Some chronic obstructive pulmonary disease will originate in neonatal intensive care units

Cytokine profiles at birth and the risk of developing severe respiratory distress and chronic lung disease

Background:

Neonates with the diagnosis of respiratory distress syndrome (RDS) were studied to investigate possible associations between cytokine levels at birth and developing severe RDS or chronic lung disease (CLD).

Materials and Methods:

This was a cross-sectional study on serum and bronchoalveolar lavage (BAL) samples collected within hours of birth from infants with moderate and severe RDS. Twenty infants with moderate RDS and 20 infants with severe RDS were studied. RDS was diagnosed on the basis of radiographic findings, respiratory distress, and an increasing oxygen requirement. RDS severity was graded based on the radiological findings and Downe's Score. CLD was diagnosed when infants were still on supplemented O₂ by at least 28 days of age. Levels of the cytokines interleukin (IL)-1β, IL-6, IL-8, IL-10, and tumor necrosis factor alpha were measured using enzyme-linked immunosorbent assay. “Statistical analysis was performed using the SPSS for Windows, (SPSS Inc., Chicago, IL, USA).”

Results:

Levels of the proinflammatory cytokines IL-8 and IL-1β were significantly higher in BAL of infants with severe RDS than those with moderate RDS (P = 0.007 and P = 0.02, respectively). IL-8 levels were also significantly higher in BAL and serum of infants who later progressed to CLD than in those who did not (P = 0.03 for both). The IL-8/IL-10 cytokine ratio was significantly higher in the BAL of severe RDS infants than in moderate RDS (P = 0.01) and in the serum of infants who progressed to CLD than in those who did not (P = 0.03).

Conclusion:

Levels of IL-8 and the IL-8/IL-10 ratio measured soon after birth were associated with severity of RDS as well as progression to CLD. Early measurement of cytokines levels and ratios may contribute to the prognosis and management of RDS and CLD.

Obstructive pulmonary disease in old age among individuals born preterm

There are only few studies of the association between preterm birth and risk of chronic lung disease in old age. The aim of this study was to assess the association between poor fetal growth, preterm birth, sex and risk of asthma and Chronic Obstructive Pulmonary Disease (COPD) in adulthood. We have followed up a cohort of all infants born preterm (<35 weeks) or with low birth weight (<2,000 and <2,100 g for girls and boys, respectively) and an equal number of controls in a source population of 250,000 individuals born from 1925 through 1949 in Sweden (6,425 subjects in total). Cases of asthma and COPD were identified through the Swedish Patient Register and we considered cohort subjects as cases if they had a main or additional discharge diagnosis of asthma or COPD. For any obstructive airways disease, there was a statistically significant increase in risk with decreasing birth weight and gestational duration among women but not among men. Compared to women born at term, women born before 32 weeks of gestation had a hazard ratio for any obstructive airways disease and asthma of 2.77 (95% CI 1.39-5.54) and 5.67 (1.73-18.6), respectively. Low birth weight and preterm birth are risk factors for obstructive airways disease also among the old, but the importance of these risk factors differs between the sexes.

The prevalence and risk factors of allergic and respiratory symptoms in a regional cohort of extremely low birth weight children (<1000 g)

BACKGROUND

Children who were <1000 g (ELBW extremely low birth weight) at birth more frequently present with wheezing which is the most common reason that pediatric consultation is sought. Therefore asthma is diagnosed very often. However is the asthma that is diagnosed in ELBW subjects atopic in origin, or is there a different etiology?

AIM

To determine if ELBW infants are at higher risk for the development of allergic and respiratory symptoms and to establish if there were any specific risk factors for these symptoms.

METHODS

81 children born with a mean birthweight of 845 g (91% of available cohort) were evaluated at the mean age 6.7 years. The control group included 40 full-term children. The children were examined for clinical signs of allergy, and were subjected to the following tests: serum total IgE, skin prick tests (SPT), exhaled nitric oxide measurement (FeNO) and spirometry.

RESULTS

ELBW children had wheezing episodes more often (64% vs. 25%; OR (odds ratio): 5.38; 95% CI (confidence interval): 2.14-13.8) and were diagnosed more frequently with asthma (32% vs. 7.5%; OR: 5.83, 95% CI: 1.52-26) than their term born peers. The most important risk factors for wheezing persistence were hospitalization and wheezing episodes in first 24 months of life. Mean serum tIgE level (geometric mean: 32+/-4 vs. 56+/-4 kU/L; p=0.002) was higher and the number of children with positive results of tIgE level (12% vs. 32%; p=0.02) were more frequent in the control group. Children from the control group also more frequently had SPT, however this data was not statistically significant (11% vs. 24%; p=0.09). All of the ELBW had normal FeNO level (<=20 ppb), but 5 children from the control group had abnormal results (p=0.02). There was no difference between the groups in the occurrence of allergic symptoms.

CONCLUSION

ELBW children have more frequent respiratory, but not allergic problems at the age of 6-7 years compared to children born at term. The need for rehospitalization in the first 2 years of life, was a more important risk factor of future respiratory problems at the age of 7 than perinatal factors, the diagnosis of bronchopulmonary dysplasia or allergy.

Preterm birth and respiratory disease in later life

Chronic respiratory diseases are a common complication of preterm birth, particularly among very immature infants or those suffering from bronchopulmonary dysplasia. Major progress in the treatment of preterm newborns has changed the pattern of late respiratory complications. The major respiratory problem in infancy and early childhood is respiratory exacerbations caused by infections (particularly viral ones), which need hospitalization. The symptoms become mild in school-age children; however, a group of children still present with chronic airway obstruction defined by recurrent episodes of wheezing and decreased lung function tests (decreased forced expiratory volume). For some preterm infants, particularly those with bronchopulmonary dysplasia, obstructive lung disease persists into adulthood. They are very likely to develop chronic obstructive pulmonary disease or similar disease later in life. In these patients, a program of lung function monitoring and pulmonary prophylaxis by means of elimination of specific risk factors in adulthood is advisable.

Lung function in infants and young children with chronic lung disease of infancy: the next steps?

Over the past year, a series of papers have reviewed the literature concerning assessment and interpretation of lung function in infants and young children with chronic lung disease of infancy. This manuscript, which represents the final paper in that series, summarizes the findings to date and highlights key areas for future research. Despite the huge literature in this field, interpretation of results and their use in guiding clinical management are still limited by difficulties in 'normalizing data' according to body size and maturation and selection of appropriate control groups. Furthermore, sensitive tests that more closely reflect the underlying pathophysiology of 'new' bronchopulmonary dysplasia, together with simple and reliable methods of assessing lung maturity at birth and true oxygen requirements at specified time points are urgently required. Research in this field is also challenged by the need to separate the independent effects of genetic predisposition, gene-environment interactions, preterm delivery, neonatal respiratory disorders and various treatment strategies on the growing lung. The extent to which disruption of lung growth following premature exposure to the extra-uterine environment leads to an earlier or more aggravated decline in respiratory function in later adult life remains to be elucidated. Whatever its origin, given the increasing survival of smaller and more immature infants, the long term sequelae of neonatal lung disease, are likely to continue to change, requiring ongoing, carefully designed longitudinal studies. Future research strategies need to encompass a multicenter, multi-disciplinary, collaborative approach with closer links between clinicians and basic scientists, to ensure that the most relevant research questions are addressed using appropriate methodology and that findings are implemented into clinical practice in a more timely fashion.