Anesthesia and analgesia
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Anesthesia and analgesia · Jun 1995
Reversal of residual neuromuscular block with neostigmine at one to four hours after a single intubating dose of vecuronium.
The purpose of this study was to measure the degree of residual neuromuscular block at different times after a single dose of vecuronium, and to evaluate the effectiveness of two different doses of neostigmine in antagonizing this residual block. Train-of-four (TOF) ratios were examined for up to 4 h after a single dose of vecuronium, 0.1 mg/kg, in 60 patients during nitrous oxide/isoflurane/fentanyl anesthesia. The effect of neostigmine, 40 micrograms/kg, was studied at 1,2,3, or 4 h. ⋯ One patient, at 1 h, had a TOF ratio of 0.00 and this did not reach 0.75 until 57 min after neostigmine, 40 micrograms/kg. There was a high incidence (50%) of adverse cardiovascular effects after both doses of neostigmine. In making the decision as to whether neostigmine should be administered, the risk to the patient of residual neuromuscular block must be balanced against the adverse cardiovascular effects of the neostigmine.
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Anesthesia and analgesia · Jun 1995
Activation of the Bezold-Jarisch reflex in the sitting position for shoulder arthroscopy using interscalene block.
A retrospective analysis of 116 patients who underwent shoulder arthroscopy in the sitting position with interscalene block (ISB) revealed 20 patients who experienced potentially dangerous vasovagal events characterized by sudden severe hypotension and bradycardia (Group 1). The event occurred 61 +/- 18 min after the block placement. Ninety-six patients (Group 2) did not experience a vasovagal event. ⋯ All patients received epinephrine in their local anesthetic for ISB, incision sites, and articular irrigating solution. Total and weight-corrected epinephrine doses differed significantly between groups (lowest in Group 2A, P < 0.01). Activation of the Bezold-Jarisch reflex, induced by increased circulating epinephrine levels and the sitting position, is the postulated mechanism.
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Anesthesia and analgesia · Jun 1995
Inadequate antagonism of vecuronium-induced neuromuscular block by neostigmine during sevoflurane or isoflurane anesthesia.
To examine the effects of discontinuing sevoflurane or isoflurane anesthesia (1 minimum alveolar anesthetic concentration [MAC] of end-tidal concentrations, together with 66% N2O/O2) on the reversal of vecuronium-induced neuromuscular blockade (an initial dose = 100 micrograms/kg), the electromyographic response of the abductor digiti minimi was monitored at 20-s intervals after train-of-four (TOF) stimulation of the ulnar nerve in 192 ASA grades I and II patients. When the amplitudes of the first response (T1) had recovered to 10% of the control, neostigmine (0;spontaneous recovery, 10, 20, 30, 40, or 55 micrograms/kg, eight patients each) was given and the ratio of the fourth TOF to the first response (TOFR) was monitored at 1-min intervals for 15 min in the presence of the volatile anesthetics, or after discontinuation of anesthetic administration. ⋯ The dose-response curves for neostigmine (10, 20, 30, and 40 micrograms/kg) were constructed using the TOFR values at 5-11 min, from which the ED50 values (a neostigmine dose required for a TOFR value of 50%) were derived. Sevoflurane impaired neostigmine antagonism more than isoflurane, as demonstrated by the significantly higher ED50 values at 7-11 min (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)