).

Main Results:

• Bronchial collateral pressure (Pbr: 14.4 ± 1.0 mmHg) was similar to Pao (15.0 ± 0.8 mmHg).
• Pbr significantly differed from Pvo (11.3 ± 0.5 mmHg; P < 0.01).
• Pbr was independent of systemic arterial pressure and bronchial vessel diameter.

Conclusions:

• Bronchial collateral pressure in postobstructive pulmonary vasculopathy closely approximates precapillary pulmonary artery pressure.
• The majority of pressure drop in bronchial collaterals occurs in vessels larger than 350 microns.
• These findings highlight the importance of larger bronchial vessels in regulating collateral flow dynamics.