A Review of Spinal Cord Injury Patients Requiring Mechanical Ventilation, 2003-2007

Project Director/Lead Investigator: Mitchell Cohen, MD

Brief Summary of Project: Spinal cord injury (SCI) is common after both blunt and penetrating trauma and often leaves a patient ventilator dependent in the ICU. This is a retrospective medical record review of patients who suffered a spinal cord injury and required mechanical ventilation. Whether these patients have the respiratory ability to warrant an attempt at extubation remains an important unanswered question. We hypothesized that we could identify the level of cord injury and factors associated with successful extubation after spinal cord injury.

Specific Aims:
1. To identify predictors of mechanical ventilation requirements, including factors associated with successful extubation, in patients with SCI.
2. To identify outcomes associated with respiratory ability in patients with SCI.

Studies/Results: We reviewed a total of 80 patients who suffered a spinal cord injury and admitted to the San Francisco General Hospital between 2003-2007. A total of 59 (74%) patients were discharged from the hospital requiring no supplementary ventilatory support. Twenty (25%) patients required a tracheostomy. Four percent of patients expired due to SCI-associated complications. Seventy-six patients (95%) had at least one weaning or extubation attempt. Of these, 46 (61%) were successfully extubated on the first attempt, while 30 (39%) failed at least one weaning or extubation attempt. Only 4 patients (5%) progressed directly to tracheostomy with no attempt at wean or extubation. All patients requiring ventilatory assistance on discharge had cervical spine injury. We compared outcomes of patients who had failed weaning and extubation attempts to those patients who were successfully extubated on the first attempt. Forty-six patients of the 77 surviving to discharge (60%) were successfully weaned and extubated on the first attempt, 18 (23%) patients failed at least one weaning or extubation attempt, and 12 (16%) patients failed multiple attempts. Of patients in whom extubation was attempted, those who extubated successfully on the first attempt had shorter ICU stay (8.5±9.3 vs. 29.9±24.5; p<0.001), more ventilator-free days (22.6±6.7 vs. 8.4±9.7; p<0.001), and shorter hospital stay (26.6±23.9 vs. 45.8±45.8; p=0.009) compared to those patients failing one or more weaning or extubation attempts. Patients failing one or more attempts also had a higher incidence of VAP (83% vs. 15%; p<0.001). Of interest, patients that had one failure still had a 61% chance of subsequent successful extubation at the time of discharge; the successful extubation rate dropped to 17% in patients failing multiple attempts. We observed that patients with an attempted extubation before tracheostomy had similar hospital and ICU stay as well as similar rates of VAP compared with those who underwent tracheostomy empirically. The role and timing of tracheostomy in the mechanically-ventilated SCI patient has not been clearly resolved, with wide variation in clinical practice and few evidence-based guidelines. Our data demonstrate that there is a subset of patients that can be successfully weaned and extubated. This highlights the need for further study to enumerate prospective guidelines to identify those SCI patients who merit trial extubation versus those who may benefit from immediate empiric tracheostomy, and at what time post-injury this is optimally performed.

Significance and Future: Although the clinical challenges of ventilator management in patients with SCI are well appreciated, there are no studies or clear clinical guidelines regarding criteria for weaning and extubation after injury. Specifically, structured protocols for weaning and extubation attempts in SCI patients do not exist, and the role and timing of tracheostomy is unclear.

We reviewed our patient experience with the aim of identifying possible predictors of successful extubation in a spinal cord-injured cohort. Our results showed that more than 40% of cervical SCI patients remained ventilator dependent at discharge or transfer; conversely however, more than 50% of our cervical SCI patients were able to be successfully weaned and extubated, with associated shorter ICU and hospital stays as well as reduced incidence of VAP. We determined a large multicenter trial is required to correctly address these questions, to ascertain specific predictors of successful extubation, and to assemble prospective guidelines to guide performance and timing of tracheostomy.
The manuscript is currently in review at the Journal of Trauma.

We have organized a multicenter trial with the Western Trauma Association to expand our single-center findings. Currently 10 sites have expressed interest in this study and are actively applying for IRB approval to participate in our multicenter trial. We hope to have data collected and analyzed within 12-18 months.