Increased pulmonary vascular permeability after bone marrow injection in sheep

Area of Science:

• Physiology
• Pathology

Background:

• Pulmonary edema can result from increased pulmonary vascular permeability.
• The role of bone marrow embolism in altering pulmonary fluid balance is not fully understood.

Purpose of the Study:

• To investigate the effects of bone marrow injection on pulmonary fluid and protein exchange in sheep.
• To determine if free fatty acid toxicity or secondary thrombosis mediate these effects.

Main Methods:

• Sheep were injected with varying amounts of bone marrow into the pulmonary circulation.
• Pulmonary lymph flow, protein clearance, plasma free fatty acids, fibrinogen, fibrin degradation products, and leukocyte counts were measured.

Main Results:

• Bone marrow injection caused pulmonary edema, increased pulmonary lymph flow, and elevated protein clearance, indicative of increased endothelial permeability.
• Plasma free fatty acid concentrations did not change; lymph fatty acid clearance increased in parallel with protein clearance.
• Intravascular coagulation was evidenced by decreased fibrinogen and increased fibrin degradation products, accompanied by a rapid decrease in leukocyte count.

Conclusions:

• Bone marrow embolism increases pulmonary endothelial permeability in sheep.
• The observed increase in permeability is attributed to intravascular coagulation, fibrin entrapment, and leukostasis, rather than free fatty acid toxicity.