From the Guidelines
Neonates do have beta receptors in their airways, although their presence and functionality may be limited compared to older children and adults. The presence of these beta-adrenergic receptors, particularly the beta-2 subtype, is crucial for bronchodilation when stimulated 1. However, the relative immaturity of the beta receptor system in neonates explains why medications like albuterol (a beta-2 agonist) may have less pronounced effects in very young infants compared to older children and adults.
The effectiveness of bronchodilators in neonates is a topic of ongoing debate, with some studies suggesting that they may not provide significant benefits in the treatment of bronchiolitis 1. However, a more recent study suggests that the benefits of bronchodilator administration, specifically short-acting b2-agonists, likely exceed the harms for patients born preterm with recurrent respiratory symptoms including cough and wheeze 1.
Key points to consider when treating respiratory conditions in neonates include:
- The beta receptor density gradually increases with age, reaching adult levels during childhood development 1.
- The potential benefit of inhaled bronchodilators in the context of acute viral illness and bronchiolitis may differ from that of full-term infants 1.
- Despite their lower numbers, beta receptors in neonates are still functional and respond to both endogenous catecholamines and exogenous medications.
- The use of bronchodilators in neonates should be carefully considered, taking into account the potential benefits and harms, as well as the individual patient's needs and medical history 1.
From the Research
Presence of Beta Receptors in Neonates' Airway
- Beta receptors are present in the airway of neonates, as stated in the study 2, which mentions that beta 2-receptors are present from the 16th gestational week.
- This presence of beta receptors explains the possible bronchial response in the youngest children, including neonates, to beta 2-agonists 2.
- The study 3 also supports the presence of beta receptors in neonates, as it investigates the effects of repeated β2-adrenergic receptor agonist therapy on the response to rescue bronchodilation in a hyperoxic newborn mouse model.
Implications of Beta Receptors in Neonates' Airway
- The presence of beta receptors in neonates' airway suggests that they may respond to beta 2-agonists, which are commonly used as bronchodilators 2.
- However, the study 3 found that repeated β-AR agonist treatments increased the airway reactivity and attenuated the response to a rescue bronchodilator in a hyperoxia-exposed neonatal mouse model.
- This finding may have clinical consequences for preterm infants with neonatal lung injury, who are already prone to airway hyperreactivity 3.