Electromagnetic inductance plethysmography to study airflow after nebulized saline in bronchiolitis

Spirometric effects from therapeutic interventions in infants with severe respiratory distress cannot readily be measured, hampering development of better treatment for acute bronchiolitis. Inhaled normal saline is regularly used in these infants, with little knowledge of how this influences lung physiology.

Assess feasibility of infant lung function testing using electromagnetic inductance plethysmography (EIP) in a clinical setting in a busy pediatric department, and explore effects from inhaled normal saline on tidal flow-volume loops in infants with acute bronchiolitis.

Observational study conducted at the Children's Clinic, Haukeland University Hospital, Bergen, Norway during the winters 2016 and 2017, enrolling children with bronchiolitis below six months of age. EIP was performed immediately before and 5 and 20 min after saline inhalation. EIP is a noninvasive method to measure tidal breathing parameters by quantifying volume changes in the chest and abdomen during respiration. The method consists of an electromagnet/antenna and a patient vest.

EIP was successfully applied in 36/45 (80%) enrolled infants at mean (standard deviation) age 2.9 (2.5) months, after a hospital stay of 2.2 (1.9) days. After saline inhalation, tidal expiratory to inspiratory time ratio (Te/Ti) had increased significantly, whereas the other relevant flow/volume parameters had changed numerically in a direction compatible with a more obstructive pattern.

EIP could successfully be used to obtain tidal breathing parameters in infants with respiratory distress and appears a promising tool for assessment of therapeutic interventions in bronchiolitis. Saline inhalations should be used with caution as placebo in intervention studies.