Associations Between Nutrition Markers and Muscle Mass on Bioimpedance Analysis in Patients Receiving Parenteral Nutrition.

Background: Parenteral nutrition (PN) is used for malnourished patients and those intolerant of enteral nutrition. This pilot study assessed repeatability of bioimpedance analysis (BIA) in critically ill patients and association with nutrition markers and patients' length of hospital stay.

Methods: Twenty-two patients receiving PN, after major surgery or during critical illness, were enrolled and underwent serial BIA and Subjective Global Assessment (SGA) by a dietitian. Repeatability of BIA was assessed by repeating BIA measurements within 10 minutes in 18 of the 22 study patients (82%).

Results: All BIA parameters were repeatable with strong intraclass correlation coefficients (>0.78). Phase angle (PhA), reflective of muscle mass, was significantly associated with serum albumin (R = 0.198, P < .001), total lymphocyte count (R = 0.083, P = .018), and body mass index (R = 0.084, P = .015). Of the 48 SGAs performed, 4 were considered severely malnourished, and all were associated with low PhA (<5°) compared with only 53% and 33% for those considered to be moderately malnourished and well nourished, respectively (χ test: P = .042). Low PhA was significantly associated with an increased length of hospital stay compared with those without low PhA (median 36 vs 16 days, respectively; P < .001).

Conclusion: BIA is repeatable in critically ill patients receiving PN. Low PhA was prevalent for those judged as severely malnourished and was associated with reduced total lymphocyte count and serum albumin and prolonged length of hospital stay compared with those with a higher PhA.