Anesthesiology
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Comparative Study
Acute pain and central nervous system arousal do not restore impaired hypoxic ventilatory response during sevoflurane sedation.
To quantify the effects of acute pain on ventilatory control in the awake and sedated human volunteer, the acute hypoxic ventilatory response was studied in the absence and presence of noxious stimulation before and during 0.1 minimum alveolar concentration sevoflurane inhalation. ⋯ The observation that acute pain caused an increase in baseline ventilation with no effect on the acute hypoxic ventilatory response indicates that acute pain interacted with ventilatory control without modifying the effect of low-dose sevoflurane on the peripheral chemoreflex loop. Acute pain increased the level of arousal significantly during sevoflurane inhalation but did not restore the approximately 30% depression of the acute hypoxic ventilatory response by sevoflurane. The central nervous system arousal state per se did not contribute to the impairment of the acute hypoxic ventilatory response by sevoflurane.
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Comparative Study
Heparinase I (neutralase) reversal of systemic anticoagulation.
Protamine causes multiple adverse reactions. Heparinase I, a specific enzyme that inactivates heparin, is a possible alternative to protamine. In this study, the authors examined the efficacy of heparinase I to reverse heparin-induced anticoagulation in vitro and compared heparinase I to protamine as an antagonist of heparin-induced anticoagulation in dogs. ⋯ Both heparinase I and protamine effectively reversed heparin anticoagulation. However, as opposed to protamine, heparinase I did not produce any significant hemodynamic changes when given as a bolus to dogs.
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Comparative Study
Phenylephrine increases cerebral blood flow during low-flow hypothermic cardiopulmonary bypass in baboons.
Although low-flow cardiopulmonary bypass (CPB) has become a preferred technique for the surgical repair of complex cardiac lesions in children, the relative hypotension and decrease in cerebral blood flow (CBF) associated with low flow may contribute to the occurrence of postoperative neurologic injury. Therefore, it was determined whether phenylephrine administered to increase arterial blood pressure during low-flow CPB increases CBF. ⋯ Although low-flow CPB resulted in a marked decrease in CBF compared with prebypass and full-flow bypass, phenylephrine administered to double arterial pressure during low-flow bypass produced a proportional increase in CBF.
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Volatile anesthetics, such as halothane and isoflurane, have been reported to affect the endothelium mediated relaxation of vascular smooth muscle cells. Because the activity of the constitutive nitric oxide synthase in endothelial cells depends on the availability of intracellular Ca2+, there is a definite possibility that the observed inhibitory effect of volatile anesthetics involves an action on the agonist-evoked internal Ca2+ mobilization and/or Ca2+ influx in these cells. Therefore, a study was undertaken to determine how halothane and isoflurane affect the Ca2+ signalling process in vascular endothelial cells. ⋯ These observations suggest that the effects of halothane and isoflurane on Ca2+ homeostasis in BAE cells reflect, for the most part, a reduction of the thapsigargin- or bradykinin-evoked Ca2+ influx, which would be consequent to a cellular depolarization caused by an inhibition of the Ca(2+)-dependent K+ channel activity initiated after cell stimulation.