JOURNAL HOME CME HOME THIS MONTH PAST ISSUES ETOC COLLECTIONS AUTHORS REVIEWERS EDITORIAL BOARD FEEDBACK RSS HELP
		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Zalunardo, M. P. Articles by Pasch, T. Search for Related Content PubMed PubMed Citation Articles by Zalunardo, M. P. Articles by Pasch, T. Related Collections Pharmacology

---

ANESTHETIC PHARMACOLOGY

Preoperative Clonidine Blunts Hyperadrenergic and Hyperdynamic Responses to Prolonged Tourniquet Pressure During General Anesthesia

Marco P. Zalunardo, MD^*, Daniel Serafino, MD^*, Patricia Szelloe, MD^*, Fabia Weisser, MD^*, Andreas Zollinger, MD, Burkhardt Seifert, PhD, and Thomas Pasch, MD^*

*Institute of Anesthesiology, University Hospital, Zürich, Switzerland; Institute of Anesthesiology, Triemli City Hospital, Zürich, Switzerland; Department of Biostatistics, University of Zürich, Zürich, Switzerland

Address correspondence and reprint requests to Marco P. Zalunardo, MD, Institute of Anesthesiology, University Hospital Zürich, Rämistrasse 100, CH - 8091 Zürich, Switzerland. Address e-mail to marco.zalunardo{at}ifa.usz.ch

Although the mechanism of tourniquet-induced hypertension is still unclear, plasma norepinephrine concentrations continuously increase in parallel to arterial blood pressure during tourniquet inflation. Clonidine attenuates hyperadrenergic and hyperdynamic responses. We investigated the effects of clonidine on prolonged tourniquet inflation. Twenty-nine patients scheduled for elective orthopedic surgery were randomly assigned to receive IV clonidine (3 µg/kg; n = 14) or placebo (n = 15) before tourniquet inflation of the lower limbs under general anesthesia in a double-blinded manner. Arterial blood pressure, heart rate, epinephrine, and norepinephrine plasma concentrations were measured before tourniquet inflation, 60 min after tourniquet inflation, just before tourniquet deflation, and 20 min after tourniquet deflation. Mean arterial blood pressure and norepinephrine plasma-concentrations were significantly lower in the Clonidine group compared with Control after 60 min tourniquet inflation (P = 0.016; P = 0.006). Immediately before deflation of the tourniquet, the difference for mean arterial pressure between groups was even more pronounced (P = 0.005). Twenty minutes after deflation mean arterial blood pressure in the Control group was still increased and significantly higher compared with the Clonidine group (P = 0.002). In conclusion, preoperative IV clonidine blunts hyperadrenergic and hyperdynamic responses resulting from prolonged tourniquet inflation under general anesthesia in ASA class I–II patients.

IMPLICATIONS: Tourniquet inflation is associated with a continuous increase in arterial blood pressure and sympathetic outflow. This study shows that IV clonidine effectively blunts increases of both arterial blood pressure and plasma norepinephrine concentrations.

Anesthesia & Analgesia® is published for the International Anesthesia Research Society® by Lippincott Williams & Wilkins with the assistance of Stanford University Libraries' HighWire Press®. Copyright 2006 by the International Anesthesia Research Society. Online ISSN: 1526-7598   Print ISSN: 0003-2999