Work of Breathing in Bronchiolitis Under Non-invasive Ventilation

Severe acute viral bronchiolitis is the leading cause of pediatric intensive care admission. The first-line recommended ventilation support is continuous positive airway pressure (CPAP), which reduces the work of breathing (WOB) and improves gas exchange. Although Non invasive Positive Pressure Ventilation (NiPPV) is increasingly used in case of CPAP failure to avoid intubation, no study has yet evaluated if this support could effectively reduce the effort of breathing.

Our hypothesis is that NiPPV could reduce WOB more effectively than CPAP alone, and might lead to reduce intubation in the most severe bronchiolitis.

The purpose of this study is to compare WOB between CPAP and NiPPV, thanks to esophageal pressure measurement, in infants hospitalized for severe acute bronchiolitis.

Severe acute viral bronchiolitis is the leading cause of pediatric intensive care admission. The first-line recommended ventilation support is non invasive ventilation (NIV) with continuous positive airway pressure (CPAP), which has been proved to reduce the work of breathing (WOB) and improve gas exchange. Non invasive Positive Pressure Ventilation (NiPPV) is increasingly used in case of CPAP failure to avoid intubation. Nevertheless, no study has ever evaluated its effectiveness on the discharge of respiratory muscles in severe bronchiolitis.

Measurement of esophageal and gastric pressures with an esogastric catheter allows an estimation of WOB thanks to the calculation of the esophageal pressure-time product (PTPes), and a calculation of the transdiaphragmatic pressure (Pdi) as the difference between gastric and esophageal pressures. This minimally invasive technique can be used at the bedside to assess the efficacy of ventilation support and is now increasingly used in Intensive Care Units to assist ventilation-targeted strategies.

Our hypothesis is that NiPPV could reduce WOB more effectively than CPAP alone, and might lead to reduce intubation in the most severe bronchiolitis.

The main purpose of this study is to compare PTPes/min between CPAP and NiPPV in infants hospitalized for severe acute bronchiolitis.

Secondary objectives are i) to compare other parameters of WOB, gas exchanges and breathing pattern in both ventilator supports ii) to compare the rate of patient-ventilator asynchronies in 2 different setting of NiPPV ("clinical" and "physiological") iii) to assess if NiPPV is associated with reduced intubation rate, time under sedation and ventilation, and length of hospitalization as compared to CPAP.

Eligibility Criteria:
Inclusion Criteria:

* Clinical and radiological diagnosis of bronchiolitis
* Need for non-invasive ventilation support (NiPPV or CPAP) with a modified Wood clinical asthma score (m-WCAS)\> 4 and / or hypercapnic acidosis (pH \<7.3 and / or pCO2\> 50mmHg)
* Written parental informed consent

Exclusion Criteria:

* Contraindication to nasogastric tube (recent surgery of the esophagus, esophageal malformation at risk of perforation, severe coagulopathy)
* Absolute or relative contraindication to NIV

  * Respiratory collapse: coma (GCS \<12) and / or more than 3 apneas per hour with bradycardia \<90 / min and / or SpO2 \<90%
  * Pneumothorax
* Preexisting disorder that may influence WOB

  * Neuromuscular disease
  * Chronic respiratory failure already under NIV or tracheostomy at home
* No social security