Comparison of Low and High Tidal Volumes in Acute Spinal Cord Injury

Background: Respiratory complications associated with mechanical ventilation (MV) are the leading cause of morbidity and mortality following acute spinal cord injury (SCI). Emerging evidence suggests pneumonia is also associated with reduced neurologic recovery. Therefore, pneumonia prevention is of primary importance to improve outcomes. In the non-SCI population, MV with lower tidal volume (Vt) has been shown to reduce inflammation and rates of pneumonia. High Vt MV results in disruption of pulmonary endothelium and release of inflammatory mediators, which play a role in the development of pulmonary complications. In contrast, guidelines for SCI practitioners recommend MV with higher Vt without strong evidence. Objective: The primary objective of this study is to evaluate the feasibility of conducting a randomized control trial comparing MV with high vs. low Vt. Secondary objectives include a comparison of clinical outcomes and inflammatory mediators between these groups. Methods: Study population: Adults with acute traumatic SCI admitted to an acute inpatient rehabilitation facility on MV. Subjects will be randomized to receive either a lower Vt of 8-10 cc/kg predicted body weight (pbw) or a high Vt of 14-16 ml/kg pbw. Study participants will be randomly assigned to high tidal volume (14-16 ml/kg pbw) or low tidal volume of 8 to 10 ml/kg pbw within 48 hrs of admission, stratified based on vital capacity at admission to ensure equal allocation of those with most severe respiratory impairment and unlikely to wean from the vent. Importance of knowledge gained from the study: Investigators believe the completion of this study will add to the fund of knowledge of respiratory management of people with SCI, especially at the early stages of the injury, including reducing respiratory complications in people with SCI who are at very high risk of severe respiratory complications which is the main cause of morbidity and mortality in this population.