Clonidine decreases intraoperative bleeding in middle ear microsurgery

Background: The antihypertensive drug clonidine is a centrally acting alpha (2) agonist useful as a premedicant because of its sedative, anxiolytic, a nd analgesic properties. We examined the effect of clonidine given as an or al preanesthetic medication in producing a bloodless surgical field in pati ents undergoing middle ear microsurgery. We also evaluated whether the admi nistration of clonidine would alter the reflex cardiovascular response to l aryngoscopy and endotracheal intubation, anesthetic requirement, postoperat ive pain intensity and consumption of analgesics, and pre- and postoperativ e sedation and anxiety. Methods: A prospective, randomized, double-blind clinical trial was perform ed in 40 patients scheduled for elective middle ear surgery under general a nesthesia. Twenty-one patients received clonidine (300 mug p.o.) 90 min pri or to arrival at the operating theater and 19 received placebo (control gro up). The hemodynamic endpoint of the anesthetic management was maintenance of hypotension for producing a bloodless surgical field. The desired contro l of the cardiovascular system was attained with isoflurane (inspired conce ntration increments of 0.25 vol% up to a maximum of 1.5 vol%)+/- fentanyl ( bolus of 1 mug . kg(-1))+/- urapidil (bolus of 0.3 mg . kg(-1)) as needed. Intraoperative bleeding was assessed on a four-point scale from 0=no bleedi ng to 3=abundant bleeding. Results: There was less bleeding in the clonidine group (mean +/- SEM) than in the control group (0.75 +/-0.3 vs 1.1 +/-0.3 P <0.05). Patients given c lonidine required a mean inspired isoflurane concentration of 0.63 +/-0.1 v ol% as compared with 1.01 +/-0.2 vol% in controls (P <0.05). Fentanyl requi rements were also significantly lower (57.10 vs 79.42 mug . kg(-1), P <0.05 ). Four clonidine-treated patients required urapidil to achieve satisfactor y hypotension as compared with 11 controls (P <0.05). Clonidine attenuated the associated cardiovascular response following laryngoscopy and intubatio n, and was more effective than placebo in achieving a satisfactory preopera tive sedation and decreasing intensity of postoperative pain. Preoperative anxiety and incidence of adverse events was similar in both soups. Conclusion: Premedication with clonidine reduced bleeding in middle ear mic rosurgery, attenuated hyperdynamic response to tracheal intubation, and red uced isoflurane, fentanyl, and urapidil requirements for controlled hypoten sion.