Isoflurane

Decrease in blood pressure is dose dependent due to peripheral vasodilation; cardiac output is maintained. Use caution in patients who are hypovolemic, hypotensive, or hemodynamically compromised; use caution in patients with coronary artery disease to avoid risk of myocardial ischemia. May prolong the QT interval and rarely torsades de pointes; use caution in patients at risk of QT prolongation. May produce cardiac steal (due to coronary vasodilation) and reflex tachycardia, but does not depress cardiac conduction nor does it sensitize the myocardium to catecholamine-induced arrhythmias like halothane (not available in the United States) (Golembiewski 2004).

May cause decrease in hepatic, renal, and splenic blood flow (Gelman 1984).

Postoperative mild to severe hepatic dysfunction (some fatal) and hepatitis have been reported; may cause sensitivity hepatitis in patients who have been sensitized by previous exposure to halogenated anesthetics.

Use of inhaled anesthetics has been associated with rare cases of perioperative hyperkalemia that have resulted in cardiac arrhythmias (including fatalities) in pediatric patients; concomitant use of succinylcholine was associated with many of the reported cases, but not all. Risk of hyperkalemia is increased in pediatric patients with underlying neuromuscular disease (eg, Duchenne muscular dystrophy). Other abnormalities may include elevation in creatinine kinase (CK) and myoglobinuria. Monitor closely for hyperkalemic-associated arrhythmias; aggressively identify and treat.

Dilates the cerebral vasculature and may, in certain conditions, increase intracranial pressure.

May trigger malignant hyperthermia; use is contraindicated in patients susceptible to malignant hyperthermia.

Increased blood loss comparable with that seen with halothane has been reported during abortions.

Causes dose-dependent respiratory depression and blunted ventilatory response to hypoxia and hypercapnia (Golembiewski 2004). Disease-related concerns:

In a scientific statement from the American Heart Association, isoflurane has been determined to be an agent that may exacerbate underlying myocardial dysfunction (magnitude: major) (AHA [Page 2016]). Concurrent drug therapy issues:

Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information. Special populations:

In pediatric and neonatal patients Special handling:

There is no specific work exposure limit established for isoflurane. However, the National Institute for Occupational Safety and Health (NIOSH) recommends no worker be exposed to >2 ppm (ceiling concentrations) over a period of 1 hour. Precautions (eg, adequate ventilation, scavenging-systems, minimizing leaks/spills) can help to lessen any potential risk. Other warnings/precautions:

Reaction of isoflurane with desiccated CO2 absorbents produce carbon monoxide, which may result in elevated carboxyhemoglobin levels in some patients.