Anesthesia and analgesia
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Anesthesia and analgesia · Mar 2005
Cardiac arrest during neuraxial anesthesia: frequency and predisposing factors associated with survival.
The frequency and predisposing factors associated with cardiac arrest during neuraxial anesthesia remain undefined, and the survival outcome data are contradictory. In this retrospective study, we evaluated the frequency of cardiac arrest, as well as the association of preexisting medical conditions and periarrest events with survival after cardiac arrest during neuraxial anesthesia between 1983 and 2002. To assess whether survival after cardiac arrest differs for patients who arrest during neuraxial versus general anesthesia, data were also obtained for patients who experienced cardiac arrest under general anesthesia during similar surgical procedures during the same time interval. ⋯ Hospital survival was significantly improved for patients who arrested during neuraxial anesthesia versus general anesthesia (65% vs 31%; P = 0.013). The association of improved survival with neuraxial anesthesia remained statistically significant after adjusting for all patient/procedural characteristics, with the exception of ASA classification and emergency procedures. We conclude that a cardiac arrest during neuraxial anesthesia is associated with an equal or better likelihood of survival than a cardiac arrest during general anesthesia.
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Anesthesia and analgesia · Mar 2005
The effects of propofol or sevoflurane on the estimated cerebral perfusion pressure and zero flow pressure.
The zero flow pressure (ZFP) is the pressure at which blood flow ceases through a vascular bed. Using transcranial Doppler ultrasonography, we investigated the effects of propofol or sevoflurane on the estimated cerebral perfusion pressure (eCPP) and ZFP in the cerebral circulation. Twenty-three healthy patients undergoing nonneurosurgical procedures under general anesthesia were studied. ⋯ The eCPP decreased significantly in the propofol group (median, from 58 to 41 mm Hg) but not in the sevoflurane group (from 60 to 62 mm Hg). Correspondingly, ZFP increased significantly in the propofol group (from 25 to 33 mm Hg) and it decreased significantly in the sevoflurane group (from 27 to 7 mm Hg). Hypocapnia did not change eCPP or ZFP in the propofol group, but it significantly decreased eCPP and increased ZFP in the sevoflurane group.
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Anesthesia and analgesia · Mar 2005
Enantioselective actions of bupivacaine and ropivacaine on coronary vascular resistance at cardiotoxic concentrations.
The main concern with the use of the long-acting local anesthetics bupivacaine and ropivacaine is inadvertent IV injection, which exposes the heart to toxic drug concentrations. We tested the hypothesis that these chiral anesthetics exert enantioselective actions on coronary vascular tone, the regulation of which does not involve voltage-gated Na(+) channels. Coronary perfusion pressure (CPP) was continuously measured in isolated hearts perfused via the aorta at a constant flow rate. ⋯ We also showed that the putative uncoupler bupivacaine did not depolarize mitochondria in intact ventricular myocytes. In conclusion, the long-acting local anesthetics have enantioselective actions on coronary resistance vessels. Racemic bupivacaine and R(+)-bupivacaine are coronary vasodilators, whereas S(-)-bupivacaine, S(-)-ropivacaine and, to a lesser extent, R(+)-ropivacaine all induce coronary vasoconstriction.