Journal of critical care
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Journal of critical care · Jun 1994
Implications of a biphasic two-compartment model of constant flow ventilation for the clinical setting.
To investigate the theoretical effects of changing frequency (f), duty cycle (D), or end-inspiratory pause length on the distribution of ventilation and compartmental pressure in a heterogeneous, two compartment pulmonary model inflated by constant flow. ⋯ In a linear, two compartment model of the respiratory system, disparity of compartmental end-expiratory pressures is the primary mechanism by which changes of f, D, or pause alter the distribution of ventilation during inflation with constant flow. Ventilation is less evenly distributed than peak alveolar pressure, and there are limits to the beneficial effects on the distribution of ventilation to be gained from manipulations of machine settings.
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Journal of critical care · Jun 1994
Hemodynamic effects following injection of venom from the scorpion Leiurus quinquestriatus.
The present study tested the hypothesis that scorpion sting induces left ventricular (LV) hypokinesia and myocardial ischemia shortly after injection due to reduction of coronary blood flow (CBF) and increased oxygen demand. ⋯ Myocardial ischemia does not occur in this dog model immediately following administration of scorpion venom. There are significant peripheral circulatory effects of the venom, which account for many of the hemodynamic changes.
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The dose-response relationship of commercially available preparations of methohexital, pentobarbital, phenobarbital, and thiopental and their respective drug-free solutions on granulocyte function was investigated to evaluate whether suppression of neutrophil chemiluminescence is mediated by the barbiturates themselves or by their drug-free solutions. Furthermore, it was assessed whether suppression of chemiluminescence is due to an interaction mainly with neutrophils or to free radical scavenging. ⋯ With the exception of thiopental, barbiturates do not impair oxygen radical production during phagocytosis of neutrophils.
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Journal of critical care · Mar 1994
Comparative StudyThe effects of intravenous L-arginine supplementation on systemic and pulmonary hemodynamics and oxygen utilization during group B streptococcal sepsis in piglets.
In these investigations, three questions were addressed. First, to what extent did inhibition of endothelium-derived relaxation factor (EDRF) mimic the hemodynamic disturbances noted in a piglet model of neonatal group B streptococcal (GBS) sepsis? Second, to what extent would an attempt to augment EDRF production reverse the hemodynamic effects of continued GBS infusion in septic piglets? Third, to what extent would an attempt to augment EDRF production affect hemodynamics in piglets who were not septic. ⋯ EDRF inhibition with NNLA appeared to model GBS infusion partially but not completely. L-ARG appeared to produce desirable hemodynamic effects during GBS sepsis when compared with the consequences of ongoing GBS infusion without L-ARG. Given the constellation of increased pulmonary and systemic vascular resistance often observed during neonatal GBS sepsis in human infants, all these effects of L-ARG, if extrapolated from our piglets to the clinical arena, would appear to be beneficial. Particularly in the context of deleterious consequences resulting shunting or right ventricular decompensation from increased afterload), L-ARG administration might prove clinically useful.
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Journal of critical care · Mar 1994
ReviewReport of the American-European Consensus conference on acute respiratory distress syndrome: definitions, mechanisms, relevant outcomes, and clinical trial coordination. Consensus Committee.
The acute respiratory distress syndrome (ARDS), a process of nonhydrostatic pulmonary edema and hypoxemia associated with a variety of etiologies, carries a high morbidity rate, mortality rate (10% to 90%), and financial cost. The reported annual incidence in the United States is 150,000 cases, but this figure has been challenged and may be different in Europe. ⋯ The European American Consensus Committee on ARDS was formed to focus on these issues and on the pathophysiologic mechanisms of the process. It was felt that international coordination between North America and Europe in clinical studies of ARDS was becoming increasingly important to address the recent plethora of potential therapeutic agents for the prevention and treatment of ARDS.