Biomedical subjects
Publications and source records attributed to H L Halliday.
Twenty two babies who developed bronchopulmonary dysplasia were compared with 22 babies matched for gestational age who did not. Those with bronchopulmonary dysplasia weighed less at birth and had lower energy intakes from day 7 to day 56. Undernutrition before and after birth is a major problem in babies who develop bronchopulmonary dysplasia.
There is controversy over the effect of hypertension in pregnancy on the incidence of neonatal respiratory distress syndrome. We investigated the association between maternal hypertension and the incidence of respiratory distress syndrome in 268 very low birthweight babies of less than 34 weeks' gestation. A lower incidence of respiratory distress syndrome was associated with growth retardation and membrane rupture greater than 24 hours. Maternal hypertension was associated with an increased incidence of respiratory distress syndrome. We used the multiple logistic regression model to control for confounding variables, as the maternal and neonatal factors associated with respiratory distress syndrome were not evenly distributed between the two groups. After adjustment for birth weight, gestational age, growth retardation, and membrane rupture greater than 24 hours, the risk of developing respiratory distress syndrome was significantly greater in babies of hypertensive mothers. Significance was lost when labour before delivery and mode of delivery were taken into account. The increased incidence of respiratory distress syndrome in babies of hypertensive mothers may be due to the absence of labour before delivery because of the greater likelihood of caesarean section.
Very low birth weight infants often receive multiple blood transfusions. We measured the plasma levels of the trace elements selenium, manganese, and glutathione peroxidase in 20 very low birth weight infants prior to blood transfusion and then at 24, 48 and 72 h after transfusion. There was no detectable change in mean selenium or glutathione peroxidase concentrations after transfusion, but the mean (SD) plasma manganese increased from 3.8 (1.5) to 6.0 (2.3) micrograms/l at 72 h.
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A retrospective study of 17 babies admitted to the neonatal intensive care unit of the Royal Maternity Hospital, Belfast, was undertaken to determine the causes and prognosis of conjugated hyperbilirubinaemia (direct fraction greater than 20% of total) over a five year period. Mean gestational age was 29 weeks and mean birth weight was 1,240g with a 2:1 male preponderance. All babies had a complicated clinical course involving prolonged periods of parenteral nutrition and many episodes of sepsis. Liver damage was not found to be a contributory factor to death in any baby who died before the age of one year. Bilirubin levels in the survivors had returned to normal within one year. No permanent pathological cause of cholestasis, such as biliary atresia, was ascribable to any of the cases, indicating that extensive investigation to exclude anatomical causes in this population is unlikely to prove rewarding.
OBJECTIVE: To estimate the cost of treating babies with severe respiratory distress syndrome with natural porcine surfactant. DESIGN: Retrospective controlled survey. SETTING: Regional neonatal intensive care unit, Belfast. PATIENTS: 33 Preterm babies with severe respiratory distress syndrome who were enrolled in a European multicentre trial during 1985-7. 19 Babies were treated with surfactant and 14 served as controls. INTERVENTIONS: Treatment with natural porcine surfactant. MAIN OUTCOME MEASURE: Cost associated with surfactant replacement treatment per extra survivor in the treatment group and cost per quality adjusted life year for each extra survivor. RESULTS: Fifteen (79%) of the 19 treated babies and five (36%) of the 14 control babies survived. On average, the control babies required 20 days in hospital compared with 61 days for the treated babies (or 95 [corrected] days per extra survivor in the treatment group). The cost per extra survivor in the treatment group was pounds 13,720, with the cost per quality adjusted life year estimated at pounds 710. CONCLUSION: These costs compare favourably with those of established forms of treatment in adults. Thus surfactant replacement treatment for severe respiratory distress syndrome is fairly inexpensive and cost effective.
Surfactant replacement for respiratory distress syndrome (RDS) following very prolonged rupture of the membranes (PROM) is of uncertain value. Seven preterm babies born after PROM (median 48 days, range 22-61 days) were compared with 14 babies without PROM. All had clinical and radiological evidence of severe RDS, requiring mechanical ventilation with inspired oxygen concentrations greater than or equal to 60%. Indices of oxygenation and "compliance" were compared before and serially up to 4 h after surfactant treatment. Before treatment the PROM babies had more severe lung disease, based upon higher inspired oxygen concentration and mean airway pressure, and lower arterial/alveolar oxygen tension ratio and ventilator efficiency index. These indices were significantly worse in the PROM group than the comparison group at all times after treatment. The poor response of the PROM group, perhaps because of pulmonary hypoplasia, suggests that surfactant replacement may not be beneficial for RDS in these babies.
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Glutathione peroxidase (GPX) and selenium are important in the prevention of cellular oxidant damage. Whole-blood GPX and plasma selenium were measured at birth and sequentially afterwards in 75 preterm babies. GPX activity at birth was 2.74 +/- 0.08 (mean +/- SEM) U/ml. Mean GPX activity remained relatively unchanged for up to 70 days postnatal age. Plasma selenium at birth was 0.43 +/- 0.02 (mean +/- SEM) mumol/l), decreasing to low levels by 10 weeks postnatal age. Neither GPX activity nor plasma selenium was related to birth weight, gestational age or infant sex.
Fetal hydrops (hydrops fetalis) remains a significant cause of fetal and neonatal mortality. The decreased incidence of rhesus iso-immunisation due to prophylaxis with rhesus immune globulin (anti-D), improved antenatal ultrasound screening, and advances in neonatal intensive care have greatly altered the clinical outlook in this condition. A retrospective review of all 27 liveborn cases of hydrops in the Royal Maternity Hospital, Belfast in the period 1974-89 showed that in the last five years 40% of cases were non-immune in origin. The mortality rate fell from 100% in the first part of the study to 50% in the second.
OBJECTIVE: To compare the mortality in babies refused admission to a regional perinatal centre with that in babies accepted for intensive care in the centre. DESIGN: Retrospective study with group comparison. SETTING: Based at the Royal Maternity Hospital, Belfast, with follow up of patients in all obstetric units in Northern Ireland. PATIENTS: Requests for transfer of 675 babies to the regional perinatal centre (prenatally and postnatally) were made from hospitals in Northern Ireland between January 1984 and December 1986. In all, 343 babies were refused admission to the centre, and complete data were available for 332 of them. These babies were either admitted to other neonatal intensive care units (261 babies) or remained in hospitals with only special care cots (71 babies). MAIN OUTCOME MEASURE: Short term mortality. RESULTS: Seventy of the 332 babies refused admission to the centre died compared with 51 of the 333 who were admitted. Multivariate analysis based on a logistic model showed a non-significant increase in mortality among babies treated in other intensive care units compared with babies treated in the centre (relative odds 1.2; 95% confidence interval 0.7 to 1.9). The increase in mortality in babies who remained in a special care baby unit, however, was significant (3.5; 1.7 to 7.0). This increase was particularly significant in babies born at less than or equal to 32 weeks' gestation and who weighed less than 1500 g (8.4; 2.5 to 28.1). CONCLUSIONS: The results of the study confirm the benefits of neonatal intensive care and its particular value in improving survival in babies of low birth weight. As the babies were refused admission to the regional perinatal centre because intensive care cots were not available this deficiency should be corrected.
Doppler ultrasound measurements of pulmonary blood flow in 20 babies with severe respiratory distress syndrome treated in a randomised controlled trial of surfactant replacement showed that the immediate improvement of oxygenation was not associated with a significant increase in pulmonary blood flow. Reduction in ventilator settings and increases in the extent of chest wall movements measured by a cardiorespiratory monitor suggested that the improvement after surfactant had been given was a result of alveolar stabilisation and increased pulmonary compliance. Further simultaneous studies of pulmonary blood flow and pulmonary compliance are needed to confirm these findings.
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A 14 year review of meningitis in babies showed that overall mortality and survival without handicap has not improved. The failure to improve the prognosis of these babies during a period when overall perinatal mortality fell rapidly is because smaller babies are being affected and different organisms are being cultured.
More than 600 preterm babies have been enrolled in randomised controlled trials of natural surfactant replacement to prevent or treat the respiratory distress syndrome. Four types of natural surfactant, prepared from animal lungs or human amniotic fluid, have been used. Each contains mainly phospholipids and small amounts (1-5%) of apoproteins. Two types of trial have been used to test these natural surfactants. In prophylaxis studies, babies less than 30 weeks of gestation are given surfactant intratracheally at birth. These studies show a reduction in mortality and pneumothorax and an increase in survival without bronchopulmonary dysplasia (BPD) in treated babies compared to matched controls. In rescue studies, where ill babies are given surfactant about 5 h after birth, there is a reduction in mortality, pneumothorax, intraventricular haemorrhage and BPD, and an increase in survival without BPD. However, treated babies also show an increased incidence of patent ductus arteriosus which has been the only side effect noted to date. All these surfactant preparations show similar effects and studies comparing the different types are unlikely to be undertaken as large numbers of babies would need to be enrolled to show differences. Many uncertainties remain, however, and include the dose of surfactant needed, whether repeat dosing is better than single dosing, whether treatment of less-ill babies is justified, and the results of long-term follow-up studies.
Obstetric and perinatal data for 387 very low birthweight infants (less than or equal to 1500 g) who were admitted to a neonatal intensive care unit were used to derive and test a multivariate statistical model for predicting shortly after birth the risk of death before hospital discharge. Using the gestational age, the Apgar score at 5 minutes and the presence or absence of respiratory distress, the model correctly predicted outcome for 94% of survivors but for only 53% of deaths. The model successfully identified a subgroup with a low (less than 1 in 20) predicted risk of death. This subgroup comprised over one-third of the infants but included 47% of the survivors and only 5% of the deaths. The probabilities derived from the model are tabulated and may help paediatricians in maternity units without neonatal intensive care facilities to decide which very low birthweight infants to transfer for additional care.
As part of a multicentre study of porcine surfactant administration in respiratory distress syndrome, 29 babies weighing 2000 g or less were studied in the neonatal intensive care unit of the Royal Maternity Hospital, Belfast. Fourteen babies of a mean gestational age of 28.1 weeks were randomly allocated to the treatment group (200 mg/kg phospholipid given intratracheally) and 15 babies of a mean gestational age of 28.7 weeks formed the control group. All babies had severe respiratory distress syndrome (oxygen requirement over 60%, mechanical ventilation, and age 15 hours or less). Almost immediate improvement in oxygenation was seen in the treated group so that oxygen concentrations could be reduced and remained significantly lower than those of control babies for the first seven days of life. Alveolar-arterial oxygen gradients were also significantly different for the first five days after treatment. More babies in the treatment group survived (79% v 40%) but the difference was not significant. The incidence of pneumothorax and of intraventricular haemorrhage, however, was significantly lower in treated babies compared with controls. For babies weighing less than 1200 g the risk of developing or extending intraventricular haemorrhage after entry to the study was also reduced in the treatment group (29% v 100%).
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