RESUMEN
We sought to document arterial oxygen saturation relative to changes in the right ventricular pressure/left ventricular pressure ratio (RVP/LVP ratio), an index of pulmonary arterial pressure, in infants born at high altitude. We performed pulse oximetry and echocardiography in 15 healthy infants born in Leadville, Colo. (3100 m), at 6 to 24 hours, 24 to 48 hours, 1 week, 2 months, and 4 months of age. Pulse oximetry was done under conditions of wakefulness, feeding, and active and quiet sleep. All infants received supplemental O2 at delivery and during postnatal transition; all oximetry measurements were performed with infants breathing room air. The mean arterial O2 saturation ranged from 80.6% +/- 5.3% to 91.1% +/- 1.7% during the 4 months. Values fell during the first week after birth and then rose gradually to attain near-birth values at 2 and 4 months of age. Arterial O2 saturation was uniform among behavioral states at 6 to 24 hours and 24 to 48 hours of age. After 1 week of age, values were highest during wakefulness, intermediate during feeding and active sleep, and lowest during quiet sleep. The RVP/LVP ratio remained in the normal or mildly elevated range throughout the study period. We conclude that the RVP/LVP ratio promptly becomes normal at high altitude, and despite low arterial O2 saturation in the first weeks to months after birth, healthy newborn infants at 3100 m show little evidence of acute pulmonary hypertension.
Asunto(s)
Altitud , Recién Nacido/fisiología , Oxígeno/sangre , Arteria Pulmonar/fisiología , Factores de Edad , Presión Sanguínea , Femenino , Frecuencia Cardíaca , Humanos , Masculino , Valores de Referencia , RespiraciónRESUMEN
We studied the efficacy of low-dose nitric oxide inhalation in nine consecutive patients with severe persistent pulmonary hypertension of the newborn (PPHN) who were candidates for extracorporeal membrane oxygenation (ECMO). All patients had marked hypoxemia despite aggressive ventilator management and echocardiographic evidence of pulmonary hypertension. Associated diagnoses included meconium aspiration syndrome (3 patients), sepsis (3 patients), and congenital diaphragmatic hernia (2 patients). Infants were initially treated with inhaled nitric oxide at 20 ppm for 4 hours and then at 6 ppm for 20 hours. In all infants, oxygenation promptly improved (arterial/alveolar oxygen ratio, 0.077 +/- 0.016 at baseline vs 0.193 +/- 0.030 at 4 hours; p < 0.001) without a decrease in systemic blood pressure. Sustained improvement in oxygenation was achieved in eight patients treated with inhaled nitric oxide for 24 hours at 6 ppm (arterial/alveolar oxygen ratio, 0.270 +/- 0.053 at 24 hours; p < 0.001 vs baseline). One patient with overwhelming sepsis had an initial improvement of oxygenation with nitric oxide but required ECMO for multiorgan and cardiac dysfunction. We conclude that low doses of nitric oxide cause sustained clinical improvement in severe PPHN and may reduce the need for ECMO. However, immediate availability of ECMO is important in selected cases of PPHN complicated by severe systemic hemodynamic collapse.
Asunto(s)
Óxido Nítrico/administración & dosificación , Síndrome de Circulación Fetal Persistente/tratamiento farmacológico , Vasodilatadores/administración & dosificación , Enfermedad Aguda , Administración por Inhalación , Evaluación de Medicamentos , Ecocardiografía , Oxigenación por Membrana Extracorpórea , Humanos , Recién Nacido , Oxígeno/sangre , Síndrome de Circulación Fetal Persistente/sangre , Síndrome de Circulación Fetal Persistente/diagnóstico por imagen , Insuficiencia Respiratoria/sangre , Insuficiencia Respiratoria/diagnóstico por imagen , Insuficiencia Respiratoria/tratamiento farmacológico , Factores de TiempoRESUMEN
To assess the natural history of Kawasaki syndrome and its effect on maximal voluntary work and cardiorespiratory fitness, we performed cycle ergometry testing in 47 patients who had had the syndrome. Forty-one patients performed maximal effort as judged by achievement of 95% predicted heart rate response. Oxygen consumption, carbon dioxide production, and minute ventilation were performed in 23 patients. There was no difference in maximal voluntary work (total work, mean power) or maximal oxygen consumption between case subjects and control subjects. There were no differences between patients with and those without aneurysms. Serial exercise studies were performed in 10 patients; of these, two with initially normal exercise study findings had decreased maximal voluntary work and oxygen consumption with ischemic changes, and both were at high risk for the development of stenotic or occlusive coronary arteries. The other eight patients had normal cardiorespiratory reserve and no ischemic changes with serial studies. These results suggest that patients have normal cardiorespiratory fitness after Kawasaki syndrome. With the development of ischemic heart disease, they may have decreased cardiorespiratory reserve. Serial evaluation of cardiorespiratory fitness may demonstrate ischemic heart disease.
Asunto(s)
Prueba de Esfuerzo , Síndrome Mucocutáneo Linfonodular/fisiopatología , Consumo de Oxígeno , Adolescente , Niño , Preescolar , Enfermedad Coronaria/etiología , Enfermedad Coronaria/fisiopatología , Femenino , Humanos , Lactante , Masculino , Síndrome Mucocutáneo Linfonodular/complicaciones , Aptitud Física , Estudios ProspectivosRESUMEN
The intestinal absorption of sodium taurocholate was studied in fetuses, neonates, infants, children, and adults. Absorption rates were measured in vitro in everted rings of jejunum and ileum. Mucosal accumulation of 3H-taurocholate against a concentration gradient was consistently demonstrated in rings of ileum from adults, children, and infants older than 8 months, whereas fetal and neonatal ileal mucosal concentrations were not significantly above those in the incubation medium after exposure of the mucosa to 0.003, 0.03, and 0.3 mM taurocholate. There were no significant differences in mucosal uptake of taurocholate by perinatal jejunal and ileal rings. Incubations of mucosa from older infants, children, and adults in 0.3 mM taurocholate exhibited saturation phenomena. It is concluded that the ileal mechanism for active transport of taurocholate is undeveloped in the fetus and newborn infant. It is probable that the enterohepatic circulation of bile salt during the perinatal period is limited to that fraction of bile salt absorbed passively. The results suggest that losses of bile salt from the immature intestine may contribute to the steatorrhea and so-called diarrhea of newborn infants.