Efficacy and Safety of Glutamine-supplemented Parenteral Nutrition in Surgical ICU Patients: An American Multicenter Randomized Controlled Trial

This was a 1:1 randomized controlled trial at 5 US centers in 150 adult surgical ICU patients requiring parenteral nutrition after cardiac, vascular, or intestinal surgery. Eligible patients were 18 to 90 years old, had BMI <40 kg/m2 before surgery, and did not have significant renal or hepatic failure or shock at entry.

The active regimen was intravenous parenteral nutrition supplemented with alanyl-glutamine dipeptide at 0.5 g/kg/day, delivered as a 20% alanyl-glutamine dipeptide solution admixed into PN and continued for up to 28 days after enrollment. The comparator was standard glutamine-free PN.

Glutamine-supplemented PN was safe but did not improve clinical outcomes versus standard PN. Six-month mortality was 31.4% with GLN-PN and 29.7% with STD-PN (hazard ratio 1.05, 95% CI 0.58-1.88; P = 0.88), and 28-day mortality was 14.7% versus 16.0%. Hospital-acquired infections were also similar, with any infection in 52 GLN-PN events versus 39 STD-PN events and rates of 28 versus 25 per 1000 hospital days (P = 0.70). No serious adverse event was related to the study PN.

The trial enrolled only 150 postoperative SICU patients, limiting power to detect modest benefits or harms. Results may be specific to this surgical ICU population and to a setting where enteral nutrition was advanced as indicated alongside PN, which could dilute any isolated glutamine effect.