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The relationship between head injury severity and hemodynamic response to tracheal intubation

INTRODUCTION The acutely injured brain is sensitive to fluctuations in blood pressure. During tracheal intubation, airway stimulation provokes acute surges in blood pressure that have the potential to cause further harm in patients with intracranial pathology. Although reduced consciousness is thought to suppress airway reflexes, its influence on these hemodynamic reflexes is unknown. We aimed to investigate the relationship between head injury severity and hemodynamic response to laryngoscopy and intubation. METHODS This retrospective observational study included 97 consecutive patients with head injuries who underwent prehospital tracheal intubation by a physician-led helicopter emergency medical service. The primary outcome was the acute hemodynamic response to the procedure. Secondary outcomes included the incidence of serious intracranial pathology and mortality. RESULTS A hypertensive response to laryngoscopy and tracheal intubation occurred in 80% of patients. In 11% of patients, blood pressure increased by ≥100%. The hemodynamic response was attenuated with increasing head injury severity but unpredictably and not to clinically acceptable levels. The incidence of serious intracranial bleeding (61%) and raised intracranial pressure (22%) was high in patients with head injuries, requiring tracheal intubation. CONCLUSION A clinically significant hemodynamic response to laryngoscopy and intubation is common in patients with head injuries and is not effectively attenuated by increasing head injury severity. The need to attenuate the hemodynamic response should be assessed independently of head injury severity. LEVEL OF EVIDENCE Therapeutic study, level III.