Comparison of the Effect of Low-dose and Standard-dose Dexmedetomidine Infusion on Neurological Outcomes in Patients With Aneurysmal Subarachnoid Hemorrhage Undergoing Aneurysmal Neck Clipping: a Randomized Controlled Trial

BACKGROUND: Recent studies have shown a potential neuroprotective role of dexmedetomidine in subarachnoid hemorrhage. However, its effect on neurological outcomes and optimal dosing regimen remains unclear. METHODS: We randomized 75 adults with good grade aneurysmal subarachnoid hemorrhage undergoing clipping to receive dexmedetomidine, low-dose (Group D1,0.2 μg kg -1 h -1 , n = 25), standard dose (Group D2, 0.5 μg kg -1 h -1 , n = 25), or normal saline (Group C, n = 25) commenced postinduction of anesthesia and continued for 24 hours. Our primary objective was to assess rates of good functional outcome, defined as a modified Rankin Scale (mRS) Score of 0 to 2, at hospital discharge. Secondary outcomes included rates of good functional outcome at 3 months, levels of blood lactate, S100β, and Neuron Specific Enolase (NSE), incidence of vasospasm, delayed cerebral ischemia (DCI), and cerebral dysautoregulation. RESULTS: Neurological outcome at discharge was better in Group D1 as compared to Group C (mRS 0 to 2, Group D1 vs. C; 19 (76%) vs. 9 (36%), P = 0.02), while it was similar in Group D2 as compared to D1 and C. Neurological outcome at 3 months was comparable among the 3 groups. The lactate levels were significantly lower in Group D1 as compared to Groups D2 and C at 12 and 24 hours. The levels of NSE and S100β were significantly lower in D1 and D2 as compared to Group C. Other measured parameters were comparable. CONCLUSION: Low-dose dexmedetomidine was associated with a favourable neurological outcome at discharge compared to the control group. Larger trials are necessary to conclusively establish the neuroprotective effect of dexmedetomidine.