Acute effects of dobutamine and dopamine on renal and respiratory functions in patients on prolonged mechanical ventilation.
1. It is known that positive pressure mechanical ventilation (PPMV) decreases diuresis and increases extravascular water, thereby impairing pulmonary gas exchange. Sympathomimetic amines are commonly used to relieve these effects. To compare the effects of dobutamine (DT) and dopamine (DP) on renal and pulmonary function, we studied 30 patients submitted to continuous PPMV for at least 72 h. All were in stable hemodynamic conditions. Patients had pulmonary insufficiency of different etiology. The drugs were randomly administered by continuous intravenous infusion at the dose of 4 to 6 micrograms kg-1 min-1 for 3 h. An interval of 60 min was allowed to elapse between treatments. 2. A significant increase in arterial pressure and heart rate occurred with both drugs (P less than 0.05). DP increased urinary flow by 93.7% (1.6 +/- 0.1 to 3.1 +/- 0.4 ml/min; P less than 0.05) and Na excretion fraction (NaEF) by 35.5% (P less than 0.05). In contrast, DT reduced NaEF by 58.9% (P less than 0.05) and had no effect on urinary flow. Neither drug altered creatinine clearance. 3. The alveolo-arterial O2 difference (A-aO2D), which was 370 +/- 20 mmHg during the control period, increased to 394 +/- 20 mmHg after DP and decreased to 355 +/- 22 mmHg after DT, the difference being statistically significant (P less than 0.05). Pulmonary shunt (%) and the venous pO2 (mmHg) did not change during the infusion of DP or DT. 4. In conclusion, an acute increase in salt and water excretion does not necessarily lead to an immediate reduction in pulmonary "shunt".(ABSTRACT TRUNCATED AT 250 WORDS)
Ramires
J A
JA
Instituto do Coração, Faculdade de Medicina, Universidade de São Paulo, Brasil.
Tsanaclis
A
A
Gimenez
H C
HC
da-Luz
P L
PL
Pileggi
F
F
D000293:Adolescent; D000328:Adult; D000368:Aged; D004280:Dobutamine / Q000008:administration & dosage / Q000494:pharmacology*; D004298:Dopamine / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D007262:Infusions, Intravenous; D007668:Kidney / Q000187:drug effects / Q000502:physiology*; D008168:Lung / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D011175:Positive-Pressure Respiration; D011652:Pulmonary Circulation / Q000187:drug effects; D011897:Random Allocation; D012079:Renal Circulation / Q000187:drug effects; D012131:Respiratory Insufficiency / Q000503:physiopathology / Q000628:therapy
D004280:Dobutamine; D004298:Dopamine