Bronchial hyper-responsiveness after preterm birth

Abstract

Being born preterm often adversely affects later lung function. Airway obstruction and bronchial hyperresponsiveness (BHR) are common findings. Respiratory symptoms in asthma and in lung disease after preterm birth might appear similar, but clinical experience and studies indicate that symptoms secondary to preterm birth reflect a separate disease entity. BHR is a defining feature of asthma, but can also be found in other lung disorders and in subjects without respiratory symptoms. We review different methods to assess BHR, and findings reported from studies that have investigated BHR after preterm birth. The area appeared understudied with relatively few and heterogeneous articles identified, and lack of a pervasive understanding. BHR seemed related to low gestational age at delivery and a neonatal history of bronchopulmonary dysplasia. No studies reported associations between BHR after preterm birth and the markers of eosinophilic inflammatory airway responses typically found in asthma. This should be borne in mind when treating preterm born individuals with BHR and airway symptoms.

Bronchial hyper‐responsiveness in preterm‐born subjects: A systematic review and meta‐analysis

“…As different mechanisms may potentially be identified using direct (assessing smooth muscle phenotypes and responses) and indirect methods (pathways of inflammatory mediators), to assess BHR, we classified the studies using direct and indirect means to assess BHR. This is an important distinction to make as there is a suggestion that BHR responses may be different in asthma and in lung disease of preterm‐born children: Kim et al reported children with asthma responded to both methacholine and adenosine 5′‐monophosphate but children with CLD only responded to the methacholine suggesting that continuing inflammation may not be a factor in preterm‐born subjects.…”

“…The nature of the airway narrowing observed in preterm‐born children can be tested using pharmacological stimuli, for example directly acting on smooth muscle cells’ receptors or indirectly via the release of mediators by pro‐inflammatory airway cells . This process of assessment of bronchial hyper‐responsiveness (BHR) has been extensively used in asthma, although it is not as discriminatory as expected as many asymptomatic subjects may have increased BHR and those with the disease may not .…”

Pulmonary function in former very low birth weight preterm infants in the first year of life

“…The linear regression analysis has shown that the factors associated with impaired performance in pulmonary function tests were low gestational age, intrauterine growth restriction, use of mechanical ventilation and recurrent wheezing. In all of these situations, impairment in pulmonary function appears to be related to obstruction of small airways and bronchial hyper responsiveness [18]. Regarding prematurity and intrauterine growth restriction, it seems that, besides changes in pulmonary flow, lung growth is also impaired, as shown by altered pulmonary volume measurements [19,20].…”

Asthma: A Loss of Post-natal Homeostatic Control of Airways Smooth Muscle With Regression Toward a Pre-natal State

“…"Non-atopic" Asthma in Pre-term and Small for Gestational Age Infants Pre-term individuals are an interesting group, in whom there is a significantly higher rate of asthma (as defined by demonstrable bronchodilator responsiveness) than the general population and in whom atopy appears not to be a significant risk factor (117)(118)(119)(120)(121). Around 20% of such individuals may demonstrate significant bronchodilator responsiveness.…”