British journal of anaesthesia
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Randomized Controlled Trial Clinical Trial
Interaction of a subanaesthetic concentration of isoflurane with midazolam: effects on responsiveness, learning and memory.
There are situations in which "light" anaesthesia combined with neuromuscular block is the only anaesthetic regimen that can be tolerated safely by the patient. Benzodiazepines have hypnotic and specific amnesic effects. Therefore, we have examined the interaction of midazolam with a subanaesthetic dose of isoflurane (0.2% end-expired concentration) in 28 healthy volunteers. ⋯ Recognition was also absent after administration of midazolam 0.06 mg kg-1 and at the 3-min and 15-min assessments after administration of midazolam 0.03 mg kg-1. Responsiveness was more frequent with midazolam 0.03 mg kg-1 than with 0.06 mg kg-1 and increased over time. We conclude that a larger dose of midazolam or isoflurane, or both, may be necessary to abolish responsiveness.
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Randomized Controlled Trial Clinical Trial
Gastro-oesophageal reflux with the laryngeal mask during day-case gynaecological laparoscopy.
We have evaluated if breathing spontaneously via a laryngeal mask airway is associated with a higher risk of gastro-oesophageal reflux compared with positive pressure ventilation via a laryngeal mask airway in 40 patients undergoing day-case gynaecological laparoscopy. Patients were allocated randomly to receive either positive pressure ventilation or breathe spontaneously via a laryngeal mask airway. Using continuous oesophageal pH monitoring, three patients in the ventilated group and one in the spontaneous breathing group had gastrooesophageal reflux (P = 0.29). We found no evidence to suggest that breathing spontaneously via a laryngeal mask airway increased the risk of gastro-oesophageal reflux compared with positive pressure ventilation in this group of patients.
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison between extradural infusion of ropivacaine or bupivacaine for the prevention of postoperative pain after total knee arthroplasty.
We have compared the analgesia and motor block produced by extradural infusions of ropivacaine and bupivacaine after total knee arthroplasty. Fifty-two patients received 8 ml h1 of either 0.2% ropivacaine or 0.2% bupivacaine by extradural infusion for 24 h after operation. Analgesia was assessed by postoperative visual analogue scale (VAS) and morphine consumption. ⋯ Median morphine consumption was 30.7 mg in the ropivacaine group and 20.5 mg in the bupivacaine group. In the ropivacaine group, 50% of patients compared with 19% in the bupivacaine group had no motor block 2 h after operation, increasing to 88% for ropivacaine and 56% for bupivacaine by 24 h. Bupivacaine produced significantly more frequent and intense motor block over the 24 h (P = 0.015).
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of S(-)-bupivacaine with racemic (RS)-bupivacaine in supraclavicular brachial plexus block.
Bupivacaine is used widely as a local anaesthetic but has potential for severe cardiovascular and central nervous system (CNS) toxicity. It has an asymmetric carbon atom giving it a chiral centre, and the commercial preparation is a racemic mixture of its two enantiomers: dextro or R(+)-bupivacaine and levo or S(-)-bupivacaine. Preclinical studies have demonstrated reduced cardiotoxicity and CNS toxicity for S(-)-bupivacaine. ⋯ Duration of sensory block was prolonged with wide interpatient variation: 892 (SD 250) min, 1039 (317) min and 896 (284) min for 0.25% S(-)-bupivacaine, 0.5% S(-)-bupivacaine and 0.5% RS-bupivacaine, respectively. There were no differences in the overall success rate of the technique. We conclude that S(-)-bupivacaine was suitable for local anaesthetic use in brachial plexus block anaesthesia.
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Randomized Controlled Trial Clinical Trial
Category generation testing in the search for implicit memory during general anaesthesia.
We gave auditory examples of two semantic categories through headphones to 100 surgical patients anaesthetized with propofol and enflurane. This presentation was made during certain stages of the procedure, potentially associated with arousal, and during steady-state anaesthesia. Postoperative review using category generation tests showed successful priming in a pre-induction group but no evidence of implicit memory in the anaesthetized groups. These results suggest that timing an auditory input to coincide with surgical stimulation does not increase the probability of retrieval of information by this type of testing.