Cardioplegic Dosage

The following information is suggested as a guide and is subject to variation according to the preference and experience of the surgeon.

It is required that 10 mL (840 mg) of 8.4% Sodium Bicarbonate Injection, USP (10 mEq each of sodium and bicarbonate) be added aseptically and thoroughly mixed with each 1000 mL of cardioplegic solution to adjust pH. Use 10 mL of 8.4% Sodium Bicarbonate Injection, USP, to achieve the approximate pH of 7.8 when measured at room temperature. Use of any other Sodium Bicarbonate Injection may not achieve this pH due to the varying pH's of Sodium Bicarbonate Injections. Due to its inherent instability with other components, sodium bicarbonate must be added just prior to administration. After this addition, the solution must be used within 24 hours. The solution should be cooled to 4°C prior to use.

Following institution of cardiopulmonary bypass at perfusate temperatures of 28° to 30°C, and after cross-clamping of the ascending aorta, the buffered solution is administered by rapid infusion into the aortic root. The initial rate of infusion may be 300 mL/m2/minute (about 540 mL/min in a 5'8", 70 kg adult with 1.8 square meters of surface area) given for a period of two to four minutes. Concurrent external cooling (regional hypothermia of the pericardium) may be accomplished by instilling a refrigerated (4°C) physiologic solution such as Normosol®-R (balanced electrolyte replacement solution) or Ringer's Injection, USP into the chest cavity.

Should myocardial electromechanical activity persist or recur, the solution may be reinfused at a rate of 300 mL/m2/min for a period of two minutes. Reinfusion of the solution may be repeated every 20 to 30 minutes or sooner if myocardial temperature rises above 15° to 20°C or returning cardiac activity is observed. The regional hypothermia solution around the heart also may be replenished continuously or periodically in order to maintain adequate hypothermia. Suction may be used to remove warmed infusates. An implanted thermistor probe may be used to monitor myocardial temperature.

The volumes of solution instilled into the aortic root may vary depending on the duration or type of open heart surgical procedure.

Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit (See PRECAUTIONS).