Anesthesia and analgesia
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Anesthesia and analgesia · Mar 2013
Treatment with a highly selective β₁ antagonist causes dose-dependent impairment of cerebral perfusion after hemodilution in rats.
Acute β-blockade has been associated with a dose-dependent increase in adverse outcomes, including stroke and mortality. Acute blood loss contributes to the incidence of these adverse events. In an attempt to link the risks of acute blood loss and β-blockade, animal studies have demonstrated that acute β-blockade impairs cerebral perfusion after hemodilution. We expanded on these findings by testing the hypothesis that acute β-blockade with a highly β(1)-specific antagonist (nebivolol) causes dose-dependent cerebral hypoxia during hemodilution. ⋯ Our data demonstrate that nebivolol resulted in a dose-dependent decrease in cerebral oxygen delivery after hemodilution as reflected by a decrease in brain tissue Po(2) and an increase in hypoxic protein responses (HIF-1α and nNOS). Low-dose nebivolol treatment did not result in worsened tissue hypoxia after hemodilution, despite comparable effects on HR and CO. These data support the hypothesis that acute β-blockade with a highly β(1)-specific antagonist causes a dose-dependent impairment in cerebral perfusion during hemodilution.
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Anesthesia and analgesia · Mar 2013
Magnetic interference of cardiac pacemakers from a surgical magnetic drape.
Sterile magnetic drapes are frequently used during surgery to hold metal instruments on the sterile field. Magnetic fields may potentially interfere with the function of cardiovascular implantable electronic devices such as pacemakers and implantable cardioverter defibrillators. In this study, we evaluated the potential magnetic interference of magnetic drapes on pacemaker function. ⋯ Magnetic drapes may cause magnetic interference with cardiac pacemakers, and this interference ceases at a caudal distance of 15 cm. Magnetic interference seems more likely in patients with lower body weight. Careful monitoring of the pulse and electrocardiogram for asynchronous pacing activity should be considered when magnetic drapes are used in patients with cardiovascular implantable electronic devices.
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Anesthesia and analgesia · Mar 2013
Comparative StudyThe TaperGuard™ endotracheal tube intracuff pressure increase is less than that of the Hi-Lo™ tube during nitrous oxide exposure: a model trachea study.
Studies have compared sealing effects of the newly developed tapered endotracheal tube cuff with the conventional cylindrical cuff. In this study, we compared the difference between cuffs with regard to the increase in intracuff pressure during nitrous oxide (N(2)O) exposure. ⋯ During general anesthesia with N(2)O, the intracuff pressure of tapered endotracheal tube cuffs did not increase as rapidly as it did in conventional high-volume, low-pressure cuffs. The pressure in both types of cuffs increased rapidly when exposed to 66% N(2)O, and hence continuous or frequent monitoring is recommended.
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Anesthesia and analgesia · Mar 2013
Comparative StudyThe pyrrole etomidate analog carboetomidate potently inhibits human 5-HT3A receptor function: comparisons with etomidate and potential implications for emetogenesis.
5-Hydroxytryptamine type 3 (5-HT(3)) receptors are excitatory ion channels belonging to the cys-loop family of ligand-gated ion channels. They are involved in nausea and vomiting and their antagonists are used clinically as antiemetic drugs. We previously reported the development of a novel pyrrole analog of etomidate, (R)-ethyl 1-(1-phenylethyl)-1H-pyrrole-2-carboxylate (carboetomidate), which retains etomidate's desirable anesthetic and hemodynamic properties, but lacks its potent inhibitory effect on adrenocorticotropic hormone-stimulated steroid synthesis. Also in contrast to etomidate, carboetomidate potently inhibits nicotinic acetylcholine receptors. Because nicotinic acetylcholine and 5-HT(3) receptors are highly homologous, we hypothesized that carboetomidate might also potently inhibit 5-HT(3) receptors with potentially important implications for the drug's emetogenic activity. In the current studies, we investigated and compared modulation of 5-HT(3A) receptors by carboetomidate and etomidate. ⋯ In contrast to etomidate, carboetomidate inhibits 5-HT(3A) receptor-mediated currents at hypnotic concentrations. This inhibition is primarily the result of enhancing the rate of desensitization. Because carboetomidate potently inhibits 5-HT(3A) receptors, it may be less emetogenic than etomidate.
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Anesthesia and analgesia · Mar 2013
Randomized Controlled TrialDetection of tidal recruitment/overdistension in lung-healthy mechanically ventilated patients under general anesthesia.
The volume-dependent single compartment model (VDSCM) has been applied for identification of overdistension in mechanically ventilated patients with acute lung injury. In this observational study we evaluated the use of the VDSCM to identify tidal recruitment/overdistension induced by tidal volume (Vt) and positive end-expiratory pressure (PEEP) in lung-healthy anesthetized subjects. ⋯ The distension index %E(2), derived from the VDSCM considering flow-dependencies, seems able to identify tidal recruitment/overdistension induced by Vt and PEEP independent of flow waveform in healthy lung-anesthetized patients.