Respiratory muscle activity and weaning from mechanical ventilation after spinal trauma: the ACCESSIT study.

RATIONALE: Spinal trauma, especially when associated with spinal cord injury (SCI), can impair respiratory muscle function and complicate early weaning from mechanical ventilation (MV).

OBJECTIVES

In patients admitted for spinal trauma requiring MV, to prospectively assess and monitor the coordination, structure, and activity of non-invasively accessible respiratory muscles, in relation to weaning outcomes up to the first weaning attempt.

METHODS

We enrolled adult patients with traumatic spine injury, requiring MV in the trauma-neuro intensive care unit (ICU) at St. Micheal's Hospital in Toronto. Rib cage-abdomen synchrony was assessed with respiratory inductive plethysmography, while respiratory muscle thickness and activity were measured with ultrasound and surface electromyography. Patients not expected to survive the first 48 hours were not included. The relationship between muscle parameters and weaning outcome was assessed through logistic regression and time dependent Cox proportional hazards models.

RESULTS

We enrolled 30 trauma patients: 67% male, median age 48 (35-64); half had confirmed SCI. Four (13.3%) died in ICU and 18 (60%) were weaned at first attempt, with no difference between SCI and non-SCI. Konno-Mead plots suggested strong association between paradoxical breathing and early weaning failure, with larger total and inspiratory loop area (normalized to tidal volume) in patients who failed weaning (area under the curve = 0.95 [95% confidence interval [CI] 0.80-1.00]), regardless of the SCI status. Paradoxical inward rib cage movement was observed in 70% of failure patients versus 27% in success, P = 0.05. Failure patients had progressive reduced internal oblique thickness (4.0 ± 0.7 vs 5.2 ± 1.3 mm, P = 0.03) and increased parasternal intercostal thickness (3.2 ± 1.2 vs. 2.3 ± 0.6 mm, P = 0.07), both being associated with probability of early weaning failure (OR = 0.88 and OR = 1.16, respectively).

CONCLUSIONS

Paradoxical breathing, inward thoracic inspiratory motion and changes in respiratory muscle thickness characterize early weaning failure after spinal trauma, independently of SCI presence.

CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT05207046.