Search PubMed⌕ Search

Biomedical subjects

H L Halliday

Publications and source records attributed to H L Halliday.

At least 55 records · Page 3Linked to original sources
PubMed1999

The effect of early feeding on the neonatal blood glucose level at 1-hour of age.

Early infant feeding after birth is being promoted, although it is unclear whether this has any effect on carbohydrate metabolism. We planned to measure the capillary glucose at one hour (1 h) of age in a group of infants from non-diabetic pregnancies using the HemoCue B-Glucose system to see if the timing and method of early feeding would influence this result. Seventy-five term infants were studied, 22 of which were breast-fed, 24 bottle fed and 29 not fed during the first hour after birth. The mean whole blood glucose results were 2.34 mmol/l, 2.52 mmol/l and 2.58 mmol/l respectively (P = NS). The first two groups were fed at a median of 22 minutes before sampling. We conclude that the timing and method of early feeding in the newborn have no significant effect on the blood glucose level measured at 1 h of age, and this remains a reliable outcome measure in studies of glucose metabolism in pregnancy.

Blood Glucose↗
PubMed1999

Clinical trials of postnatal corticosteroids: inhaled and systemic.

Chronic lung disease (CLD) remains a common problem in neonatal intensive care units. Corticosteroids are being used increasingly to prevent or treat CLD. Uncertainties remain including the timing, duration and route of administration, and ratio of benefits to costs. This paper reviews the outcome of 39 randomized clinical trials of postnatal corticosteroid treatment. Twenty-five trials studied systemic steroids at three different postnatal ages; early (<96 h), moderately early (7-14 days), and delayed (>3 weeks). Fourteen-trials studied inhaled steroids (early: <7 days; late: >14 days) and inhaled versus systemic steroids. Systemic steroids have short-term beneficial effects improving gas exchange and lung mechanics to facilitate earlier extubation when used at any postnatal age in infants who are ventilator dependent. Early and moderately early steroids also reduce the risk of CLD at both 28 days and 36 weeks. For moderately early steroid use, there is also a reduction in neonatal mortality with 1 extra survivor for approximately every 16 babies treated (95% confidence interval 9-55). Proven adverse effects are either gastro-intestinal (bleeding) or metabolic (hyperglycaemia and hypertension). Unproven but potential adverse effects include decreased brain and lung growth. Inhaled steroids have been studied less thoroughly. Some studies report improvement in gas exchange and lung mechanics, but long-term benefits are not apparent to date in the published material. Trials comparing inhaled and systemic steroids suggest a more rapid response with the latter, but no significant differences in the rate of CLD at either 28 days or 36 weeks were found. Further research is necessary to define the roles of systemic and inhaled steroids in the prevention and treatment of CLD and to allow comparison of benefits to costs.

Administration, Inhalation↗
PubMed1998

Principles of surfactant replacement.

Surfactant therapy is an established part of routine clinical management of babies with respiratory distress syndrome. An initial dose of about 100 mg/kg is usually needed to compensate for the well documented deficiency of alveolar surfactant in these babies, and repeated treatment is required in many cases. Recent experimental and clinical data indicate that large doses of exogenous surfactant may be beneficial also in conditions characterized by inactivation of surfactant, caused by, for example, aspiration of meconium, infection, or disturbed alveolar permeability with leakage of plasma proteins into the airspaces. The acute response to surfactant therapy depends on the quality of the exogenous material (modified natural surfactants are generally more effective than protein-free synthetic surfactants), timing of treatment in relation to the clinical course (treatment at an early stage of the disease is better than late treatment, and may reduce the subsequent need for mechanical ventilation), and mode of delivery (rapid instillation via a tracheal tube leads to more uniform distribution and is more effective than slow airway infusion). Treatment with aerosolized surfactant improves lung function in animal models of surfactant deficiency or depletion, but is usually associated with large losses of the nebulized material in the delivery system. Furthermore, data from experiments on immature newborn lambs indicate that treatment response may depend on the mode of resuscitation at birth, and that manual ventilation with just a few large breaths may compromise the effect of subsequent surfactant therapy. The widespread clinical use of surfactant has reduced neonatal mortality and lowered costs for intensive care in developed countries. The hydrophobic surfactant proteins SP-B and SP-C are probably essential for optimal biophysical and physiological activity of exogenous surfactants isolated from mammalian lungs, and the dose-effectiveness (in part reflecting resistance to inactivation) can be further improved by enrichment with SP-A. The development of new artificial surfactant substitutes, based on synthetic analogues of the native surfactant proteins, is an important challenge for future research.

Biological Products↗
PubMed1998

Incidence of molecular forms of bile salt-stimulated lipase in preterm and term human milk.

Preterm and term human milk samples obtained at various times after delivery were analyzed for the presence of molecular forms of the human milk enzyme, bile salt-stimulated lipase (BSSL). Thirty-five percent of both the preterm and term milk samples contained two molecular forms of BSSL, of variable molecular mass. The remainder contained only one molecular species of either 115 kD (50%) or 120 kD (15%). The number of molecular forms present was not related to length of lactation, maternal age, gestation, or maternal blood group. The specific activity of BSSL purified from term milk was similar to that purified from preterm milk, and there was no difference in specific activity whether one or two molecular forms were present. This study demonstrates heterogeneity of both molecular mass and molecular forms. We conclude that preterm babies fed their own mother's milk are unlikely to be disadvantaged with respect to fat digestion as BSSL secreted in preterm milk appears to be very similar to that produced in term milk, although we cannot exclude other functional differences.

Adult↗
PubMed1998

Gastro-intestinal complications following neonatal cardiac catheterisation.

BACKGROUND: Infants with congenital cyanotic heart disease are at increased risk of developing necrotising enterocolitis (NEC). We examined a cohort of infants with congenital cyanotic heart disease in order to assess the role of cardiac catheterisation in the pathogenesis of NEC. METHODS: Sixty-five infants with congenital cyanotic heart disease were assessed in a retrospective study. The incidence of gastrointestinal complications was compared between infants who required cardiac catheterisation and those who did not. RESULTS: There were 38 infants who required cardiac catheterisation and 27 who did not. Both groups were similar for known risk factors for NEC. Eleven of the catheterised infants developed bloody stools versus 4 of the non-catheterised infants (OR 2.34; 95% CI 0.65-8.36). Five of the catheterised infants developed classical NEC versus none of the non-catheterised infants (OR 4.24; 95% CI 0.47-38.5). Four of the five infants who developed NEC did so during re-introduction of feeds following cardiac catheterisation. CONCLUSION: Infants with congenital cyanotic heart disease appear to be at a greater risk of gastrointestinal complications including necrotising enterocolitis in the days following cardiac catheterisation. We suggest a more cautious approach to feeding is required during this period.

Cardiac Catheterization↗
PubMed1998

Which interventions for neonatal respiratory failure are effective?

AIM: To review the evidence from clinical trials of various interventions to treat and prevent respiratory failure in the neonate and to determine which interventions are effective and which require further study. METHODS: Randomized controlled trials and/or meta-analyses of trials of interventions for neonatal respiratory failure were sought from databases including the Cochrane Collaboration. The results were synthesized as typical relative risks and typical risk differences, with 95% confidence intervals (CI). RESULTS: The following interventions were effective: conventional mechanical ventilation (absolute reduction in mortality 12%, 95% CI 4-21%), continuous positive airway pressure (absolute reduction in mortality 15%, 95% CI 1-28%), surfactant therapy (absolute reduction in mortality 4 to 9%, 95% CI 1-13%), and extracorporeal membrane oxygenation (absolute reduction in mortality 29%; 95% CI 15-42%). High frequency oscillatory ventilation with a volume recruitment strategy and inhaled nitric oxide appeared promising, but have not yet reduced mortality. Prenatal corticosteroids (absolute reduction in mortality 4%; 95% CI 2-6%) and amnioinfusion (effect on mortality not yet possible to estimate) prevented respiratory failure, but routine endotracheal intubation and suctioning of the airways at birth in vigorous meconium-stained term babies did not prove effective. CONCLUSIONS: Assisted ventilation, surfactant therapy, and extra-corporeal membrane oxygenation are effective, but it is uncertain how each should be applied in an individual infant. More research is needed to evaluate combinations of effective interventions, and effectiveness of high frequency oscillation and inhaled nitric oxide. Routine intubation and suctioning of the airways at birth in meconium-stained vigorous neonates is not recommended.

Humans↗
PubMed1997

Lyso-phosphatidylcholine and outcome of preterm babies with respiratory distress syndrome treated with surfactant.

Phosphatidylcholine (PC) is the predominant phospholipid in natural surfactant preparations. A metabolic intermediate, lyso-PC, is potentially injurious to the lungs. In the present study, tracheal aspirates from preterm babies with respiratory distress syndrome treated with surfactant were examined for the presence of lyso-PC to determine if there was any correlation with outcome. Eighteen babies were assigned to receive initially either 100 or 200 mg/kg Curosurf followed by up to three further 100-mg/kg doses if required. Lyso-PC was present in aspirates taken 12-24 h after the last treatment from nine of 11 infants who initially received 200 mg/kg but in only one from seven receiving 100 mg/kg initially, and was dependent on the total dose of phospholipid administered. Three babies in the low-dose group developed bronchopulmonary dysplasia, whereas two in the high-dose group were non-survivors, however we could not correlate the presence of lyso-PC with adverse long-term outcome in this group of preterm infants.

Biological Products↗
PubMed1997

Behavioural adjustment in school of very low birthweight children.

The school-based behavioural adjustment at 7-8 years of a cohort of 243 prematurely born, very low birthweight (< 1501 g) children and their normal birthweight controls is reported. The findings indicate that the children born preterm (both male and female) were rated by their teachers as expressing more behaviour problems than their controls, and were less well adjusted to the school environment. The deficits noted in the preterms applied across the social classes, with no amelioration noted in preterms of higher social class. It is speculated that the problem behaviours reflect a failure in self-regulatory functions.

Attention Deficit Disorder with Hyperactivity↗
PubMed1997

Synthetic or natural surfactants.

Surfactant replacement therapy is one of the most studied interventions in neonatal medicine, with many thousands of infants having been enrolled in randomized clinical trials. It is clear that surfactant therapy reduces neonatal mortality and the risk of pulmonary air leaks in babies with or at risk of developing respiratory distress syndrome. Yet some doubts linger over other aspects of this therapy, despite it having been an acceptable and proven therapy for the past 7-10 years. As regards timing of treatment, the earlier the better, with true prophylaxis being reserved for babies of less than 28 week's gestation. Natural surfactant preparations containing surfactant proteins B and C act more rapidly than their synthetic protein-free counterparts and probably also have a greater impact on reducing neonatal mortality and pulmonary air leaks. Fears raised about immunological effects, prion transmission and chemical contamination of natural surfactants have not been substantiated. Long-term follow-up studies do not show any differences in outcome between treated and non-treated infants, except that the incidence and severity of retinopathy of prematurity might be reduced by treatment with natural surfactant. Further research is needed and this will include more detailed follow-up studies, newer indications for surfactant therapy and the testing of newer preparations with synthetic peptides or protein analogues added.

Humans↗
PubMed1997

Randomised controlled trial of an aggressive nutritional regimen in sick very low birthweight infants.

AIMS: To improve energy intake in sick very low birthweight (VLBW) infants; to decrease growth problems, lessen pulmonary morbidity, shorten hospital stay, and avoid possible feeding related morbidity. Morbidity in VLBW infants thought to be associated with parenteral and enteral feeding includes bronchopulmonary dysplasia, necrotising enterocolitis, septicaemia, cholestasis and osteopenia of prematurity. METHODS: A prospective randomised controlled trial (RCT) comparing two types of nutritional intervention was performed involving 125 sick VLBW infants in the setting of a regional neonatal intensive care unit. Babies were randomly allocated to either an aggressive nutritional regimen (group A) or a control group (group B). Babies in group B received a conservative nutritional regimen while group A received a package of more aggressive parenteral and enteral nutrition. Statistical analysis was done using Student's t test, the Mann-Whitney U test, the chi 2 test and logistic regression. RESULTS: There was an excess of sicker babies in group A, as measured by initial disease severity (P < 0.01), but mean total energy intakes were significantly higher (P < 0.001) in group A at days 3 to 42 while receiving total or partial parenteral nutrition. Survival and the incidences of bronchopulmonary dysplasia, septicaemia, cholestasis, osteopenia and necrotising enterocolitis were similar in both groups. Growth in early life and at discharge from hospital was significantly better in babies in group A. There were no decreases in pulmonary morbidity or hospital stay. CONCLUSION: Nutritional intake in sick VLBW infants can be improved without increasing the risk of adverse clinical or metabolic sequelae. Improved nutritional intake resulted in better growth, both in discharge, but did not decrease pulmonary morbidity or shorten hospital stay.

Bacterial Infections↗
PubMed1996

Treatment of severe meconium aspiration syndrome with porcine surfactant. Collaborative Surfactant Study Group.

UNLABELLED: This study is based on clinical data from a retrospective series of 54 infants with meconium aspiration syndrome treated with porcine surfactant at a median age of 14 h (range 1-176 h). Median arterial/ alveolar oxygen tension ratio (a/A PO2 ratio) before treatment was 0.08 (range 0.02-0.23) and oxygenation index 25 (range 6-110). After treatment with surfactant at an initial dose of 50-200 mg/kg there was a modest but statistically significant increase in a/APO2 ratio associated with a reduction of oxygenation index. Ten (18%) babies showed a 3-4 fold increase in a/APO2 ratio within 1-2 h of treatment. Twenty-four (44%) babies showed little or no response by 1-2 h with the remaining infants showing modest improvement in oxygenation. One third of babies required repeated doses of surfactant. Twenty-eight day survival was 81%, with two babies requiring extracorporeal membrane oxygenation. CONCLUSION: Natural surfactant treatment of severe meconium aspiration may prove to be a useful intervention and randomised controlled clinical trials should be undertaken.

Biological Products↗
PubMed1996

Controversies: synthetic or natural surfactant. The case for natural surfactant.

Surfactant replacement therapy for respiratory distress syndrome (RDS) is not new, the first trials having been performed over 30 years ago. These early trials used synthetic protein-free surfactants administered as aerosols and were unsuccessful. Since 1980 a variety of natural and synthetic surfactant preparations have been used to treat or prevent RDS, and both demonstrate clinical effects. I have used evidence derived from 3 areas to demonstrate the superiority of natural surfactants: in vitro physical properties, in vivo physiological effects and the results of comparative clinical trials. using the pulsating bubble surfactometer, the surface tension at maximum and minimum bubble size are significantly lower for natural compared to synthetic surfactants (31 and 0 mN/m versus 53 and 29 mN/m respectively). Physiological effects of surfactants have been compared in immature rabbits and lambs and both models demonstrate the superiority of natural surfactants. For example in immature rabbits lung compliance values after 60 minutes of ventilation are 0.60 ml/cmH2O in natural surfactant treated animals, 0.44 ml/cmH2O in synthetic surfactant treated animals and 0.34 ml/cmH2O in controls (p < 0.01). The technique of meta-analysis was used to analyse the outcome of 6 comparative clinical trials of natural and synthetic surfactants. These 6 studies included 3536 babies and 5 of them compared Survanta (a bovine natural surfactant) and Exosurf (a synthetic protein-free surfactant). One study compared Infasurf (another bovine natural surfactant with Exosurf). Meta-analysis shows a 19% reduction in the odds of neonatal death for natural compared to synthetic surfactant treated babies (OR, 0.81; 95% CI 0.66-0.98). For bronchopulmonary dysplasia there was a non-significant reduction in risk for Survanta-treated babies (OR, 0.93; 95% CO 0.78-1.10). In summary, there is now clear evidence of physiological and clinical superiority of natural compared to synthetic surfactants. Surfactant proteins B and C are needed to facilitate rapid adsorption and spreading of phospholipids. They also account for the more rapid clinical action allowing oxygen and ventilator pressures to be lowered soon after administration. The odds of neonatal mortality are reduced by about 20% if natural surfactants are preferred to their synthetic protein-free counterparts. Long-term follow-up studies of babies treated with both types of surfactant should be a top priority.

Animals↗
PubMed1996

Natural vs synthetic surfactants in neonatal respiratory distress syndrome.

This review examines the 11 randomised clinical trials that have compared different surfactant preparations. Seven trials, enrolling 2488 infants with respiratory distress syndrome (RDS), compared the natural surfactant beractant (Survanta) with the synthetic surfactant colfosceril palmitate (Exosurf Neonatal). Infants treated with beractant had lower oxygen requirements for at least 3 days than those treated with colfosceril palmitate. The infants treated with beractant also had lower risks of neonatal mortality [odds ratio (OR) 0.81; 95% confidence interval (CI) 0.65 to 1.01], retinopathy of prematurity (OR 0.81; 95% CI 0.66 to 0.99), and the combined endpoint of death or bronchopulmonary dysplasia (OR 0.86; 95% CI 0.75 to 0.99), compared with those treated with colfosceril palmitate. Calf lung surfactant extract (CLSE; Infasurf), another natural surfactant, has been compared with colfosceril palmitate in 2 studies: in one as prophylaxis and in the other as rescue therapy. Similar, although nonsignificant, advantages were found for the natural surfactant compared with the synthetic surfactant. In 6 of these 9 trials there was a significant reduction in the odds of pulmonary air leaks (OR 0.53; 95% CI 0.41 to 0.64) for infants treated with natural compared with synthetic surfactants. In 7 trials (3554 infants) comparing natural and synthetic surfactants to treat RDS (6 comparing beractant and colfosceril palmitate, and one CLSE and colfosceril palmitate), there was a significantly reduced risk of neonatal mortality (OR 0.80; 95% CI 0.66 to 0.97) with natural compared with synthetic surfactant treatment. In 2 further trials, different natural surfactant preparations have been compared. Reduced oxygen needs for 24 hours after treatment were found for CLSE and Curosurf (porcine-derived lung surfactant, PLS) when each was compared with beractant. Apparent longer term benefits from these surfactants were not statistically proven. Further trials are needed to be certain of the differences between the various surfactant preparations.

Humans↗