Control of autonomic dysreflexia in patients with high level of chronic spinal cord injury during cystoscopy

Background Autonomic dysreflexia (AD) is a clinical emergency that frequently occurs in patients with spinal cord injury (SCI) during cystoscopy. It should be treated by removing the stimulus and by medications. We aimed in this study to evaluate the effect of adding magnesium sulfate to dexmedetomidine infusion to control AD in high-level chronic SCI patients during cystoscopy. Patients and methods Forty patients with chronic SCI at the level of T6 or above scheduled for cystoscopy were randomly divided into two groups: the dex group, in which the patients received dexmedetomidine infusion 1 µg/kg for 10 min, followed by 0.5 µg/kg/min; and the Mg group, in which patients received a single i.v. dose of magnesium sulfate 50 mg/kg in addition to the same infusion of dexmedetomidine. Blood pressure (BP) and heart rate (HR) were recorded for each patient, and serum magnesium, epinephrine, and norepinephrine levels were estimated preoperatively, intraoperatively, and postoperatively. Results Results showed a significant elevation in intraoperative BP in the Dex group 10 min after cystoscopy and persisted for 20 min compared with the presedation level in the same group and with the same readings in the Mg group. HR dropped down in the Dex group 15 min after cystoscopy and persisted for 15 min compared with the presedation reading in the same group and with the same readings in the Mg group. Serum magnesium was significantly higher intraoperatively and postoperatively in the Mg group, whereas serum epinephrine and serum norepinephrine were significantly higher intraoperatively and postoperatively in the Dex group compared with the presedation level in the same group and with the same readings in the Mg group. Seven patients (35%) in the Dex group experienced a dysreflexic episode [increase in systolic blood pressure (SBP) 30 mmHg or more compared with the presedation reading]; two of them showed elevation of SBP more than 160 mmHg and needed to be treated. On the other hand, only one patient in the Mg group (5%) experienced a dysreflexic episode (SBP 135 mmHg) with no need for medication. Conclusion Addition of a single i.v. dose of magnesium sulfate to dexmedetomidine infusion provides a better control of BP and HR, and reduces the incidence of AD during cystoscopy in patients with high level of chronic SCI.