Recurrent respiratory symptoms in the first year of life following preterm delivery

The Next Frontier of Prematurity: Predicting Respiratory Morbidity During the First Two Years of Life in Extremely Premature Babies

Background

Advances in perinatal and neonatal medicine have led to an increasing number of infants surviving extreme prematurity (≤27 weeks gestational age, GA). The goal of this study was to examine the respiratory outcomes after neonatal intensive care unit (NICU) discharge of this vulnerable population. We hypothesized that the rates of respiratory hospitalizations are disproportionally higher in the subset of infants born ≤27 weeks GA relative to premature infants born 28-32 weeks GA.

Methodology

A retrospective longitudinal study of severe premature children (≤32 weeks GA, n = 183) was conducted. We subdivided our sample into extremely preterm infants (≤27 weeks GA; n = 101) and those born very preterm (28-32 weeks GA; n = 82). Our main outcome was the presence of respiratory hospitalizations within 24 months of NICU discharge.

Results

Extremely premature infants had more than three times higher odds of respiratory hospitalization at 24 months relative to infants born 28-32 weeks GA (adjusted odds ratio = 3.4; 95% confidence interval = 1.8, 6.4; p < 0.01). The increased risk of respiratory hospitalization in extremely premature infants was independent of GA. Regression models identified that the duration of supplemental oxygen and Black/African American ethnicity were significant predictors of respiratory hospitalizations in both prematurity groups independent of gender and birth weight.

Conclusions

The results support that babies born ≤27 weeks GA represent a distinct high-risk group of severely premature infants that needs novel preventive strategies and targeted interventions to improve their respiratory outcomes after NICU discharge.

Risk factors for bronchiolitis, recurrent wheezing, and related hospitalization in preterm infants during the first year of life

BACKGROUND

Airway diseases are highly prevalent in infants and cause significant morbidity. We aimed to determine the incidence and risk factors for respiratory morbidity in a Spanish cohort of moderate-to-late preterm (MLP) infants prospectively followed during their first year of life.

METHODS

SAREPREM is a multicenter, prospective, longitudinal study. Preterm infants born at 32-35 weeks of gestation with no comorbidities were enrolled within 2 weeks of life and followed at 2-4 weeks, 6, and 12 months of age. Multivariate mixed-models were performed to identify independent risk factors associated with (i) development of bronchiolitis, (ii) recurrent wheezing, or (iii) related hospital admissions.

RESULTS

Overall, 977 preterm infants were included, and 766 (78.4%) completed follow-up. Of those, 365 (47.7%) developed bronchiolitis during the first year, 144 (18.8%) recurrent wheezing, and 48 (6.3%) were hospitalized. While low birthweight, day care attendance (DCA) and school-age siblings were significantly and independently associated with both the development of bronchiolitis and recurrent wheezing, lower maternal age increased the risk for bronchiolitis and respiratory-related hospitalizations. Lastly, mechanical ventilation was associated with a higher risk of bronchiolitis and history of asthma in any parent increased the likelihood of developing recurrent wheezing.

CONCLUSIONS

In this study, several non-modifiable parameters (family history of asthma, low birthweight, need for mechanical ventilation) and modifiable parameters (young maternal age, DCA, or exposure to school-age siblings) were identified as significant risk factors for the development of bronchiolitis and recurrent wheezing during the first year of life in MLP infants.

Factors associated with rehospitalizations of very low birthweight infants: impact of a transition home support and education program

OBJECTIVE

To determine the effects of a transition-home education and support program, BPD, and health insurance type on VLBW infant rehospitalizations at 3 and 7 months corrected age. It was hypothesized that the transition-home program would be associated with decreased rehospitalizations between Phase 1 and 2, and public health insurance and BPD would be associated with increased rehospitalizations.

METHODS

274 infants with birth weight <1500 g were enrolled in two successive years of a transition-home program (Phase 1-start-up) and (Phase 2-full implementation) and followed to 7 months CA.

RESULTS

The Phase 2 rehospitalization rates were lower but not statistically significant at both 3 months (20% and 15%; p=0.246), and 7 months (24% and 17%; p=0.171). Infants with public insurance had twice as many rehospitalizations by 3 months (28% versus 11%; p=0.018) in Phase 1. In regression analyses the intervention effects did not achieve significance for the cohort at 3 months (OR=0.63; CI=0.33 to 1.20) or 7 months (OR=0.61; CI=0.33 to 1.13). BPD and public insurance did not reach significance in the models whereas siblings were significantly associated with increased odds of rehospitalization. In subgroup analyses for infants on pubic health insurance the intervention significantly decreased the odds of rehospitalization between Phase 1 and 2(OR=0.43; CI=0.19 to 0.96) at 3 months.

CONCLUSIONS

Our findings suggest that a transition-home program may be beneficial to reduce the rehospitalization rate for VLBW infants, and infants on public insurance may derive greater benefit.

Respiratory symptoms in preterm infants: burden of disease in the first year of life

Objective

While respiratory symptoms in the first year of life are relatively well described for term infants, data for preterm infants are scarce. We aimed to describe the burden of respiratory disease in a group of preterm infants with and without bronchopulmonary dysplasia (BPD) and to assess the association of respiratory symptoms with perinatal, genetic and environmental risk factors.

Methods

Single centre birth cohort study: prospective recording of perinatal risk factors and retrospective assessment of respiratory symptoms during the first year of life by standardised questionnaires. Main outcome measures: Cough and wheeze (common symptoms), re-hospitalisation and need for inhalation therapy (severe outcomes). Patients: 126 preterms (median gestational age 28.7 weeks; 78 with, 48 without BPD) hospitalised at the University Children's Hospital of Bern, Switzerland 1999-2006.

Results

Cough occurred in 80%, wheeze in 44%, rehospitalisation in 25% and long term inhalation therapy in wheezers in 13% of the preterm infants. Using logistic regression, the main risk factor for common symptoms was frequent contact with other children. Severe outcomes were associated with maximal peak inspiratory pressure, arterial cord blood pH, APGAR and CRIB-Score.

Conclusions

Cough in preterm infants is as common as in term infants, whereas wheeze, inhalation therapy and re-hospitalisations occur more often. Severe outcomes are associated with perinatal risk factors. Preterm infants who did not qualify for BPD according to latest guidelines also showed a significant burden of respiratory disease in the first year of life.

Is there a link between wheezing in early childhood and adverse birth outcomes? A systematic review

We aimed to provide a summary of the existing published knowledge on the association between adverse birth outcomes and the development of wheezing during the first two years of life. We carried out a systematic review of epidemiological studies within the MEDLINE database. Epidemiological studies on human subjects, published in English, were included in the review. A comprehensive literature search yielded 72 studies for further consideration. Following the application of the eligibility criteria we identified nine studies. A positive association and an excess risk of wheezing during the first two years of life were revealed for adverse birth outcomes.

[Incidence of wheezing and associated risk factors in the first 6 months of life of a cohort in Valencia (Spain)]

OBJECTIVES

To determine the incidence of wheezing at 6 months of life in the town of Alzira (Valencia, Spain), and to analyse associated risk factors.

METHODS

We included 636 newborns in a longitudinal birth cohort study between March 2007 and November 2008. Data were collected from hospital and primary care medical records and from questionnaires sent at 6 months post-natal. Bivariate and multivariate Cox regression analysis were performed to examine the risk factors associated with wheezing.

RESULTS

At 6 months, 25.2% of infants had had 1 or more episodes of wheezing, whereas 5.6% had had 3 or more episodes. Emergency visits were reported in 11.6% of the infants, treatment with oral corticosteroids in 6.6% and admission to hospital in 4%. Independent risk factors for wheezing were male sex (relative risk [RR]: 2.1, 95% confidence interval [95% CI]: 1.5 to 2.9), younger gestational age (RR: 1.1, 95% CI: 1.0 to 1.2), season of birth between July and September (RR: 3.5, 95% CI: 2.0 to 5.9) and between October and December (RR: 2.0, 95% CI: 1.1 to 3.6), younger maternal age (RR: 1.0, 95% CI: 1.0 to 1.1), having siblings (RR: 3.1, 95% CI: 2.2 to 4.5), exposure to smoke (RR: 1.4, 95% CI: 12.0 to 2.0) and history of maternal asthma (RR: 1.7, 95% CI: 1.0 to 3.0). Breast feeding for at least 3 months (RR: 0.6, 95% CI: 0.4 to 0.8) and having immigrant parents (RR: 0.6, 95% CI: 0.4 to 0.9) were protective against wheezing.

CONCLUSION

A high cumulative incidence of wheezing in the first 6 months of life was found in our population, in comparison with data reported in other cohort studies. Estimated risk factors were generally in accordance with those described by other authors. Having siblings and season of birth between July and September were the most important risk factors, reflecting the role of viral infections in the pathogenesis of wheezing in early childhood.

Ontogeny and phagocytic function of baboon lung dendritic cells

Dendritic cells (DCs) are the most potent antigen-presenting cells, but the ontogeny and functions of lung DCs are not known during prenatal period. Here, we isolated lung DC population from fetal (125 −175dGA) and adult baboons. The cells were stained with fluorochrome-conjugated-HLA-DP, DQ, DR, CD1a, CD11c, CD14, CD40, CD80, CD86, CD209, CMKLR1, ILT7-specific antibodies, and staining was analyzed by Flow-cytometry. The phagocytic function was investigated by incubating the cells with fluorescent-labeled Escherichia coli bioparticles and analyzed by Flow-cytometry and fluorescence microscopy. The fetal baboon lung DCs expressed low levels of HLA-DP, DQ, DR, CD11c and CD86 as compared to adult baboon lung DCs and showed distinct DC morphology. The fetal lung DCs were also less capable of phagocytosing E. coli as compared to the adult lung DCs (p<0.05). In conclusion, the fetal lung DCs are not only phenotypically immature, but also less efficient in phagocytosing E. coli.

One-year respiratory outcomes of preterm infants enrolled in the Nitric Oxide (to prevent) Chronic Lung Disease trial

OBJECTIVE

To identify whether inhaled nitric oxide treatment decreased indicators of long-term pulmonary morbidities after discharge from the neonatal intensive care unit.

STUDY DESIGN

The Nitric Oxide (to Prevent) Chronic Lung Disease trial enrolled preterm infants (<1250 g) between 7 to 21 days of age who were ventilated and at high risk for bronchopulmonary dysplasia. Follow-up occurred at 12 +/- 3 months of age adjusted for prematurity; long-term pulmonary morbidity and other outcomes were reported by parents during structured blinded interviews.

RESULTS

A total of 456 infants (85%) were seen at 1 year. Compared with control infants, infants randomized to inhaled nitric oxide received significantly less bronchodilators (odds ratio [OR] 0.53 [95% confidence interval 0.36-0.78]), inhaled steroids (OR 0.50 [0.32-0.77]), systemic steroids (OR 0.56 [0.32-0.97]), diuretics (OR 0.54 [0.34-0.85]), and supplemental oxygen (OR 0.65 [0.44-0.95]) after discharge from the neonatal intensive care unit. There were no significant differences between parental report of rehospitalizations (OR 0.83 [0.57-1.21]) or wheezing or whistling in the chest (OR 0.70 [0.48-1.03]).

CONCLUSIONS

Infants treated with inhaled nitric oxide received fewer outpatient respiratory medications than the control group. However, any decision to institute routine use of this dosing regimen should also take into account the results of the 24-month neurodevelopmental assessment.

Risk factors of bronchial hyperresponsiveness in children with wheezing-associated respiratory infection

The objectives of this study were to identify possible risk factors of bronchial hyperesponsiveness (BHR) in children up to 5 years of age with wheezing-associated respiratory infection (WARI), and to study the prevalence of BHR. Children up to 5 years of age with WARI were enrolled in the study. The parents or caregivers of children were asked about their demographic data and clinical histories. Physical examination and clinical score assessment were performed. Pulmonary function tests, i.e., tidal breathing flow volume (TBFV), were performed to measure tidal breathing parameters before and after salbutamol nebulization. If volume at peak tidal expiratory flow/expiratory tidal volume and time to peak expiratory flow/total expiratory time increased > or = 20%, or tidal expiratory flow at 25% of tidal volume/peak tidal expiratory flow increased > or = 20% after nebulization therapy, BHR was diagnosed. The number in the positive BHR group was used to calculate the prevalence of BHR, and clinical features were compared with those of the negative BHR group. Categorical data were analyzed for statistical significance (P < 0.05) by chi-square test or Fisher's exact test, or Student's t-test, as appropriate. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for those with statistical significance. One hundred and six wheezing children underwent pulmonary function tests before and after salbutamol nebulization. With the aforementioned criteria, 41 cases (38.7%) were diagnosed with BHR. History of reactive airway disease, (OR, 6.31; 95% CI, 1.68-25), maternal history of asthma (OR, 3.45; 95% CI, 1.34-9), breastfeeding less than 3 months (OR, 3.18; 95% CI, 1.26-8.12), and passive smoking (OR, 3; 95% CI, 1.15-7.62) were significant risk factors of BHR. The eosinophil count was significantly higher in the BHR (+) group particularly, in children 1-5 years of age (P < or = 0.01). Patchy infiltrates were more commonly found in patients with negative BHR but not statistically significant. In conclusion, a history of reactive airway disease, maternal history, breastfeeding less than 3 months, and passive smoking were significant risk factors for BHR.

Frequent wheeze at follow up of very preterm infants: which factors are predictive?

OBJECTIVE

To determine if chest radiograph appearance at 28 days or 36 weeks postmenstrual age (PMA) can predict recurrent wheeze or cough at follow up in prematurely born infants more effectively than readily available clinical data.

DESIGN

Chest radiographs of infants entered into the UKOS trial, who had had a chest radiograph at 28 days and 36 weeks PMA and completed six months of follow up, were assessed for the presence of fibrosis, interstitial shadows, cystic elements, and hyperinflation. At 6 months of corrected age, the occurrence and frequency of wheeze and cough since discharge were determined using a symptom questionnaire.

PATIENTS

A total of 185 infants with a median gestational age of 26 (range 23-28) weeks.

RESULTS

Thirty seven infants wheezed more than once a week, compared with the rest of the cohort. These infants had significantly higher chest radiograph scores at 28 days (p = 0.020) and 36 weeks PMA (p = 0.005), with significantly higher scores at 28 days for fibrosis (p = 0.017) and at 36 weeks PMA for fibrosis (p = 0.001) and cystic elements (p = 0.0007). They had also been ventilated for longer (p = 0.013). Forty four infants coughed more than once a week; they did not differ significantly from the rest of the cohort. An abnormal chest radiograph score at 36 weeks PMA had the largest area under the receiver operator characteristic curve with regard to prediction of frequent wheeze.

CONCLUSION

An abnormal chest radiograph appearance at 36 weeks PMA predicts frequent wheeze at follow up and appears to be a better predictor than readily available clinical data.

Very low birthweight and asthma by age seven years in a national cohort

Several studies have suggested that very low birthweight (VLBW < 1500 g) is associated with increased rates of respiratory problems in childhood and that the presence of chronic lung disease further increases the risk. We aimed to assess rates of asthma at 7-8 years of age in a national cohort of VLBW infants born in 1986 and for whom perinatal data were available. Two hundred ninety-nine former VLBW children (96% of surviving children living in New Zealand) were assessed at a home visit. Parents were asked a comprehensive questionnaire, including three questions aimed at assessing morbidity from asthma: 1) was the child diagnosed as having asthma before age 7 years; 2) was the child still experiencing asthma at the age of 7 years; and 3) was the child prescribed daily medication for asthma at the age of 7 years. Overall, 50% of the cohort had been diagnosed with asthma before age 7, compared with 27% of a sample of New Zealand children assessed contemporaneously in an international study; 32% had asthma at age 7, and 11% were taking daily medication. All three categories of asthma were associated with a family history of asthma, but there was no association with any perinatal factors. A diagnosis of asthma before age 7 was more likely when the mother smoked in pregnancy (P < 0.005) and currently smoked (P < 0.01), and trended so when parents lacked high school qualifications and in Maori or Pacific Island families (P < 0.10). In contrast, daily medication was more frequent when parents had educational qualifications and in non-Maori or Pacific Island families (P < 0.05). On multiple logistic regression, a family history of asthma was a significant predictor for any and current asthma (P < 0.001) and daily medication (P < 0.05); maternal smoking in pregnancy was a significant predictor for any asthma (P < 0.05); and non-Maori or Pacific Island ethnicity was a significant predictor for asthma treatment (P < 0.05). We conclude that rates of childhood asthma are high in this VLBW cohort, but the high prevalence appears to be unrelated to perinatal factors, including respiratory morbidity. There are suggestions that social factors contribute to both asthma risk and treatment.

Pulmonary function in children with initial low birth weight

The objective of this analysis was to examine the effect of low birth weight and prematurity on bronchial air-flow, bronchial reactivity, airway symptoms and asthma diagnosis at school age. A cross-sectional epidemiological study was performed in three small towns in the eastern part of Germany on 2470 school children aged 5-14 (89.1% of eligible children). A 78 item questionnaire to determine risk factors at birth and in early childhood was employed. 7.8% of the children were born before completing 38 gestational weeks; 6.6% had a birth weight less than 2500 g. Pulmonary function analysis were done by a mobile plethysmography at the school. There were only weak restrictions in lung volume in term low birth weight (LBW) children (100 ml lower TLC, p = 0.107), and flow (257 ml lower PEFR, p = 0.108), were low. However, bronchial hyper-responsiveness indicated by 292 ml lower FEV1.0 after cold air bronchial provocation, was significantly increased compared to term normal birth weight children (p < 0.001). The effect of LBW was less in older children, only slightly stronger in girls and increased in children mechanically ventilated during the postnatal period. Correspondingly, there was a higher prevalence of diagnosed asthma in term LBW children (OR 1.6, 95%-confidence interval 1.0-2.6), however these were without an increased risk for any allergic sensitization. LBW, therefore, seems to be a risk factor for smaller lungs and hyperreactive airways primarily in term born children, whereas in preterm children the immature bronchial system seems to be recover by school age.

Assessment of prematurely born children at follow-up using a tidal breathing parameter

Prematurely born children frequently have respiratory problems at follow-up. A non-invasive and easily performed lung function test would greatly facilitate their evaluation and appropriate treatment. We have, therefore, assessed whether the shape of the tidal breathing expiratory flow curve would give useful information in such a population. One hundred and twenty traces were randomly selected from plethysmographic measurements of thoracic gas volume and airway resistance made during a follow-up study of a prematurely born population. The children had a median gestational age of 29 (range 23-35, interquartile range 27-31) weeks and postnatal age at the time of measurement of 11 (range 6-24, interquartile range 7-13) months. From the flow and volume signals, the mean time to reach peak tidal expiratory flow as a proportion of the total expiratory time (tPTEF : tE) was determined for each child. The median tPTEF : tE differed significantly between children who, in the neonatal period, had or had not required mechanical ventilation (p < 0.001) and had or had not had an increased inspired oxygen requirement (p < 0.01), and who were or were not symptomatic at follow-up (p < 0.001). Logistic regression analysis demonstrated that a low tPTEF : tE ratio was independently associated with symptom status. These results suggest that assessment of a tidal breathing parameter during follow-up of prematurely born children may be useful. As tPTEF : tE can be measured without sedation, relatively quickly and with simple equipment, potentially large study populations could be investigated, and this technique should now be evaluated in a non-sedated group of young prematurely born children.

First trimester invasive procedures: effects on symptom status and lung volume in very young children

First trimester procedures have been associated with perinatal lung function abnormalities that may suggest subsequent respiratory problems. Our aim was, therefore, to assess the impact of first trimester invasive procedures [early amniocentesis (EA) and chorion villus sampling (CVS)] on respiratory morbidity in very young children. A questionnaire was issued to parents of 439 EA and 453 CVS (subjects), and 435 controls (their mothers had undergone no invasive procedures) when their children were one year old. Data were also obtained from diary cards issued to a subset of 278 of the EA, 262 of the CVS, and 264 of the control infants followed prospectively. Functional residual capacity (FRC) was measured at a median age of 5 months (range: 0.25-24) in 159 children whose mothers had undergone EA, 168 following CVS and in 165 controls. Analysis of the one-year questionnaire demonstrated an excess of symptomatic infants in the EA group (31%) compared to the CVS (22%; P < 0.01) and control groups (17%; P < 0.01). Findings from the prospective follow-up study confirmed those results and also demonstrated an increase in chest-related hospital admissions in the EA group (3%) compared to the controls (0.4%; P < 0.05). Logistic regression analysis revealed that positive symptom status related significantly to EA and CVS interventions (P < 0.0001), bottle feeding (P < 0.001), parental smoking (P < 0.01), a family history of atopy (P < 0.01), and immaturity (P < 0.01). In the control group, FRC correlated best with weight (r = 0.92). The mean FRC of the EA and CVS groups was higher than that of the controls (P < 0.01). A higher proportion of children had an FRC two standard deviations above the controls' mean in the EA group (n = 14) compared to the CVS group (n = 3; P < 0.01). The symptomatic infants tended to have higher FRCs than the asymptomatic children. We conclude that first trimester procedures are associated with increased respiratory morbidity in very young children.

Inhaled nedocromil sodium in symptomatic young children born prematurely

The efficacy of a non-steroidal anti-inflammatory agent (nedocromil sodium, NS) has been assessed in young children born prematurely who had recurrent respiratory symptoms at follow-up. In a randomized, double-blind cross-over trial, either two puffs of NS (2 mg puff-1) or placebo were administered three times a day via a spacer device and face mask. Fifteen children, median gestational age 27 weeks, birthweight 1100 g and postnatal age 12 months were studied. The symptom score was lower in the last 2 weeks of the active period (median score 26) compared to the run-in period (median score 55) and the last 2 weeks of the placebo period (median score 50), P < 0.01. The maximum possible symptom score for a 2-week period was 210. Compared to the run-in period, children required fewer days of bronchodilator therapy in the last 2 weeks of the active treatment (P < 0.01), but not in the placebo period. Although results of functional residual capacity (FRC) measurements were available on only 13 of the 15 children, these did demonstrate a significant change in FRC over the active, but not the placebo, period. These data suggest that NS is a useful prophylactic agent for children born prematurely and who are symptomatic at follow-up.

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.

Recurrent wheezing in very preterm infants

AIMS

To document the prevalence of, and identify risk factors for, recurrent wheezing treated with bronchodilators in the first year of life.

METHODS

Parental history and neonatal data were collected prospectively in a regional cohort of very preterm infants (< 33 weeks). Data on maternal smoking, siblings at home, breast feeding, respiratory symptoms, and hospital re-admissions were documented at 12 months.

RESULTS

Outcome data were available for 525/560 (95%) of survivors. The incidence of recurrent wheeze was 76/525 (14.5%) in very preterm infants and 20/657 (3%) in a cohort of term newborns. Significant risk factors for recurrent wheeze in very preterm infants were parental history of asthma, maternal smoking, siblings at home, neonatal oxygen supplementation at 28 days, 36, and 40 weeks of gestation.

CONCLUSIONS

Wheezing respiratory illnesses are common in very preterm infants. The factors involved are similar to those in more mature infants, with the addition of immaturity and neonatal lung injury.

Respiratory illness in families of preterm infants with chronic lung disease

AIMS--To examine the relation, based on two types of questionnaires, between (1) chronic lung disease of the newborn (CLDN) and lower respiratory illness (LRI) in siblings, and between (2) CLDN and asthma, chronic obstruction pulmonary disease (COPD), or allergy in parents and grandparents. METHODS--Data from 209 children born before 32 weeks of gestation were randomly taken from the records of three neonatal units. Taking into account age and gender, the excess of LRI was calculated for each family compared with the average of all families. Subsequently whether CLDN was associated with an excess of LRI in the family was tested. RESULTS--Thirty one (14.8%) children were diagnosed as having CLDN. The family probability index for LRI did not differ between children with or without CLDN. The prevalence of COPD, asthma, and allergy in parents of children with CLDN was similar to that of children without CLDN. The prevalence of LRI was 18.1% in study children, 29.6% in children with CLDN, and 16.9% in children without CLDN (P < 0.01). These prevalences were higher compared with that of a group of term siblings (9.3%) (P = 0.05). CONCLUSIONS--These findings suggest that CLDN in preterm children is not related to a genetic or familial predisposition towards asthma, COPD, or allergy.

Relationship between lung function results in the first year of life and respiratory morbidity in early childhood in patients born prematurely

The relationship between lung function results at 6 months and 1 year of age to respiratory symptoms in the first 3 years of life in prematurely born population has been determined. In 88 infants (median gestational age, 29 weeks) thoracic gas volume (TGV) and airway resistance (R(aw)) was measured and specific conductance (SGaw) calculated at 6 months and 1 year of age. During 3 years of prospective follow-up neither TGV measured at either 6 months or 1 year, nor R(aw) and SGaw at 6 months, differed significantly between infants who were asymptomatic or symptomatic. At 1 year, however, R(aw) and SGaw were significantly higher and lower respectively in patients who were symptomatic than in those who were asymptomatic in any of the 3 years. An elevated R(aw) (> or = 50 cmH2O/L/s) measured at 1 year, but not at 6 months, was associated with a significant relative risk of symptoms in the first, second, and third year of life. We conclude that in prematurely born patients an abnormal airway resistance at 1 year predicts symptoms in early childhood.

Airways resistance and lung volume before and after bronchodilator therapy in symptomatic preterm infants

Preterm infants who are symptomatic at follow-up frequently have a high airways resistance (RAW) and a low functional residual capacity to thoracic gas volume ratio (FRC:TGV). The aim of this study was to assess the effect of bronchodilator therapy on these lung function abnormalities. Thirty-four infants who had recurrent respiratory symptoms and a median gestational age 28 weeks, were studied at a median postnatal age of 10 months (range 6-20). TGV and RAW were measured using a plethysmographic technique and FRC by helium gas dilution. Specific conductance (SGAW) was calculated from TGV and RAW. All measurements were made immediately before and 15 min after nebulized salbutamol. Administration of nebulized salbutamol was associated with a reduction of RAW (P < 0.001) and an increase in SGAW (P < 0.001), FRC (P < 0.001). These effects on lung function were independent of postnatal age.

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.

Neonatal meconium aspiration syndrome and respiratory morbidity during infancy

Respiratory morbidity in the first 6 months of life of 35 infants who had had neonatal meconium aspiration syndrome (MAS) was compared to that of 70 controls, also born at term, matched for gender and ethnic origin. The number of infants in the two groups who were symptomatic was compared. Infants were described as symptomatic if, following discharge from hospital, they had at least one episode of wheezing and/or coughing which lasted for 3 days or more. There was no significant difference between the two groups regarding parental smoking or the proportion of infants who had a family history of atopy. A significantly greater proportion of the MAS group (49%) than of the control group (20%) was symptomatic at follow-up. Eight (23%) infants with MAS and 2 (3%) controls had symptoms which necessitated regular bronchodilator therapy. The 8 infants with MAS who were on maintenance bronchodilator therapy had required significantly longer neonatal respiratory support and had larger lung volumes at follow-up than the other 27 infants. We conclude that neonatal meconium aspiration syndrome is associated with increased respiratory morbidity in the first 6 months of life.

The effect of sodium cromoglycate on upper and lower respiratory symptoms in children born prematurely

The aims of this study were to assess whether sodium cromoglycate (SCG) was an effective prophylaxis against both upper and lower respiratory tract signs and to determine factors which affected the site and magnitude of the response to SCG. Sixteen children born prematurely were entered into a randomised placebo-controlled trial at 15 months of age (range 4-31 months). The patients received, in random order, either 3 weeks' treatment with SCG (5 mg) or placebo, both given four times a day by inhalation via a spacer device. Parents were asked to record the occurrence and severity of their child's upper respiratory tract signs; sneezing and runny nose and lower respiratory tract signs; day and night time cough and wheeze. During the active compared to the placebo period there was an overall reduction of 47% and 53% in upper and lower respiratory tract signs, respectively. The magnitude of response to SCG as assessed by either the change in upper or lower respiratory tract signs was not significantly related to the patient's gestational or postnatal age, the occurrence of neonatal chronic lung disease, family history of atopy or the order in which the therapy was administered. We conclude that inhaled SCG may be a useful prophylaxis for both upper and lower respiratory tract signs for children born prematurely and less than 3 years of age.

Effects of prematurity and intrauterine growth on respiratory health and lung function in childhood

OBJECTIVE

To determine whether birth weight and gestational age are associated with respiratory illness and lung function in children aged 5-11 years.

DESIGN

Cross sectional analysis of parent reported birth weight, gestational age, and respiratory symptoms; parental smoking and social conditions; forced vital capacity (FVC), forced expiratory volume in one second (FEV1), forced expiratory rates between 25% and 75% and 75% and 85% (FEF25-75 and FEF75-85), and height.

SETTING

Primary schools in England and Scotland in 1990.

SUBJECTS

5573 children aged 5-11 (63.3% of eligible children) had respiratory symptoms analysed and 2036 children (67.1% of eligible children) had lung function measured.

MAIN OUTCOME MEASURES

Symptoms of asthma, bronchitis, occasional and frequent wheeze, cough first thing in the morning, and cough at any other time and lung function.

RESULTS

Birth weight adjusted for gestational age was significantly associated with all lung function measurements, except FEF25-75. The association remained for FVC (b = 0.475, 95% confidence interval 0.181 to 0.769) and FEV1 (b = 0.502, 0.204 to 0.800) after adjustment for gestational age, parental smoking, and social factors. FEF75-85 was the only lung function related to gestational age. Respiratory symptoms, especially wheeze most days (adjusted odds ratio 0.9, 0.84 to 0.97) were significantly associated with prematurity. Every extra week of gestation reduced the risk of severe wheeze by about 10%.

CONCLUSIONS

Lung function is affected mainly by intrauterine environment while respiratory illness, especially wheezing, in childhood is related to prematurity.

Nebulized sodium cromoglycate in preterm infants--protection against water challenge-induced bronchoconstriction

Nebulized water is an effective bronchoprovocative agent in asthmatic adults and children. The aim of this study was to assess the bronchoconstrictor effect of this agent in preterm infants studied at follow-up and if their response to it was altered by pre-treatment with nebulized sodium cromoglycate. Lung function, thoracic gas volume and airway resistance, was measured by whole body plethysmography and specific conductance (SGAW) calculated. Measurements were made before and after nebulized saline, nebulized water (first water challenge), nebulized sodium cromoglycate and again nebulized water (second water challenge). There was no significant change in SGAW following either normal saline or sodium cromoglycate. In nine infants SGAW deteriorated by more than 16% (twice the coefficient of variation of the measurement) after the first water challenge but only in one after the second water challenge (P < 0.01). We conclude that nebulized water is an effective bronchoconstrictor in preterm infants and that sodium cromoglycate can protect against this challenge.

Risk factors for developing wheezing and asthma in childhood

Wheezing lower respiratory tract illness in infancy and asthma share the clinical findings of wheezing and respiratory distress. Although the link between wheezing lower respiratory tract illness in infancy and the subsequent development of asthma is a limited one, both conditions do share some common risk factors, including exposure to environmental tobacco smoke, difficult living conditions (low socioeconomic class, crowding, allergen exposure), and increased risk in males. The impact of baseline lung function on wheezing lower respiratory tract illness risk is substantial and may be independent of airway reactivity. In contrast, the development of chronic airway inflammation mediated by allergic sensitization plays a central role in the development of persistent asthma. Although the endogenous risks for these two outcomes may be fixed, it is clear that caregivers may help to reduce or eliminate the exogenous risks listed earlier by parental education and improvement of the living conditions of young children.

Randomised trial of inhaled steroids in preterm infants with respiratory symptoms at follow up

BACKGROUND

Preterm infants often suffer from recurrent respiratory symptoms at follow up. Although these infants are responsive to treatment with bronchodilators some continue to wheeze or cough despite treatment. In a randomised double blind placebo controlled trial, the ability of inhaled steroids to reduce recurrent respiratory symptoms and the requirement for bronchodilator treatment in preterm infants less than two years of age has been assessed.

METHODS

Eighteen premature infants with mean gestational age 28 weeks and postnatal age 10.5 months were recruited. The study consisted of two six week treatment periods separated by a two week washout period. The infants received either 200 micrograms of beclomethasone dipropionate or placebo as one puff twice daily from an inhaler, through a spacer and a face mask. Parents kept a daily record of their infants' respiratory tract symptoms (wheeze and cough) and use of bronchodilators. Functional residual capacity (FRC) was measured at the beginning and end of each six week period.

RESULTS

The symptom score was reduced by 37% in the active compared with the placebo period. During the active period the infants had a mean of 28 bronchodilator free days, compared with 22 days in the placebo period. The FRC improved significantly in the active but not the placebo period.

CONCLUSION

Regular dosage with beclomethasone by inhalation is a useful treatment for preterm infants with respiratory symptoms.

Persistence of respiratory symptoms into the second year of life: predictive factors in infants born preterm

Preterm infants frequently suffer from recurrent respiratory symptoms in the first year of life. Our aims were to assess if such respiratory morbidity persisted beyond the first year and to define the predictive factors. One hundred and seventeen infants (median gestational age 29 weeks) were followed prospectively for two years. Thirty-eight infants had symptoms only in the first year (group A) and in a further 20 infants, symptoms were present in both years (group B). Comparison of these two groups revealed no significant difference in birth weight or gestational age, but the duration of ventilation and increased inspired oxygen concentration were significantly longer in group B. Significantly more infants in group B had had an air leak in the neonatal period, and airways resistance at six months of age was also significantly higher in group B. We conclude that infants with severe neonatal respiratory distress are likely to have persisting respiratory morbidity and that respiratory function measurements at six months of age provide the most accurate predictor of chronic respiratory symptoms.

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 less than 1500 g 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.

Inhaled sodium cromoglycate for pre-term children with respiratory symptoms at follow-up

Children born prematurely frequently have recurrent respiratory symptoms at follow-up and benefit from bronchodilator therapy. We have assessed if regular inhaled sodium cromoglycate would reduce this respiratory morbidity and need for bronchodilator therapy. Sixteen symptomatic children (median gestational age 29 weeks, post-natal age 15 months) were entered into a randomized double-blind, placebo-controlled trial. In two 3-week periods, the patients received either placebo or sodium cromoglycate (5 mg) as one puff q.d.s. from an inhaler via a coffee cup. Parents recorded their child's symptoms and need for bronchodilator therapy throughout and lung function was assessed by measurement of functional residual capacity (FRC) at the beginning and end of each 3-week period. The symptom score was reduced by 49% in the active compared to the placebo period (P less than 0.01) and bronchodilator was taken on a mean of 2.9 days per infant in the active period compared to 7.9 days in the placebo period (P less than 0.01). There was a significant improvement in FRC in ten of 16 patients over the active period but only in two infants over the placebo period (P less than 0.01). We conclude regular inhaled sodium cromoglycate is useful prophylaxis for symptomatic pre-term children.

The follow-up care of babies discharged from special care baby units in England and Wales between 1988 and 1989

This survey of District Health Authorities in England and Wales forms part of a wider study into the needs of babies discharged from special care baby units in South Glamorgan Health Authority. The aim of the survey was to find out what types of care were offered to babies who had been in a Special Care Baby Unit (SCBU) and their families following the babies' discharge from hospital. This in turn raised interesting issues concerning the community care of these babies and their families which are discussed in this article.

Ipratropium bromide for symptomatic preterm infants

Twelve preterm infants, median gestational age 31.5 weeks, were entered into a randomised, placebo-controlled trial of bronchodilator therapy. Their postnatal age was a median of 17.5 months and all suffered from recurrent respiratory symptoms. The infants received either inhaled placebo or 40 micrograms of ipratropium bromide (active therapy) three times a day utilising a coffee cup as a spacer device. Each therapy was administered for 2 weeks. The symptom score during the active period was reduced by 59% compared to the placebo period (P less than 0.01) and this was associated with 38% improvement in lung function in the active period compared to a 20% change in functional residual capacity over the placebo period (P less than 0.01). We conclude inhaled ipratropium bromide appears to be an effective treatment for symptomatic infants at follow up.

Relationship of symptoms to lung function abnormalities in preterm infants at follow-up

Recurrent respiratory symptoms are common in preterm infants in the first 2 years of life. The aim of this study was to determine the lung function abnormalities associated with such symptoms. Forty preterm infants, with a median gestational age of 29 weeks were studied at a median postnatal age of 12 months. Twenty-two suffered from recurrent symptoms, defined as wheezing and/or coughing on at least 4 days per week over the previous month. Lung function was assessed by measurement of functional residual capacity (FRC), using a helium gas dilution technique, and airway resistance (Raw) and thoracic gas volume (TGV) plethysmographically. No significant difference was found in TGV between symptomatic and asymptomatic infants, but the median FRC was lower (P less than 0.01), Raw higher (P less than 0.01), and FRC:TGV ratio lower (P less than 0.001) in the symptomatic infants. These lung function abnormalities in the symptomatic infants are suggestive of gas trapping.