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Children with uncontrolled asthma and significant reversibility might show hypoxaemia
Jessica Taytard1,2, Fatma Lacin3, Thi Lan Thanh Nguyen3
1Université Pierre et Marie Curie-Paris 6, INSERM U938, 184 Rue du Faubourg Saint-Antoine, 75012, Paris, France.
Insights
Low oxygen levels (hypoxemia) in children with asthma and airway obstruction are linked to uncontrolled asthma and significant bronchodilator response. This finding suggests different treatment needs for these patients.
Area of Science:
- Pediatric Pulmonology
- Respiratory Medicine
- Clinical Physiology
Background:
- Asthmatic children without exacerbation may have underlying airway obstruction issues.
- Low partial pressure of oxygen (PaO2) can indicate future risk but is rarely measured during pulmonary function tests.
- Different pathophysiologies of airway obstruction require tailored treatments.
Purpose of the Study:
- To investigate the prevalence and predictors of hypoxemia in children with asthma and airway obstruction, specifically in those without current exacerbations.
- To determine the relationship between asthma control, bronchodilator reversibility, and hypoxemia.
- To identify potential markers for guiding treatment strategies.
Main Methods:
- Prospective study including 51 asthmatic children with airway obstruction undergoing pulmonary function testing and blood gas analysis.
- Hypoxemia defined as PaO2 lower than -2 z-score.
- Multivariable analysis used to assess the influence of baseline FEV1, asthma control, and FEV1 reversibility on PaO2.
Main Results:
- Hypoxemia was present in 29% of the children.
- A significant bronchodilator reversibility (≥12% increase in FEV1) was observed in 72% of participants.
- Uncontrolled asthma and significant FEV1 reversibility were independently associated with lower PaO2 levels, irrespective of baseline airway obstruction severity.
Conclusions:
- Hypoxemia in non-exacerbated obstructive asthmatic children is associated with uncontrolled asthma and significant post-bronchodilator FEV1 reversibility.
- These findings suggest distinct pathophysiological mechanisms and treatment requirements.
- A composite index of 'uncontrolled asthma + FEV1 reversibility ≥12%' may help identify children at risk for hypoxemia and guide therapeutic interventions.
Abstract:
Asthmatic children free of exacerbation with airway obstruction may have low partial pressure of oxygen (PaO2) which can be a marker for future risk, but PaO2 is scarcely measured during pulmonary function testing. We prospectively included asthmatic children with airway obstruction referred for pulmonary function testing, including blood gas analysis (n = 51). Hypoxaemia, defined as a value lower than - 2 z-score, was present in 15 (29%) children, and 37 (72%) children had a significant reversibility after bronchodilator administration. The multivariable model showed a positive influence of baseline forced expiratory volume in 1 s (FEV1) on PaO2 (β coefficient 0.69, [95% CI: 0.07; 1.30]; P = 0.03), whereas uncontrolled asthma and FEV1 reversibility negatively influenced it (β coefficient - 1.59 [95% CI: - 2.74; - 0.44]; P = 0.01; and - 0.07 [95% CI: - 0.13; - 0.02]; P = 0.01, respectively). As a consequence, children with uncontrolled symptoms of asthma and FEV1 reversibility ≥ 12% were significantly more at risk of having hypoxaemia compared to children with well/partly controlled asthma or no significant reversibility of FEV1.Conclusion: Among obstructive asthmatic children without current exacerbation, hypoxaemia is more likely to be seen in children with uncontrolled asthma and a significant post-bronchodilator FEV1 reversibility, in favour of different pathophysiology and treatment requirements of their airway obstruction.What is Known:• Recommendations are to treat asthmatic children in order to control respiratory symptom and maintain normal pulmonary function.• Asthmatic children free of exacerbation may have different pathophysiology for airway obstruction (central, peripheral, inflammatory, spasticity, remodelling) and should be treated according the pathophysiology of their airway disease.What is New:• In obstructive asthmatic children free of current exacerbation, the presence of hypoxaemia (ventilation-perfusion mismatch) is influenced by asthma control and post-bronchodilator reversibility, independently of the level of baseline airway obstruction.• The presence of hypoxaemia in obstructive asthmatic children free of current exacerbation can be highly suspected by the composite index "uncontrolled asthma + FEV1reversibility ≥ 12%" which may guide treatment.
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