Long-chain versus medium-chain lipids in acute pancreatitis complicated by acute respiratory distress syndrome: effects on pulmonary hemodynamics and gas exchange

Background and Aims: In order to assess the effects of fat emulsions in patients with acute pancreatitis and acute respiratory distress syndrome (ARDS) before the pancreatic injury was complicated by infection, pulmonary hemodynamics and gas exchange were investigated during the administration of long-(LCTs) or medium-chain triacylglycerols (MCTs). Methods: This prospective trial included nine patients with acute pancreatitis and ARDS; each patient was used as his/her own control. In all cases, the needle aspiration culture of the pancreas was negative. Fat emulsion provided 50% of the energy expenditure. The patients were infused, in random order, with pure LCTs and a 1:1 mixture of LCTs/MCTs on days 1 and 2, over an 8 h period. Results: LCT infusion increased the mean pulmonary artery pressure (MPAP) from 28±5 to 35±3 mmHg, pulmonary venous admixture (Qva/Qt) from 26±5% to 36±5% and decreased arterial PO2(PaO2)/fractional inspired oxygen (FIO2) from 210±20 to 170±20 (P<0.05). The infusion of LCT/MCT 1:1 emulsions increased oxygen consumption (VO2) from 340±10 to 398±15 ml/min, cardiac output (CO) from 8.8±0.2 to 9.5±0.5 L/min and CO2production (VCO2) from 247±12 to 282±14 mL/min (P<0.05). Conclusion: LCT/MCT 1:1 mixtures are recommended in cases of acute pancreatitis and ARDS, even though infusion over a short period increases the metabolic demand.