Neurodevelopmental consequences associated with the premature neonate

Changes in neonatal care have resulted in an increased survival rate among low birth weight infants. Because their neurologic system is immature, these infants are vulnerable to neurologic injury. Major and minor neurodevelopmental consequences can result. Most preterm infants survive without serious difficulties; however, the lower the birth weight, the higher the likelihood that problems will occur. Numerous factors can increase a preterm infant's risk for disease and impairment, and the neonatal nurse can perform a significant role in minimizing this risk.     

Digoxin pharmacokinetics in premature infants

The use of camera renography under experimental conditions is described. The conductivity of the ileo-ureter formed by various surgical techniques in 24 dogs and the function of the operated kidney were studied. The non-invasive examination lasted for 20 minutes and was performed with two different labelled drugs (131I-iodohippurate and 99mTc-DTPA) and a gamma-camera calculator system. The results have shown that the ileo-ureter provided with a direct single layer uretero-ileal anastomosis ensured best the transport of urine and so it seems to be most promising for human application.     

Zidovudine pharmacokinetics in premature infants exposed to human immunodeficiency virus

We used population analysis techniques to determine zidovudine (ZDV) pharmacokinetic parameters in 15 preterm neonates (mean gestational age, 29.4 weeks; mean birth weight, 1,230 g) at a mean age of 5.5 days. The values of the pharmacokinetic parameters were as follows: clearance, 2.53 +/- 0.44 ml/min/kg; volume of distribution, 1.59 +/- 0.51 liters/kg; and half-life, 7.2 +/- 1.5 h. For seven infants studied a second time, at a mean age of 17.7 days, an increase in the mean clearance (2.33 versus 4.35 ml/min/kg; P = 0.024) and a decrease in the half-life (7.3 versus 4.4 h; P = 0.003) were found. The ZDV clearance is low and the half-life is prolonged in premature neonates, but the clearance increases and the half-life decreases with postnatal age. Potentially toxic concentrations may accumulate in serum if the standard dosage for full-term infants is used. We suggest that initial ZDV dosing should be reduced to 1.5 mg every 12 h for preterm neonates.     

Catheter-related sepsis in the neonate: thinking critically about a persistent problem

Management of ductal carcinoma in situ has become one of the most controversial topics in breast disease. While mastectomy has been the traditional treatment, many now feel it is excessive in most cases. As a result, a great effort has been made to identify pathobiological characteristics of DCIS that can be used to stratify appropriate treatment decisions. This article reviews efforts to relate pathobiological characteristics to disease management and provides treatment recommendations based on the latest evidence.     

New data on the pharmacokinetics of aminostigmine

The results of studying the pharmacokinetics of aminostigmine, a new reversible cholinesterase inhibitor produced in Russia, are discussed. Tissue radioactivity after intragastric administration of a toxic dose of aminostigmine was quite quickly absorbed from the intestinal lumen. The half-life period of aminostigmine exceeded considerably that of earlier studied carbamates and correlated with the clinical manifestations of the drug effects. This confirms that the use of aminostigmine in the treatment of neurologic and somatic diseases is preferable.     

带有限缓冲区的混合流水车间多目标调度

研究对象是带有限缓冲区混合流水车间中的多目标调度问题。以各机器前置后置缓冲区容积有限、工件以批量形式运输、运载设备的运载能力有限等作为资源限制因素,以最小化完工时间、最小化物料运输时间、最小化并行机前置缓冲区空间占用率均衡指数为目标,建立调度模型。分别采用NSGA-II、NSGA-III算法求解该模型,并对比两者之间的差别;设置不同的缓冲区容积,探究不同缓冲区容积对生产目标的影响,寻找最优缓冲区容积;建立不同模型,探究以最小化并行机前置缓冲区空间占用率均衡指数为目标的意义,最后以某船用管类生产企业的实际生产案例作为对象,通过对比优化结果与实际生产数据,验证了算法有效性。      

The pharmacokinetics and physiological effects of buprenorphine infusion in premature neonates

Whereas some people appear to cope after learning that they have human immunodeficiency virus (HIV) infection, others experience depression and suicidal ideation. In this study, 142 persons with HIV infection were administered the Center for Epidemiological Studies Depression Scale (CES-D). High levels of depression were predicted by lower perceived social support, attributions that health was influenced more by chance, high-risk sexual behavior practices, and greater number of HIV illness symptoms and greater duration of time knowing of one's own positive serostatus. Ongoing high-risk sexual behavior practices were predicted by higher levels of recreational drug use and of depression. These findings highlight the need for improved mental health services for persons with HIV conditions.     

Detecting synchronous cell assemblies with limited data and overlapping assemblies

Two statistical methods-cross-correlation (Moore et al. 1966) and gravity clustering (Gerstein et al. 1985)-were evaluated for their ability to detect synchronous cell assemblies from simulated spike train data. The two methods were first analyzed for their temporal sensitivity to synchronous cell assemblies. The presented approach places a lower bound on the amount of data required to detect a synchronous assembly. On average, both methods required the same minimum amount of recording time to detect significant pairwise correlations, but the gravity method exhibited less variance in the recording time. The precise length of recording depends on the consistency with which a neuron fires synchronously with the assembly but was independent of the assembly firing rate. Next, the statistical methods were tested with respect to their ability to differentiate two distinct assemblies that overlapped in time and space. Both statistics could adequately differentiate two overlapping synchronous assemblies. For cross-correlation, this ability deteriorates quickly when considering three or more simultaneously active, overlapping assemblies, whereas the gravity method should be more flexible in this regard. The work demonstrates the difficulty of detecting assembly phenomena from simultaneous neuronal recordings. Other statistical methods and the detection of other types of assemblies are also discussed.     

Elevated growth hormone secretory rate in premature infants: deconvolution analysis of pulsatile growth hormone secretion in the neonate

Premature infants have higher circulating concentrations of growth hormone (GH) than term infants. Previous investigations of these differences have used sampling frequencies of every 30 min with subsequent application of pulse detection algorithms, such as the CLUSTER program, to assess serum GH pulse parameters. To determine differences in GH secretory rates or GH t1/2 values between premature and term infants, we have sampled 11 neonates at 15-min intervals. We performed deconvolution analysis of the resultant plasma GH values to estimate GH secretory and clearance parameters. Five premature infants (gestational age range 24-34 wk) and six term infants (gestational age range 38-42 wk) were sampled every 15 min for 6 h. All subjects had indwelling arterial catheters. GH was measured (in duplicate) by RIA using 10 microL of plasma. Premature infants had higher secretory burst amplitudes (2.2 +/- 0.13 micrograms/L/min versus 1.4 +/- 0.27 micrograms/L/min, p = 0.02), higher production rates (product of the total number of bursts and the mean mass of GH secreted per burst, 811 +/- 173 micrograms/L/6 h versus 283 +/- 77 micrograms/L/6 h, p = 0.03), and a higher mass of GH per secretory burst (106 +/- 25 micrograms/L versus 38 +/- 11 micrograms/L, p = 0.049) than term infants. The integrated plasma GH concentration exhibited a strong trend toward a higher value in the premature infants (18,100 +/- 800 micrograms/L versus 10,200 +/- 2,700 micrograms/L, p = 0.067).(ABSTRACT TRUNCATED AT 250 WORDS)     

Pneumothorax in the neonate

Dynamic cardiomyoplasty has been performed to reinforce the myocardium in the treatment of patients with severe cardiomyopathies. At the Heart Institute of S?o Paulo University Medical School, 36 patients were submitted to cardiomyoplasty between May 1988 and December 1993. The indications were idiopathic dilated cardiomyopathy in 31, ischemic cardiomyopathy in 3, and Chagas' disease cardiomyopathy in 2 patients. Twenty-eight patients were categorized in New York Heart Association (NYHA) Class III and 8 in Class IV despite the use of maximal medical therapy. There were no hospital deaths, and patients were followed up from 2 to 70 months (mean, 24 months). Besides the improvement of NYHA functional class from 3.2 +/- 0.6 to 1.6 +/- 0.9 at 6 months of follow-up, patients also presented significant changes in the left ventricular systolic and diastolic functions. Nevertheless, 16 patients died, and 2 patients were submitted to heart transplantation during late follow-up. Actuarial survival rates were 82.3% at 1 year, 61.5% at 2 years, and 38.8% at 5 years of follow-up. Otherwise, the analysis of factors influencing the outcome showed that long-term survival was significantly affected by preoperative functional class and by pulmonary vascular resistance. The 26 patients operated in NYHA functional Class III and with pulmonary vascular resistance below 4 Wood units presented survival rates of 72.7% at 2 years and of 63% at 5 years of follow-up. In conclusion dynamic cardiomyoplasty improves functional class and left ventricular function in patients with severe cardiomyopathies. However, the long-term survival after this surgical procedure may be limited by the patients' condition before the operation.     

Thrombocytopenia in the neonate

Pediatricians caring for newborns will eventually be confronted with the problem of thrombocytopenia in the neonatal period. Familiarity with the differential diagnosis of neonatal thrombocytopenia and understanding the pathogenesis of the more common entities allows physicians to design a selective diagnostic and therapeutic plan to benefit these thrombocytopenic infants.     

The Waterston anastomosis with no deaths in the neonate

The Waterston anastomosis has been performed with no deaths in 11 consecutive neonates during the past 24 months. Seven neonates had pulmonary atresia with either single ventricle or hypoplastic right ventricle, 3 had tetralogy of Fallot, and one had severe pulmonary stenosis with a normal right ventricle. Six neonates were one day old and only one was older than 7 days. All have obtained symptomatic and documented (increase Po2) benefit. This level of success is attributed to (1) minimal delay between the recognition of cyanosis and operation (mean time between hospital admission and catheterization was 3 hours and between catheterization and operation, 4 hours); (2) correction of any base deficit prior to, during, and after operation; (3) accurate construction of the anastomosis to avoid excessive size, and (4) careful postoperative management of the pulmonary subsystem by experienced personnel. We have demonstrated that the high mortality rate previously reported for the Waterston anastomosis in the neonate can be markedly improved by an appropriate patient management program.     

The pharmacokinetics of propranolol when used with the propercuten transdermal therapeutic system (experimental data)

The pharmacokinetic studies of propranolol following the application of the propercuten transdermal therapeutic system were performed in conscious rabbits previously assigned to 3 groups. Different forms of propercuten (forte and mite) were used in different groups, different areas of its application being employed. Pulsed intravenous injections of propranolol were given to Group 1 rabbits to conduct another series of pharmacokinetic studies. The rate of drug administration to the systemic bed was 0.08 mg/h per cm propercuten. The constant injection rate was maintained during 5 days, but when propercuten was withdrawn the elimination time of propranolol was 24 hours.     

Subgaleal hemorrhage in the neonate

Subgaleal hemorrhage in the neonate, a possible complication of vacuum extraction, is a medical emergency. Neonates delivered with the assistance of vacuum extraction and displaying any signs of neurologic disturbance, blood loss, or anemia should be evaluated promptly for the possibility of hemorrhage. A case report is provided in this article to describe recognition and management of a neonate in hypovolemic shock after vaginal birth assisted by vacuum extraction.     

Population pharmacokinetic modeling in very premature infants receiving midazolam during mechanical ventilation: midazolam neonatal pharmacokinetics

BACKGROUND: Midazolam is used widely as a sedative to facilitate mechanical ventilation. This prospective study investigated the population pharmacokinetics of midazolam in very premature infants. METHODS: Midazolam (100 microg/kg) was administered as a rapid intravenous bolus dose every 4-6 h to 60 very premature neonates with a mean (range) gestational age of 27 weeks (24-31 weeks), a birth weight of 965 g (523-1,470 g), and an age of 4.5 days (2-15 days). A median (range) of four (one to four) blood samples, 0.2 ml each, were drawn at random times after the first dose or during continuous treatment, and concentrations of midazolam in serum were assayed by high-performance liquid chromatography. A population analysis was conducted using a two-compartment pharmacokinetic model using the NONMEM program. RESULTS: Average parameter values (interpatient percent coefficient of variation) for infants with birth weights 1,000 g or less were total systemic clearance (Cl(T)) = 0.783 ml/min (83%), intercompartmental clearance (Cl(Q)) = 6.53 ml/min (116%), volume of distribution of the central compartment (V1) = 473 ml (70%), and volume of distribution of the peripheral compartment (V2) = 513 ml (146%). For infants with birth weights more than 1,000 g they were as follows: Cl(T) = 1.24 ml/min (78%), Cl(Q) = 9.82 ml/min (98%), V1 = 823 ml (43%), and V2 = 1,040 ml (193%). The intrapatient variability (percent coefficient of variation) in the data was 4.5% at the mean concentration midazolam in serum of 121 ng/mL CONCLUSIONS: Serum concentration-time data were used in modeling the population pharmacokinetics of midazolam in very premature, ventilated neonates. Clearance of midazolam was markedly decreased compared with previous data from term infants and older patients. Infants weighing less than 1,000 g at birth had significantly lower clearance than those weighing more than 1,000 g.     

Surfactant treatment in the neonate with severe respiratory distress syndrome

Eighteen preterm infants severely ill with respiratory distress syndrome who required assisted ventilaton were given modified natural surfactant (Survanta) endotracheally. They had a mean +/- SEM gestational age of 31.2 +/- 0.4 weeks (range 28-34) and a mean +/- SEM birthweight of 1562 +/- 71 g (range 1160-2010). Average time of initial surfactant administration was 15 +/- 1.7 hour (range 5-24). No significant side effects were found during surfactant instillation. Post surfactant, the air entry was improved, oxygenation and arterial/alveolar gradients increased, and the levels of inspired oxygen could be reduced. Some of the radiological abnormalities were resolved. In 13 infants, patent ductus arteriosus became clinically evident, seven of whom received Indomethacin. There were 4 cases of pulmonary air leak, 5 cases of pulmonary hemorrhage and 8 cases of bronchopulmonary dysplasia. Four infants expired, two were due to severe asphyxia/shock and two died of unrelated causes. Among the 14 survivors who came for follow-up, two cases of retinopathy of prematurity had gradually regressed, one had cerebral palsy and delayed development. Surfactant rescue therapy is a supplemental beneficial treatment for severe respiratory distress syndrome while newborn intensive care concept is necessary for efficient diagnosis and treatment of RDS.     

Paracetamol disposition in normal subjects and in patients treated with antiepileptic drugs

1 The serum concentration profile of paracetamol has been determined after administration of single 1000 mg intravenous and oral doses in six normal subjects and six epileptic patients on chronic antiepileptic drug therapy. The urinary excretion of free and conjugated paracetamol has also been determined. 2 Following intravenous administration, serum paracetamol concentration declined with first-order kinetics. Both elimination rate and total body clearance were higher in the epileptic patients, although in neither case was the difference statistically significant. 3 The oral bioavailability (mean +/- s.e. mean) was significantly lower in the epileptic patients than in the normal subjects (0.77 +/- 0.03 and 0.89 +/- 0.02 respectively, P less than 0.01), whereas the urinary excretion total (free+conjugated) paracetamol was almost identical in the two groups. 4 It is suggested that the lower bioavailability of paracetamol in the epileptic patients results from enhancement of first-pass metabolism, secondary to enzyme induction.