INTRAVENOUS LIPID INFUSION INCREASES LUNG FLUID FILTRATION IN LAMBS

Abstract

In adult sheep intravenous infusion of a 10% lipid emulsion at an hourly rate of 0.25 g/kg body weight increases pulmonary microvascular pressure and filtration of fluid into the lungs, causing pulmonary lymph flow to double (J Clin Invest 61:1291, 1978). As 10% lipid usually is administered at lower rates in infants, some of whom have lung disease, we tested the effect on lung fluid balance of a continuous parenteral infusion of 10% fat emulsion at an hourly rate of 0.125 g/kg in healthy, awake newborn lambs. We measured mean pulmonary arterial (Ppa) and left atrial (Pla) pressures, arterial blood gas tensions (PaO2 and PaCO2), lung blood flow (Qb) and lymph flow (Q1), and protein concentrations in lymph (PR1) and plasma (PRp) of 5 lambs, 1 to 3 wks old. After a 2-3 h infusion of isotonic saline (control), the lambs received an infusion of 10% lipid for 3-4 h at the same rate as the preceding saline. Results (X̄ ± sx̄; *p < 0.05):Lipid infusion at a rate suitable for infants increased pulmonary microvascular pressure and lung lymph flow, and decreased lymph protein concentration, suggesting that intravenous fat causes constriction of the pulmonary circulation distal to sites of microvascular fluid exchange in lambs. Lipid infusions may thereby contribute to lung edema and impair arterial oxygenation.