Articles: nerve-block.
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Recent published data suggest that despite apparently satisfactory recovery from nondepolarising block (train-of-four ratios in excess of 0.90), even very small doses of additional relaxant may re-establish significant paralysis. We sought to verify this observation and quantify its magnitude. Twelve adult patients were studied under nitrous oxide-propofol-opioid anaesthesia and neuromuscular block was monitored electromyographically. ⋯ The control ED50 of mivacurium (calculated from the initial dose of mivacurium) averaged 43 micrograms.kg-1. When the same dose of drug was given at 95% recovery of the train-of-four ratio, the ED50 was reduced to 19 micrograms.kg-1 (p < 0.0001). Hence, there remains a considerable reduction in the neuromuscular margin of safety even at a train-of-four ratio of 0.95.
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We review the results of 312 cases of sciatic nerve blockade in the poplitea fossa for surgery of the dorsal foot. An atraumatic, insulated needle connected to a neurostimulator was used to make a single puncture using a posterior approach. The anesthetic was 1% mepivacaine (4-5 mg/kg-1). ⋯ Time of analgesia was 6 h 15 min (range 3-16 h). No complications or sequelae were recorded. We conclude that the technique is highly effective and comfortable for patients, as it requires only one puncture and gives good postoperative analgesia with no major side effects.
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Journal of anesthesia · Dec 1995
Effects of stellate ganglion block on cardiac coronary circulation.
Since the stellate ganglion contains cardiac sympathetic nerves, stellate ganglion block (SGB) may influence cardiac and coronary hemodynamics. We investigated this influence of SGB by measuring the heart rate (HR), the left circumflex coronary artery blood flow (CBF), the maximum rate of increase of the left ventricular pressure (LV max dP/dt), the cardiac output (CO), the myocardial oxygen consumption (MVO2), and the myocardial oxygen extraction ratio (MOER) in nine dogs before and after performing SGB by means of injection of 2 ml 1% mepivacaine. Left SGB resulted in a decrease of 10% in CBF and a decrease of 15% in LV max dP/dt, but HR, CO, and MVO2 remained unchanged. ⋯ Inhalation of 100% oxygen decreased MOER to the pre-SGB level in either side, thus improving the myocardial oxygen supply-demand relationship. This study suggests the possibility that SGB has deteriorative effects on the myocardial oxygen supply-demand relationship. Those effects were counteracted by the inhalation of 100% oxygen.
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Randomized Controlled Trial Clinical Trial
The neuromuscular blocking effects of vecuronium during sevoflurane, halothane and balanced anaesthesia in children.
Forty-five children aged 5-12 years were randomly allocated to receive 1.0 MAC of sevoflurane or halothane, or balanced anaesthesia with propofol and alfentanil. The ulnar nerve was stimulated every 20 s supramaximally with a train-of-four pattern and adductor pollicis electromyography was recorded. A cumulative log-probit dose-response curve of vecuronium was established. ⋯ Effective doses of vecuronium were lowest in the sevoflurane group and greatest during balanced anaesthesia; for 50% neuromuscular blockade these were 13.3% micrograms.kg-1, 21.8 micrograms.kg-1 and 36.6 micrograms.kg-1 during sevoflurane, halothane and balanced anaesthesia, respectively, p < 0.05. Recovery of neuromuscular function was slower during sevoflurane than during halothane or balanced anaesthesia. Sevoflurane potentiated vecuronium more than halothane; when compared to balanced anaesthesia the dose requirements of vecuronium were reduced by approximately 60% and 40%, respectively.
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The purpose of this study was to compare the pattern of recovery from vecuronium 0.07 mg.kg-1 induced neuromuscular blockade using post-tetanic burst count (PTBC)-(three short tetanic bursts of 0.2 msec duration every 20 msec given every second following a tetanus), and post-tetanic count (PTC)-(0.2 msec single twitch stimuli given every second following a tetanus) using an accelerometer in 60 adult patients during nitrous oxide-oxygen-isoflurane anaesthesia. In addition, the relationship among PTBC, PTC, and T1 (the 1st response in the train-of-four (TOF) stimulation) was examined to investigate whether the PTBC had an advantage over the PTC or TOF for evaluating intense neuromuscular blockade. The PTBC was greater than PTC during the 15-35 min after the administration of vecuronium (unpaired t test with Bonferroni's correction, P < 0.05). ⋯ Time from the return of PTB to that of T1 was longer than the time from the return of PTC to that of T1 (13.3 +/- 2.6 vs 9.2 +/- 2.8 min, unpaired t test, P = 0.0003). At the return of T1, PTBC was greater than PTC (14.3 +/- 6.9 vs 9.4 +/- 2.3, unpaired t test, P = 0.0153). These results suggest that, using PTBC, a more profound level of neuromuscular blockade can be evaluated than that using PTC.