ABSTRACT
The influence of haemodilution and cooling on the solubility of halothane in blood during cardiopulmonary bypass was studied in six normothermic and six hypothermic patients undergoing open-heart operations. The solubility of halothane in blood was 2.17 at 30 degrees C and 1.34 at 37 degrees C. There was also an increase in the blood/gas partition coefficient of about 8.7 per cent for each degree celsius of temperature fall. These changes in haemodiluted blood explain the different anaesthetic requirements observed in patients undergoing cardiopulmonary bypass, either at normal temperature or at moderate hypothermia.
Subject(s)
Cardiopulmonary Bypass , Halothane/blood , Hemodilution , Hypothermia, Induced , Hematocrit , Humans , OxygenatorsABSTRACT
The cardiovascular effects of two premedication regimes used in paediatric anaesthesia were studied. Eleven patients received rectal methohexitone (22 mg - kg) and 11 patients received intramuscular Innovar (0.03 ml - kg). The effect of these drugs on ventricular function was evaluated by measuring the shortening of the left ventricular minor dimension by echocardiography. No significant changes in this dimension, blood pressure, heart rate or respiratory rate were demonstrated with either drug. Both rectal methohexitone and intramuscular Innovar were shown to have minimal cardiovascular effects when used as preoperative sedation in paediatric patients. Echocardiography proved to be a valuable technique for the noninvasive evaluation of drug effects on myocardial contractility in children.