Effects of dobutamine on splanchnic tissue perfusion during partial superior mesenteric artery occlusion

The Effects of Dobutamine in Septic Shock: An Updated Narrative Review of Clinical and Experimental Studies

The key objective in the hemodynamic treatment of septic shock is the optimization of tissue perfusion and oxygenation. This is usually achieved by the utilization of fluids, vasopressors, and inotropes. Dobutamine is the inotrope most commonly recommended and used for this purpose. Despite the fact that dobutamine was introduced almost half a century ago in the treatment of septic shock, and there is widespread use of the drug, several aspects of its pharmacodynamics remain poorly understood. In normal subjects, dobutamine increases contractility and lacks a direct effect on vascular tone. This results in augmented cardiac output and blood pressure, with reflex reduction in systemic vascular resistance. In septic shock, some experimental and clinical research suggest beneficial effects on systemic and regional perfusion. Nevertheless, other studies found heterogeneous and unpredictable effects with frequent side effects. In this narrative review, we discuss the pharmacodynamic characteristics of dobutamine and its physiologic actions in different settings, with special reference to septic shock. We discuss studies showing that dobutamine frequently induces tachycardia and vasodilation, without positive actions on contractility. Since untoward effects are often found and therapeutic benefits are occasional, its profile of efficacy and safety seems low. Therefore, we recommend that the use of dobutamine in septic shock should be cautious. Before a final decision about its prescription, efficacy, and tolerance should be evaluated throughout a short period with narrow monitoring of its wanted and side effects.

The spectrum of cardiovascular effects of dobutamine - from healthy subjects to septic shock patients

Dobutamine is the inotrope most commonly used in septic shock patients to increase cardiac output and correct hypoperfusion. Although some experimental and clinical studies have shown that dobutamine can improve systemic and regional hemodynamics, other research has found that its effects are heterogenous and unpredictable. In this review, we analyze the pharmacodynamic properties of dobutamine and its physiologic effects. Our goal is to show that the effects of dobutamine might differ between healthy subjects, in experimental and clinical cardiac failure, in animal models and in patients with septic shock. We discuss evidence supporting the claim that dobutamine, in septic shock, frequently behaves as a chronotropic and vasodilatory drug, without evidence of inotropic action. Since the side effects are very common, and the therapeutic benefits are unclear, we suggest that dobutamine should be used cautiously in septic shock. Before a definitive therapeutic decision, the efficacy and tolerance of dobutamine should be assessed during a brief time with close monitoring of its positive and negative side effects.

Acute bowel ischemia after heart operations

Acute bowel ischemia is a perioperative complication that is frequently unrecognized as a cause of death after cardiac surgical procedures, with an in-hospital mortality of 50% to 100%. In recent years, controversy regarding the most appropriate approach to resolve clinical or laboratory suspicion and the limited therapeutic options have led to very little improvement in patient prognosis. This article reviews the related literature examining the actual prevalence, pathophysiologic mechanisms, predisposing factors, diagnostic tests, and therapeutic approaches providing a glance at new promising tools in diagnostic workup.

Effects of dobutamine on systemic, regional and microcirculatory perfusion parameters in septic shock: a randomized, placebo-controlled, double-blind, crossover study

PURPOSE

The role of dobutamine during septic shock resuscitation is still controversial since most clinical studies have been uncontrolled and no physiological study has unequivocally demonstrated a beneficial effect on tissue perfusion. Our objective was to determine the potential benefits of dobutamine on hemodynamic, metabolic, peripheral, hepatosplanchnic and microcirculatory perfusion parameters during early septic shock resuscitation.

METHODS

We designed a randomized, controlled, double-blind, crossover study comparing the effects of 2.5-h infusion of dobutamine (5 mcg/kg/min fixed-dose) or placebo in 20 septic shock patients with cardiac index ≥2.5 l/min/m(2) and hyperlactatemia. Primary outcome was sublingual perfused microvascular density.

RESULTS

Despite an increasing cardiac index, heart rate and left ventricular ejection fraction, dobutamine had no effect on sublingual perfused vessel density [9.0 (7.9-10.1) vs. 9.1 n/mm (7.9-9.9); p = 0.24] or microvascular flow index [2.1 (1.8-2.5) vs. 2.1 (1.9-2.5); p = 0.73] compared to placebo. No differences between dobutamine and placebo were found for the lactate levels, mixed venous-arterial pCO2 gradient, thenar muscle oxygen saturation, capillary refill time or gastric-to-arterial pCO2 gradient. The indocyanine green plasma disappearance rate [14.4 (9.5-25.6) vs. 18.8 %/min (11.7-24.6); p = 0.03] and the recovery slope of thenar muscle oxygen saturation after a vascular occlusion test [2.1 (1.1-3.1) vs. 2.5 %/s (1.2-3.4); p = 0.01] were worse with dobutamine compared to placebo.

CONCLUSIONS

Dobutamine failed to improve sublingual microcirculatory, metabolic, hepatosplanchnic or peripheral perfusion parameters despite inducing a significant increase in systemic hemodynamic variables in septic shock patients without low cardiac output but with persistent hypoperfusion.

[Diagnosis and management of acute mesenteric ischemia]

The prevalence of significant splanchnic arterial stenoses is increasing, but remains mostly asymptomatic due to abundant collateral circulation. Acute insufficiency of mesenteric arterial blood flow accounts for 60 to 70% of cases of mesenteric ischemia and results mostly from a superior mesenteric embolus. Despite major advances have been achieved in understanding the pathogenic mechanisms of bowel ischemia, its prognosis remains dismal with mortality rates about 60%. The diagnosis of acute mesenteric ischemia depends upon a high clinical suspicion, especially in patients with known risk factors. Rapid diagnosis is essential to prevent intestinal infarction. However, early signs and symptoms of mesenteric ischemia are non specific, and definitive diagnosis often requires radiologic examinations. Early and liberal implementation of angiography has been the major advance over the past 30 years which allowed increasing diagnostic accuracy of acute mesenteric ischemia. CT and MR-based angiographic techniques have emerged as alternatives less invasive and more accurate to analyse splanchnic vessels and evaluate bowel infarction. The goal of treatment of patients with acute mesenteric ischemia is to restore intestinal oxygenation as quickly as possible after initial management that includes rapid hemodynamic monitoring and support. Surgery should not be delayed in patients suspected of having intestinal necrosis.

Effects of low abdominal blood flow and dobutamine on blood flow distribution and on the hepatic arterial buffer response in anaesthetized pigs

Low cardiac output impairs the hepatic arterial buffer response (HABR). Whether this is due to low abdominal blood flow per se is not known. Dobutamine is commonly used to increase cardiac output, and it may further modify hepatosplanchnic and renal vasoregulation. We assessed the effects of isolated abdominal aortic blood flow changes and dobutamine on hepatosplanchnic and renal blood flow. Twenty-five anesthetized pigs with an abdominal aorto-aortic shunt were randomized to 2 control groups [zero (n = 6) and minimal (n = 6) shunt flow], and 2 groups with 50% reduction of abdominal blood flow and either subsequent increased abdominal blood flow by shunt reduction (n = 6) or dobutamine infusion at 5 and 10 microg kg(-1) min(-1) with constant shunt flow (n = 7). Regional (ultrasound) and local (laser Doppler) intra-abdominal blood flows were measured. The HABR was assessed during acute portal vein occlusion. Sustained low abdominal blood flow, by means of shunt activation, decreased liver, gut, and kidney blood flow similarly and reduced local microcirculatory blood flow in the jejunum. Shunt flow reduction partially restored regional blood flows but not jejunal microcirculatory blood flow. Low-but not high-dose dobutamine increased gut and celiac trunk flow whereas hepatic artery and renal blood flows remained unchanged. Neither intervention altered local blood flows. The HABR was not abolished during sustained low abdominal blood flow despite substantially reduced hepatic arterial blood flow and was not modified by dobutamine. Low-but not high-dose dobutamine redistributes blood flow toward the gut and celiac trunk. The jejunal microcirculatory flow, once impaired, is difficult to restore.

Effects of levosimendan and dobutamine in experimental acute endotoxemia: a preliminary controlled study

OBJECTIVE

To test the hypothesis that levosimendan increases systemic and intestinal oxygen delivery (DO(2)) and prevents intramucosal acidosis in septic shock.

DESIGN

Prospective, controlled experimental study.

SETTING

University-based research laboratory.

SUBJECTS

Nineteen anesthetized, mechanically ventilated sheep.

INTERVENTIONS

Endotoxin-treated sheep were randomly assigned to three groups: control (n=7), dobutamine (10 microg/kg/min, n=6) and levosimendan (100 microg/kg over 10 min followed by 100 microg/kg/h, n=6) and treated for 120 min.

MEASUREMENTS AND MAIN RESULTS

After endotoxin administration, systemic and intestinal DO(2) decreased (24.6+/-5.2 vs 15.3+/-3.4 ml/kg/min and 105.0+/-28.1 vs 55.8+/-25.9 ml/kg/min, respectively; p<0.05 for both). Arterial lactate and the intramucosal-arterial PCO(2) difference (DeltaPCO(2)) increased (1.4+/-0.3 vs 3.1+/-1.5 mmHg and 9+/-6 vs 23+/-6 mmHg mmol/l, respectively; p<0.05). Systemic DO(2) was preserved in the dobutamine-treated group (22.3+/-4.7 vs 26.8+/-7.0 ml/min/kg, p=NS) but intestinal DO(2) decreased (98.9+/-0.2 vs 68.0+/-22.9 ml/min/kg, p<0.05) and DeltaPCO(2) increased (12+/-5 vs 25+/-11 mmHg, p<0.05). The administration of levosimendan prevented declines in systemic and intestinal DO(2) (25.1+/-3.0 vs 24.0+/-6.3 ml/min/kg and 111.1+/-18.0 vs 98.2+/-23.1 ml/min/kg, p=NS for both) or increases in DeltaPCO(2) (7+/-7 vs 10+/-8, p=NS). Arterial lactate increased in both the dobutamine and levosimendan groups (1.6+/-0.3 vs 2.5+/-0.7 and 1.4+/-0.4 vs. 2.9+/-1.1 mmol/l, p=NS between groups).

CONCLUSIONS

Compared with dobutamine, levosimendan increased intestinal blood flow and diminished intramucosal acidosis in this experimental model of sepsis.

Influence of dobutamine on the variables of systemic haemodynamics, metabolism, and intestinal perfusion after cardiopulmonary resuscitation in the rat

BACKGROUND

Global left ventricular dysfunction after successful resuscitation from cardiac arrest may be treated successfully with dobutamine but the effects on intestinal perfusion are unknown.

METHODS

In 24 male Sprague-Dawley rats ventricular fibrillation was induced. After 4 min of untreated cardiac arrest, precordial chest compression was performed for 4 min; adrenaline (epinephrine) (90 microg kg(-1)) was injected, followed by defibrillation. Return of spontaneous circulation was achieved in 18 animals, which were allocated to receive saline 0.9% (control group, n = 6), dobutamine at 5 microg kg(-1) min(-1) (n = 6) or dobutamine at 10 microg kg(-1) min(-1) (n = 6). Measurements of haemodynamic variables and intestinal tonometer P(CO2) were made before induction of ventricular fibrillation and 15, 30, 60, and 120 min postresuscitation.

RESULTS

At 120 min postresuscitation, mean aortic pressure was 82 +/- 20, 104 +/- 19, and 113 +/- 15 mmHg for the control group, the dobutamine (5 microg kg(-1) min(-1)) group and the dobutamine (10 microg kg(-1) min(-1)) group (P < 0.05 for comparison of the dobutamine (10 microg kg(-1) min(-1)) group versus the control group). Respective abdominal aortic blood flow was 107 +/- 16, 133 +/- 49, and 145 +/- 18 ml min(-1) kg(-1) (P < 0.05 for comparison of the dobutamine (10 microg kg(-1) min(-1)) group versus the control group), and superior mesenteric artery blood flow was 25 +/- 9, 28 +/- 8, and 33 +/- 8 ml min(-1) kg(-1). Arterial lactate was significantly higher (P < 0.05) in the control group (2.3 +/- 0.6 mmol l(-1)) than in the dobutamine (5 microg kg(-1) min(-1)) group (1.6 +/- 0.3 mmol l(-1)) and dobutamine (10 microg kg(-1) min(-1)) group (1.5 +/- 0.3 mmol l(-1)). Tonometrically derived P(CO2) gap was highly elevated at 15 min of postresuscitation and returned to prearrest level at 120 min postresuscitation in all groups.

CONCLUSIONS

Dobutamine enhances the recovery of global haemodynamic and metabolic variables early after cardiac arrest.

Splanchnic Hypoperfusion-Directed Therapies in Trauma: A Prospective, Randomized Trial

Splanchnic hypoperfusion as reflected by gastric intramucosal acidosis has been recognized as an important determinant of outcome in shock. A comprehensive splanchnic hypoperfusion-ischemia reperfusion (IRP) protocol was evaluated against conventional shock management protocols in critical trauma patients. The study was a prospective randomized trial comparing three therapeutic approaches to hypoperfusion after severe trauma in 151 trauma patients admitted to the intensive care unit. Group 1 patients received hemodynamic support based on conventional indicators of hypoperfusion. In group 2, resuscitation was further guided by gastric tonometry-derived estimates of splanchnic hypoperfusion and included more invasive hemodynamic monitoring and additional administration of colloid or crystalloid solutions, or inotropic support. Group 3 patients additionally received therapies specifically aimed at optimizing splanchnic perfusion and minimizing oxidant-mediated damage from reperfusion. The three groups were similar based on age, Injury Severity Score, and Acute Physiology and Chronic Health Evaluation II Scores. There were no statistically significant differences in mortality rates, organ dysfunction, ventilator days, or length of stay between any of the interventions. Techniques of optimization of splanchnic perfusion and minimization of oxidant-mediated reperfusion injury evaluated in this study were not advantageous relative to standard resuscitation measures guided by conventional or tonometric measures of hypoperfusion in the therapy of occult and clinical shock in trauma patients.

Levosimendan is superior to milrinone and dobutamine in selectively increasing microvascular gastric mucosal oxygenation in dogs*

OBJECTIVE

The effect of levosimendan, a novel inotropic vasodilator (inodilator), on the microvascular gastric mucosal hemoglobin oxygenation (muHbo(2)) is unknown. A possible effect could thereby be selective for the splanchnic region or could primarily reflect changes in systemic oxygen transport (Do(2)) and/or oxygen consumption (Vo(2). We compared systemic and regional effects of levosimendan with those of established inotropes, milrinone and dobutamine.

DESIGN

Laboratory experiment.

SETTING

University animal research laboratory of experimental anesthesiology.

SUBJECTS

Chronically instrumented dogs with flow probes for cardiac output measurement.

INTERVENTIONS

Anesthetized, mechanically ventilated dogs (each group n = 6) on different days randomly received levosimendan (10 microg.kg, followed by four infusion steps: 0.125-1.0 microg.kg.min), milrinone (5.0 microg.kg, followed by 1.25-10 microg.kg.min), or dobutamine (2.5-10.0 microg.kg.min). Since these drugs may modify regional or systemic responses to fluid load, an additional predefined volume challenge was subsequently performed with hydroxyethyl starch 6% (10 mL.kg).

MEASUREMENTS AND MAIN RESULTS

We measured muHbo(2) (reflectance spectrophotometry), Do(2), Vo(2), and systemic hemodynamics. Levosimendan significantly increased muHbo(2) from baseline (approximately 55% for all groups) to 64 +/- 4% and further to 69 +/- 2% with volume challenge (mean +/- sem). At the systemic level, levosimendan alone only slightly increased Do(2) at a Vo(2). Milrinone elicited similar systemic effects (Do(2), Vo(2), hemodynamics) but failed to increase muHbo(2). Dobutamine, conversely, increased muHbo(2) to a similar extent as levosimendan; however, this was accompanied by marked increases in Do(2) and Vo(2). The gastric mucosa selectivity of these interventions, expressed as slope of the muHbo(2)/Do2 relation, was highest for levosimendan (+1.89 and +1.14, without and with volume challenge), compared with milrinone (+0.45 and + 0.47) and dobutamine (+0.48 and + 0.33).

CONCLUSIONS

Levosimendan is superior to milrinone (no significant regional effects) and dobutamine (marked systemic effects) in increasing gastric mucosal oxygenation selectively (i.e., at only moderately increased Do(2) and stable Vo(2). If our experimental data apply to the clinical setting, levosimendan may serve as an option to selectively increase gastrointestinal mucosa oxygenation in patients at risk to develop splanchnic ischemia.

Intestinale Perfusionsstörungen beim Intensivpatienten

Due to the bowel's poor tolerance of hypoxia, intestinal malperfusion presents as a grave disease with high mortality. The intensivist is confronted with this condition in association with other underlying diseases, in the course of surgery, during application of medication or associated with invasive therapy. In a critical care setting, the non-occlusive mesenteric ischemia (NOMI) is of increasing importance. Since critical care patients often lack clinical symptoms, special attention is required and one main factor of the patient's prognosis is early diagnosis. This review summarizes pathophysiology and diagnostic aspects and the range of therapeutic and preventive measures.