Journal of critical care
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Journal of critical care · Dec 1993
Absence of supply dependence of oxygen consumption in patients with septic shock.
We tested whether oxygen consumption (VO2) was dependent on oxygen delivery (QO2) in 10 patients with septic shock when QO2 was changed by the use of the inotropic agent, dobutamine. The mean acute physiology and chronic health evaluation (APACHE) II score of the patients was 27.3 +/- 8.1 with a mean blood pressure on entry of 66.8 +/- 12.4 mm Hg, and all had been volume resuscitated to a pulmonary artery occlusion pressure of greater than 10 mm Hg. We measured VO2 by analysis of respiratory gases (VO2G) while calculating VO2 by the Fick equation (VO2F) at three different O2 deliveries. ⋯ Neither lactic acidosis nor acute respiratory distress syndrome (ARDS) conferred supply dependence of VO2G, but the presence of ARDS was predictive of death in this cohort. It is concluded that VO2 is independent of QO2 in patients with septic shock and lactic acidosis. These data confirm that maximizing QO2 beyond values achieved by initial fluid and vasoactive drug resuscitation of septic shock does not improve tissue oxygenation as determined by respiratory gas measurement of VO2.
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Journal of critical care · Dec 1993
Comparative StudyEffect of pretreatment with anticonvulsants on theophylline-induced seizures in the rat.
Seizures, often with fatal outcome, are a manifestation of pronounced theophylline toxicity. Prodromal symptoms are not always apparent, and the seizures are reported to be, in certain cases, refractory to treatment with anticonvulsant drugs. The purpose of this investigation was to examine, by an established animal model, which of the commonly used anticonvulsants can reduce the central nervous system sensitivity to theophylline neurotoxicity and what should be the preferred treatment in cases in which theophylline toxicity is anticipated. ⋯ Theophylline concentrations in the cerebrospinal fluid, brain, and serum were assayed by a high-performance liquid chromatography method. It was found that pretreatment with either clonazepam, diazepam, phenobarbital, or valproic acid increased the central nervous system thresholds to the theophylline-induced seizures, whereas phenytoin and magnesium sulphate did not attenuate the sensitivity of the brain to the stimulatory action of this widely used bronchodilator. Therefore, whenever theophylline toxicity is suspected, treatment with either diazepam, clonazepam, phenobarbital, or valproic acid can reduce the hazard associated with theophylline-induced seizures.