Elizabeth John

Role of ureaplasma urealyticum in lung disease of prematurity.

AIM To examine the role of Ureaplasma urealyticum colonisation or infection in neonatal lung disease. METHODS Endotracheal aspirates from ventilated infants less than 28 weeks of gestation were cultured for U urealyticum and outcomes compared in infants with positive and negative cultures. RESULTS U urealyticum was isolated from aspirates of 39 of 143 (27%) infants. Respiratory distress syndrome (RDS) occurred significantly less often in colonised, than in non-colonised infants (p=0.002). Multivariate logistic regression analysis showed that in singleton infants, ureaplasma colonisation was the only independent (negative) predictor of RDS (OR 0.36; p=0.02). Both gestational age (OR 0.46; p=0.006) and isolation of U urealyticum (OR 3.0; p=0.05) were independent predictors of chronic lung disease (CLD), as defined by requirement for supplemental oxygen at 36 weeks of gestational age. Multiple gestation was also a major independent predictor of RDS and CLD. CONCLUSIONS Colonisation or infection with ureaplasma apparently protects premature infants against the development of RDS (suggesting intrauterine infection). However, in singleton infants, it predisposes to development of CLD, independently of gestational age. Treatment of affected infants after birth is unlikely to significantly improve the outcome and methods are required to identify and treat the women with intrauterine ureaplasmal infection, before preterm delivery occurs.

Chronic oxygen dependency in infants born at 24-32 weeks' gestation : The role of antenatal and neonatal factors

Objectives: To study the incidence of chronic oxygen dependency (COD) among ventilated survivors born at 24–32 weeks gestation from 1986 to 1994 and to identify antenatal and neonatal factors that may have changed with time; and to identify antenatal and neonatal factors that could contribute to the development of COD in infants born at 24–32 weeks gestation using a case control model.

Tracheal damage following conventional and high-frequency ventilation at low and high humidity.

ObjectivesTo compare the degree of tracheobronchial damage in newborn lambs ventilated for 6 hrs with relative humidities of 30% or 90% and continuous positive airway pressure breathing, conventional mechanical ventilation of 25 and 60 breaths/min, or high frequency flow-interrupted ventilation at 600 breaths/min. Background and MethodsTracheobronchial damage secondary to mechanical ventilation remains a major iatrogenic lesion of the newborn despite substantial advances in both mechanical design and ventilatory techniques. A histologie scoring system was used to compare the damage noted in the tracheobronchial epithelium of newborn lambs after 6 hrs of conventional mechanical ventilation or high-frequency flow-interrupted ventilation at two relative humidities.Three groups of animals were ventilated for 6 hrs with an Fio2 of 0.21 at 36.0°C and relative humidity of 90%. The first group received continuous positive airway pressure of 4 cm H2O, the second group received slow rate, conventional mechanical ventilation at 25 breaths/ min, and the third group received fast rate, conventional mechanical ventilation at 60 breaths/min. Two other groups of animals were ventilated for 6 hrs with an Fio2 of 0.21 at 36.0°C and relative humidity of 30%. The first group was ventilated with high-frequency flow-interrupted ventilation at 600 breaths/min and the second group with slow rate, conventional mechanical ventilation at 25 breaths/min. Two additional groups served as nonintubated controls; one group was killed immediately after sedation and the other group was killed after 6 hrs of sedation. ResultsThe damage was mild but significantly different from controls when 90% humidity was used and there was no difference in the histology score between continuous positive airway pressure breathing and conventional mechanical ventilation at 25 or 60 breaths/min. Significant inflammation, erosion, necrosis, and blistering occurred with both conventional mechanical ventilation at 25 breaths/min and high-frequency flow-interrupted ventilation at 600 breaths/min when 30% humidity was used. The damage was only found 5 mm below the tip of the endotracheal tube and not at 3.5 cm beyond the endotracheal tube in the trachea nor in the right main bronchus. ConclusionThese data indicate that endo-tracheal intubation and mechanical ventilation, regardless of the method of ventilation, cause damage to the tracheal mucosa, but that poorly humidified inspired gases cause significantly greater damage.

Inspired gas humidity during mechanical ventilation: Effects of humidification chamber, airway temperature probe position and environmental conditions

Objectives: To determine the inspired gas humidity during mechanical ventilation with: (i) four different humidification chambers; (ii) two airway temperature probe (ATP) positions; (iii) five different humidicrib temperatures; and (iv) insulating the inspiratory limb with bubble wrap.

Retinopathy of prematurity in infants < 32 weeks’ gestation at birth in New South Wales in 1993 and 1994

Objective: To study the incidence and severity of retinopathy of prematurity (ROP) in infants < 32 weeks’ gestation.

Treatment with hypertonic dextrose and insulin in severe hyperkalaemia of immature infants

Over a three‐year period, 12 infants received dextrose/insulin infusions for severe hyperkalaemia from a mean age of 24 h. The infants were born after 24 to 26 weeks of gestation and weighed 730 ± 172 g (mean ± SD) at birth. Serum potassium concentration ranged from 7.4 to 8.4 mmol/l(7.7 ± 0.4 mmol/l; mean ± SD). Four had cardiac arrhythmias. All infants showed an initial response, serum potassium concentration decreased below 6.5 mmol/l in 5 ± 2 h. In two infants, rebound hyperkalaemia occurred and was resistant to treatment; both infants died, one during an exchange transfusion. In the other 10 infants, infusions were ceased at a mean postnatal age of 53 h. Hyperglycaemia was the major problem during infusion and was resistant to increases in insulin concentrations. Normoglycaemia was achieved in 10 infants. The hypertonic solution consisted of a dextrose/insulin ratio of 2.2 ± 0.6 g/IU, which delivered glucose at a rate of 0.46 ± 0.15 g/kg/h, in addition to the pre‐existing stable maintenance glucose intake.

Epithelial damage beyond the tip of the endotracheal tube

The effects of ventilator rate and inspired humidity on the large airway epithelium of newborn lambs have been studied using scanning electron microscopy. Significant deciliation, denudation and necrosis occurred at both high and conventional rates if the inspired gas had low humidity. The damage observed was mild in the high humidity groups.

Persistent pulmonary hypertension of the newborn treated with hyperventilation: Clinical features and outcome

Abstract Twenty‐seven infants with severe persistent pulmonary hypertension of the newborn were seen in 33 months. Asphyxia with or without meconium aspiration was the cause in the majority of cases. Other causes were group B streptococcal sepsis and acute fetal blood loss. The mortality rate was 11%. Twenty‐three of the 24 survivors were followed. Their age at follow‐up ranged 12–37 months. The mean score for mental development was within the normal range while that for psychomotor development was 1 standard deviation below normal. Seven infants were judged to be at risk of attention deficit disorder. Predictor variables related to these outcomes were cardiotocography, meconium aspiration, first pH, highest Paco2 after resuscitation and mothers education. All infants except one were perceived as normal by their parents.

Retinopathy of prematurity in infants <29 weeks’ gestation at birth in New South Wales from 1986–92

To study the effect of increased survival of infants <29 weeks’ gestation on the incidence and severity of retinopathy of prematurity (ROP).

Evaluation of bubble clicking in gastric aspirate in the newborn

ABSTRACT. Bubble clicking, foam stability tests, L/S ratio and two dimensional thin layer chromatography were done in 26 gastric aspirates obtained from 22 babies with mature lungs and 4 babies with with hyaline membrane disease.