Effects of intravenous medium-chain triglycerides on pulmonary gas exchanges in mechanically ventilated patients

Objective: In mechanically ventilated patients, pulmonary gas exchange was investigated dur­ ing the administration of total parenteral nutri­ tion containing medium-chain triglycerides or long-chain triglycerides as fat emulsions. Design: Prospective, randomized, crossover trial (two lipid infusion periods of 8 hrs). Setting: Intensive care unit in a university hospital. Patients: Six mechanically ventilated pa­ tients, using the pressure-support mode. Interventions: Total caloric intake was adapted according to measured energy expen­ diture. Fat emulsion provided 50% ofthe energy expenditure. Patients were infused with 50% medium-chainl5O% long-chain triglycerides or 100% long-chain triglycerides in a ran«:!-om sequence. MeasurenumtsandMainResults: Oxygencon­ sumption, CO 2 production, and minute ventila­ tion were measured by indirect calorimetry. Pao 2 and Paco 2 were determined in blood samples. Medium-chain triglycerides increased oxygen consumption by 27.8% and minute ventilation by 14.3% at the end of the protocoL CO 2 produc­ tion, Pao 2 , and Paco 2 were not different between groups. Conclusions: Medium-chain triglycerides cause an increase in metabolic demand in me­ chanically ventilated patients when they are infused over a short period. Postoperative or intensive care unit patients with a low pulmo­ nary reserve should receive infusions of medium-chain triglycerides over a more prolonged period than long-chain triglycerides. (Crit Care Med 1994; 22:248-251)