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December 1996
Small, oral dose of clonidine reduces the incidence of intraoperative myocardial ischemia in patients having vascular surgery.
Stuehmeier K-D, Mainzer B, Cierpka J et al;
Anesthesiology 1996;85:706-712.
[ see abstract below ]
The application of drugs with alpha-adrenergic receptor agonist activity, e.g., clonidine, has been long promoted in various clinical contexts--the treatment of pain, and as adjunct therapy in regional and general anesthesia. Although considerable and diverse laboratory and clinical research has been devoted to this topic, only recently are reports beginning to appear in the literature, describing the systematic application of this category of drugs in the clinical practice setting.
This article is an excellent clinical review of the use of clonidine in regional anesthesia over the time frame of 1984-95. They systematically review the pharmacologic principles of related to this drug class, followed by the specific applications of clonidine administration epidurally, intrathecally and peripherally. The article summarizes the doses, predominant effects and safety considerations in a manner of use for the clinician. An extensive bibliography is helpful for the reader interested in details arising from this review.
Return to the Current Literature Review Front Page, or read the abstract:
ABSTRACT
Background: Most new perioperative myocardial ischemic episodes occur in the absence of hypertension or tachycardia. The ability of a 8-adrenoceptor agonists to inhibit central sympathetic outflow may benefit patients with coronary artery disease by increasing the myocardial oxygen supply-and-demand ratio.
Methods: A randomized double-blind study design was used in 297 patients scheduled to have elective vascular surgical procedures to evaluate the effects of 2 ug/kg-1 oral clonidine (n=145) or placebo (n=152) on the incidence of perioperative myocardial ischemic episodes, myocardial infraction, and cardiac death. Continuous real-time S-T segment trend analysis (lead II and V5) was performed during anesthesia and surgery and correlated with arterial blood pressure and heart rate before and during ischemic events. Does requirements for vasoactive and antiischemic drugs to control blood pressure and heart rate as well as episodes of myocardial ischemia (i.e., catecholamines, 8-adrenoceptor antagonists, nitrates, and systemic vasodilators) and fluid volume load were recorded.
Results: Administration of clonidine reduced the incidence of perioperative myocardial ischemic episodes from 39% (59 of 152) to 24% (35 of 145) (P < 0.01). Hemodynamic patterns, percentage of ischemic time, and the number of ischemic episodes per patient did not differ. Nonfatal myocardial infraction developed after operation in four patients receiving placebo compared with none receiving clonidine (day 2 to 21; P = 0.07). The incidence of fatal cardiac events (1 vs. 2) was not different. Dose requirements for vasoactive and antiischemic drugs did not differ between the groups, but the amount of presurgical fluid volume was slightly greater in patients receiving clonidine (951 + 388 vs. 867 + 391 ml; P < 0.03).
Conclusion: A small oral dose of clonidine, given prophylactically, can reduce the incidence of perioperative myocardial ischemic episodes without affecting hemodynamic stability in patients with suspected or documented coronary artery disease.
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