General Anesthesia Induction: inspired concentrations of 1.5–3% isoflurane usually produce surgical anesthesia in 7–10 minutes. Maintenance: surgical levels of anesthesia may be sustained with a 1–2.5% concentration when nitrous oxide is used concomitantly. An additional 0.5–1% may be required when isoflurane is given using oxygen alone. If added relaxation is required, supplemental doses of muscle relaxants may be used.
Isoflurane induces a reduction in junctional conductance by decreasing gap junction channel opening times and increasing gap junction channel closing times. Isoflurane also activates calcium dependent ATPase in the sarcoplasmic reticulum by increasing the fluidity of the lipid membrane. Also appears to bind the D subunit of ATP synthase and NADH dehydogenase. Isoflurane also binds to the GABA receptor, the large conductance Ca2+ activated potassium channel, the glutamate receptor and the glycine receptor.
Susceptibility to malignant hyperthermia. Patients in whom general anesthesia is contraindicated.Precaution: Monitor for perioperative hyperkalemia esp. in pediatric patients during post-op period and those with latent or overt neuromuscular disease (eg, Duchenne muscular dystrophy); cardiac arrhythmias and death may occur.
Caution with desiccated CO2 absorbents; replace before administration. Hyperkalemia with succinylcholine. Potentiates effects of muscle relaxants, esp. nondepolarizing muscle relaxants. MAC reduced by concomitant nitrous oxide.