Inotropic drugs in acute circulatory failure

The use of inotropic drugs in patients requiring acute circulatory support is reviewed. A knowledge of their various peripheral effects is essential if the appropriate drug is to be used.The place of pressor amines, digitalis, salbutamol and glucagon in the treatment of patients with poor tissue perfusion is limited. Of the catecholamines, adrenaline causes excessive renal vasoconstriction and peripheral gangrene, noradrenaline increases myocardial work and diminishes peripheral perfusion and isoprenaline distributes blood away from the vital organs, namely: brain, kidneys, heart and mesentery. Dopamine is a useful agent as it enhances renal blood flow in low doses and is not excessively chronotropic. Dobutamine has not yet been shown to have significant advantages over other inotropes and requires further examination.     

Shock index in diagnosing early acute hypovolemia

OBJECTIVE: The aim of this study was to determine the hemodynamic response and calculated shock index (SI=heart rate [HR]/systolic blood pressure [SBP]) in early acute blood loss. METHODS: This was a prospective observational study that enrolled healthy blood donors. Patients were excluded if not eligible for blood donation. Baseline vital signs were obtained, 450 mL of blood was removed over 20 minutes, and vital signs were repeated immediately postdonation while lying and after 1 and 5 minutes of standing. Difference was tested using a paired t test with P<.01 set for significance. RESULTS: Forty-six patients were enrolled; means for each time interval are shown below with 95% confidence intervals. CONCLUSIONS: A significant elevation in mean SI was observed in healthy volunteers after standing for 1 and 5 minutes. Although significant changes in HR and SBP were observed, these indices were still within "normal" limits. The SI may be more useful in early hemorrhage than either the HR or SBP alone.     

Place of vasoactive agents in the treatment of acute circulatory failure

Increase in total cardiac output can improve oxygen delivery to the cells. Although inotropic drugs increase primarily myocardial contractility, they can adversely affect cardiac preload and afterload. Moreover, they can dangerously increase myocardial oxygen requirements. The combined use of vasodilating agents, with fluid challenge represents a challenging but more efficient treatment of acute circulatory failure.     

急性循环衰竭中国急诊临床实践专家共识

1 概述 急性循环衰竭(acute circulatory failure,ACF),是指由于失血、细菌感染等多种原因引起的急性循环系统功能障碍,以致氧输送不能保证机体代谢需要,从而引起细胞缺氧的病理生理状况[1-2].休克是急性循环衰竭的临床表现,常常导致多器官功能衰竭,并具有较高的病死率[2].换言之,休克的最佳定义即是急性循环衰竭[3].     

Relationship between blood lactate and early hepatic dysfunction in acute circulatory failure

The purpose of this study was to assess the influence of early hepatic dysfunction on lactate level in patients with acute circulatory failure in a retrospective study. Blood lactate was compared between patients in acute circulatory failure (systolic blood pressure ≤ 80 mm Hg despite fluid challenge) with or without early hepatic dysfunction (bilirubin> 60 μmol/L or SGOT> 100 IU/L during the first 48 hours). Univariate and multivariate analysis were performed to assess the effects of early hepatic dysfunction and other clinical and biological data on serum lactate levels in patients with acute circulatory failure. The study included 92 patients, mean age 64 ± 15 years, mean simplified acute physiology score (SAPS) 18.4 ± 4.1. Early hepatic dysfunction was identified in 29 patients (32%). Mean initial blood lactate was 5.54 ± 4.78 mmol/L. Overall intensive care unit mortality was 67.3%. Although patients with and without hepatic dysfunction showed no significant difference in terms of mean SAPS, mean lowest systolic b blod pressure, and mortality, serum lactate was higher in the group with hepatic dysfunction than in the group without hepatic dysfunction (8.24 ± 6.49 mmol/L v 4.29 ± 3.09 mmol/L, P < .001). Factors independently associated with serum lactate were the existence of early hepatic dysfunction (P < .01), a nondistributive type of shock (P < .05), and the mean initial amount of epinephrine (P < .05). This study suggests that early hepatic dysfunction plays an important role in serum lactate elevation in acute circulatory failure.     

Toe temperature versus transcutaneous oxygen tension monitoring during acute circulatory failure

Measurements of toe temperature and transcutaneous PO₂ (P_tcO₂) have been both suggested for non-invasive assessment of peripheral blood flow in acute circulatory failure. The underlying principle of the two methods is that cutaneous vasoconstriction occurs early when tissue perfusion is altered. In 15 patients, we compared the two measurements during cardiogenic shock (27 measurements) or septic shock (29 measurements). Toe-ambiant temperature gradient and P_tcO₂ correlated well together (r=0.66, p(0.001) especially in hyperkinetic septic shock (r=0.79, p(0.001). In cardiogenic shock, toe-ambiant temperature correlated well with cardiac index (r=0.63), stroke index (r=0.64) and oxygen transport (r=0.65), and these correlations were stronger than for P_tcO₂. In septic shock, both techniques were poor indicators of blood flow indexes but P_tcO₂ rather correlated with arterial pressure (r=0.66) and left ventricular work (r=0.66). Trend evaluation of data revealed in cardiogenic shock that the increase in toe temperature usually preceded the increase in P_tcO₂. Since measurement of P_tcO₂ is technically more complicated, correlates less well with standard hemodynamic parameters and later reflects cardiovascular improvement, it has no advantage over measurement of toe temperature in circulatory shock. In cardiogenic shock, measurements of toe temperature can reliably track cardiac output changes. In septic states, however, non-invasive assessment of skin perfusion is of limited interest.     

Ultrasonic phlebography in circulatory failure

Ultrasound phlebography was used in 67 patients with circulatory failure and 40 normal persons to study the linear parameters of the abdominal veins. The parallelism was revealed between the intensity of circulatory failure and reduction of the changes in the main venous vessels during the respiratory test with the body being in the horizontal and vertical positions. Ultrasound phlebography of the inferior vena cava and liver veins makes it possible to establish circulatory failure in the greater circulation at an early stage. The examination of the portal veins appeared to be of the informative value only at late stages of circulatory failure.     

急性有机磷中毒致循环衰竭的血流动力学变化

目的：研究急性有机磷中毒（AOPP）致循环衰竭患者的血流动力学变化。方法：总结26例AOPP致循环衰竭患者48h内的血流动力学变化,并分析生存者与死亡者的差别。结果：与正常参考均值比较：SVI、LVSWI在48h内显著降低（P％0．01）;RVSWI在24h内显著降低（P〈0．01）;CI在16h内显著降低（P〈0．01）。与同组2h比较,生存者的CI、SVI、LVswI／RVswI在24h后明显改善（P〈0．05或P〈0．01）,血乳酸显著降低（P〈0．05或P〈0．01）;死亡者无改善。结论：AOPP致循环衰竭患者的心脏做功能力明显受损,治疗后生存者状况可以改善。     

不同年龄组患者休克指数在急性消化道出血中的应用

目的通过分析老年、非老年急性消化道出血患者休克指数（ SI）的变化,寻找不同年龄组急性消化道出血患者SI的最佳诊断切点。方法回顾2013-01～2014-01收治消化内科疑似急性消化道出血的患者,收集入院时监测的各项生命体征、年龄和性别资料。计算患者的SI值,并按照是否＞65岁划分为老年组和非老年组,进行SI的差异性分析。结果共收集200例疑似急性消化道出血患者的资料,急性消化道出血患者46例。非老年组80例,其中急性消化道出血患者17例;老年组120例,急性消化道出血患者29例;按照标准的SI切点（SI＞0．90）被认为存在急性消化道出血,敏感度（Sens）65．2％,特异度（Spec）87．7％,约登指数（Youden’s）52.9％;老年组更低的SI切点（ SI≥0．80：Sens 79．3％,Spec 90．1％、Youden’ s 69．4％）对判断急性消化道出血更好,可以减少漏诊率。结论更低的SI切点（ SI≥0．8）能更早识别老年患者急性消化道出血,提前做好抢救准备。