Thromboxane production after giving Soy Bean Oil emulsions (SBO) has been reported to induce pulmonary hypertension. Objective: To examine effects of altering FA composition of the lipid emulsion used for TPN.Methods: 2 d old piglets were instrumented with a central venous catheter. TPN was started with the fat source being randomized to either SBO(18:2ω6 55%;18:3ω6 7%) or a fish oil (FO) emulsion containing long chain FA (20:5ω3 12%;22:6ω3 28%). A control group remained with the sow. 3 d later, a thermodilution catheter was floated into the pulmonary artery (PA). Piglets were ventilated, then made hypoxic for 20 min and then for 2 h. Systemic arterial pressure (SAP), PA pressure, and Cardiac Index (Q) were measured and PVR calculated. TableConclusion: SBO administered for 3 d to the newborn piglet leads to an exaggerated increase in PVR and fall in Q during prolonged hypoxia. FO emulsion has no such effect. We speculate this effect is due to“diet” induced alterations in thromboxane synthesis.

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