[Premedication with clonidine in the neurosurgical patient: sedation, anesthetic requirements and hemodynamic perfusion]

Abstract

Objectives: To analyze the effect of premedication with clonidine on postoperative sedation, anesthetic requirements and hemodynamic repercussions in patients undergoing craniotomy due to supratentorial intracranial pathology.

Patients and methods: Twenty ASA I/II patients in a double-blind prospective study were assigned randomly to receive lorazepam (0.03 mg/kg/po, n = 10) or clonidine (0.005 mg/kg/po, n = 10) the night before and 90 minutes before surgery. Arterial pressure and heart rate were monitored continuously during and immediately after surgery (first 24 hours). Anesthetic induction was achieved with thiopental (maximum 6 mg/kg) and maintained with O2/N2O and an infusion of alfentanyl (1 microgram/kg/min). Hemodynamic response to surgical stimulus was treated with additional boluses of alfentanyl up to a maximum dose of 0.1 mg/kg and with an increase in infusion dosage to 2 micrograms/kg/min. When these were ineffective, isoflurane was given. All patients were extubated in the operating room.

Results: No differences in level of sedation were found between the two groups. The infusion dose and total amount of alfentanyl given were smaller for patients treated with clonidine (0.8 +/- 0.04 vs 0.6 +/- 0.01 microgram/kg/min and 22.4 +/- 5.3 vs 17.5 +/- 4.9 mg, respectively) (p < 0.05). No differences were found in isoflurane requirements (5/5 vs 2/8). Mean arterial pressure and heart rate were lower with clonidine from 3 minutes after intubation until the patient's arrival in the recovery room (p < 0.05), with marked bradycardia (49 +/- 5 vs 73 +/- 7 bpm) (p < 0.05) upon intubation.

Conclusions: Premedication of neurosurgical patients with clonidine offers no advantages over lorazepam with respect to sedation. Nevertheless, clonidine may offer advantages with respect to the amount of alfentanyl required and attenuation of perioperative adrenergic response.