title: Maximal oxygenation of dilute blood cardioplegic solution.
abstract: The content of dissolved O2 (the major source of O2 for the myocardium) of dilute blood cardioplegic solution (dBCS) varied widely when oxygenated at 4 degrees C by surface flow of O2 in a Bentley BCR-3500 cardiotomy reservoir. We have modified the system to consistently deliver maximally oxygenated dBCS to the heart. Laboratory studies indicated that bubbling O2 through a 16-gauge intravenous catheter in a central Luer-Lok port of the cardiotomy reservoir provided contents of dissolved O2 that were consistently near maximal. We then studied 17 patients in the operating room. The first 6 patients received dBCS oxygenated with 100% O2 with a high dissolved O2 content of 3.2 +/- 0.2 ml/dl. However, the pH of the dBCS became highly alkaline (7.83 +/- 0.11 at 37 degrees C). Therefore, in the remaining 11 patients, 2% CO2 was added to the O2. The dissolved O2 content remained high (3.3 +/- 0.1 ml/dl), and the pH was in a more physiological range (7.35 +/- 0.09 at 37 degrees C). We conclude that consistently maximal oxygenation of a dBCS at a more physiological pH can be achieved by this method.
mesh_terms: D001769:Blood; D002245:Carbon Dioxide / Q000032:analysis; D006348:Cardiac Surgical Procedures; D006324:Heart Arrest, Induced / Q000295:instrumentation / Q000379:methods*; D006400:Hematocrit; D006438:Hemodilution; D006801:Humans; D006863:Hydrogen-Ion Concentration; D010100:Oxygen / Q000008:administration & dosage* / Q000032:analysis; D010313:Partial Pressure; D012996:Solutions; D013696:Temperature
chemical_list: D012996:Solutions; D002245:Carbon Dioxide; D010100:Oxygen