British journal of anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
Do anxiety or hypocapnia predispose to apnoea after induction of anaesthesia?
We have studied the incidence of apnoea after induction of anaesthesia in patients allocated randomly to receive a standardized dose of either propofol or etomidate. We measured anxiety before operation with a standard questionnaire and end-tidal carbon dioxide concentration from a mask during breathing 35% oxygen, before induction of anaesthesia. Respiration was measured by pneumotachograph and impedance pneumograph. ⋯ There was no relationship between apnoea and end-tidal carbon dioxide concentration in these patients. Anxiety did not relate to the incidence of apnoea with either induction agent. We conclude that apnoea after induction of anaesthesia with propofol is more likely if hypocapnia is present but we could not relate apnoea or hypocapnia to anxiety in the ward before operation.
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Randomized Controlled Trial Clinical Trial
Low-dose mivacurium supplementation of prilocaine i.v. regional anaesthesia.
We have compared in two groups of five healthy volunteers, the motor effect of prilocaine i.v. regional anaesthesia of the forearm with and without addition of mivacurium 0.6 mg. Although addition of mivacurium might, theoretically, provide the benefit of increased neuromuscular block with rapid plasma cholinesterase degradation in the isolated limb, we observed prolonged forearm weakness in the mivacurium group using tests of grip strength (median recovery to 90% of control, 80 min (range 60 min to > 8 h) vs control median recovery to 90% of 16 (8-24) min) and bead transfer (median recovery to 90% of control 36 (24-48) min vs control median recovery to 90% of 12 (8-16) min). This weakness was considerably in excess of that predicted by rapid systemic degradation of mivacurium. The mivacurium group experienced symptoms of local anaesthetic toxicity which did not occur in the control group and which could not be replicated by administration of mivacurium alone.
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The maximum recommended dose for extradural infusions of bupivacaine in children older than 1 month is 0.5 mg kg-1 h-1 but there are few specific reports of the associated blood concentrations during infusions in babies. Toxic symptoms can occur in children at plasma concentrations of bupivacaine as low as 2 micrograms ml-1. We attempted to measure venous plasma concentrations of total and free bupivacaine in babies aged 3-12 months during extradural infusions given at a rate commonly used in our hospital. ⋯ One baby had a concentration of 2.02 micrograms ml-1 at 32 h and showed clear evidence of accumulation of bupivacaine. Babies can accumulate bupivacaine and achieve plasma concentrations above the threshold for toxic side effects, despite infusion rates below the currently accepted maximum. The samples size in our study was small but we believe an extradural infusion rate of 0.375 mg kg-1 h-1 is probably an absolute maximum for babies younger than 12 months.
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of induction and recovery between sevoflurane and halothane supplementation of anaesthesia in children undergoing outpatient dental extractions.
We have compared sevoflurane and halothane in a double-blind controlled study for supplementation of nitrous oxide and oxygen anaesthesia in 80 children undergoing dental extraction as outpatients. Induction of anaesthesia was more rapid in those who received sevoflurane compared with those who received halothane (89 s compared with 127 s for loss of eyelash reflex). In both groups, mean duration of administration of anaesthesia was less than 4 min. ⋯ The incidence of complications during induction and maintenance was low in both groups and return to normal appetite and activity occurred in the majority of children on the same day. More children who received halothane suffered nausea after leaving hospital. We conclude that sevoflurane is a suitable alternative to halothane, with more rapid induction of anaesthesia, but in these short procedures, awakening time was slower than after halothane.