Adjustment of nutrition support with continuous hemodiafiltration in a critically III patient

Glucose-containing dialysis solutions are commonly used for continuous renal replacement therapy. A significant portion of this glucose is transferred across the dialysis membrane, which necessitates a change in the carbohydrates being provided by alternative nutrition support. Glucose transfer usually is estimated empirically, but glucose absorption across a dialysis membrane can be measured easily during continuous dialysis because the quantity of glucose from the patient (Glu_out · BFR [blood flow rate]) plus the quantity that is absorbed across the dialysis membrane (Glu_added) must be equal to the quantity going back to the patient (Glu_in · BFR): Glu_added = (Glu_in - Glu_out) × BFR × k, where k is a conversion factor to correct for different units. This teaching case describes the course of an 83-year-old man receiving continuous dialysis, for whom adjustments to his nutrition support were made on multiple occasions on the basis of direct measurement of the amount of glucose absorbed from the dialysis solution. The described method is easy to apply at the bedside and should allow for appropriate prescription of carbohydrate calories during continuous dialysis when glucose-containing solutions are used.