Clonidine premedication: a useful adjunct in producing deliberate hypotension

Area of Science:

• Anesthesiology
• Pharmacology

Background:

• Deliberate hypotension is used in surgery to reduce blood loss and improve visualization.
• Labetalol and isoflurane are commonly used anesthetic agents for inducing hypotension.

Purpose of the Study:

• To investigate the effect of clonidine premedication on the dosage requirements of labetalol and isoflurane for achieving deliberate hypotension.
• To assess the impact of clonidine on hemodynamic parameters and urine flow during middle-ear surgery.

Main Methods:

• A randomized study involving 20 adult patients undergoing middle-ear surgery.
• Group I received pethidine premedication; Group II received pethidine plus oral clonidine.
• Anesthesia maintained with fentanyl and d-tubocurarine, with labetalol and isoflurane used for hypotension.

Main Results:

• Group II (clonidine) required significantly lower doses of labetalol (0.56 mg.kg-1 vs. 0.85 mg.kg-1) and lower isoflurane concentrations (0.6 vol% vs. 0.8 vol%) to achieve target hypotension.
• Mean arterial pressure and heart rate were similar between groups during hypotension, though initial MAP decreased in the clonidine group.
• Urine flow rates were significantly lower in the clonidine group both before and during hypotension.

Conclusions:

• Clonidine premedication effectively reduces the dose requirements for labetalol and isoflurane in patients undergoing middle-ear surgery requiring deliberate hypotension.
• Clonidine may offer an advantage in lowering anesthetic agent consumption during hypotensive anesthesia.