Circulatory shock
-
Review Comparative Study
High-dose corticosteroid therapy in human septic shock: has the jury reached a correct verdict?
Many studies have been published concerning high-dose corticosteroids (HDC) in septic shock. Most of them have been criticized for not adhering to methodologic standards. Four studies were published during the 1980s taking into consideration the criticism of previous trials. ⋯ The validity of the data presented is discussed. It is concluded that there is no unequivocal evidence that HDC is beneficial in septic shock, but it must be realized that there are tremendous difficulties in obtaining the true state of affairs in clinical trials regarding patients in septic shock. Accumulated data indicate that HDC, given as one single dose during the initial hours of gram-negative septic shock, more likely than not has a beneficial effect on mortality.
-
The cardiac mechanisms responsible for endotoxin-mediated disruptions in left ventricular (LV) contraction-relaxation dynamics have been controversial. Recently, a combination of clinical cardiodynamic studies in patients along with experimental cardiodynamic studies in endotoxemic/septic animals and isolated heart tissue has yielded corroborating evidence for a consistent deleterious alteration(s) of intrinsic LV contractility during shock syndromes. Cardiac dysfunction in shock patients and intact animals was characterized by reduced LV ejection fraction in the presence of unchanging LV stroke volume, or by reduced LV end-systolic pressure-volume ratio. ⋯ Cardiodynamic changes developed early in experimental septicemic shock syndromes (less than 4 hr) and were not irreversible. Furthermore, and this is a key element, both clinical and experimental study indicated that coronary perfusion inadequacy was not an obligatory etiologic factor in the shock-associated loss of cardiac contractile function. Thus, clinical and experimental data are now available to assemble a consensus that 1) intrinsic LV contractile reserves are diminished early during endotoxemia and sepsis and 2) this diminution is not simply a consequence of global myocardial ischemia.
-
Gram-negative septic shock remains a major clinical problem. One frequently encountered complication of sepsis is disseminated intravascular coagulation (DIC). The present study was to determine in an Escherichia coli endotoxemia awake rat model the efficacy of antithrombin-III (AT-III) prophylaxis and to explore the role of DIC in the pathogenesis of endotoxemia. ⋯ Results of this study suggest that AT-III prophylaxis is very protective above a threshold dosage in an endotoxemic rat model and that protection is in part due to ameliorating DIC. Our data also suggest that DIC occurs very early during endotoxemia and may in part be responsible for the pathogenesis of endotoxemia in the rat. We conclude that AT-III prophylaxis may be efficacious in conditions of impending DIC, such as gram-negative septicemia/endotoxemia.
-
Review Comparative Study
Oxygen consumption in septic shock: collective review.
That a decline in oxygen consumption (VO2) might herald onset of septic shock prior to hemodynamic collapse is suggested by previous observations in humans and animals in which VO2 appeared to be suppressed in systemic sepsis, despite normal or supranormal cardiac output, and in cellular and mitochondrial preparations exposed to endotoxin, despite adequate flow of perfusate. That a supranormal VO2 might be one of the best predictors of ultimate survival is suggested by data collected from humans during various stages of septic shock. To evaluate VO2 as an early indicator of sepsis, the effect of endotoxemia was observed in 20 rhesus monkeys divided into groups according to hypodynamic, normodynamic, and hyperdynamic blood flow states; the effect of sepsis was observed in seven preterminal septic humans during the final hours of their lives. ⋯ Probability of survival in sepsis appears to be enhanced by VO2 and cardiac output that are supranormal; yet even when VO2 is elevated, death can ensue within minutes to hours. Significant decline in VO2 is a grave prognostic sign, almost always preceded by a relatively easily detected hemodynamic change. Systemic VO2 appears to represent neither a specific early indicator of sepsis nor a certain prognosticator of survival outcome; it might provide useful information regarding adequacy of resuscitation.
-
Review Comparative Study
Effects of glucose-insulin-potassium (GIK) on myocardial blood flow and metabolism in canine endotoxin shock.
Glucose-insulin-potassium (GIK) has beneficial effects during endotoxin shock, possibly through improvement of myocardial function, but the mechanism is not clear. We have studied the effects of GIK on left ventricular function, coronary flow, and oxygen consumption in controls and dogs treated with endotoxin (1.5 mg/kg-1). The animals were anaesthetized (etomidate 4 mg/kg-1/hr-1) and ventilated (N2O:O2 = 2:1). ⋯ Endotoxin decreased the ratio of endo- to epicardial flow. GIK did not change this ratio. However, for the same endo to epi ratio, increased CBF implies increased flow to endocardium.