Admission ASIA motor score predicting the need for tracheostomy after cervical spinal cord injury.

BACKGROUND

Respiratory compromise and the need for tracheostomy are common after cervical spinal cord injury (cSCI). The purpose of the study was to evaluate if admission American Spinal Injury Association (ASIA) motor score is associated with the need for tracheostomy following cSCI.

METHODS

The trauma registry identified patients with isolated cSCI during a 3-year period. Patients with an Abbreviated Injury Scale score greater than 3 in other body regions were excluded. Medical records were reviewed for demographics, admission ASIA motor score, ASIA Impairment Scale (AIS), anatomic level of injury, need for a tracheostomy, and length of stay (LOS). Logistic regression models were constructed to examine the effect of admission ASIA motor scores on the outcome of tracheostomy. Cox proportional hazards models were fit to determine risk factors for time to tracheostomy.

RESULTS

A total of 128 patients were identified. Seventy-four patients had a tracheostomy performed on mean (SD) hospital Day 9 (4). Median admission ASIA motor score was 22.0 (interquartile range [IQR], 8-54). Median anatomic level of injury was 5 (IQR, 4-6). Patients requiring tracheostomy had significantly lower median admission ASIA motor score (9 [IQR, 3-17] vs. 57 [IQR, 30-77], p < 0.001) and were more likely to be an AIS A. There was no difference in median anatomic level of injury (5 [IQR, 4-5.8] vs. 5 [IQR, 4-6], p = nonsignificant). ASIA motor scores less than 10 had an unadjusted odds ratio for requiring tracheostomy of 56 (95 confidence interval, 7-426). Following adjustment for independent risk factors, the odds ratio for ASIA motor score less than 10 remained statistically significant at 22 (confidence interval, 3-180). Among patients with incomplete cSCI, ASIA motor scores increased significantly from AIS B to AIS D, while Injury Severity Score (ISS), LOS and intensive care unit LOS declined significantly. Of those patients without a tracheostomy, 100% had an ASIA motor score greater than 10, 98% had an ASIA motor score greater than 20, and 86% had an ASIA motor score greater than 25. Among patients with an ASIA motor score less than 10, 100% had a tracheostomy; among patients with an ASIA motor score less than 20, 96% had a tracheostomy. Among patients with a tracheostomy, 91% were an AIS B or C, while 85% of patients classified as AIS D did not have a tracheostomy.

CONCLUSION

Tracheostomy after cSCI is common. Lower admission ASIA motor score and "complete" cSCI are significantly associated with the need for tracheostomy. Anatomic level of injury was not associated with tracheostomy after cSCI. Classification of incomplete patients by AIS indicates that ASIA motor score may be used as a surrogate for grade of injury. When looking only at patients with an "incomplete" cSCI, those with an admission ASIA score of less than 10 should have an early tracheostomy. Those with an AIS D scale should not be considered for early tracheostomy.

LEVEL OF EVIDENCE

Therapeutic/care management, level II.