To the Editor:--Shangraw et al. described the use of dichloroacetate during liver transplantation (OLTX). Although we agree with the authors' concerns that too much NaHCO3is potentially problematic, we have taken a different approach to lactic acidosis during liver transplantation.
There is conflicting evidence in the literature concerning the potential harm of acidosis. Much evidence exists that there are no significant enhancements to myocardial performance and responsiveness to catecholamines as long as the pH is greater than 7.1. Additionally, we believe that the acidosis in OLTX differs from most lactic acidoses in that it usually arises as a result of inadequate clearance by the diseased or excised liver rather than a situation where excessive production from tissue hypoperfusion or hypoxia overwhelms a normal liver. Although lactic acidosis during OLTX may result from tissue hypoperfusion, much of the lactic acid load results from administration of banked blood. With this in mind, we have elected not to treat acidosis except in the rare cases when the patient has significant cardiac rhythm disturbances or severe fulminant liver disease for which bicarbonate infusion was started preoperatively in the intensive care unit.
We have cared for more than 250 liver transplant patients without correcting acidosis and have not made any attempts to correct pH with ventilation. Blood pH commonly decreases to less than 7.30. which is the threshold for treatment in other centers and was used in Shangraw et al.'s study. In those rare instances (about six cases) when bicarbonate was given to treat acidosis, we noted no subsequent changes in hemodynamics. This is consistent with observations of others treating lactic acidosis in nontransplant settings. [4,5]We therefore eliminated the potential problems of hypernatremia and metabolic alkalosis intraoperatively and any contribution that intraoperative bicarbonate therapy makes toward abnormalities in the postoperative period.
In summary, we agree with Shangraw et al. that the administration of large doses of sodium bicarbonate should be avoided, but we believe the goal usually can be achieved by simply resetting our setpoints for the lower limits of tolerable pH. In our experience, a pH greater than 7.10 is tolerated by the majority of patients undergoing OLTX without significant hemodynamic instability.
David L. Bogdonoff, M.D.; Assistant Professor of Anesthesiology and Surgery.
Burkhard F. Spiekermann, M.D.; Assistant Professor of Anesthesiology; Box 238; Department of Anesthesiology; University of Virginia Health Sciences Center; Charlottesville, Virginia 22908.
(Accepted for publication on March 22, 1995.)