Testing the Ability of Gentle Chest Pressure to Maintain Peripheral Oxygenation in Intubated Pediatric Patients

BACKGROUND Airway management is different in the pediatric population compared to adults mainly due to the differences in respiratory physiology and anatomy. The oxygen consumption is about three times as high in children than in adults resulting in a higher impact on oxygen delivery and reserve should there be a problem with ventilation in children. During inspiration, the vertical dimension of the chest cavity is increased and the rib margins are lifted and moved out, causing an increase in the transverse diameter of the thorax. This generates a negative pressure in the intrapleural space between the lungs and the chest wall resulting in lung inflation. The rib cages of young children are very pliable. One of the theoretical ways to improve the efficiency of lung inflation in small children with such compliant rib cage is to apply 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 on the chest is released and the thorax recoils passively ("springs open"), a negative intrathoracic pressure is generated. This effectively "sucks" air into the lungs along the pressure gradient. Although age-related pliability differences may be present, we do not expect this to be a significant factor in using the chest pressure technique successfully.

We previously demonstrated that application of gentle pressure on the right chest of pediatric patients generated 20% of the tidal volume achieved with mechanical ventilation, regardless of whether the patient was intubated or not. Chest pressure was monitored using a force transducer and did not exceed the patient's body weight. Indeed, the pressure used was considerably less than what would be administered during cardiopulmonary resuscitation. There was little variation across age ranges; for each age group, we observed a difference of less than 1 mL/kg compared to the overall mean tidal volume. Our study also showed that the gentle chest pressure technique was well-tolerated by pediatric patients of any age (neonate to adolescent), and no adverse events were encountered, supporting this technique as a very low-risk maneuver.

While these results are encouraging, the study did not provide detailed information on how much peripheral oxygenation (SpO2) is achieved with the gentle chest pressure technique. An editorial that accompanied the published study supports further investigation of the technique, including the extent to which it provides ventilation and its ability to provide adequate oxygenation. In this study, we wish to perform the technique on pediatric patients to determine if it can be used to maintain SpO2 for a significant length of time. For safety purposes, all trials will be done on patients whose tracheae have been intubated.

OBJECTIVE To determine if a gentle chest pressure technique can be used to maintain SpO2 over 90% significantly longer than allowing SpO2 to desaturate spontaneously.

HYPOTHESIS Gentle chest pressure can maintain SpO2 over 90% for significantly longer than if tissues are allowed to desaturate spontaneously.