Anesthesiology
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Comparative Study
Measurement of carboxyhemoglobin and methemoglobin by pulse oximetry: a human volunteer study.
A new eight-wavelength pulse oximeter is designed to measure methemoglobin and carboxyhemoglobin, in addition to the usual measurements of hemoglobin oxygen saturation and pulse rate. This study examines this device's ability to measure dyshemoglobins in human volunteers in whom controlled levels of methemoglobin and carboxyhemoglobin are induced. ⋯ The Masimo Rad-57 is the first commercially available pulse oximeter that can measure methemoglobin and carboxyhemoglobin, and it therefore represents an expansion of our oxygenation monitoring capability.
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Comparative Study
Performance characteristics of five new anesthesia ventilators and four intensive care ventilators in pressure-support mode: a comparative bench study.
During the past few years, many manufacturers have introduced new modes of ventilation in anesthesia ventilators, especially partial-pressure modalities. The current bench test study was designed to compare triggering and pressurization of five new anesthesia ventilators with four intensive care unit ventilators. ⋯ Regarding trigger sensitivity and the system's ability to meet inspiratory flow during pressure-supported breaths, the most recent anesthesia ventilators have comparable performances of recent-generation intensive care unit ventilators.
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Whether isoflurane preconditioning produces delayed neuroprotection in the spinal cord is unclear. The authors tested the hypothesis that isoflurane produces delayed preconditioning against spinal cord ischemic injury and, further, that the beneficial effect is dependent on free radicals. ⋯ Isoflurane produces delayed preconditioning against spinal cord ischemic injury, and the beneficial effect may be dependent on the release of free radicals.
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Mask ventilation is an essential element of airway management that has rarely been studied as the primary outcome. The authors sought to determine the incidence and predictors of difficult and impossible mask ventilation. ⋯ The authors observed the incidence of grade 3 MV to be 1.4%, similar to studies with the same definition of difficult MV. Presence of a beard is the only easily modifiable independent risk factor for difficult MV. The mandibular protrusion test may be an essential element of the airway examination.
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Local anesthetics exert central nervous system (CNS) toxicity by inhibiting intracerebral neuronal activity, while epinephrine augments the CNS toxicity of intravenously administered local anesthetics. Viewed together, increases of extracellular concentrations of local anesthetics in the brain may be directly associated with increased CNS toxicity. The authors examined the hypothesis that epinephrine enhances the CNS toxicity of lidocaine by increasing the extracellular concentration in the brain. ⋯ Concomitant administration of epinephrine significantly enhanced the CNS toxicity of intravenously administered lidocaine. Increased extracellular concentration in the brain would be related to this mechanism.