Anesthesiology
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Propofol is a common sedative hypnotic for the induction and maintenance of anesthesia. Clinicians typically moderate the dose of propofol or choose a different sedative hypnotic in the setting of severe intravascular volume depletion. Previous work has established that hemorrhagic shock influences both the pharmacokinetics and pharmacodynamics of propofol in the rat. To investigate this further, the authors studied the influence of hemorrhagic shock on the pharmacology of propofol in a swine isobaric hemorrhage model. ⋯ Hemorrhagic shock altered the pharmacokinetics and pharmacodynamics of propofol. Changes in intercompartmental clearances and an increase in the potency of propofol suggest that less propofol would be required to achieve a desired drug effect during hemorrhagic shock.
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Experimental and clinical studies have shown reduction in intrapulmonary shunt with improved oxygenation by spontaneous breathing with airway pressure release ventilation (APRV) in acute lung injury. The mechanisms of these findings are not clear. The authors hypothesized that spontaneous breathing results in better aeration of lung tissue and that improvement in oxygenation can be explained by these changes. This hypothesis was studied in a porcine model of oleic acid-induced lung injury. ⋯ The results support the hypothesis that spontaneous breathing during APRV improves oxygenation mainly by recruitment of nonaerated lung and improved aeration of the lungs.
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The authors determined the incidence of cardiac arrest and predictors of survival following perioperative cardiac arrest in a large population of patients at a tertiary referral center. ⋯ The overall frequency of arrest for patients receiving anesthesia decreased during the study period. Most arrests were not due to anesthesia-related causes, and most patients experiencing anesthesia-related arrest survived to hospital discharge. Although many factors determining survival may not be amenable to modification, the fact that arrests during nonregular working hours had worse outcomes may indicate that the availability of human resources influences survival.
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Developmental differences in short- and long-term responses to pain, especially surgical pain, have received minimal attention. The purpose of the present study was to examine postoperative responses in rats of developmental ages paralleling the infant to young adult human. ⋯ The more rapid recovery of the younger animals from the mechanical allodynia but not thermal hypersensitivity after surgery suggests the presence of developmental differences in modulation of A-fiber sensitization after surgery. However, the lack of age difference in recovery of thermal hypersensitivity after surgery suggests that sensitization of C-fiber input has a similar time course of resolution of pain over the ages studied in this model. The neural bases for these developmental differences are under study and may lead to a better understanding of pain during development and altered approaches to treatment of postoperative pain in neonates and infants.
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Editorial Comment
Is routine endotracheal intubation as safe as we think or wish?