INCREASING SPLANCHNIC BLOOD-FLOW IN THE CRITICALLY ILL

Study objective: To assess the effect of low dose dopexamine and dopam ine on splanchnic blood flow as measured by gastric intramucosal pH, h epatic metabolism of lidocaine (lignocaine) to monoethylglycinexylidid e (MEGX), and plasma disappearance rate of indocyanine green (ICG). De sign: Single-blind randomization of patients,vith a gastric intramucos al acidosis to receive dopexamine (ten patients), dopamine (ten patien ts), 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 respon se syndrome, were mechanically ventilated, and had pulmonary artery ca theters 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 measu rements of gastric intramucosal pH, MEGX formation from lidocaine, ICG plasma disappearance rate, heart rate, mean arterial pressure, pulmon ary artery occlusion pressure, cardiac index, oxygen delivery index, o xygen 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 wh ich a repeated set of the measurements was taken. Results: Dopexamine at a low dose had no effect on any of the systemic measurements. The m edian 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). Dopam ine had no effect on any of the measured variables. There were no chan ges in the control group. Conclusions: Low-dose dopexamine increases s planchnic blood now as measured by gastric intramucosal pH, MEGX forma tion 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 i n this study, dopamine had no effect on splanchnic blood flow. Dopexam ine may be useful in the management of splanchnic ischemia in the crit ically ill.