Anesthesia and analgesia
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Anesthesia and analgesia · Aug 2002
Case ReportsAccelerated idioventricular rhythm associated with desflurane administration.
The rapid administration of desflurane results in transient hypertension and tachycardia, especially in the presence of sympathetic imbalance. We report a case in which rapid administration of desflurane precipitated an accelerated idioventricular rhythm in a patient. This may have been related to a period of inadequate anesthesia.
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Anesthesia and analgesia · Aug 2002
Case ReportsSuccessful one-lung ventilation in a patient with aberrant tracheal bronchus.
We report a 47-yr-old patient who underwent surgery for esophageal cancer. Because of the isolated ventilation of the right upper lobe after occlusion of the right mainstem bronchus, bronchoscopic re-confirmation exposed an aberrant tracheal bronchus. A Fogarty tube was introduced to block the tracheal bronchus and provide one-lung ventilation.
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Anesthesia and analgesia · Aug 2002
Intraoperative tachycardia and hypertension are independently associated with adverse outcome in noncardiac surgery of long duration.
Relatively little is known about the influence of intraoperative hemodynamic variables on surgical outcomes. We drew subjects (n = 797) from a study of patients undergoing major noncardiac surgery. The physiological component of the POSSUM (Physiological and Operative Severity Score for the enUmeration of Mortality) operative risk stratification index was determined, and intraoperative measurements of heart rate (HR), mean arterial blood pressure, and systolic arterial blood pressure (SAP) were retrieved from computerized anesthesia records. For every 5-min epoch during the surgery, HR, mean arterial blood pressure, and SAP were each classified as low, normal, or high. Negative surgical outcome (NSO) was defined as a hospital stay of >10 days with a morbid condition or death during the hospital stay. Statistical analyses included Mantel-Haenszel tests and multiple logistic regression. There was no significant association between hemodynamic variables and NSO with short operations. In 388 patients with operations longer than the median time of 220 min, NSO occurred in 15.6%. Controlling for POSSUM score and operation time beyond 220 min, both high HR (odds ratio, 2.704; P = 0.01) and high SAP (odds ratio, 2.095; P = 0.009) were associated with NSO in longer operations. Thus, intraoperative tachycardia and hypertension were associated independently with adverse outcomes after major noncardiac surgery of long duration, over and above the risk imparted by underlying medical conditions. ⋯ Intraoperative tachycardia and hypertension were associated with negative postoperative outcomes after major noncardiac surgery of long duration. These results imply that intraoperative tachycardia and hypertension may have independent effects on outcome over and above the risk imparted by underlying medical conditions.
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Anesthesia and analgesia · Aug 2002
Case ReportsFalsely increased bispectral index values in a series of patients undergoing cardiac surgery using forced-air-warming therapy of the head.
Falsely increased bispectral index (BIS) values of >70 occur during forced-warm-air therapy in patients undergoing cardiac surgery. When forced-warm-air therapy for the head is used (as in ultra-fast-tracking cardiac patients), BIS interpretation needs careful examination. Falsely increased BIS values can easily be recognized when the warm-air flow is stopped. Within 2-3 min, BIS returns to a much lower, "true" value.
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Anesthesia and analgesia · Aug 2002
Characterization of the interactions between volatile anesthetics and neuromuscular blockers at the muscle nicotinic acetylcholine receptor.
Volatile anesthetics enhance the neuromuscular blockade produced by nondepolarizing muscle relaxants (NDMRs). The neuromuscular junction is a postulated site of this interaction. We tested the hypothesis that volatile anesthetic enhancement of muscle relaxation is the result of combined drug effects on the nicotinic acetylcholine receptor. The adult mouse muscle nicotinic acetylcholine receptor (alpha(2), beta, delta, epsilon) was heterologously expressed in Xenopus laevis oocytes. Concentration-effect curves for the inhibition of acetylcholine-induced currents were established for vecuronium, d-tubocurarine, isoflurane, and sevoflurane. Subsequently, inhibitory effects of NDMRs were studied in the presence of the volatile anesthetics at a concentration equivalent to half the concentration producing a 50% inhibition alone. All individually tested compounds produced rapid and readily reversible concentration-dependent inhibition. The calculated 50% inhibitory concentration values were 9.9 nM (95% confidence interval [CI], 8.4-11.4 nM), 43.4 nM (95% CI, 33.6-53.3 nM), 897 microM (95% CI, 699-1150 microM), and 818 microM (95% CI, 685-1001 microM) for vecuronium, d-tubocurarine, isoflurane, and sevoflurane, respectively. Coapplication of either isoflurane or sevoflurane significantly enhanced the inhibitory effects of vecuronium and d-tubocurarine, especially so at small concentrations of NDMRs. Volatile anesthetics increase the potency of NDMRs, possibly by enhancing antagonist affinity at the receptor site. This effect may contribute to the clinically observable enhancement of neuromuscular blockade by volatile anesthetics. ⋯ Isoflurane and sevoflurane enhance the receptor blocking effects of nondepolarizing muscle relaxants on nicotinic acetylcholine receptors.