Continuous renal replacement therapy: a potential source of calories in the critically ill.

Overfeeding can lead to multiple metabolic and clinical complications and has been associated with increased mortality in the critically ill. Continuous venovenous hemofiltration (CVVH) represents a potential source of calories that is poorly recognized and may contribute to overfeeding complications. We aimed to quantify the systemic caloric contribution of acid-citrate-dextrose regional anticoagulation and dextrose-containing replacement fluids in the CVVH circuit. This was a prospective study in 10 critically ill adult patients who received CVVH from April 2014 to June 2014. Serial pre- and postfilter blood samples ( = 4 each) were drawn and analyzed for glucose and citrate concentrations on each of 2 consecutive days. Participants included 5 men and 5 women with a mean ± SEM age of 61 ± 4 y (range: 42-84 y) and body mass index (in kg/m) of 28 ± 2 (range: 18.3-36.2). There was generally good agreement between data on the 2 study days (CV: 7-11%). Mean ± SEM pre- and postfilter venous plasma glucose concentrations in the aggregate group were 152 ± 10 and 178 ± 9 mg/dL, respectively. Net glucose uptake from the CVVH circuit was 54 ± 5 mg/min and provided 295 ± 28 kcal/d. Prefilter plasma glucose concentrations were higher in patients with diabetes ( = 5) than in those without diabetes (168 ± 12 compared with 140 ± 14 mg/dL; < 0.05); however, net glucose uptake was similar (46 ± 8 compared with 61 ± 6 mg/min; = 0.15). Mean ± SEM pre- and postfilter venous plasma citrate concentrations were 1 ± 0.1 and 3.1 ± 0.2 mmol/L, respectively. Net citrate uptake from the CVVH circuit was 60 ± 2 mg/min and provided 218 ± 8 kcal/d. During CVVH there was a substantial net uptake of both glucose and citrate that delivered exogenous energy and provided ∼512 kcal/d. Failure to account for this source of calories in critically ill patients receiving nutrition on CVVH may result in overfeeding.