To examine the serial changes of left ventricular output and regional blood flow distribution during the early neonatal period, we measured blood flow volume in the ascending aorta, middle cerebral artery, celiac artery, superior mesenteric artery, and renal artery in 23 normal term infants at 1, 4-8, 24, and 96 h after birth. The blood flow volume in each vessel was measured by the pulsed Doppler technique. In the middle cerebral artery, celiac artery, and superior mesenteric artery, the blood flow volume at 1 and 4-8 h of age was significantly lower than after 24 h of age. In contrast, renal artery blood flow volume did not change significantly throughout the study period. The reduced organ blood flow volume soon after birth was related to a low diastolic blood flow in the major vessels, and the percent diastolic integral of blood flow velocity in each vessel showed an inverse linear correlation with the diameter of the ductus arteriosus. The left ventricular output 1 h after birth was 365 +/- 69 mL/kg/min, which was significantly higher than after 4-8 h of age. Left ventricular output gradually declined to 301 +/- 63 mL/kg/min at 4-8 h of age (p < 0.05 versus 96 h), 272 +/- 48 mL/kg/min at 24 h, and 258 +/- 54 mL/kg/min at 96 h. There was a significant positive correlation between left ventricular output and the ductus arteriosus diameter.(ABSTRACT TRUNCATED AT 250 WORDS)
In the event of sustained intrapartum fetal bradycardia, delivery by emergency cesarean within 25 minutes improved long-term neonatal neurologic outcome.
Objective-To investigate serial changes in the pattern of flow in the pulmonary vein during the early neonatal period. Methods-Pulsed Doppler echocardiography was used to measure flow in the right upper pulmonary vein in 26 normal newborn infants. Peak flow velocity during systole (S) and diastole (D) and flow velocity at indents between the systolic and diastolic fraction (0) and between the diastolic and systolic fraction (X) were measured 1, 4-8, 24, and 96 hours after birth. The heart rate and diameter of the ductus arteriosus were measured simultaneously. Results-Continuous and phasic high flow velocity waveforms were seen 1 and 4-8 hours after birth. The mean (SD) peak flow velocities of X, S, 0, and D an hour after birth were 35 2 (13.6) cmls (Br HeartrJ 1994;71:182-186) Echocardiographic examination of abnormal pulmonary vein flow during the neonatal period is useful in the diagnosis of total anomalous pulmonary venous return, congenital pulmonary vein stenosis, and persistent pulmonary hypertension in cyanotic neonates.' None the less, the normal pattern of pulmonary vein flow during the newborn period has not yet been established. It is believed that the considerable increase pulmonary blood volume and the rapid decline in pulmonary arterial pressure at birth are likely to influence the pulmonary venous flow pattern. A considerable left to right shunt through the ductus arteriosus immediately after birth adds to the much increased pulmonary circulatory volume.7We used pulsed Doppler echocardiography to study serial changes in the pattern of pulmonary vein flow in healthy infants during the early neonatal period. In most infants the ductus arteriosus is closed or starting to close within 24 to 48 hours after birth. We studied the effect of ductal closure on the pulmonary venous flow. 819 Because the tachypnoeic and periodic respiratory patterns of neonates may affect the pulmonary circulation we also examined the influence of respiration on the pattern of flow in the pulmonary vein. Patients and methods PATIENTSInformed consent was obtained before delivery from each mother with an uncomplicated pregnancy. We studied 26 neonates 1, 4-8, 24, and 96 hours after birth. Gestational age at birth, calculated from the first day of the last menstrual period, was 37-40 weeks (mean 38 weeks) and birth weight was 2310-3824 g (mean 3039 g). The infants were normal at birth and were of an appropriate size. None showed any evidence of congenital heart disease or abnormality of any other organ system.
The population pharmacokinetics of panipenem was studied in 23 neonates. Their postconceptional age (PCA) was 24.7-42.6 weeks and their body weight was 530-4455 g at initiation of therapy. Panipenem was infused over a period of 60 min in a dose of 10.2-34.7 mg/kg bd in 21 patients, tid in one patient and four times daily in one patient for a mean of 10.7 days. Blood samples were obtained just before the infusion and 1-2 h after and again 6 h after the infusion. All the data for the 108 serum panipenem concentrations were evaluated with a non-linear mixed-effect model (NONMEM with first-order method), a computer program designed for population pharmacokinetic analysis. One- and two-compartment population pharmacokinetic parameters were measured. The two-compartment parameters were as follows: panipenem clearance CL = 0.150 L/h, central volume of distribution = 0.54 L, intercompartmental clearance = 0.014 L/h and peripheral volume of distribution = 0.28 L. The one-compartment parameters were CL = 0.175 L/h and volume of distribution = 0.55 L. In the fitting process using the one-compartment model, significantly fixed effects related to CL were PCA, postnatal age (PNA), gestational age (GA), body weight (BW) and serum creatinine, and that for the distribution volume (V) was BW. CL showed a logarithmic rise with PCA (CL = 0.00176 x exp(0.14 x PCA)). The CL levels in the patients with PCA < 33 weeks (0.098 L/h) were significantly lower (P < 0.001) than those with PCA > or = 33 weeks (0.25 L/h). The final formulae for the population pharmacokinetic parameters are as follows: CL = 0.0832 (PCA < 33 weeks), CL = 0.179 x BW (PCA > or = 33 weeks), V = 0.53 x BW (coefficient of variation; 23.9% for CL, 28.5% for V). Based on these data, a simulated time-concentration curve was compared with that for adult data in a clinical Phase I study. Our findings suggest that the panipenem dosage regimen of 10-20 mg/kg every 12 h should yield concentrations within the accepted therapeutic range.
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