British journal of anaesthesia
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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.
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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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Randomized Controlled Trial Comparative Study Clinical Trial Controlled Clinical Trial
Manual compared with target-controlled infusion of propofol.
We studied 160 ASA I-II patients, anaesthetized with propofol by infusion, using either a manually controlled or target-controlled infusion system. Patients were anaesthetized by eight consultant anaesthetists who had little or no previous experience of the use of propofol by infusion. In addition to propofol, patients received temazepam premedication, a single dose of fentanyl and 67% nitrous oxide in oxygen. ⋯ With the exception of a clinically insignificant difference in heart rate, haemodynamic variables were similar in the two groups. Six of the eight anaesthetists found the target-controlled system easier to use, and seven would use the target-controlled system in preference to a manually controlled infusion. Anaesthetists without prior experience of propofol infusion anaesthesia quickly became familiar with both manual and target-controlled techniques, and expressed a clear preference for the target-controlled system.
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Randomized Controlled Trial Comparative Study Clinical Trial
Extradural, paravertebral and intercostal nerve blocks for post-thoracotomy pain.
Forty-five patients were allocated randomly to receive either a single intrathoracic block of four intercostal nerves, a continuous thoracic extradural infusion or a continuous paravertebral infusion of bupivacaine. Patients were allowed additional i.v. boluses of morphine via a PCA device. ⋯ There were no significant differences between the groups in pain, morphine consumption, respiratory function or adverse events. Moderate to severe respiratory depression was detected in 14 patients more than 2 h after operation.
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Randomized Controlled Trial Comparative Study Clinical Trial
Effect of crystalloid and colloid preloading on uteroplacental and maternal haemodynamic state during spinal anaesthesia for caesarean section.
We have studied the effects of crystalloid 1 litre (lactated Ringer's) or colloid 0.5 litre (hydroxyethyl starch) preloading in 26 healthy parturients undergoing elective Caesarean section under spinal anaesthesia. Maternal placental uterine artery circulation was measured using a pulsed colour Doppler technique with simultaneous measurement of maternal haemodynamics. A high incidence of maternal hypotension was observed during spinal anaesthesia in the crystalloid group (62%) but the incidence was lower in the colloid group (38%). ⋯ These individual increases in PI were transient and always returned to baseline values within 2 min. These results suggest that preloading with either solution is ineffective in preventing maternal hypotension and that changes in maternal heart rate, systolic arterial pressure and central venous pressure during spinal anaesthesia were not associated with rapid individual increases in uteroplacental vascular resistance. These changes seemed not to have any major effect, however, on the clinical condition of the newborn, as assessed by Apgar scores and umbilical artery pH values.