Journal of critical care
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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
Comparative StudyThe effect of adrenergic agonists on the systemic response to hemorrhage.
Systemic blood loss elicits a variety of reflex cardiovascular responses, which preserve cardiac output as possible and preserve arterial blood pressure when cardiac output decreases. When compensatory venoconstriction is exhausted, hemorrhage reduces oxygen delivery (QO2), and systemic vasoconstriction competes with local metabolic vasodilation to preserve tissue oxygen uptake (VO2). Through their effects on vascular tone and blood flow distribution, adrenergic agents might interfere with the physiological responses to reduced O2 delivery. This study was designed to determine the effects of dobutamine and norepinephrine on oxygen extraction and systemic vascular resistance during progressive hemorrhage. ⋯ Norepinephrine and dobutamine appear to block reflex vasoconstriction, and mechanistic explanations for this finding remain speculative. Despite inhibition of reflex vasoconstriction, neither dobutamine nor norepinephrine significantly impaired oxygen extraction during hemorrhage.
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Journal of critical care · Mar 1994
Hormonal profiles in a canine model of the brain-dead organ donor.
The aim of the present study was to determine the effect of brain death on the circulating hormone levels. ⋯ The operative procedure alone led to the decrease in the plasma thyroid hormone levels. The inability of the BD group to increase plasma CORT, NE, and EPI may contribute to the hemodynamic deterioration and eventual somatic death.
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Journal of critical care · Dec 1993
A physical chemical approach to the analysis of acid-base balance in the clinical setting.
We evaluated the clinical application of a model of acid-base balance, which is based on quantitative physical chemical principles (Stewart model). This model postulates that acid-base balance is normally determined by the difference in concentration between strong cations and anions (strong ion difference [SID]), PCO2, and weak acids (primarily proteins). We measured electrolytes and blood gases in arterial blood samples from 21 patients in a medical or surgical intensive care unit or emergency room of a tertiary care hospital. ⋯ It could also be calculated from the difference between the standard Siggaard-Anderson calculation of base excess and base excess attributable to free water, [Cl-], and proteins (ie, base-excess gap). Our results indicate that the SID gap, base excess gap, and anion gap reflect the presence of unmeasured ions, and both the anion-gap and base-excess gap provide readily available estimates of the SID gap. This provides a simple bedside approach for using the Stewart model to analyze the nonrespiratory component of clinical acid-base disorders and indicates that, in addition to unmeasured anions, unmeasured cations can be present.
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Journal of critical care · Dec 1993
Comparative StudyImportance of tonicity of carbicarb on the functional and metabolic responses of the acidotic isolated heart.
In this study, the physiological and metabolic effects of Carbicarb administered as an isotonic (150 mmol/L Na[n[]I+) or hypertonic (1 mol/L Na[n[]I+) solution over 2 minutes in the acidotic isolated heart were compared. Physiological monitoring as well as 31P and 23Na nuclear magnetic resonance spectroscopy were performed. Both isotonic and hypertonic Carbicarb induced comparable dose-dependent increases in intracellular pH as well as decreases in inorganic phosphate and increases in creatine phosphate concentrations, which were sustained for 20 minutes. ⋯ In this setting, hypertonic Carbicarb induced a large transient increase in cytosolic sodium, whereas isotonic Carbicarb caused immediate and sustained decreases in cytosolic sodium. These data suggest that isotonic Carbicarb may have more beneficial effects on cardiac function than hypertonic Carbicarb. These effects may be related to associated changes in cytosolic sodium.