Vichien Lorch

Should Fewer Premature Infants Be Screened for Retinopathy of Prematurity in the Managed Care Era

Objective.u2003To determine appropriate upper limits for gestational age and birth weight when screening infants for retinopathy of prematurity (ROP). Design.u2003Retrospective survey. Setting.u2003Tertiary neonatal intensive care nursery. Patients.u2003Seven hundred seven infants born July 1, 1990 to June 30, 1996 and screened for ROP according to the 1988 to 1996 American Academy of Pediatrics guidelines. Outcome Measures.u2003Maximum stage of ROP with respect to birth weight and gestational age. Results.u2003No ROP more than Stage 1 was observed in infants with gestational ages ≥32 weeks or birth weights ≥1500 g. All cases of threshold and Stage 4 ROP were confined to infants with gestational ages ≤30 weeks or birth weights <1200 g. Conclusions.u2003The latest American Academy of Pediatrics screening guidelines for ROP are discretionary for infants with birth weights >1500 g or gestational ages >28 weeks. If ROP screening is limited to infants with birth weights of ≤1500 g, 34.2% fewer infants would require screening compared with the previous <1800 g recommendation, while missing no cases of ROP more than Stage 1. A gestational age cut-off of ≤28 weeks, however, is less desirable, and could potentially miss several infants with more advanced retinopathy (including Stage 4). If ROP screening criteria were instead modified to include infants of gestational ages <32 weeks, the number of patients requiring screening could be reduced 29.1% compared with the previous recommendation of <35 weeks, again without missing any cases of ROP more than Stage 1. Use of such a screening strategy (birth weight <1500 g or gestational age <32 weeks) is predicted to save in excess of 1.5 million dollars annually in the United States, while missing no cases of ROP more than Stage 1.

Improved fluid management utilizing humidified incubators in extremely low birth weight infants

OBJECTIVE: To compare fluid and electrolyte management in extremely low birth weight (ELBW) infants nursed in humidified versus nonhumidified incubators.STUDY DESIGN: Setting — tertiary intensive care nursery. Subjects — all infants with birth weight <1000 g admitted 1/95 to 1/99 who were treated with incubators and survived for >96 hours (N=155). Intervention — retrospective comparison of daily weights, fluid intakes, urine outputs, and serum electrolytes between group 1 (n=70, nonhumidified incubators, born 1/95 to 1/97) and group 2 (n=85, humidified incubators, born 1/97 to 1/99) over the first 4 days after birth.RESULTS: Despite similar daily weight losses between groups, group 1 infants received higher fluid intakes, had lower urine outputs, and had a higher incidence of hypernatremia, hyperkalemia, and azotemia (p<0.05). Although no differences in mortality or the incidence of patent ductus arteriosus, bronchopulmonary dysplasia, or the overall rate of nosocomial infections were observed, the proportion of gram-negative isolates increased significantly (62%, p<0.05) following the introduction of humidified incubators.CONCLUSIONS: ELBW weight infants nursed in humidified incubators have lower fluid requirements, improved electrolyte balance, and higher urine outputs during the first 4 days after birth compared to those nursed in nonhumidified incubators.

Responses of small intrapulmonary arteries to vasoactive compounds in the fetal and neonatal lamb: Norepinephrine, epinephrine, serotonin, and potassium chloride

ABSTRACT: Despite considerable study, the mechanisms responsible for the transition of the pulmonary circulation from the fetal to newborn life remain obscure. We compared the responses of third and fourth generation pulmonary arteries to norepinephrine, epinephrine, serotonin, and KC1 from lambs 7 d preterm and 1, 7, and 21 d of age to assess differences between age and third and fourth generations of the pulmonary arterial tree during the transitional period. Preterm vessels were significantly smaller in internal diameter than all other aged vessels for both generations. Fourth generation vessel response to KC1 increased with age (94 ± 1 5 mg/mm2, preterm; 259 ± 3 1 mg/mm2, 21 d). Third generation vessel response to KC1 did not change with age (135 ± 15 mg/mm2, preterm; 158 ± 1 8 mg/mm2, 21 d). There were no differences in maximum response to norepinephrine and epinephrine between ages; however, third generation vessel response to these compounds was significantly greater (30-60% of maximum KC1 response) than fourth generation vessel response (0- 10%). Third and fourth generation vessels had the same maximum response to serotonin regardless of age or generation. Third generation vessels were significantly reduced in sensitivity (log molar concentration which produced 50% of the maximum response—EC5o) to norepinephrine at d 1 (5.89 ± 0.12 log molar) and 7 (5.90 ± 0.21) compared to preterm (6.48 ± 0.10) and 21 d of age (6.50 ± .03). Both third and fourth generation vessels were less sensitive to serotonin at d 1 (5.04 ± 0.17, third; 5.61 ± 0.10, fourth) compared to d 7 (5.77 ± 0.13, third; 6.36 ± 0.12, fourth) and 21 d (5.82 ± 0.24, third; 6.50 ± 0.15, fourth). A similar nonsignificant trend occurred in third generation vessels to epinephrine at d 1 and 7 compared to vessels at preterm and 21 d of age. Greater than 75% of fourth generation vessels did not respond to norepinephrine and epinephrine. The small intrapulmonary arteries of the neonate are undergoing dynamic changes in physiologic response which are dependent upon age and generation

Plasma Carnitine Alterations in Premature Infants Receiving Various Nutritional Regimes

Plasma carnitine, carnitine esters, and triglyceride concentrations were determined in 36 appropriate-forgestational-age (AGA) infants at various stages of prematurity throughout hospitalization to determine the effect of a carnitine-free and carnitine-containing diet on plasma carnitine and triglyceride concentrations. The infants were entered into one of three experimental groups based on birth weight: group I less than 1.0 kg; group II 1.0-1.51 kg; and group III 1.52-2.5 kg. Throughout the study subjects were placed on appropriate nutritional regimes which included hyperalimentation (HA), intravenous (iv) fat emulsion (Intralipid), Portagen, Enfamil-24 Premature Formula, Enfamil-20, and breastmilk. Blood samples were drawn from each infant at birth, days 1-5,7 then weekly, also before and after each nutritional intervention to determine carnitine and triglyceride concentrations. Results showed that plasma total carnitine and nonesterified carnitine decreased in all groups when the infants were maintained on a carnitine-free diet (HA, Intralipid, Portagen). In general, the carnitine levels continued to decrease until a carnitine-containing diet was initiated. Once a carnitine-containing diet was begun, plasma total carnitine (TC) and nonesterified carnitine (NEC) levels increased at fairly similar rates in all groups. However, an inverse relationship between carnitine and triglyceride (TG) concentrations were not seen in these infants. This would indicate that most premature infants require exogenous carnitine to maintain the plasma concentration of carnitine. However, a decreased concentration of plasma carnitine was not correlated with an elevated TG level under the conditions of this study.

Parenteral Alimentation in the Neonate

Effects of neonatal starvation, neonatal nutritional requirements, composition of infusates, growth, and complications of parenteral alimentation are discussed.

Altered platelet-activating factor levels and acetylhydrolase activities are associated with increasing severity of bronchopulmonary dysplasia

Lipid inflammatory mediators are thought to play an important role in the pathogenesis of neonatal lung injury and bronchopulmonary dysplasia (BPD). Because preliminary studies from the intensive care nursery of the University of Tennessee Medical Center, Knoxville, revealed linear increased in blood platelet-activating factor (PAF) levels in very low birthweight infants developing chronic lung disease and lower cord blood PAF acetylhydrolase activities in premature infants, it was theorized that altered platelet-activating factor levels and PAF acetylhydrolase activities are associated with increasing severity of BPD. Platelet-activating factor levels (blood and tracheal lavage) and PAF acetylhydrolase activities (blood and tracheal lavage) were measured over days 1 to 2, 3 to 5 and 6 to 7 in 16 ventilated infants and weekly in 9 infants with bronchopulmonary dysplasia. Platelet-activating factor values were normalized per nanogram of lavage blood urea nitrogen. Severity of bronchopulmonary dysplasia was estimated using the scoring system developed by Toce. Mean blood and lavage PAF levels and PAF acetylhydrolase activities were compared in infants developing bronchopulmonary dysplasia with those without the disease over the first seven days of life. Infants developing chronic lung disease were significantly smaller and of younger gestational age. In infants with bronchopulmonary dysplasia, higher PAF levels in blood were seen on days 3 to 5, along with increased lavage acetylhydrolase activities on days 1 to 2. Increased levels of PAF in lavage on days 3 to 5 were associated with increasing severity of bronchopulmonary dysplasia. Altered blood and lavage platelet-activating factor levels and PAF acetylhydrolase activities appear to be associated with the pathogenesis and severity of bronchopulmonary dysplasia.

A low power wireless apnea detection system based on pyroelectric sensor

The paper presents a fully integrated system for apnea detection. Apnea has been one of the leading causes of death in the USA and it is even more critical for premature neonatal infants. A prototype device with the pyroelectric sensor and a wireless telemetry designed in 0.5 μm CMOS process is presented which overcomes the complexity of the point of care diagnosis of sleeping disorders.

IMPROVED FAT AND CA ABSORPTION IN L.B.W. INFANTS FED A MEDIUM CHAIN TRIGLYCERIDE CONTAINING FORMULA

Premature infants are reported to have decreased fat absorption. Because of energy requirements and limitation of gastric capacity, new formulae are sought which will provide absorbable and utilizable fats. In the current study fat absorption in L.B.W. infants fed formulae containing combinations of soy oil, corn oil, coconut oil and medium chain triglycerides was studied.Thirty infants 1250 to 1850 grams were divided randomly into three groups and fed one of three formulae for 21 days. Formula A contained fat as 30% soy, 30% corn and 40% medium chain triglycerides; Formula B, 40% soy, 40% corn and 20% coconut; and Formula C, 100% corn. Three day stool collection were marked by use of Red carmine and collected from 5 to 8 and 12 to 15 days of life. Infants on Formula A had the best mean absorption for both periods of 84.6 and 86.7%; B 73.5 and 81.0% and in C the least absorption of 66.6 and 72.4%. Mean blood cholesterol levels in each group were under 100 mg at 21 days of age. Calcium absorption was best in Formula A. No statistical difference for weight, length and head circumference growth was noted and there were no untoward clinical symptoms.Direct absorption of medium chain triglycerides into the portal system may be responsible for the increased fat absorption and could prove advantageous to low birth weight infants.

A low power wearable respiration monitoring sensor using pyroelectric transducer

This paper presents a fully integrated low-power wearable respiration monitoring system using a pyroelectric transducer. Many chronic respiratory diseases such as asthma and apnea are leading causes of death worldwide which are even more critical for premature neonatal infants. Currently, the diagnosis of apnea requires the infants to go through overnight clinical sleep analysis, also known as polysomnography for 12 to 24-hour period. During this process numerous sensors are attached to the sensitive skin of the infants resulting in irritation and inconvenience. To overcome this problem a novel point-of-care respiration monitoring system has been proposed. At the front-end of the sensor a PVDF (Polyvinylidene Fluoride) based pyroelectric transducer is used which could be placed under the nasal cavity or inside a cannula of the subject. The charge generated by the transducer due to the nasal air flow is then converted to a proportional voltage signal by an operational transconductance amplifier (OTA) based charge amplifier. The subsequent signal processing blocks detect and process the signal coming out of the charge amplifier if it lies within the voltage range that corresponds to an apneic event. Once the signal is detected an alarm signal is generated indicating the occurrence of an apneic event. The light-weight design and smaller footprint of the transducer as well as the integrated devices make it suitable as a wearable sensor for non-invasive respiration monitoring. A prototype device with the integrated circuit fabricated using 0.5µm CMOS process is presented in the paper which can prevent many major disorders that can lead to neonatal mortality.

Medical Devices for Pediatric Apnea Monitoring and Therapy: Past and New Trends

Apnea in the pediatric population is associated with increased morbidity and mortality in a large number of developed as well as developing countries. It is even more prominent in preterm newborn infants and is commonly referred to as apnea of prematurity. Its current diagnosis and therapy involve the use of traditional technologies, which often result in discomfort to the infants due to the use of invasive devices attached to their sensitive skin, especially in overnight clinical sleep analysis (for over a 12- or 24-h period). Emerging trends for the point-of-care diagnosis of this sleep disorder are focused on the design of integrated devices for less complex and noninvasive monitoring. This paper presents a review of the state of the art of clinical technologies and methodologies for sleep apnea detection and their pros and cons, with particular focus on their working principles and relevance to pediatrics. Moreover, an in-depth discussion on emerging future technologies envisioned to be integral parts of the daily home-based applications is included in the paper.