Anesthesiology
-
Multicenter Study Clinical Trial
Electrocardiographic and hemodynamic changes and their association with myocardial infarction during coronary artery bypass surgery. A multicenter study. Multicenter Study of Perioperative Ischemia (McSPI) Research Group.
Electrocardiographic (ECG) changes during coronary artery bypass graft surgery have not been described in detail in a large multicenter population. The authors describe these ECG changes and evaluate them, along with demographic and clinical characteristics and intraoperative hemodynamic alterations, as predictors of myocardial infarction (MI) as defined by two sets of criteria. ⋯ Major ECG changes occurred in 58% of patients during coronary artery bypass graft surgery, primarily within 8 h after release of aortic occlusion. Multicenter data collection revealed a substantial variation in the incidence of MI and an overall incidence of up to 25%, with most MI occurring within 16 h after release of aortic occlusion. Intraoperative monitoring of ECG and hemodynamics has incremental value for predicting MI.
-
Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of cuffed and uncuffed endotracheal tubes in young children during general anesthesia.
Uncuffed endotracheal tubes are routinely used in young children. This study tests a formula for selecting appropriately sized cuffed endotracheal tubes and compares the use of cuffed versus uncuffed endotracheal tubes for patients whose lungs are mechanically ventilated during anesthesia. ⋯ Our formula for cuffed tube selection is appropriate for young children. Advantages of cuffed endotracheal tubes include avoidance of repeated laryngoscopy, use of low fresh gas flow, and reduction of the concentration of anesthetics detectable in the operating room. We conclude that cuffed endotracheal tubes may be used routinely during controlled ventilation in full-term newborns and children during anesthesia.
-
After bolus doses of nondepolarizing muscle relaxants, the adductor pollicis recovers from paralysis more slowly than the diaphragm and the laryngeal adductors, suggesting that the adductor pollicis is more sensitive than the respiratory muscles to effects of those drugs. In contrast, during onset, the respiratory muscles are paralyzed more rapidly than the adductor pollicis, suggesting that the respiratory muscles are more sensitive than the adductor pollicis. To reconcile these apparently conflicting findings, we determined vecuronium's pharmacokinetics and its pharmacodynamics at both the adductor pollicis and the laryngeal adductors. ⋯ More rapid equilibration between plasma and laryngeal adductor vecuronium concentrations explains why onset is more rapid at the laryngeal adductors than at the adductor pollicis. During recovery, both rapid equilibration and lesser sensitivity of the laryngeal adductors contribute to earlier recovery.
-
Comparative Study
In vivo imaging of nitrous oxide-induced changes in cerebral activation during noxious heat stimuli.
Although previous studies have provided some insight into the pharmacologic aspects of nitrous oxide analgesia, the neural circuits mediating its antinociceptive effect remain relatively unexplored. Position emission tomography was used in nine volunteers to identify the loci of nitrous oxide-modulated cerebral responses to a peripheral noxious stimulus. ⋯ Nitrous oxide, at 20% concentration, appears to modulate pain processing in the brain's medial pain system, and also activates the infralimbic and orbitofrontal cortices. The potential contribution of the affected brain areas to nitrous oxide analgesia is discussed.
-
General anesthetics are thought to produce their hypnotic effects mainly by acting at ligand-gated ionic channels in the central nervous system (CNS). Although it is well established that volatile anesthetics significantly modify the activity of the acetylcholine nicotinic receptors of the neuromuscular junction, little is known about their actions on the acetylcholine receptors in the CNS. In this study, the effects of halothane and isoflurane on the regulation of dopamine (DA) (gamma-aminobutyric acid [GABA]) depolarization-evoked release mediated by nicotinic (muscarinic) presynaptic receptors were studied in the rat striatum. ⋯ Clinically relevant concentrations of halothane and isoflurane significantly, but differentially, alter the presynaptic cholinergic regulation of the release of inhibitory neurotransmitters in the striatum. These results suggest that the cholinergic transmission may represent an important and specific presynaptic target for volatile anesthetics in the CNS.