Safety and efficacy of intravenous Carbicarb in patients undergoing surgery: comparison with sodium bicarbonate in the treatment of mild metabolic acidosis. SPI Research Group. Study of Perioperative Ischemia.
OBJECTIVE
To compare the safety and efficacy of intravenous Carbicarb with intravenous sodium bicarbonate in well-oxygenated patients who developed metabolic acidosis while undergoing major surgery. Carbicarb is an equimolar solution of sodium bicarbonate and sodium carbonate (Na2CO3). It does not undergo significant breakdown to CO2 and H2O, nor does it increase CO2 concentrations to the same extent as does pure sodium bicarbonate. Because of these characteristics, Carbicarb may be a more suitable agent than bicarbonate in the treatment of metabolic acidosis.


METHODS
Prospective, double-blind, randomized, multicenter trial.


METHODS
Veterans Affairs Medical Center (a teaching hospital of the University of California, San Francisco), and the University of Massachusetts Medical Center, Worcester, MA.


METHODS
We prospectively studied 36 patients who underwent either cardiac surgery or major noncardiac surgery and developed intraoperative metabolic acidosis (pH < 7.35 and whose serum bicarbonate concentration decreased by > 3 mmol).


METHODS
Patients were randomly assigned to receive either sodium bicarbonate (1 mEq sodium/mL, n = 18) or 1 mol Carbicarb (1 mEq sodium/mL, n = 18) administered by intravenous bolus over a 30-sec period.


RESULTS
For Carbicarb-treated patients, the mean arterial pH increased from 7.31 +/- 0.008 (baseline) to 7.36 +/- 0.009 10 mins after treatment; for the sodium bicarbonate-treated patients, the mean pH increased from 7.31 +/- 0.006 to 7.37 +/- 0.01. The increases in pH were statistically significant for both groups (p = .0001). There was no statistically significant difference between treatment groups in the number of repetitions of initial dose that was required to correct acidosis. Hemodynamic variables remained unchanged in both treatment groups during the study period, with the exception of the mean cardiac output which increased from 6.1 +/- 0.4 (baseline) to 6.9 +/- 1.4 L/min (60 mins after treatment) in a subset of Carbicarb-treated patients and decreased from 6.7 +/- 1.3 to 6.0 +/- 1.2 L/min in a subset of sodium bicarbonate-treated patients, p = .048 (between groups); and the mean pulmonary artery occlusion pressure decreased from 19 +/- 2 mm Hg (baseline) to 8 +/- 3 mm Hg (45 mins after treatment) in the Carbicarb-treated patients, and decreased from 18 +/- 2 to 13 +/- 4 mm Hg in the sodium bicarbonate-treated patients, p = .012 (between groups). Systemic utilization of lactate increased from 0.3 +/- 1.0 mmol/min (baseline) to 5.6 +/- 4.3 mmol/min (45 mins after treatment) in Carbicarb-treated patients, and increased from 1.0 +/- 0.6 mmol/min (baseline) to 1.5 +/- 1.3 mmol/min in the sodium bicarbonate-treated patients, p = .033 (between groups). The administration of Carbicarb was safe. No patients were discontinued from the study because of adverse events.


CONCLUSIONS
Carbicarb corrects metabolic acidosis as well as sodium bicarbonate. However, the potential therapeutic advantage of Carbicarb remains to be determined, especially in patients with more severe metabolic acidosis.
Leung
J M
JM
Department of Anesthesiology, University of California, San Francisco 94115.
Landow
L
L
Franks
M
M
Soja-Strzepa
D
D
Heard
S O
SO
Arieff
A I
AI
Mangano
D T
DT
D000138:Acidosis / Q000188:drug therapy*; D000328:Adult; D000368:Aged; D001784:Blood Gas Analysis; D002254:Carbonates / Q000627:therapeutic use*; D003422:Critical Care; D004311:Double-Blind Method; D004338:Drug Combinations; D006439:Hemodynamics; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007275:Injections, Intravenous; D007431:Intraoperative Complications / Q000188:drug therapy*; D008875:Middle Aged; D015337:Multicenter Studies as Topic; D017202:Myocardial Ischemia / Q000175:diagnosis; D011446:Prospective Studies; D012449:Safety; D017693:Sodium Bicarbonate / Q000627:therapeutic use*
D002254:Carbonates; D004338:Drug Combinations; C046283:sodium bicarbonate, sodium carbonate drug combination; D017693:Sodium Bicarbonate