The impact of lactate-buffered high-volume hemofiltration on acid-base balance.
OBJECTIVE
To evaluate the effect of high-volume hemofiltration (HVHF) with lactate-buffered replacement fluids on acid-base balance.


METHODS
Randomized crossover study.


METHODS
Intensive Care Unit of Tertiary Medical Center


METHODS
Ten patients with septic shock and acute renal failure.


METHODS
Random allocation to 8 h of isovolemic high-volume hemofiltration (ultrafiltration rate: 6 l/h) or 8 h of isovolemic continuous venovenous hemofiltration (ultrafiltration rate: 1 l/h) with lactate-buffered replacement fluid with subsequent crossover.


RESULTS
We measured blood gases, electrolytes, albumin, and lactate concentrations and completed quantitative biophysical analysis of acid-base balance changes. Before high-volume hemofiltration, patients had a slight metabolic alkalosis [pH: 7.42; base excess (BE) 2.4 mEq/l] despite hyperlactatemia (lactate: 2.51 mmol/l). After 2 h of high-volume hemofiltration, the mean lactate concentration increased to 7.30 mmol/l ( p=0.0001). However, a decrease in chloride, strong ion difference effective, and strong ion gap (SIG) compensated for the effect of iatrogenic hyperlactatemia so that the pH only decreased to 7.39 ( p=0.05) and the BE to -0.15 ( p=0.001). After 6 h, despite persistent hyperlactatemia (7 mmol/l), the pH had returned to 7.42 and the BE to 2.45 mEq/l. These changes remained essentially stable at 8 h. Similar but less intense changes occurred during continuous venovenous hemofiltration.


CONCLUSIONS
HVHF with lactate-buffered replacement fluids induces iatrogenic hyperlactatemia. However, such hyperlactatemia only has a mild and transient acidifying effect. A decrease in chloride and strong ion difference effective and the removal of unmeasured anions all rapidly compensate for this effect.
Cole
Louise
L
Department of Intensive Care, Austin and Repatriation Medical Centre, Studley Road, 3084, Heidelberg, Victoria, Australia.
Bellomo
Rinaldo
R
Baldwin
Ian
I
Hayhoe
Matthew
M
Ronco
Claudio
C
D000136:Acid-Base Equilibrium; D058186:Acute Kidney Injury / Q000628:therapy; D018592:Cross-Over Studies; D006440:Hemofiltration / Q000379:methods*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007773:Lactates; D012772:Shock, Septic / Q000628:therapy
D007773:Lactates