Margaret Pendray

Selenium deficiency in low birth weight neonates: An unrecognized problem

To determine whether selenium deficiency is common among low birth weight infants in our neonatal intensive care unit, we surveyed blood samples from healthy full-term and preterm infants born in our hospital over a 3-month period. Selenium was measured by electrothermal atomic absorption spectrometry. Glutathione peroxidase was measured in plasma by an automated method. Baseline (less than 72 hours postnatal) selenium concentration and glutathione peroxidase activity were significantly lower in low birth weight infants than in full-term babies. Sequential selenium analyses were obtained in 16 sick low birth weight neonates who remained in the intensive care nursery for up to 6 weeks because of lung disease. All were fed parenterally without supplemental selenium, with or without oral intake, for periods varying from 3 to 60 days. All had a marked decrease from baseline selenium levels, and values below the detection limit of our assay were found in seven infants. Selenium deficiency is much more common in small infants than is generally realized, but the clinical significance in neonates is poorly understood.

Variations in rates of nosocomial infection among Canadian neonatal intensive care units may be practice-related

BackgroundNosocomial infection (NI), particularly with positive blood or cerebrospinal fluid bacterial cultures, is a major cause of morbidity in neonatal intensive care units (NICUs). Rates of NI appear to vary substantially between NICUs. The aim of this study was to determine risk factors for NI, as well as the risk-adjusted variations in NI rates among Canadian NICUs.MethodsFrom January 1996 to October 1997, data on demographics, intervention, illness severity and NI rates were submitted from 17 Canadian NICUs. Infants admitted at <4 days of age were included. NI was defined as a positive blood or cerebrospinal fluid culture after > 48 hrs in hospital.Results765 (23.5%) of 3253 infants <1500 g and 328 (2.5%) of 13228 infants ≥1500 g developed at least one episode of NI. Over 95% of episodes were due to nosocomial bacteremia. Major morbidity was more common amongst those with NI versus those without. Mortality was more strongly associated with NI versus those without for infants ≥1500 g, but not for infants <1500 g. Multiple logistic regression analysis showed that for infants <1500 g, risk factors for NI included gestation <29 weeks, outborn status, increased acuity on day 1, mechanical ventilation and parenteral nutrition. When NICUs were compared for babies <1500 g, the odds ratios for NI ranged from 0.2 (95% confidence interval [CI] 0.1 to 0.4) to 8.6 (95% CI 4.1 to 18.2) when compared to a reference site. This trend persisted after adjustment for risk factors, and was also found in larger babies.ConclusionRates of nosocomial infection in Canadian NICUs vary considerably, even after adjustment for known risk factors. The implication is that this variation is due to differences in clinical practices and therefore may be amenable to interventions that alter practice.

Spontaneous endotoxinemia in premature infants: correlations with oral feeding and bowel dysfunction.

Infants admitted to a tertiary care nursery were tested serially to determine the frequency and epidemiology of spontaneous endotoxinemia, a phenomenon suggested by previous studies. Plasma and stools were tested for endotoxin-like activity (ELA) using a Limulus amoebocyte lysate method and results were correlated with clinical data. We detected ELA in plasma of 28 of 47 infants (60%) tested throughout their hospital stay: only two of 58 separate episodes could be attributed to infection. Endotoxinemia was not consistently associated with classical signs of fever, shock, and jaundice. Prior to oral feeding, little or no ELA was detected in stools and endotoxinemia was ascertained in only six of 45 infants (13%). With feeding, fecal ELA concentrations rose sharply, and endotoxinemia was detected in 56% of remaining infants (p < 0.001). Bowel disease predisposed to endotoxinemia: 16 of 20 infants (80%) with necrotizing enterocolitis or difficult establishment on feeding were affected, compared to five of 17 infants (29%) without such problems (p < 0.01). Fecal ELA concentrations were not abnormally elevated in those with bowel disease. We conclude that endotoxinemia occurs commonly in immature infants as their fecal flora develops with feeding but the amount of circulating endotoxin required for injury and the patterns this takes require further investigation.

Serum zinc, copper, retinol-binding protein, prealbumin, and ceruloplasmin concentrations in infants receiving intravenous zinc and copper supplementation

One hundred twenty-seven newborn infants requiring parenteral nutrition were randomly assigned to receive differing amounts of zinc (40 to 400 micrograms/kg/day) and copper (20 or 40 micrograms/kg/day) supplementation within five birth weight groups (600 to 2,500 gm). The serum zinc concentration remained relatively constant in the group receiving the most zinc supplementation after two weeks of therapy, but declined sharply in the groups receiving less supplementation. No effect of increased copper intake was noted on ceruloplasmin values, but a difference in serum copper concentrations was noted at two weeks. No correlation was noted between serum zinc and copper values or among those for serum zinc, retinol-binding protein, and prealbumin. Reference ranges were defined for serum zinc, copper, retinol-binding protein, prealbumin, and ceruloplasmin in the preterm infant.

Peak inspiratory pressure requirements in infants born weighing less than 750 g.

The possibility that peak inspiratory pressure requirements or the arterial:alveolar oxygen ratio can predict the clinical outcome in infants weighing less than 750 g at birth was explored in a consecutive series. Nine of 10 infants (90%) with a peak inspiratory pressure requirement of more than 18 cm H2O at 48 hours or more than 16 cm H2O at 72 hours from age subsequently died later of respiratory causes (defined as death after 72 hours of pulmonary interstitial emphysema, bronchopulmonary dysplasia, or cor pulmonale). Twenty of 21 remaining infants (95%) survived until discharge. Using these data a 95th centile for peak inspiratory pressure requirement during the first 72 hours of life was constructed. The potential value of this centile in predicting later death of respiratory causes was examined in a separate series. Twelve of 15 infants (80%) whose peak inspiratory pressure requirements remained below the 95th centile, or were not ventilated (n = 6), survived. In contrast, 11 of 12 (92%) infants whose requirements crossed the 95th centile died later of respiratory causes. The infants who died had more radiological changes and higher mean arterial carbon dioxide pressure than survivors suggesting that the severity of the initial lung disease rather than the way that ventilation was managed determined prognosis. Peak inspiratory pressure requirement was more useful than arterial:alveolar oxygen ratio in clearly distinguishing between survivors and infants who died later of respiratory causes.

1365 HYPOTHERMIA IN TRANSPORTED NEONATES: REWARMING EFFECT OF RADIANT HEAT VERSUS WARMED AIR INCUBATORS

Of 231 neonates transported to this centre in the last year 64 (28%) had a core temperature of< 36°C when examined prior to transport. Two types of transport incubator are in use; a conventional system with circulating warmed air (WA) and one using a radiant heat (RH) source. Allocation of incubators depends on availability and is largely random. Review of transport records shows 27 (42%) of the hypothermic infants rewarmed in transit with a rise in temperature above 36.5°C. 10 (25%) of the 40 infants nursed in WA units rewarmed and 17 (70%) of the 24 transported under RH. In cold babies WA unit environmental temperature is set 2°C above skin temperature and the skin servo of the RH unit at 36.8°C. Mean weights for rewarmed and persistently cold groups were comparable, as were time of day, season and mean duration of transport. Lowest incidence of rewarming was on short transports (<2 hours from initiating transport care to admission) In 2 infants who failed to rewarm core temperature was unrecordable prior to transport and with 2 others equipment malfunction occurred. 6 (20%) of those who remained cold in WA units actually lost body heat in transit. Neonatal mortality was 17% in the rewarmed compared with 37% among those who remained cold. Although initial morbidity and management are relevant, among hypothermic infants transported to this centre those nursed in radiant heat transport incubators appear to have a greater potential for rewarming than those in warmed air units, and those that do rewarm have a lower neonatal mortality than those who remain cold.

STAFF FATALITIES FOLLOWING A PERINATAL TRANSPORT ACCIDENT; ETHICAL ISSUES AND STAFF SUPPORT. 163

STAFF FATALITIES FOLLOWING A PERINATAL TRANSPORT ACCIDENT; ETHICAL ISSUES AND STAFF SUPPORT. 163

COMPARATIVE COSTS AND OUTCOMES OF THREE TRANSPORT TEAM MODELS 947

Objectives: Since there is little literature on the cost-effectiveness of different infant, pediatric and maternal transport team(ITT) models in current use, we compared costs and outcomes of the Emergency Medical Technician (EMT) based but physician supported ITT team in British Columbia with two other commonly used models in North America: dedicated nurse teams (RN), and combined physician/nurse/respiratory therapist teams (CT).

DOES TREATMENT WITH DEXAMETHASONE AFFECT THE IMMUNOLOGICAL RESPONSE TO ANTIGENIC CHALLENGE OF INFANTS BORN PRETERM? 1717

To assess the effect if any of treatment with dexamethasone (Dex) on the serologic response to routine neoantigens of infants born preterm; we compared the ability of infants treated with Dex for bronchopulmonary dysplasia (BPD) and matched controls to respond to a highly immunogenic Haemophilus Influenzae type b conjugate vaccine (PedvaxHib; Merck Sharp). Consecutive eligible infants born preterm (26-32 weeks gestation) admitted to two tertiary neonatal care units (British Columbias Childrens and the Royal Columbian Hospitals) were studied. Immunisation with PedvaxHib, DTP-IPV was done after 8 weeks chronological age. Serum obtained 2 months later was tested for anti-PRP by IgG ELISA. The primary outcome measure was the response to dose 1 of PedvaxHib, expressed as the proportion seropositive (anti-PRP level≥ 0.15μg/ml). 66 infants were included: 28 treated with Dex (study group) and 38 not (controls). Mean gestational age was 27 weeks (26-31 weeks) for study group and 30 weeks (26-32 weeks) for controls; mean chronological age at vaccination was 12 weeks (8-24 weeks) for study group and 8 weeks (8-11 weeks) for controls, while the mean post-conception ages at vaccination were 39 and 38 weeks respectively. Study group vaccination was given at a mean of 36 days(10-86 days) after the last Dex dose. Six (21.4%) Dex group and 21 (55.3%) control group infants were seropositive (2 sided p = 0.01, Fishers exact test). Treatment with dexamethasone may have decreased the ability of infants born preterm to respond to a potent neoantigen, although both preterm groups respond less well to this vaccine than full term infants are reported to.