Hemodynamic and Vascular Permeability Effects of Lipid Emulsion in the Isolated Canine Lung Lobe

Abstract

The isolated canine right lower lung lobe (RLL) perfused with autogenous blood at constant flow was used to study the effects of a parenteral lipid emulsion, Liposyn 10%, on pulmonary hemodynamics and vascular permeability. Lobes were placed into four groups: (1) control lobes (C; n = 6), which were infused via the lobar artery with normal saline at 1 ml· min^-1 for 30 min; (2) lipid emulsion lobes (L; n = 6), which were infused via the lobar artery with Liposyn 10% at 1 ml· min^-1 for 15 min; (3) lobes infused with both Liposyn 10% and 0.25 to 6.0 mg of lipoprotein lipase (LL; n = 4); and (4) lobes infused with 0.13 to 6.0 mg of lipoprotein lipase alone (LP; n = 6). Liposyn infusion alone caused no changes in lobar hemodynamics compared to group C. Over time there were no differences between groups C and L on venous Po₂, P_CO2, or pH. Post-infusion weight gain (over 10 to 14 min) averaged 0.23 ± 0.08, 0.19 ± 0.07, 0.66 ± 0.23, and 3.00 ± 1.46 g· min^-1· 100 g^-1 RLL for groups C, L, LP, and LL, respectively (p < 0.05, for group LL compared to Group C). The pulmonary filtration coefficient (K_f) was determined as an index of vascular permeability. Groups C and L had K_f values of 0.07 ± 0.01 and 0.28 ± 0.22 ml · min^-1· mm Hg^-1· 100 g^-1 (mean ± SE), respectively, which did not differ significantly (p > 0.05). Liposyn 10%, given in a concentration larger than that used clinically, produced no untoward pulmonary vascular effects. In the presence of Liposyn, liberation of free fatty acids by lipoprotein lipase is, however, rapidly damaging to lung microvessels. (Journal of Parenteral and Enteral Nutrition 14:376-380, 1990)