RESUMO
OBJECTIVE: To study the effects of dopamine on renal, mesenteric, and cerebral blood flow in sick preterm neonates. STUDY DESIGN: The pulsatility index was used to assess the dopamine-induced changes in renal, mesenteric, and cerebral blood flow by means of color Doppler ultrasonography in 23 nonhypotensive preterm neonates (birth weight: 981 +/- 314 g; postnatal age: <2 days). Dopamine was given at a dose of 6.1 +/- 3.0 microgram/kg per minute to combat oliguria, impaired peripheral perfusion, or both. Blood flow velocity measurements were made before and during dopamine administration, with each patient serving as his or her own control subject. RESULTS: Dopamine significantly increased blood pressure and urine output. Dopamine decreased the pulsatility index in the renal artery (2.98 +/- 1.18 vs 1.68 +/- 0.45; P <.05) while the pulsatility index in the superior mesenteric and medial cerebral artery was not affected. Thus renal blood flow increased while mesenteric and cerebral blood flow remained unchanged during dopamine treatment. The increase in renal blood flow was independent of the blood pressure changes. CONCLUSIONS: These findings suggest a functionally mature renal, but not mesenteric, vasodilatory dopaminergic response in the preterm neonate. The observations also indicate the lack of an effect of low- to medium-dose dopamine on cerebral hemodynamics in the nonhypotensive preterm neonate.
Assuntos
Cardiotônicos/farmacologia , Circulação Cerebrovascular/efeitos dos fármacos , Dopamina/farmacologia , Doenças do Prematuro/fisiopatologia , Circulação Renal/efeitos dos fármacos , Circulação Esplâncnica/efeitos dos fármacos , Velocidade do Fluxo Sanguíneo/efeitos dos fármacos , Pressão Sanguínea/efeitos dos fármacos , Frequência Cardíaca/efeitos dos fármacos , Hemodinâmica/efeitos dos fármacos , Humanos , Recém-Nascido , Recém-Nascido Prematuro , Estudos Prospectivos , Fluxo Pulsátil/efeitos dos fármacosRESUMO
Between March 1986 and April 1990, 22 consecutive fetuses (at gestational ages of 21 to 38 weeks) with a suspected diagnosis of critical (ductus-dependent) left ventricular outflow tract obstruction on fetal echocardiogram were referred to our center for delivery and surgical treatment. Diagnoses were hypoplastic left heart syndrome (n = 16), valvular aortic stenosis (n = 2), common atrioventricular canal with subaortic stenosis (n = 3), and single ventricle with subaortic stenosis (n = 1). Postnatal echocardiography revealed that fetal echocardiography was correct in predicting left ventricular outflow tract obstruction to be critical in all but one patient, for a positive predictive value of 96%. Of the 21 patients with true, critical left ventricular outflow tract obstruction, 17 patients underwent cardiac surgery as neonates (birth to 6 days of age, median 2 days); 13 (or 77%) survived and were discharged from the hospital. In addition, one patient underwent successful balloon aortic valvotomy for critical valvular aortic stenosis but later died of sepsis. Lethal chromosomal and congenital abnormalities should be sought and are contraindications for this approach. In utero transport of fetuses with suspected critical left ventricular outflow tract obstruction to a neonatal cardiac surgical center can result in improved neonatal condition and may improve overall survival.