Anaesthesia
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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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The effects of propofol on cerebrospinal fluid pressure, mean arterial pressure, cerebral perfusion pressure and heart rate were studied during induction, tracheal intubation and skin incision in 23 patients scheduled for elective craniotomy. Premedication consisted of midazolam 0.1 mg/kg intramuscularly and metoprolol 1 mg/kg orally. Measurements were made or derived at time zero and 0.5, 1, 1.5, 2 and 3 minutes after an induction dose of propofol 1.5 mg/kg. ⋯ Heart rate did not change. Propofol combined with moderate dose of fentanyl, obtunded the usual cerebrospinal fluid and arterial pressure responses to intubation and other noxious stimuli. Thus propofol seems to be a suitable intravenous anaesthetic agent for induction and maintenance in neuroanaesthesia.
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Randomized Controlled Trial Clinical Trial
Reducing the risks of laryngoscopy in anaesthetised infants.
We have evaluated the use of oxygen insufflation during laryngoscopy with an Oxyscope laryngoscope blade compared to conventional laryngoscopy for maintenance of transcutaneous PO2 during intubation of anaesthetised, spontaneously breathing infants. Twenty healthy children aged between 1 and 24 months were anaesthetised with halothane in oxygen. Laryngoscopy and intubation were performed in a double-blind fashion using a Miller No. 1 Oxyscope blade either with or without oxygen insufflation. ⋯ Transcutaneous oxygen tension decreased by 7.1% (SD 6.1%) when oxygen insufflation was used, compared to 33.0% (SD 15.1%) without oxygen insufflation (p less than 0.0001). There were no significant differences in mean duration of laryngoscopy or patient age. We conclude that oxygen insufflation during laryngoscopy and intubation of spontaneously breathing, anaesthetised infants effectively minimises the decrease in transcutaneous oxygen tension from pre-laryngoscopy levels, and makes instrumentation of the airway safer.
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Randomized Controlled Trial Comparative Study Clinical Trial
Intrathecal buprenorphine for postoperative analgesia in the elderly patient.
Ninety patients aged 56-85 years scheduled for suprapubic prostatectomy, randomly received intrathecally either bupivacaine 30 mg (group A, n = 30), bupivacaine 30 mg plus buprenorphine 0.03 mg (group B, n = 30) or bupivacaine 30 mg plus buprenorphine 0.045 mg (group C, n = 30). Prolonged postoperative analgesia, minimal disturbance of consciousness and comfortable breathing were common to the groups that received buprenorphine. ⋯ The only side effects found in the buprenorphine groups were nausea and vomiting in 11 and 14 patients, respectively, in groups B and C. Our study shows that buprenorphine is an effective analgesic, suitable for the management of postoperative pain in elderly patients.