Isoflurane Dosage

Applies to the following strengths: 100%

Usual Adult Dose for Anesthesia

Premedication should be selected on an individual basis, considering that secretions are weakly stimulated by this drug and the heart rate is usually increased. Anticholinergic drugs may be needed.

Induction with this drug in oxygen or in combination with oxygen-nitrous oxide mixtures may produce coughing, breath holding, or laryngospasm. These may be avoided by using a hypnotic dose of an ultra-short-acting barbiturate. Inspired concentrations of 1.5% to 3% isoflurane usually produce surgical anesthesia in 7 to 10 minutes.

Maintenance: Surgical levels of anesthesia may be sustained with a 1% to 2.5% concentration when nitrous oxide is used concomitantly. An additional 0.5% to 1% may be required when this drug is given using oxygen alone. If added relaxation is required, supplemental doses of muscle relaxants may be used.

Comments: See the product information and consult local protocol for further information.

Use: For induction and maintenance of general anesthesia (adequate data have not been developed to establish its application in obstetrical anesthesia)

Usual Pediatric Dose for Anesthesia

Renal Dose Adjustments

Data not available

Liver Dose Adjustments

Data not available

Dose Adjustments

The level of blood pressure during maintenance is an inverse function of isoflurane concentration in the absence of other complicating problems. Excessive decreases may be due to depth of anesthesia and in such instances may be corrected by lightening anesthesia.

Precautions

CONTRAINDICATIONS:

Hypersensitivity to the active component or any of the ingredients
Hypersensitivity to other halogenated agents.
Known or suspected genetic susceptibility to malignant hyperthermia

Consult WARNINGS section for additional precautions.

Dialysis

Data not available

Other Comments

Inspired Concentration: The concentration of isoflurane being delivered from a vaporizer during anesthesia should be known. This may be accomplished by using either vaporizers calibrated specifically for isoflurane or vaporizers from which delivered flows can be calculated, such as vaporizers delivering a saturated vapor, which is then diluted.

The delivered concentration from vaporizers not specifically calibrated for isoflurane, but from which delivered flows can be calculated, may be calculated using the formula:
% isoflurane = 100 PvFv/FT (PA - PV)
Where PA = Pressure of Atmosphere
PV = Vapor Pressure of isoflurane
FV = Flow of gas through vaporizer (mL/min)
FT = Total gas flow (mL/min)

Isoflurane contains no stabilizer. Nothing in the agent alters calibration or operation of these vaporizers.

General:

This drug should only be administered by an anesthetist.
Since the depth of an anesthesia can change rapidly, only vaporizers that have been specially calibrated for this product should be used.
The extent of blood pressure reduction and respiratory depression can be an indication of the extent or depth of anesthesia; decreases may respond to reducing the inspired concentration of isoflurane.
Spontaneous respiration should be continuously monitored and assisted if necessary.
With the use of halogenated anesthetics, disruption of the liver function, icterus, and fatal liver necrosis have been reported. Such reactions appear to indicate hypersensitivity. Cirrhosis, viral hepatitis, or other preexisting liver disease can be a reason not to select a halogenated anesthetic.

Patient advice:

This drug may cause a slight decrease in intellectual function for 2 or 3 days following anesthesia. Changes in mood may persist for up to 6 days after administration.