COMPARISON OF LACTATE AND BICARBONATE BUFFERED HEMOFILTRATION FLUIDS - USE IN CRITICALLY ILL PATIENTS

Objective. To compare acid-base balance, lactate concentration, and ha emodynamic and O-2 transport variables during haemofiltration with rep lacement fluid containing 44.5 mmol/l Na+ lactate or 40 mmol/l Na+ HCO 3- and 3 mmol/l lactic acid. Design. A prospective, randomized trial. Setting. A multidisciplinary, adult intensive care unit in a universit y hospital. Patients. Forty acidotic patients who required haemofiltra tion, were dependent on mechanical ventilation, and had FA catheters i n situ. Interventions. During haemofiltration patients received lactat e or bicarbonate replacement fluid at a mean rate of 1.7 l/h (SD 0.3). Arterial blood gases, plasma lactate, and haemodynamic and O-2 transp ort variables were measured before and after 12 and 24 h haemofiltrati on. Ultrafiltrate was collected for lactate estimation. Measurements a nd main results. As means (SD). The net gain of lactate was 63 mmol/h (12 mmol) with Na+ lactate and 0 mmol/h (0.3 mmol) with Na+ HCO3-. The re was a significant increase in pH and [lactate] in both groups, but [lactate] was higher in patients receiving lactate. Twenty-one patient s survived to ICU discharge, these patients were significantly less ac idotic after filtration (lactate group: 0h: pH 7.23 (0.09), [lactate] 2.4 mmol/l (1.7);12 h: pH 7.34 (0.09), [lactate] 4.7 mmol/l (2.4); 24 h: pH 7.36 (0.07), [lactate] 4.7 mmol (2.7), HCO3 group: 0 h: pH 7.23 (0.09), [lactate] 2.3 (1.3); 12 h: pH 7.32 (0.06), [lactate] 2.9 mmol/ l (1.8); 24 h: pH 7.35 (0.08), [lactate] 2.8 mmol/l (2.0), Base defici t: survivors: 0 h: 9 mmol/l (4); 12 h: 2 mmol/l (3), Non-survivors: 0 h: 10 mmol/l (3); 12 h: 6 mmol/l (3)). Haemodynamic and O-2 transport variables were not significantly affected by treatment group or outcom e. Conclusions. The degree of correction of acidosis during the first 24h of haemofiltration was determined by patients outcome but was not affected by the substitution of bicarbonate- for lactate-containing re placement fluids.