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A Randomized Trial of Supplemental Parenteral Nutrition in Under and Over Weight Critically (TOP UP)

Principal Investigator(s):

Daren Heyland

Critically ill patients are often hypermetabolic and can rapidly become nutritionally compromised. Malnutrition is prevalent in these patients and has been associated with increased morbidity and mortality. Standard nutrition therapy, i.e. provision of calories, protein and other nutrients consists primarily of enteral nutrition (via a feeding tube into the gastrointestinal tract), parenteral nutrition (via an intravenous tube into the blood), or occasionally a combination of both.

However, the provision of nutrition is sub-optimal and the majority of critically-ill patients do not meet nutritional requirements. Recent studies report that average energy intakes of critically ill patients are only 49% to 70% of calculated requirements. Despite repeated, sustained efforts over the past few years, the investigators have not significantly improved the amount of calories delivered via the enteral route. This leads us to conclude that if the investigators are to be successful at increasing the provision of calories and protein to patients at-risk, the investigators will have to supplement the calories via the parenteral route.

Critically ill patients that are at extremes of weight are at a higher nutritional risk and have higher mortality rates. A recent International multicenter observational study of 2772 ICU patients from 165 ICUs showed a significant inverse linear relationship between the odds of mortality and total daily calories received. Increased amounts of calories was most important for the BMI < 20 group followed by the BMI 20 -< 25 group and BMI > 35 group with no benefit of increased calorie intake for patients in the BMI 25 -< 35 group. Feeding an additional 1000 kcals almost halved the odds of 60-day mortality in patients with a BMI < 25 or > 35. Similar results were observed for feeding an additional 30 grams of protein per day.

Thus, a prospective randomized trial is warranted to confirm our hypothesis that in patients with a BMI of < 25 and those with a BMI > 35 increasing the provision of more energy and protein can impact clinical outcomes. The results of this study will serve to answer some fundamental questions with regards to impact of amount of energy and protein delivered to nutritional at-risk ICU patients and will inform current practice.

Study Intervention

Patients will be randomized to one of 2 interventions: enteral nutrition alone or enteral nutrition plus parenteral nutrition (supplemental PN group).

View publication A randomized trial of supplemental parenteral nutrition in underweight and overweight critically ill patients: the TOP-UP pilot trial


Rupinder Dhaliwal (Project Leader) and Maureen Dansereau (Project Assistant)


Paul Wischmeyer (US Co-Principal Investigator)