Effects of different doses in continuous veno-venous hemofiltration on plasma lactate in critically ill patients

Many studies have shown that continuous renal replacement therapy (CRRT) could clean lactate and treat the hyper-lactatemia. On the contrary, some other studies found that filter lactate clearance only accounted for a very small part of total lactate clearance and the hemofilter's contribution to the overall lactate clearance was negligible. The objective of this study was to evaluate the effects of various doses of continuous veno-venous hemofiltration (CVVH) on plasma lactate elimination in critically ill patients.

Patients were divided into three groups according to their incipient plasma lactate concentration. Group A: lactate ≤ 2 mmol/L, group B: lactate 2-5 mmol/L, group C: lactate ≥ 5 mmol/L. Three different doses (20 ml × kg(-1)× h(-1), 35 ml × kg(-1)× h(-1) and 45 ml × kg(-1)× h(-1)) of CVVH were applied to critically ill patients who experiencing CVVH. The concentrations of plasma lactate in pre-(A), post-dialyzer (V) sites and ultrafiltrate were measured after each dosage of CVVH was carried out for 30 minutes. Rate of lactate clearance by the filter (RLC) and filter lactate clearance (FLC) and Lactate-Sieving Coefficient (LSC) were calculated under different circumstances, including different doses of CVVH and different incipient lactate levels.

Fifteen patients were enrolled and 104 blood samples were drawn and lactate concentrations were measured in this study. RLC was found increased ((9.36 ± 9.73) mmol/h, (13.92 ± 12.56) mmol/h and (16.52 ± 12.71) mmol/h, P < 0.05 respectively) with the dose of CVVH increased. RLC was also increased ((3.46 ± 1.46), (10.38 ± 5.50) and (24.53 ± 14.69) mmol/h, P < 0.05 respectively) with the incipient lactate increased. FLC was increased ((1.95 ± 0.63), (2.95 ± 0.74) and (3.45 ± 0.54) L/h, P < 0.05 respectively) with the dose of CVVH increased. There was no significant difference of LSC in different doses of CVVH and different incipient lactate levels.

Plasma lactate can be eliminated by CVVH and different doses of CVVH affect the rate of lactate clearance in critically ill patients.