British journal of anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of continuous brachial plexus infusion of butorphanol, mepivacaine and mepivacaine-butorphanol mixtures for postoperative analgesia.
We have reported recently that continuous administration of butorphanol into the brachial plexus sheath provided analgesia of a quality superior to that of continuous i.v. administration. In the present study, we have compared postoperative pain relief produced by continuous infusion of one of three types of solution into the axillary sheath: opioid alone, local anaesthetic alone or a mixture of local anaesthetic and opioid. In patients undergoing upper extremity surgery with continuous axillary brachial plexus block, we injected one of the three solutions into the axillary neurovascular sheath: butorphanol 2 mg (group B), 0.5% mepivacaine alone (group M) and 0.5% mepivacaine-butorphanol (group MB); the volume of each solution was 50 ml, administered at a rate of 50 ml per 24 h. At 3 h after operation, visual analogue scale (VAS) scores were significantly higher in group M than in group MB (P < 0.01), and higher in group B than in group MB (P < 0.05).
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Randomized Controlled Trial Clinical Trial
Effect of nebulized lignocaine on airway irritation and haemodynamic changes during induction of anaesthesia with desflurane.
This study was designed to assess the effect of nebulized lignocaine or saline given before induction on the quality of induction of anaesthesia with desflurane in unpremedicated, young, adult males. Of the first six patients, five developed laryngospasm, breath-holding, coughing and increased secretions. In four patients oxygen saturation decreased to 92% or less. ⋯ The incidence and severity of complications were not decreased by administration of nebulized lignocaine and were higher than those reported by other workers. We conclude that in unpremedicated, young, adult males, induction of anaesthesia with desflurane and nitrous oxide in oxygen was associated with a high incidence of respiratory irritant effects, tachycardia, hypertension and post-induction bradyarrhythmia. We also found that lignocaine, as used in this study, did not appear to obtund the cardiovascular and respiratory complications during inhalation induction using desflurane.
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Comparative Study
Evaluation of the Pneupac Ventipac portable ventilator: comparison of performance in a mechanical lung and anaesthetized patients.
The performance of the Pneupac Ventipac portable gas-powered ventilator was evaluated in two stages. The accuracy of delivery of the ventilator was assessed using a mechanical lung model at different combinations of compliance and airway resistance to simulate normal and diseased lungs. The performance of the ventilator was then assessed in 20 anaesthetized patients. ⋯ Delivered tidal volume was between -19 and +12% of the present tidal volume in the group of anaesthetized patients using the ventilator in airmix mode. The ventilator was reliable and simple to use, and performance was within acceptable limits in the anaesthetized patients. However, we recommend that a means of verifying the adequacy of ventilation should always be used when transporting critically ill or anaesthetized patients with any portable ventilator, particularly when lung compliance or airway resistance may be abnormal.
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Randomized Controlled Trial Clinical Trial
Effect of i.v. lignocaine on the breathing of patients anaesthetized with propofol.
Local anaesthetics are ventilatory depressants, but previous investigators have not commented on the effects on ventilatory timing. There is concern about the possible ventilatory depression caused by systemic absorption of local anaesthetics injected extradurally. We have studied ASA grade I patients anaesthetized with a propofol infusion and breathing spontaneously; they were given in random order lignocaine 1.5 mg kg-1 i.v. and an equivalent volume of 0.9% saline. ⋯ Lignocaine had no effect on or promoted bimodality of expiratory time. End-tidal carbon dioxide increased by a mean of 0.1%; the largest individual change was 0.3%. This suggests that lignocaine may have reduced the metabolic rate, affecting ventilation indirectly, but we conclude that lignocaine in a normal extradural dose should not be an important ventilatory depressant.
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Median nerve somatosensory evoked responses (MnSSER) were recorded in 15 healthy adult patients, ASA I-II, before and during orthopaedic surgery. After induction of anaesthesia with fentanyl 0.1-0.15 mg, etomidate 0.3 mg kg-1 and vecuronium 0.1 mg kg-1, anaesthesia was maintained with 0.6% isoflurane (end-tidal) and 66% nitrous oxide in oxygen. MnSSER were recorded after establishment of steady-state anaesthesia at baseline, during preparation (n = 11) and continuously after the start of surgery. ⋯ During intense surgical stimulation (e.g. periosteal stimulation) the peak-to-peak amplitude N20P25 increased significantly by more than 45% (P < 0.05), whereas latencies of all components did not change over time. These data indicate that MnSSER may be reliably monitored in the intraoperative period during steady-state isoflurane-nitrous oxide anaesthesia. In addition, concurrent changes in haemodynamic variables during nociceptive stimulation support the hypothesis that reversal of isoflurane-nitrous oxide-induced suppression of MnSSER may indicate increased nociceptive input when depth of anaesthesia is inadequate.