Characterization of the spontaneous breathing variability in healthy children at rest: a prospective observational study

Abstract

Introduction: Spontaneous breathing demonstrates appreciable breath-by-breath variations in rate and volume, even at rest. This natural variability is beneficial for lung structure and function, and is often disrupted in pulmonary diseases or mechanical ventilation. Despite the recognition of its importance, the variability of breathing in children is not well characterized. We aimed at describing the characteristics of breathing variability in healthy children at rest.

Methods: 47 healthy children aged 1 to 12 years old were recruited during pre-anesthesia visits, prior to minor elective surgeries. Children with respiratory-tract diseases or history of snoring or sleep apnoea were excluded. Breathing was recorded overnight at home during 16 hours using respiratory inductance plethysmography (RIP).

Results: Forty-one cases were analysed in 3 age groups (group 1: 12 to 23 months, n=9; group 2: 2 to 6 years n=15; group 3: 6 to 12y, n=17). Six cases were excluded because of RIP band misplacement. Respiratory rate (RR) presented a mean coefficient of variation (CV) of 21.1% (14.9–27.3, 95% conf. interval), 19.6% (15.9–23.4) and 16.6% (13.8–19.3) in groups 1, 2 and 3, respectively. The CV of tidal volume (VT), derived from respiratory inductance, was 17.6% (11.9–23.3), 14.9% (11.9–17.9) and 15.3% (12.3–18.2) in groups 1, 2 and 3, respectively. There was no evidence for statistical differences between groups.

Conclusions: Spontaneous breathing RR and VT vary considerably in healthy children at rest, independently of age. These aspects of pediatric respiratory physiology provide healthy reference values for the assessment of lung diseases or mechanical ventilation.