Comparison of two different doses of dexmedetomidine on attenuation of optic nerve sheath diameter changes during laparoscopic cholecystectomy: An interventional prospective single-centred study

Introduction Laparoscopic cholecystectomy requires carbon dioxide pneumoperitoneum and changes in patient positioning, both of which can pathologically increase intracranial pressure (ICP). Measurement of the optic nerve sheath diameter (ONSD) by ultrasonography is a well-established, non-invasive method to monitor ICP. This study investigated how dexmedetomidine, administered at different doses, affects the extent of ONSD increase and stabilizes hemodynamic parameters during the surgery. Methods In this interventional prospective single-centred study, 75 ASA I/II patients were divided consecutively into three groups (n=25 each): Group NS received normal saline, Group D-0.3 received dexmedetomidine at 0.3 µg/kg/hr, and Group D-0.6 received dexmedetomidine at 0.6 µg/kg/hr. The primary endpoint was the observed ONSD values, assessed via ultrasonography at baseline (T0), 10 and 30 minutes after pneumoperitoneum initiation (T1 and T2), and 10 minutes after exsufflation (T3). Secondary outcomes assessed perioperative hemodynamic stability and sedation levels. Results Baseline demographics were similar across groups (P > 0.05). Group D-0.6 demonstrated significantly smaller ONSD values (4.67 ± 0.34, 4.59 ± 0.38 and 4.80 ± 0.30) at T1, T2, and T3 compared to Groups D-0.3 (5.74 ± 0.30, 6.12 ± 0.32 and 5.16 ± 0.33) and NS (5.66 ± 0.50, 6.20 ± 0.51 and 5.05 ± 0.42) (P < 0.005), with the greatest reduction observed at T2. Dexmedetomidine produced a dose-dependent decrease in heart rate and systolic blood pressure during periods of maximal surgical stress (P < 0.05), while maintaining stable mean arterial pressure and diastolic blood pressure. No episodes of bradycardia, hypotension and excessive sedation were recorded in any of 75 patients. Conclusion Dexmedetomidine effectively attenuated the laproscopy-induced increase in ONSD, a non-invasive surrogate of ICP, in a dose dependent manner, with an infusion rate of 0.6 µg/kg/hr showing a greater effect than 0.3 µg/kg/hr and preserved perioperative hemodynamic stability.