Table 2.

Simulation of effluent dosing under different continuous RRT modalities in our patient, assuming 100 ml/h of fluid removal rate is required to achieve a net ultrafiltration goal of net negative 50 ml/h as prescribed

Simulation of effluent dosing under different CRRT modalities
CVVHDF: total ultrafiltration rate (2000 ml/h)a + dialysate rate (2000 ml/h) + fluid removal rate (100 ml/h) = effluent dose of 30.4 ml/kg per h → 26.8 ml/kg per h after predilution adjustment (30.4×0.88)b assuming 50% of replacement fluid as prefilter (preblood pump =1000 ml/h)
CVVH: total ultrafiltration rate (4000 ml/h)a + fluid removal rate (100 ml/h) = effluent dose of 30.4 ml/kg per h → 23.7 ml/kg per h after predilution adjustment (30.4×0.78)b assuming 50% of replacement fluid as prefilter (preblood pump =2000 ml/h)
CVVHD: dialysate rate (4000 ml/h) + fluid removal rate (100 ml/h) = effluent dose of 30.4 ml/kg per h
  • Plasma flow rate (ml/h), blood flow rate (ml/min) ×60 (min/h) × (1-HCT); where HCT is the current hematocrit of the patient (HCT 30% for the case of our patient). CVVHDF, continuous veno-venous hemodiafiltration; CVVH, continuous veno-venous hemofiltration; CVVHD, continuous veno-venous hemodialysis.

  • a Total ultrafiltration rate (ml/h) = preblood pump or prefilter replacement fluid rate + postfilter replacement fluid rate.

  • b Dilution factor for predilution: Plasma flow rate (ml/h)/[Plasma flow rate (ml/h) + prefilter replacement fluid rate (ml/h)] = 0.88 for our patient (1000 ml/h prefilter replacement fluid in CVVHDF) and 0.78 (assuming 2000 ml/h of prefilter replacement fluid in CVVH).