Dopexamine prevents depression of mesenteric blood flow caused by positive end-expiratory pressure in rats.
BACKGROUND
The purpose of this study was to investigate the effects of two vasoactive agents, dopamine and dopexamine, on the depression of mesenteric blood flow caused by positive end-expiratory pressure (PEEP) during mechanical ventilation.


METHODS
Sprague-Dawley rats were mechanically ventilated with either no PEEP (control group) or increasing levels of PEEP (PEEP group) up to 20 cm H2O pressure. We evaluated PEEP's effect on blood pressure, cardiac output (CO), and the mesenteric microcirculation with a continuous infusion of 2.5 or 12.5 micrograms/kg/min dopamine or 1, 3, or 5 micrograms/kg/min dopexamine.


RESULTS
PEEP caused a 20% to 25% decrease in mean arterial pressure and a 30% decrease in CO at both 15 and 20 cm H2O of PEEP (all p < 0.05 versus baseline). Low dose dopamine partially corrected the decrease in CO to 16% and 21% below baseline at 15 and 20 cm H2O of PEEP, respectively (both p < 0.05 versus PEEP group) and partially ameliorated the depression of mesenteric blood flow associated with the application of PEEP. High dose dopamine did not positively affect either CO or mesenteric blood flow. Dopexamine had little effect on CO compared with dopamine. All three doses of dopexamine blocked the effect of PEEP on mesenteric blood flow (p < 0.05 compared with the PEEP group at all levels of PEEP, p < 0.05 compared with the low dose dopamine group at 15 and 20 cm H2O of PEEP).


CONCLUSIONS
Dopexamine is superior to dopamine in protecting mesenteric blood flow in the face of increasing levels of PEEP.
Steinberg
S
S
Department of Surgery, Tulane University School of Medicine, New Orleans, La, USA.
Azar
G
G
Love
R
R
Lee
R
R
Choe
E
E
Flint
L
L
D000818:Animals; D002302:Cardiac Output / Q000187:drug effects; D004298:Dopamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D008297:Male; D011175:Positive-Pressure Respiration / Q000009:adverse effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013152:Splanchnic Circulation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology*
D014665:Vasodilator Agents; C046318:dopexamine; D004298:Dopamine