Dexmedetomidine attenuates the increase of ultrasonographic optic nerve sheath diameter as a surrogate for intracranial pressure in patients undergoing robot-assisted laparoscopic prostatectomy: A randomized double-blind controlled trial

BACKGROUND: Pneumoperitoneum and steep Trendelenburg position during robot-assisted laparoscopic prostatectomy (RALP) can increase intracranial pressure (ICP). Dexmedetomidine, a highly selective alpha-2 adrenergic receptor agonist, can cause cerebral vasoconstriction and decrease cerebral blood flow by stimulating the postsynaptic alpha-2 adrenergic receptors on cerebral blood vessels. However, the effects of dexmedetomidine on ICP are controversial and have not been evaluated during RALP under the establishment of pneumoperitoneum in the steep Trendelenburg position. Therefore, we evaluated the effect of dexmedetomidine on optic nerve sheath diameter (ONSD) as a surrogate for assessing ICP during RALP. METHODS: Patients were randomly allocated to receive dexmedetomidine (n = 63) (loading dose, 1 μg/kg for 10 minutes and continuous infusion, 0.4 μg/kg/hr) or normal saline (n = 63). The ONSD was measured at 10 minutes after induction of anesthesia in the supine position (T1), 30 minutes (T2) and 60 minutes (T3) after establishment of pneumoperitoneum in the steep Trendelenburg position, and at closing the skin in the supine position (T4). Hemodynamic and respiratory variables were measured at every time point. RESULTS: ONSDs at T2, T3, and T4 were significantly smaller in the dexmedetomidine group than in the control group (5.26 ± 0.25 mm vs 5.71 ± 0.26 mm, 5.29 ± 0.24 mm vs 5.81 ± 0.23 mm, and 4.97 ± 0.24 mm vs 5.15 ± 0.28 mm, all P <.001). ONSDs at T2, T3, and T4 were significantly increased compared to T1 in both groups. Hemodynamic and respiratory variables, except heart rate, did not significantly differ between the 2 groups. The bradycardia and atropine administration were not significantly different between the 2 groups. CONCLUSION: Dexmedetomidine attenuates the increase of ONSD during RALP, suggesting that intraoperative dexmedetomidine administration may effectively attenuate the ICP increase during pneumoperitoneum in the Trendelenburg position.