Anesthesia and analgesia
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Anesthesia and analgesia · Jun 1995
Changes in plasma cholinesterase activity and mivacurium neuromuscular block in response to normothermic cardiopulmonary bypass.
The effect of reduced plasma cholinesterase (ChE) activity in response to normothermic cardiopulmonary bypass (CPB) on mivacurium neuromuscular block was studied in nine patients anesthetized with propofol/fentanyl. Mivacurium was injected intravenously as an initial bolus of 150 micrograms/kg; repeat doses of 75 micrograms/kg were given when the evoked twitch tension attained 75% of control. ⋯ Their DUR25% (time from end of injection to recovery of neuromuscular transmission to 25% of control) were 13 +/- 3 min (means +/- SD) before, 14 +/- 4 min during, and 16 +/- 4 min (P < 0.05) after CPB. It is concluded, that, although markedly reducing the patient's previously normal ChE activity, normothermic CPB had little effect on the time characteristics of mivacurium neuromuscular block.
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Anesthesia and analgesia · Jun 1995
Comparative StudyResuscitation from bupivacaine-induced asystole in rats: comparison of different cardioactive drugs.
The objective of this study was to compare the success of resuscitation attempts with different cardioactive drugs after bupivacaine-induced asystole. Saline, amrinone (1 mg/kg), dopamine (5 micrograms/kg), norepinephrine (2 micrograms/kg), epinephrine (10 micrograms/kg), or isoproterenol (1 microgram/kg) were tested. Sixty rats assigned to six treatment groups (n = 10/group) were lightly anesthetized (0.5% halothane, 70% N2O), paralyzed (doxacurium), and given bupivacaine intravenously at 4 mg.kg-1.min-1 until asystole. ⋯ Cardiac rhythm disturbance disappeared within 20 min after successful resuscitation with norepinephrine. Amrinone was no more effective than saline in treating bupivacaine-induced asystole. A drug such as norepinephrine, which has both cardiostimulator (beta 1-receptor agonist) and peripheral vasoconstrictor (alpha 1-receptor agonist) activity, may be the drug of choice for treating asystole induced by bupivacaine.
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Spinal neostigmine produces analgesia in chronically prepared rats, but not in sheep. However, since pain itself activates bulbospinal inhibitory pathways, neostigmine may be more effective in the postoperative period. We examined in sheep the antinociceptive effect of intrathecal neostigmine in the acute postoperative period and determined the muscarinic receptor subtype activated by neostigmine. ⋯ In contrast, intrathecal neostigmine caused no antinociception in another similar study performed at least 5 days after surgery. Pirenzepine, but not AFDX-116, abolished antinociception from neostigmine, suggesting an action on M1 subtype muscarinic receptors. Intrathecal neostigmine is antinociceptive in sheep during the acute postoperative period, and these data suggest that spinal cholinergic tone, and hence intrathecal neostigmine's analgesic effect, may be enhanced during the acute postoperative period.
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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)
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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.