Low-dose dopamine in critically ill oliguric patients: the influence of the renin-angiotensin system.
OBJECTIVE
To assess the effect of low-dose dopamine on urine output and natriuresis in critically ill oliguric patients and the relationship of this response to the renin-angiotensin aldosterone system.


METHODS
A prospective, controlled study.


METHODS
A multidisciplinary intensive care unit of a teaching hospital.


METHODS
Critically ill, volume-resuscitated, oliguric patients.


METHODS
Dopamine was infused at a rate of 2 micrograms/kg/min. The change in urine output and sodium excretion was measured over a 6-hour period. Plasma Renin Activity (PRA) and serum aldosterone were measured before commencing low-dose dopamine.


METHODS
Patients whose mean urine output increased by greater than 20 ml/hour were considered to have responded to low-dose dopamine.


RESULTS
Nine patients were studied. Five of the nine patients responded to low-dose dopamine. The mean increase in urine volume was 58.4 ml/hr in the responders compared with 5.0 ml/hr in the nonresponders. The mean PRA (normal, 0.8 to 2.5 ng/ml/hr) was 5.7 ng/ml/hr in the responders compared with 26.8 ng/ml/hr in the nonresponders (p = 0.042). A significant inverse correlation existed between the PRA and the increase in urinary output (r = -0.75; p = 0.019).


CONCLUSIONS
The response to renal dopamine in critically ill patients appears to be dependent on the interaction between the vasodilating-natriuretic effect of dopamine and the vasoconstricting antinatriuretic effect of the renin-angiotensin aldosterone system.
Marik
P E
PE
Baragwanath Hospital Intensive Care Unit, Soweto, South Africa.
D000293:Adolescent; D000328:Adult; D000450:Aldosterone / Q000097:blood; D001794:Blood Pressure; D002302:Cardiac Output; D003404:Creatinine / Q000097:blood; D016638:Critical Illness; D004298:Dopamine / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D006784:Hospitals, Teaching; D006801:Humans; D007262:Infusions, Intravenous; D007362:Intensive Care Units; D008875:Middle Aged; D009846:Oliguria / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology; D011446:Prospective Studies; D012083:Renin / Q000097:blood; D012084:Renin-Angiotensin System / Q000187:drug effects*; D012964:Sodium / Q000652:urine
D000450:Aldosterone; D012964:Sodium; D003404:Creatinine; D012083:Renin; D004298:Dopamine