Table 5.

Theoretical effects of a posthemofilter 5% dextrose infusion on glucose metabolism during pre-/post-dilution continuous venovenous hemofiltration

D5W infusion, ml/h3080160240300
CHO load, mg/kg·min0.280.741.482.222.78
PGlu, without carbohydrate metabolism for 24-h, mg/dl125500110017002150
Maintenance metabolic rate, mg/kg·min0.150.621.362.102.65
Prehemofilter PNa, mM117.0117.0116.9116.8116.8
  • The effects of a 5% dextrose infusion on glucose metabolism in a hypothetical, nondiabetic, 42-year-old, 178-cm, 90-kg man with Watson volume 48 L and PNa(0) 116 mM (see text, Case 1) after 24 hours of CVVH are displayed. CVVH parameters are: NaRF, 130 mM; QP, 225 ml/min; combined prehemofilter RF and posthemofilter D5W flow rate, 1.1 L/h (18.3 ml/min); and net ultrafiltration rate, 0 ml/min. Calculations are based on an extracellular fluid volume of 16 L (48 L × 0.33), without expansion of the extracellular fluid space from glucose accumulation. All CHO metabolism is assumed to originate from the D5W infusion. With no CHO metabolism, increasing the CHO load (row 2) by increasing the D5W infusion rate from 0 to 300 ml/h rapidly increases PGlu (row 3). The respective glucose metabolic rates required to maintain PGlu at 100 mg/dl for increasing D5W infusion rates are shown (row 4). The minimal dilutional effect of the increasing D5W infusion rate on hemofilter inlet PNa is shown (row 5). CVVH, continuous venovenous hemofiltration; D5W, 5% dextrose solution; CHO, carbohydrate; PGlu, plasma glucose concentration; PNa(0), plasma [Na] at time (t) = 0; NaRF, RF [Na]; QP, plasma flow rate; RF, unadjusted replacement fluid; [Na], sodium concentration.