busy clinicians sometimes think twice before reading studies of animal models . yes , it sounds interesting , but is it really going to change my practice ? there is so much else i should be reading ... this writer does not mean to cast aspersions on such an attitude - and , in fact , share sit , at least to some extent . the report in the previous issue of critical care by bangash and colleagues is one such study . dopexamine is a dopamine analog that stimulates -adrenergic and dopamine 1 and 2 receptors , conferring some vasodilatory effects . dopexamine has classically been considered a vasoactive agent with inotropic effects , perhaps with more prominent effects in some regional vascular beds . as such , dopexamine has been tested in clinical trials to optimize hemodynamics , either in patients with shock or as part of a perioperative regimen . myocardial dysfunction occurs in a subset of patients with septic shock , so a strategy of increasing cardiac output and thus oxygen delivery in this setting made some sense . implementation of this strategy using dobutamine , with or without norepinephrine , to improve cardiac output topredetermined supranormal levels in all patients did not improve outcomes [ 3 - 5 ] , and use of inotropic therapy for this purpose is not recommended in current guidelines . subsequent reports of potentially deleterious proinflammatory effects of catecholamines provided mechanistic support for their lack of efficacy when used indiscriminately . use of dopexamine targeted to increase oxygen delivery to > 600 ml / minute / m , however , was shown in a randomized trial reported in 1993 to decrease mortality in the perioperative period . whether this resulted from differential hemodynamic effects of dopexamine compared with other agents , perhaps selective vasodilation of regional circulations , or whether use of inotropes for perioperative optimization is different from their use in other settings some reports using perioperative dopexamine found reduced morbidity or mortality , confirming the initial study , but others found no difference from conventional treatment [ 10 - 12 ] . a patient - level meta - analysis suggested that some of the differences might be explained by the dose of dopexamine employed . other studies indicated that dopexamine - in part due to 2-adrenergic effects , but also through other pathways - might have immunomodulatory effects , especially in the spleen . the current study investigated both hemodynamic and inflammatory effects of a low dose of dobutamine in a rodent model of endotoxemia . dopexamine reduced the systemic inflammatory response to endotoxin , including cytokine release , endothelial adhesion molecules , and oxidative stress , without substantially changing systemic hemodynamics , either blood pressure or stroke volume . regional flow , assessed by laser doppler in the mesenteric circulation , was also not changed by dopexamine - yet lactate levels and organ function were improved . while immunomodulatory effects of dopexamine were demonstrated in this study , these results contrast with those of a recent clinical investigation , also carried out by this same group , in which dopexamine improved global oxygen delivery , microvascular flow and tissue oxygenation but did not change the inflammatory response to surgery . perhaps the difference could result in part from microcirculatory heterogeneity , something not assessed by the laser doppler methodology used in this study . previous studies have shown that regional heterogeneity may be a good predictor of outcome in shock states , and such heterogeneity might contribute to both perfusion abnormalities and production of lactate in sepsis and other inflammatory states . thus , while this study convincingly demonstrates immunomodulatory effects of dopexamine in this model , it seems possible that microcirculatory hemodynamic effects are also playing a role . this animal study addresses some of the mystery of why effects of dopexamine may differ from those of other catecholamines , but that mystery is not yet fully solved . hemodynamics rule , and those who understand them rock , but this study reminds us that catecholamines have inflammatory effects that must be taken into account when considering their use . animal studies are usually pursued as part of a reductionist approach aimed at controlling as many variables as possible in order to isolate mechanistic effects , but their interpretation and extrapolation to the clinical setting reminds us that in critical care , clinicians think of effects on different systems all together . carefully conducted studies such as this one counteract the nihilistic tendency to think that mechanisms are too complicated and thus only hard clinical endpoints in patients are of any value , and encourage the sort of integrative approach that makes progress possible .
dopexamine is a dopamine analog that has been used for hemodynamic optimization in a number of clinical settings . 
 this animal investigation showed anti - inflammatory effects of dopexamine in a rat endotoxin model without effects on global or regional flow , but it is not time to dispense with hemodynamics altogether just yet . 
 rather , an integrative approach to the effects of catecholamines , considering both inflammatory and hemodynamic effects , including those on the microcirculation , can help clinicians best understand how to employ them in clinical practice .