Anaesthesia
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Randomized Controlled Trial Clinical Trial
An investigation of the potential morphine sparing effect of midazolam.
The effect of a bolus and continuous infusion of midazolam on postoperative morphine consumption was assessed in a placebo-controlled, double-blind, randomly allocated trial of 50 patients undergoing elective abdominal hysterectomy. Patients in the trial group received a bolus dose of midazolam 5 mg.70 kg-1 at induction followed by an infusion at a rate of 1 mg.70 kg-1.h-1 over the next 48 h. Morphine consumption in the midazolam group was significantly lower in the first 12 h postoperatively (p < 0.02) but there was no significant difference between the two groups thereafter. ⋯ Also, a significantly greater number of patients in the midazolam group required no antiemetic medication over the 48 h study period (p < 0.05). Assessment of sedation revealed no significant difference between groups. We conclude that low dose midazolam has a significant, but short-lived, morphine sparing effect.
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Randomized Controlled Trial Comparative Study Clinical Trial
The effect of pretreatment with ketorolac on pain during intravenous injection of propofol.
A randomised, double-blind, controlled trial was undertaken to compare three different methods of reducing pain during the intravenous injection of propofol. In 101 patients undergoing daycase surgery, verbal rating scores for pain during injection of propofol were compared immediately after intravenous pretreatment with ketorolac 10 mg, lignocaine 10 mg or saline. Neither pain during injection (p = 0.129), nor venous sequelae at 7 days postoperatively were significantly different between the three treatments. Pain during propofol injection remains a confounding clinical problem.
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Comparative Study
The effect of four different surgical prone positions on cardiovascular parameters in healthy volunteers.
Twenty healthy volunteers were placed in four different surgical prone positions: on pillows, on an evacuatable mattress, on pelvic props and in the knee-chest position. The normal supine position was used as a control for the measurement of cardiovascular parameters. Mean arterial pressure was measured by automated oscillotonometry. ⋯ Cardiac index and total vascular resistance index were derived from these data. No significant changes in heart rate or mean arterial pressure occurred when the volunteers were moved from the supine position to any of the four prone positions or when returned to the supine position again. Cardiac index decreased significantly on going from the supine to the knee-chest position (20%) and onto the props (17%) but not onto the evacuatable mattress (11%) or the pillows (3%).
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We describe a patient with osteogenesis imperfecta who developed tachycardia, metabolic and respiratory acidosis (pH 7.14, PCO2 8.4 kPa, BE -8.5 mmol.l-1) and hyperthermia up to 40 degrees C during anaesthesia with barbiturates, fentanyl, pancuronium, and nitrous oxide. Malignant hyperthermia was suspected and the patient treated accordingly. Two years later the in-vitro contracture test for malignant hyperthermia was completely normal. We conclude that hypermetabolism in patients with osteogenesis imperfecta is due to unknown mechanisms other than malignant hyperthermia.
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The stability of propofol emulsion following the addition of various amounts of lignocaine solution was investigated. The investigations used were macroscopic and microscopic observations and electroacoustic determination of both droplet size and zeta potential. ⋯ Resultant changes are unlikely to be clinically important following the addition of less than 20 mg of lignocaine to 200 mg of propofol (20 ml of propofol emulsion). It is recommended, however, that anaesthetists consider the possibility of destabilisation of propofol emulsion when adding larger doses of lignocaine, or when there is a delay between formulation and administration of the propofol-lignocaine mixtures.