Anesthesiology
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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.
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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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Comparative Study
The blood/gas solubilities of sevoflurane, isoflurane, halothane, and serum constituent concentrations in neonates and adults.
To determine the effect of prematurity on the solubility of volatile anesthetics in blood, the authors measured the blood/gas partition coefficients of sevoflurane, isoflurane, and halothane and the serum concentrations of albumin, globulin, cholesterol, and triglycerides in umbilical venous blood from ten preterm and eight full-term neonates and in venous blood from eight fasting adult volunteers. The authors found that the blood/gas partition coefficient of sevoflurane did not differ significantly among the three age groups. The partition coefficients of isoflurane and halothane in preterm neonates did not differ significantly from those in full-term neonates. ⋯ The blood/gas partition coefficients of the three volatile anesthetics in preterm neonates did not change significantly with gestational age. The blood/gas partition coefficients of sevoflurane, isoflurane and halothane for all three age groups combined correlated only with the serum concentration of cholesterol. The authors conclude that the blood/gas partition coefficients of isoflurane, halothane, and sevoflurane in preterm neonates are similar to those in full term neonates and that gestational age does not significantly affect the blood/gas solubility.
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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.