***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Objectives : To compare the effects of dobutamine and dopexamine on systemic hemodynamics , lactate metabolism , renal function and the intramucosal-arterial PCO2 gap in norepinephrine-treated septic shock . Design : A prospect i ve , interventional , r and omized clinical trial . Setting : Adult medical/surgical intensive care unit in a university hospital . Patients : After volume resuscitation , 24 patients were treated with norepinephrine alone titrated to obtain a mean arterial pressure of 75 mmHg and a cardiac index greater than 3.5 l/min-1 · m-2 . Interventions : Patients were r and omized to receive an infusion of dobutamine ( n = 12 ) ( 5 μg/kg per min ) or dopexamine ( n = 12 ) ( 1 μg/kg per min ) . Measurements and main results : Baseline measurements included : hemodynamic parameters , renal parameters ( diuresis , creatinine clearance and urinary sodium excretion ) , gastric mucosal-arterial PCO2 gap , arterial and mixed venous gases and arterial lactate and pyruvate levels . These measurements were repeated after 1 ( H1 ) , 4 ( H4 ) and 24 ( H24 ) h. No difference was found between dobutamine and dopexamine among H0 and H1 , H4 and H24 values for hemodynamics  . Dobutamine and dopexamine at low doses had no significant effect on mean arterial pressure , heart rate , cardiac index , oxygen delivery , oxygen consumption and pulmonary artery occlusion pressure . No patients developed arrhythmia or electrocardiographic signs of myocardial ischemia . After 4 and 24 h lactate concentration decreased in the dobutamine group from 2.4 ± 1 mmol/l to 1.7 ± 0.7 mmol/l and 1.5 ± 0.4 mmol/l , respectively , while it increased in the dopexamine group from 2.3 ± 1 mmol/l to 2.7 ± 1 mmol/l after 4 h and returned to baseline values after 24 h ( 2.2 ± 0.6 ) . After 24 h the lactate/pyruvate ratio decreased in the dobutamine group from 15 ± 5 to 12 ± 3 ( p < 0.05 ) while it was unchanged in the dopexamine group ( from 16 ± 6 to 17 ± 4 ) . Arterial pH increased in the dobutamine group from 7.35 ± 0.05 to 7.38 ± 0.07 ( p < 0.05 ) while it was unchanged in the dopexamine group ( from 7.34 ± 0.01 to 7.35 ± 0.10 ) . The PCO2 gap decreased after 1 and 4 h in both the dobutamine and dopexamine groups ( p < 0.05 with respect to baseline ) . When looking at individual responses , however , patients from both groups exhibited an increased gastric PCO2 gap . No difference was found between dobutamine and dopexamine for renal parameters . Conclusions : In norepinephrine-treated septic shock , low doses of neither dobutamine nor dopexamine caused significant effects on systemic hemodynamics and renal function and both dobutamine and dopexamine inconsistently improved the PCO2 gap . The present results support the need for individual measurement of the effects of catecholamine on the PCO2 gap PURPOSE Colonic ischemia after aortic surgery is associated with increased mortality and morbidity rates . This study was conducted as a single-center side arm to a multicenter , r and omized , placebo-controlled study to evaluate the effect of dopexamine hydrochloride on its incidence . METHODS Thirty patients , mean age 65.1 years ( range , 46 - 84 ) , undergoing elective infrarenal aortic surgery were entered . Preoperative hemodynamic and respiratory parameters were optimized . Patients were then r and omly assigned to receive a perioperative infusion of dopexamine at 2 microg/kg per minute ( n = 12 ) or 0.9 % saline placebo ( n = 18 ) . All patients underwent colonoscopy and biopsy preoperatively and 1 week postoperatively . Specimens were assessed for evidence of mucosal ischemia , presence of mast cell tryptase , myeloperoxidase activity , and both the inducible and endothelial isoforms of nitric oxide synthase . RESULTS There was no significant difference in perioperative fluid and blood requirements or hemodynamic and respiratory parameters between the two groups . However , there was significantly less evidence of mucosal ischemic changes in dopexamine-treated patients ( n = 1 ) compared with placebo ( n = 8) ( P = .049 ) . Furthermore , when preoperative biopsies were compared with those performed 1 week postoperatively , nine ( 50 % ) patients in the placebo group and two ( 16.7 % ) in the dopexamine group scored worse . Although there was no significant difference in inflammatory markers between the two groups , both mast cell tryptase and myeloperoxidase expression were increased in patients with histologic evidence of ischemia ( P < .05 ) . Furthermore , inducible nitric oxide synthase staining within the vascular ( P = .001 ) and lamina propria ( P < .05 ) components of the mucosa was also significantly greater . CONCLUSION A perioperative dopexamine infusion affords significant histologic protection to colonic mucosa after aortic surgery Abstract Objective : To determine whether a ) pre-operative measurement of gastric intramucosal pHi is predictive for mortality and morbidity in high-risk surgical patients and b ) peri-operative improvement of global oxygen delivery ( DO2 ) with fluids and dopexamine leads to increased gastric pHi and c ) either improved global perfusion or improved splanchnic perfusion is related to the prevention of multiple organ failure ( MOF ) . Design : Retrospective analysis of a double-blind , placebo-controlled , r and omised study . Setting : General intensive care units from 14 hospitals . Patients : Two hundred eighty-six high-risk surgical patients . Interventions : Swan-Ganz and tonometer catheter placement ; patients were stabilised pre-operatively using fluids , blood and /or oxygen to preset goals before receiving placebo or two doses of dopexamine ( 0.5 or 2.0 µg·kg·min ) peri-operatively . Measurements and results : Haemodynamic assessment ( including DO2 and oxygen consumption ( VO2 ) ) was performed together with measurement of gastric mucosal pHi pre-operatively and directly , 2 , 6 , 12 , 24 and 36 h post-operatively . Retrospectively , patients were divided pre-operatively into two sub-groups based on the optimal cut-off value for mortality of the first pHi measurement after induction of anaesthesia as calculated by a receiver operator characteristic ( ROC ) curve analysis – low pHi group ( < 7.35 ) and normal pHi ( ≥7.35 ) . Mortality in the low pHi , was higher than in the normal pHi , group ( 16.8 vs 2.3 % ; p=0.0001 ) . In the normal pHi group dopexamine , which was given prior to the first pHi measurement , had no effect on pHi , while DO2 increased significantly . In this group MOF score and number of patients with MOF remained similar for the treatment sub-groups . In the low pHi group gastric pHi increased significantly during dopexamine infusion ( p=0.008 ) , despite the lack of an increase in DO2 and VO2 . In this group the MOF score and the number of patients developing MOF decreased significantly with the use of dopexamine ( p=0.04 ) . In both groups bicarbonate levels remained similar for the treatment sub-groups . Conclusions : In high-risk surgical patients pre-operative measurement of pHi was predictive for mortality . The peri-operative response of pHi to dopexamine seemed to be dependent on pre-operative gastric pHi Abstract Objective : To compare the effects of dopexamine and dopamine on the mucosal permeability of the gastrointestinal tract ( GIT ) . Design : Prospect i ve , r and omised clinical trial . Setting : Intensive care unit of a postgraduate teaching hospital , London , Engl and . Patients : Thirty patients undergoing elective surgery involving cardiopulmonary bypass , performed by a single surgeon . Interventions : Patients were r and omly assigned to receive either dopexamine 2.0 μg/kg per min or dopamine 2.5 μg/kg per min for the duration of the study period . Measurements and main results : Hemodynamic parameters and gastric intramucosal pH ( pHi ) were measured at intervals throughout the study . GIT permeability was measured once , post-operatively , using the ratio of absorbed lactulose to L-rhamnose . The groups were similar with respect to demographics , pre- and post-operative risk factors . The lactulose/rhamnose ratio was ( mean ± SEM ) 0.44 ± 0.10 in the dopexamine group vs 0.65 ± 0.08 in that receiving dopamine ( p < 0.05 ) . The dopexamine group had a significantly higher oxygen delivery preoperatively ( 479.5 ± 32.0 ml/min per m2 vs 344.4 ± 23.9 ml/min per m2 for dopamine , p < 0.01 ) , but no other significant differences emerged between the groups . Conclusions : Compared to dopamine , dopexamine  reduces GIT permeability following surgery involving cardiopulmonary bypass . The mechanism of this effect remains unclear STUDY OBJECTIVE To assess the effect of low dose dopexamine and dopamine on  splanchnic blood flow  as measured by gastric intramucosal pH , hepatic metabolism of lidocaine ( lignocaine ) to monoethylglycinexy-lidide ( MEGX ) , and plasma disappearance rate of indocyanine green ( ICG ) . DESIGN Single-blind r and omization of patients with a gastric intramucosal acidosis to receive dopexamine ( ten patients ) , dopamine ( ten patients ) , or saline solution ( five control patients ) for 2 h. SETTING All 25 patients were in the ICU of Guys ' Hospital . PATIENTS All patients met the criteria for the diagnosis of the systemic inflammatory response syndrome , were mechanically ventilated , and had pulmonary artery catheters placed . All had a low gastric intramucosal pH and had a median first 24-h acute physiology and chronic health evaluation ( II ) score of 22 ( range , 7 to 40 ) . MEASUREMENTS AND INTERVENTIONS Baseline measurements of gastric intramucosal pH , MEGX formation from lidocaine , ICG plasma disappearance rate , heart rate , mean arterial pressure , pulmonary artery occlusion pressure , cardiac index , oxygen delivery index , oxygen uptake index , systemic vascular resistance , and arterial pH were taken . Dopexamine ( 1 mg.kg-1.min-1 ) , dopamine ( 2.5 mg.kg-1.min-1 ) , or 0.9 % saline solution was then infused for 2 h , after which a repeated set of the measurements was taken . RESULTS Dopexamine at a low dose had no effect on any of the systemic measurements . The median intramucosal pH rose from 7.23 to 7.35 ( p < 0.005 ) , the median ICG plasma disappearance rate from 7.6 to 11.3%.min-1 ( p < 0.02 ) , and the median MEGX concentration from 4 to 10.2 ng.mL-1 ( p < 0.005 ) . Dopamine had no effect on any of the measured variables . There were no changes in the control group . CONCLUSIONS Low-dose dopexamine increases splanchnic blood flow as measured by gastric intramucosal pH , MEGX formation from lidocaine , and ICG clearance . The lack of any change in the systemic measurements suggests that these effects are the result of a selective vasodilatation of the splanchnic vessels . At the dose used in this study , dopamine had no effect on splanchnic blood flow .  Dopexamine may be useful in the management of splanchnic ischemia in the critically ill Correction of the splanchnic oxygen deficit indicated by low gastric intramucosal pH ( pHi < 7.35 ) appears to reduce ICU mortality . Dopexamine hydrochloride is in clinical use for this purpose but its efficacy has not been fully investigated . We report the results of a prospect i ve , r and omized , placebo-controlled study with a crossover design to assess the efficacy of dopexamine in correcting low pHi . Twelve patients in whom pHi < 7.32 was detected during eight-hourly monitoring were r and omized to receive either incremental dopexamine ( 4 - 6 μg/kg/min ) with colloid or 5 % dextrose for three hours prior to crossover . There was no difference in pHi between treatments despite cardiovascular effects  during dopexamine infusion . There was , however , a time-related increase in pHi 
    Output:
    
Dopexamine may have beneficial effects on renal perfusion in patients undergoing cardiac surgery but appears to have little or no benefit on gastric mucosal pHi in the same patient population .
In critically ill patients none of the studies demonstrated a beneficial effect of dopexamine on either hepatosplanchnic or renal perfusion .
There is insufficient evidence to offer reliable recommendations on the clinical use of dopexamine for the protection of either hepatosplanchnic or renal perfusion in high-risk surgical patients .
Furthermore , there is no current evidence to support a role for dopexamine in protecting either hepatosplanchnic or renal perfusion in critically ill patients