Effect of dopamine on gastrointestinal motility during critical illness

Objective: To document the action of dopamine on gastrointestinal motility in mechanically ventilated patients. Design: Cross-over, randomized, placeb o-controlled study. Setting: General intensive care unit (ICU) in a univers ity hospital. Patients: Twelve mechanically ventilated patients in a stable hemodynamic condition, with no contraindication to enteral feeding. Interv entions: Dopamine (4 mu g/kg per minute) and placebo were infused over 8 h (4 h fasting, followed immediately by 4 h nasogastric feeding at 100 kcal p er hour) on two consecutive days, in a random order. Pressure changes in th e gastric antrum (four sites) and in the duodenum (two sites) were recorded by perfused catheter manometry. Each session started with the institution of dopamine or placebo infusion. Measurements and results: The migrating mo tor complex and its three successive phases were identified (phase I, perio d of quiescence; phase II, period of irregular contractile activity; phase III or activity front, period of high-frequency, regular contractions). Con tractions and activity fronts at each site were quantified during fasting a nd feeding. The mean duration of the fasting migrating motor complex was de termined in the duodenum, as well as the contribution of each phase (phases I, II, III) to the length of the complete cycle. The propagation character istics of each activity front were assessed visually. The number of contrac tions was lower in the antrum (p = 0.024) and phase III motor activity high er in the duodenum [incidence of activity fronts (p = 0.008); number of pha se III contractions (p = 0.009)] during dopamine infusion than with placebo . These modifications observed under dopamine were related to decreased ant ral contractions during fasting (p = 0.050), increased incidence of activit y fronts during feeding (p = 0.031), and increased number of phase III cont ractions during fasting (p = 0.037). In both groups (placebo and dopamine) activity fronts rarely started in the antrum, and abnormally propagated act ivity fronts were found in the duodenum in some patients. Conclusions: Low- dose dopamine adversely affects gastroduodenal motility in mechanically ven tilated critically ill patients.