Dexmedetomidine versus Lidocaine for Intubation in Traumatic Brain Injury: A Double-Blind Randomized Trial with Post Hoc Equivalence Analysis

Abstract

Background. Laryngoscopy-induced pressure surges and induction-related hypotension threaten the injured brain. Dexmedetomidine and lidocaine blunt the intubation response, but their relative effect in traumatic brain injury (TBI) is uncertain.

Objective. To estimate the difference in the mean arterial pressure (MAP) response to intubation between the two agents and to define, post hoc, the differences excluded.

Methods. In a double-blind randomized trial, 71 adults with TBI received dexmedetomidine 1 µg/kg over 10 min (n = 37) or lidocaine 1.5 mg/kg over 2 min plus an 8-min saline sham (n = 34) before standardized induction; lidocaine ended about 11 min before laryngoscopy. The primary outcome was the change in MAP from baseline to 1 min after intubation. The trial was not registered. Analyses included Welch estimation, post hoc two one-sided tests (TOST), ANCOVA and exact tests.

Results. MAP fell by 11.5 mmHg with lidocaine and 12.8 mmHg with dexmedetomidine; no pressor response occurred. The difference (dexmedetomidine − lidocaine) was −1.30 mmHg (95% CI −4.14 to 1.54; p = 0.365); adjusted, −1.66 mmHg (−4.31 to 1.00). Post hoc, differences beyond ±4 mmHg were excluded (TOST p = 0.031). Heart rate did not differ (Holm p = 1.000). Ephedrine was needed in 3/37 versus 2/34 and atropine in 2/37 versus 1/34 (both p = 1.000).

Conclusion. In adults with predominantly mild-to-moderate TBI, MAP responses to intubation with the two agents differed by about 4 mmHg or less post hoc, with infrequent rescue therapy. Without a placebo arm, neither agent’s own effect can be quantified.