Non-invasive Ventilation Generated by External Chest Pressure in Children

Airway management in the pediatric population differs from the adult population because of differences in their respiratory physiology and anatomy. For example the oxygen consumption is about three times higher in children as compared to adults; therefore, if there is a problem ventilating a child there is a higher impact on oxygen delivery and oxygen reserve. Current guidelines recommend that in respiratory emergencies where one "cannot ventilate and cannot intubate" that a cricothyroidectomy (insertion of a needle through the cricothyroid membrane in the neck) be performed. This procedure is very invasive and difficult to perform, especially in a small child. Since timing and simplicity are essential to successful airway management it is hypothesized that the investigators could utilize the physiological principles behind breathing to ventilate these children using the release of applied pressure to their chest. During, inspiration, the vertical and transverse dimensions of the thorax are increased, generating a negative pressure between the intrapleural space and the chest wall, allowing for air to be drawn into the lungs. As children have a very compliant rib cage one of the theoretical ways to improve lung inflation is to apply external pressure on the chest. The intrathoracic pressure increases above atmospheric pressure and air preferentially flows out of the lungs according to the pressure gradient. When the pressure is released and the chest recoils passively, a negative intrathoracic pressure is generated, which allows for air to flow into the lungs according to the pressure gradient created. If a sufficient tidal volume is generated by the release of pressure from the chest this could potentially become a simple, non-invasive, life-saving technique in children with difficult airways. By adapting the principles described above, it is possible that tidal volume and therefore, gas exchange can take place on release of the pressure applied to the chest.