Clonidine, a centrally-acting antihypertensive agent known to reduce central sympathetic outflow and modulate presynaptic transmitters' release, has shown to suppress central noradrenergic hyperactivity induced by immobilization stress in
animals,
by
decreasing the MAC of halothane and the dose of narcotics required to prevent reflex cardiovascular response to noxious stimuli, and to have potent analgesic properties in humans. These characteristics suggest that clonidine might be a useful
adjunct to
the anesthetic management of patients with preexisting hypertension.
Accordingly, we determined the clinical efficacy and safety on analgesia, sedation and hemodynamic stability in the perioperative period.
Thirty patients (ASA physical status II-III) with a history of arterial hypertension, scheduled for elective orthopedic surgery were randomly assigned to two groups. We applied CPA-clonidine patch (6.9 mg/㎠, 0.2 mg delivered daily) or placebo
patch to
each groups, 48 hours prior to induction of anesthesia. Antihypertensive medication was continued until the morning of the scheduled surgery. All patients received premedication of atropine and lorazepam, and induced anesthesia with thiopental
and
succinylcholine, and maintained with enflurane and 50% nitrous oxide, while sustaining the BP and pulse rate at acceptable range. For the relief of pain postoperatively, diclofenac and fentanyl were administered intramuscularly on demand.
@ES The results were as follows:
@EN 1) The change of hemodynamic responses in clonidine group was less compared to the placebo group.
2) Intraoperative anesthetic requirement for enflurane in clonidine group were significantly lower than placebo group.
3) Postoperative analgetic requirement in clonidine group were significantly lower than placebo group. In clonidine group, 5 cases out of 15 cases were required no analgetics, and the incidence of administration of additional fentanyl was
decreased to
5 cases, comparing with 10 cases in placebo group.
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