Effect of Fast vs Slow Intralipid Infusion on Gas Exchange, Pulmonary Hemodynamics, and Prostaglandin Metabolism

Intralipid (20 percent, 500 ml) was infused fast (5 h) or slow (10 h) randomly in patients with lung injury to relate changes in plasma prostaglandin (PG) concentrations to gas exchange and pulmonary hemodynamics. Data were collected at baseline, midpoint of infusion, and 2 h following infusion. Vasodilator and vasoconstrictor PG metabolites, 6-keto-PGF1α, and thromboxane B2, respectively, were measured in radial arterial blood samples. Slow Intralipid infusion increased shunt fraction (QS/QT) without changing mean pulmonary artery pressure (MPAP), whereas fast Intralipid infusion increased MPAP without changing Qs/QT. Prostaglandin levels did not change significantly during either infusion. However, in both groups when the PC substrate was removed, hemodynamic and metabolite values decreased in parallel. In conclusion, we were unable to demonstrate a cause and effect relationship between plasma levels of 6-keto-PGF1α and thromboxane B2 and the observed pulmonary hemodynamic response to slow or fast Intralipid infusion.