Anaesthesia
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Comparative Study
Bladder temperature as an estimate of body temperature during cardiopulmonary bypass.
Bladder temperature measured by a thermistor-tipped urinary catheter, was compared to oesophageal, nasopharyngeal, rectal and cutaneous temperatures in 33 patients during cardiopulmonary bypass. The bladder site was warmer than all other monitored sites in the pre-bypass period and showed least variation in temperature. The rate of change of bladder temperature during cooling and rewarming on bypass was significantly (p less than 0.01) lower than for oesophageal and nasopharyngeal temperatures, but was greater than or similar to the rate of change of rectal and cutaneous temperatures. This method of temperature measurement was found to be satisfactory during major surgery and also during the postoperative period in the intensive care unit.
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The effects of a bolus injection of propofol on mean intracranial pressure were studied in six adult, comatose patients who had severe head injuries. Propofol 2 mg/kg was given intravenously over 90 seconds when the mean intracranial pressure reached or exceeded 25 mmHg. Arterial blood gas values, heart rate and central venous pressure remained stable at all measurements. ⋯ The mean (SEM) intracranial pressure decreased statistically significantly (p less than 0.05) at 30 seconds and at 1 and 2 minutes, from 25 (3) to 11 (4) mmHg. The cerebral perfusion pressure decreased statistically significantly from 92 (8) mmHg at all measurements (p less than 0.05). The lowest value at 3 minutes was 50 (7) mmHg but in four patients at that time the perfusion pressure was below 50 mmHg.
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The pharmacokinetics of a constant rate infusion of propofol were studied in 11 patients who received total intravenous anaesthesia for ENT surgery. Alfentanil was administered as an exponentially decreasing infusion using a computer-assisted infusion device with a constant target plasma alfentanil concentration of 300 ng/ml. Propofol was infused at a constant rate of 6 mg/kg/hours. ⋯ Only three data sets were significantly underestimated after the infusion was stopped (mean bias 11.9% (SD 25.5]. The elimination half-life of alfentanil was approximately 75 minutes (SD 21). We conclude that alfentanil does not interfere with the pharmacokinetic profile of propofol but that propofol induces higher plasma alfentanil concentrations than expected.
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Comparative Study
Comparison of a total intravenous anaesthetic technique using a propofol infusion, with an inhalational technique using enflurane for day case surgery.
A total intravenous anaesthetic technique with a propofol infusion for maintenance of anaesthesia was compared with an inhalational technique that used oxygen, nitrous oxide and enflurane in 98 unpremedicated patients who presented for day case surgery. Overall quality of anaesthesia during induction and maintenance was comparable in both groups. ⋯ Recovery times and scores using the Steward scoring system were not significantly different. Nausea and vomiting were slightly less frequent in the propofol group.
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The haemodynamic response to tracheal intubation was compared in 303 patients in whom anaesthesia was induced with either thiopentone 4 mg/kg, etomidate 0.3 mg/kg or propofol 2.5 mg/kg, with and without fentanyl 2 micrograms/kg. There was after propofol alone a significant decrease in arterial blood pressure, which did not increase above control values after intubation. ⋯ Increases in heart rate occurred with all agents after laryngoscopy. The use of fentanyl resulted in arterial pressures lower than those after the induction agent alone, and in an attenuation, but not abolition of the responses to laryngoscopy and intubation.