Anesthesiology
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In order to evaluate reversal time from very intense neuromuscular blockade caused by a continuous infusion of atracurium, the time course of neostigmine induced reversal from different levels of neuromuscular blockade was evaluated using the post-tetanic count (PTC) and the train-of-four (TOF) in 30 patients anesthetized with nitrous oxide, fentanyl, and thiopental. Reversal time (time from administration of neostigmine at different PTC levels to a TOF ratio of 0.7) was found to depend upon the degree of blockade at the time of reversal. ⋯ Total recovery time (spontaneous recovery plus reversal time) was not shortened by an early injection of neostigmine. It is concluded that neostigmine administration during intense neuromuscular blockade following atracurium infusion does not shorten total recovery time and offers no clinical advantages.
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The influence of halothane and isoflurane on alpha-adrenergic-mediated vasoconstriction before and following calcium channel modulation was investigated in chronically instrumented dogs. After ganglionic, cholinergic, and beta-adrenergic blockade, systemic hemodynamic responses following equieffective pressor doses of phenylephrine (0.6 micrograms/kg iv), a selective alpha 1 agonist, and azepexole [B-HT 933] (20 micrograms/kg iv), a selective alpha 2 agonist, were obtained. The calcium channel stimulator Bay k 8644 (0.5 and 1 micrograms.kg-1.min-1) was infused intravenously for 10 min and phenylephrine and azepexole administered at the end of each infusion. ⋯ Halothane and isoflurane produced significant (P less than 0.05) attenuation of the increase in arterial pressure after bolus administration of phenylephrine and azepexole. Bay k 8644 augmented the pressor responses mediated by both phenylephrine and azepexole in all three groups. Thus, halothane and isoflurane nonselectively reduced the pressor response to both alpha 1- and alpha 2-adrenergic receptor stimulation and this was probably not mediated by inhibition of transmembrane calcium flux through dihydropyridine sensitive channels.
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Randomized Controlled Trial Comparative Study Clinical Trial
Postoperative apnea in former preterm infants: prospective comparison of spinal and general anesthesia.
Thirty-six former preterm infants undergoing inguinal hernia repair were studied. All were less than or equal to 51 weeks postconceptual age at the time of operation. Patients were randomly assigned to receive general or spinal anesthesia. ⋯ Two of these five infants had no prior history of apnea. When infants with no prior history of apnea were analyzed separately, there was no statistically significant increased incidence of apnea in children receiving general versus spinal anesthesia with or without ketamine sedation. Because of the small numbers of patients studied, and the multiple factors that may influence the incidence of postoperative apnea (e.g., prior history of neonatal apnea), standard postoperative respiratory monitoring of these high-risk infants is still recommended following all anesthetic techniques.
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Adverse outcomes associated with respiratory events constitute the single largest class of injury in the American Society of Anesthesiology Closed Claims Study (522 of 1541 cases; 34%). Death or brain damage occurred in 85% of cases. The median cost of settlement or jury award was +200,000. ⋯ The esophageal intubation group was notable for a recurring diagnostic failure: in 48% of cases where auscultation of breath sounds was performed and documented, this test led to the erroneous conclusion that the endotracheal tube was correctly located in the trachea. Claims for difficult tracheal intubation were distinguished by a comparatively small proportion of cases (36%) in which the outcome was considered preventable with better monitoring. A better understanding of respiratory risks may require investigative protocols that initiate data collection immediately upon the recognition of a critical incident or adverse outcome.