F. Giffin

Respiratory morbidity in preschool children born prematurely. Relationship to adverse neonatal events

Respiratory morbidity, recurrent cough and/or wheeze and lung function abnormalities are common even outside infancy in preschool children born prematurely. Throughout the first 5 years of life, adverse neonatal events such as immaturity at birth and a requirement for prolonged respiratory support are significantly associated with positive symptom status. In the older preschool child, however, there is some evidence to suggest that other factors, such as a family history of atopy, may be equally important. The development of recurrent symptoms even at 4 years of age can be predicted accurately from the results of lung function measurements made in infancy, and hopefully such data will facilitate the introduction of effective intervention strategies. Lung function abnormalities are more marked in symptomatic patients and, in older children, seem to reflect increased airway responsiveness rather than having a significant relationship to adverse neonatal events. The hospital readmission rate for respiratory disorders, however, is certainly adversely affected by extremely low birthweight and neonatal chronic lung disease, as well as current symptom status. These data highlight that strategies to reduce extremely premature delivery and its consequences should favourably influence respiratory morbidity in preschool children.

Inhaled versus systemic steroids in chronic oxygen dependency of preterm infants

Abstract The speed of action and side-effects of systemic versus inhaled steroids was compared in infants with mild-moderate oxygen dependency. Forty infants (median gestational age 27 weeks) were randomized to receive either 10 days of dexamethasone (systemic group) or budesonide (100 μg qds) (inhaled group). At randomization, there was no significant difference in the gestational or postnatal age, inspired oxygen requirements or compliance of the respiratory system of the two groups. After 36 h of treatment, there were significant changes (P < 0.01) in both the inspired oxygen concentration and compliance of the respiratory system in the systemic but not the inhaled group. Only after 1 week of inhaled therapy were improvements in respiratory status noted but, even at that time, the inspired oxygen requirement was significantly lower in the systemic versus the inhaled group. In the systemic group only, however, were there significant increases in blood pressure. Conclusion Systemically administered rather than inhaled steroids appear to have a faster onset of action.

Temporary impairment of lung function in infants with anterior abdominal wall defects who have undergone surgery.

Compliance of the respiratory system (CRS) was measured before and after surgical intervention in 14 infants who had anterior abdominal wall defects (AWD) (7 exomphalos, 7 gastroschisis). The median gestational age was 37 weeks (range, 34 to 40) and median birth weight was 2.38 kg (range, 1.94 to 3.45). The infants had stiff lungs before surgery (median CRS, 0.58 mL/cm H2(O)/kg). During the first and second postoperative days, the median CRS decreased to 0.33 mL/cm H2(O)/kg (P < .05). In seven cases, measurements also were obtained on the third and fourth postoperative days, which showed an increase in the median CRS (day 3, 0.47 mL/cm H2(O)/kg; P < .05). These findings show that in infants with AWD, primary surgical closure is associated with deterioration of lung function, but this effect is temporary.

Respiratory morbidity in young school children born prematurely--chronic lung disease is not a risk factor?

AbstractChildren born prematurely and recruited into a prospective follow up study were examined at 5 years of age. Our aim was to determine actiological associations of respiratory symptoms in such children and in particular, to determine the importance of severe chronic lung disease (CLD, oxygen dependence beyond 36 weeks post conceptional age). Respiratory status was documented from parental history in 103 children of median gestational age 29 weeks (range 23–35), 17 of whom had suffered from severe CLD. In 90 of the 103 children lung function had been assessed at 1 year of age. Regression analysis revealed that neither severe CLD nor other perinatal variables, but only a family history of atopy, significantly related to a positive symptom status. A high airways resistance at 1 year also significantly related to positive symptom status.ConclusionReduction in severe CLD (oxygen dependence beyond 36 weeks postconceptional age) may make relatively little impact on respiratory morbidity in young school children born prematurely.

Manoeuvres to elevate mean airway pressure, effects on blood gases and lung function in children with and without pulmonary pathology

Abstract During mechanical ventilation, mean airway pressure (MAP) can be increased by a variety of manoeuvres, for example increasing inspiratory time or elevating the positive end expiratory pressure (PEEP). It seemed likely that the effect on blood gases and lung function of a particular manoeuvre to increase MAP would be influenced by the presence of respiratory pathology and thus the manoeuvre best at improving respiratory status in children with an abnormal chest radiograph appearance would differ from that most efficacious in children without such a problem. The aim of this study was to test that hypothesis. Twenty-two children, median age 15 months (range 2.5 weeks–10 years) were examined. Group 1 (n= 10) had no chest radiograph abnormalities and group 2 (n= 12) lobar collapse and/or consolidation. The patients were studied at baseline settings and at an elevated MAP resulting from (in random order) an increase in inspiratory time (T1), pressure PEEP or peak inspiratory pressure (PIP). In group 1, elevating PIP improved oxygenation and carbon dioxide elimination (P < 0.01) and prolonging T1 improved oxygenation (P < 0.05). In group 2, only raising PEEP significantly improved oxygenation (P < 0.01), but this was associated with carbon dioxide retention (P < 0.01). Conclusion The presence of lung pathology does influence which manoeuvre should be used to elevate MAP to improve blood gases in the paediatric population.

Prediction of respiratory morbidity in the third year of life in children born prematurely

We have tested the hypothesis that recurrent respiratory symptoms in the third year of life in patients born prematurely were more likely to reflect a family history of atopy rather than adverse neonatal events. Comparison of 28 symptomatic and 72 asymptomatic children revealed that a family history of atopy (p<0.01), prolonged dependencc on respiratory support in the neonatal period (p<0.01) and extreme immaturity (p<0.02) were significantly commoner in the symptomatic group. The relative risk of having symptoms was 2.27 for a family history of atopy, 2.48 for prolonged dependence on respiratory support and 1.7 for low gestational age. We conclude that respiratory morbidity in the third year of life following premature delivery has a multifactorial aetiology.

Does the duration of oxygen dependence after birth influence subsequent respiratory morbidity

The relationship of respiratory morbidity at follow up to the development and type of “neonatal” chronic lung disease has been assessed. Three groups, each of ten infants matched for gestational age and gender, were compared. Group A had Type I chronic lung disease and group B bronchopulmonary (BPD), the most severe form of neonatal chronic lung disease (Type II CLD); group C had developed neither Type I or Type II CLD. Group B compared to group A compared to group C required a significantly longer duration of oxygen therapy on the neonatal unit. All three groups were prospectively followed; the occurrence of symptoms was documented in each of the first 3 years of life and lung function was measured using a plethysmographic technique at the end of year 1. In all 3 years a significantly greater proportion of groups A and B were symptomatic compared to group C, but there was no significant difference in the proportion so affected between groups A and B. Airway resistance was higher in both groups A and B compared to C but only reached statistical significance on comparing groups A and C. We conclude oxygen dependency beyond 1 month of age, irrespective of the development of BPD, significantly increases respiratory morbidity at follow up.

Does a family history of atopy influence lung function at follow‐up of infants born prematurely?

The aim of this study was to assess whether a family history of atopy influenced lung function at follow‐up of infants born prematurely. Analysis was made of thoracic gas volume and airways resistance measurements performed at 1 year of age in 86 infants born at a median gestational age of 29 weeks. These measurements had been made during a prospective follow‐up study. The 30 infants with a family history of atopy were found to have a higher airways resistance (median 35 cmH2O/l/s) than the 56 infants without such a family history (median 30cmH2O/l/s) (p < 0.05). However, when the results from 18 infants with a family history of atopy were compared with 18 controls who were matched for requirement for neonatal ventilation, parental smoking and were within at least 1 week of gestational age, no significant difference in airways resistance was found between the two groups. Multiple regression analysis demonstrated that gestational age and birth weight explained the apparent relationship between a family history of atopy and an elevated airways resistance at follow‐up.

Risk factors for hyperinflation in young schoolchildren born prematurely.

Abstract Lung function abnormalities, including hyperinflation, are common in young children born prematurely. The aim of this study was, in such patients, to determine factors associated with hyperinflation, that is an elevated lung volume. Lung volume was estimated by measuring functional residual capacity (FRC) before and after bronchodilator therapy in 41 5-year-old children who had been born prematurely at a median of 30 weeks gestational age. Hyperinflation was defined as an FRC greater than 120% of that predicted for height and a positive bronchodilator response as a greater than or equal to 10% change in FRC. Twelve (29%) of the children were symptomatic at 5 years, their median FRC (132%) was significantly higher than that of the asymptomatic children (109%), P < 0.01. Twelve (29%) children were hyperinflated; a greater proportion of the hyperinflated compared to the non-hyperinflated patients were symptomatic at 5 years (7 or 58% versus 5 or 17%) (P < 0.05) and responded to bronchodilator therapy (9 or 75% versus 4 or 14%) (P < 0.01). Regression analysis demonstrated that hyperinflation related significantly only to current symptom status, but not perinatal variables. Conclusion Hyperinflation in young children born prematurely reflects current symptom status and not adverse neonatal events.

Effect of positive end expiratory pressure and mean airway pressure on respiratory compliance and gas exchange in children with liver disease

The effect of positive end expiratory pressure (PEEP) and mean airway pressure (MAP) on respiratory compliance and gas exchange was assessed in children with liver disease. In the first study of 12 patients, PEEP was decreased either by 3 cmH2O below the baseline level (the childs original level) or to 0 cmH2O and then increased to 3 cmH2O above the baseline. Decreasing PEEP impaired compliance (P<0.01), and oxygenation (P<0.05), whereas increasing PEEP improved compliance (P<0.05) and oxygenation (P<0.05). Neither increasing nor decreasing PEEP caused significant changes in the carbon dioxide levels. In the second study, 24 children were studied at their baseline settings and then after increasing the PEEP by 3 cmH2O while simultaneously lowering the peak inspiratory pressure (PIP) to maintain MAP constant (12 children had lung function measurements). In the group overall increasing PEEP while decreasing PIP resulted in an insignificant change inpaO2, but a significant increasepaCO2 (P<0.01) and reduction in tidal volume (P<0.01), the change in compliance was not significant. After a second period at the baseline settings, in 12 children inspiratory time (TI) was increased while keeping MAP constant by reducing PIP. No significant change inpaO2 or compliance was experienced, butpaCO2 increased (P<0.05) and tidal volume decreased (P<0.01). In the other 12 children MAP was increased by prolonging TI. Increasing MAP had a variable effect and the changes inpaO2 andpaCO2 were not significant. No critical MAP level with regard to oxygenation was demonstrated. We conclude that in children with liver disease, increasing PEEP can improve oxygenation and compliance, but the MAP level alone does not determine oxygenation.