Improving Muscle Function in Nutritionally at Risk, Elderly Patients

The investigators propose to conduct a randomized, control trial of HMB supplementation in elderly patients (≥65 years of age) with acute respiratory failure, who are identified at high risk for malnutrition by ICU-specific nutritional risk scores. Patients will receive either 3g of HMB daily, or control, daily until day 28 following randomization (even if discharged).the investigators will measure functional outcomes using standard, validated measures prior and after discharge. The investigators hypothesize that this inexpensive nutrient, HMB, along with our supportive measures, reduces muscle loss, improves physical muscle function, and improves quality of life in the longer term following critical illness.