Acute deteriorations in neonatal chronic lung disease

Preterm infants with chronic lung disease (CLD) have frequent respiratory relapses. The aim of this study was to assess the aetiology of such deteriorations and in particular the proportion due to viral infections. During the study period 118 preterm infants with birth weight <1500g were consecutively admitted to the neonatal intensive care unit; 22 (18.6%) developed CLD. At the onset of all respiratory deteriorations, infants were examined for the presence of patent ductus arteriosus, apnoea or aspiration; they were also carefully screened for both viral and bacterial infection. The 22 infants had a total of 74 episodes of respiratory deterioration; median 3 per baby (range 1–8). Two episodes were associated with patent ductus arteriosus, 18 with apnoea and 5 with aspiration. Infection was suspected or proven in association with all other episodes. On ten occasions the infants had positive blood cultures and on a further eight, bacteria were isolated only from the endotracheal or nasopharyngeal secretions. On the remaining 31 occasions, 27 associated with chest X-ray film abnormalities, infection was suspected, but no bacteria isolated. Viral infections were identified in association with 8 (11%) of these episodes. We conclude viral infection should be considered as a cause of otherwise unexplained respiratory deteriorations in infants with neonatal CLD.     

Longitudinal assessment of infant lung function following pregnancies complicated by prolonged and preterm rupture of the membranes

Serial measurements of functional residual capacity (FRC) were made in 22 infants (median gestational age at delivery 32 weeks, range 25–40) during the first 2 years of life. All infants had been delivered from pregnancies complicated by prolonged and preterm rupture of the membranes (PPROM) of at least 1 week in duration. The onset of membrane rupture was at a median of 26 weeks (range 15–32) with a median duration of 5.5 weeks (range 1–21). The mean FRC at all postnatal ages studied: 25 ml/kg at 6 and 12 months and 24ml/kg at 18 and 24 months did not differ significantly from the control population (mean 24ml/kg). There was, however, a wider scatter of results in the study population: four infants born very preterm consistently had FRC results above the 95% confidence limits of the controls but only two infants had FRCs consistently below this range. These results suggest PPROM may not be an invariable association of abnormal antenatal lung growth.     

Synchronous intermittent mandatory ventilation modes compared with patient triggered ventilation during weaning.

The efficacy of combining rate and pressure reduction during weaning by synchronous intermittent mandatory ventilation (SIMV) were compared with weaning by patient triggered ventilation (PTV) (pressure reduction alone) in two randomised trials. Regardless of ventilation mode, pressure was reduced to the same level according to the size of the infant. In the first trial, the SIMV rate was also reduced progressively to a minimum of 20 breaths/minute, and in the second to five breaths/minute. Forty premature infants aged 15 days of age or less were randomly allocated into each trial. No significant differences were found in the first trial between ventilation modes in either the duration of weaning or the number of infants in whom weaning failed. In the second trial, the duration of weaning was shorter by PTV than by SIMV (median 24 hours, range 7-432 v 50 hours, range 12-500; p < 0.05); weaning failed in two infants in the PTV group and in five in the SIMV group. It is concluded that weaning by a combination of pressure and rate reduction, such as can be achieved during SIMV, offers no significant advantage over pressure reduction alone.     

Patient triggered ventilation in premature neonates.

Patient triggered ventilation using oesophageal pressure changes was assessed in eight premature neonates. Respiratory activity was reliably recorded and positive pressure inflation occurred synchronously with inspiration. Peristalsis resulted in only minimal interference. During patient triggered ventilation, inflating volume and oxygenation increased significantly compared with periods of conventional ventilation.     

Immediate effects of albumin infusion in ill premature neonates.

Ten normotensive premature infants with idiopathic respiratory distress syndrome, and albumin concentrations of less than 30 g/l were given 5 ml/kg of 20% salt poor albumin by infusion. Concentrations measured six hours after infusion had increased significantly and these were associated with significant reduction in weight and improvement in urine output.     

Expanded use of surfactant replacement therapy

There are a number of respiratory diseases affecting infants in which there is surfactant dysfunction or deficiency. Surfactant is inactivated by cholesterol, free fatty acids and bilirubin in meconium aspiration syndrome, by haemoglobin and red blood cell lipids in pulmonary haemorrhage and plasma proteins are the culprit in conditions associated with increased alveolar capillary permeability. Surfactant production can be adversely affected by damage to the type 2 pneumocytes by viruses and neutrophil derived reactive oxygen metabolites. Not surprisingly, therefore, the efficacy of exogenous surfactant has been tested, usually in animal models and anecdotal series in “non respiratory distress syndrome” respiratory disorders. Improvements in oxygenation have usually been described. Relatively few randomized trials, however, have been performed, but those undertaken have demonstrated longer term benefits. In term infants with severe respiratory failure, surfactant administration significantly shortened the duration of extracorporeal membrane oygenation and, in those in the early phase of severe respiratory failure or with meconium aspiration syndrome, it significantly reduced the need for extracorporeal membrane oygenation. In meconium aspiration syndrome, a smaller number of surfactant treated patients compared to controls developed airleaks. Surfactant administration was also associated with a reduction in the duration of ventilation and intensive care unit stay in patients with meconium aspiration syndrome or bronchiolitis. Those data are very promising and should encourage studies to identify the optimum type of surfactant, dosage regimen and administration method. Conclusion Further randomized trials are required to fully assess the efficacy and cost benefit ratio of surfactant treatment in “non respiratory distress syndrome” respiratory diseases. Received: 24 January 2000 / Accepted: 6 April 2000     

Blood pressure levels of preterm infants in the first year of life

Systolic blood pressure was measured in 36 infants with median gestational age of 29 weeks (range 24–35 weeks) and birth weight of 1160 g (range 642–1500 g). Measurements were made at 1, 6 and 12 weeks, and subsequently at 12-weekly intervals during the first year of life. No infant developed chronic lung disease. Systolic blood pressure increased over the first 24 weeks ( p < 0.001) to a mean value of 95 mmHg, but did not change significantly over the next 24 weeks. These data provide a reference range of blood pressure levels during the first year of life for infants born at an early gestational age.