Pulmonary capillary and permeability during hemorrhagic shock

Area of Science:

• Pulmonary physiology
• Cardiovascular research
• Hemodynamic shock

Background:

• Horseradish peroxidase (HRP) previously characterized normal canine pulmonary capillary membrane.
• Hemorrhagic shock effects on pulmonary capillaries require further investigation.

Purpose of the Study:

• To investigate alterations in canine pulmonary capillaries post-hemorrhagic shock.
• To assess the impact of hemorrhagic shock on pulmonary transcapillary pressure, lymphatic flow, and filtration coefficients.

Main Methods:

• Utilized horseradish peroxidase (HRP) technique to study pulmonary capillary membrane.
• Applied Starling's equation to estimate transcapillary pressure.
• Measured lung lymphatic flow and protein concentrations.
• Calculated filtration coefficients during normotensive and hypotensive periods.

Main Results:

• Hemorrhagic shock led to decreased or unchanged pulmonary transcapillary pressure.
• Significant increase in lung lymphatic flow observed during shock (P < 0.01).
• Filtration coefficients significantly increased (P < 0.01), indicating enhanced permeability.
• Pulmonary lymphatic protein concentrations remained unaltered, suggesting proportional solute and water transport.

Conclusions:

• Hemorrhagic shock alters pulmonary capillary permeability without changing the relative transport of water and protein.
• Increased filtration coefficients and lymphatic flow suggest a more permeable capillary membrane.
• Findings align with independent observations of minimal endothelial junction changes post-shock.