Isoflurane (Forane) mnemonic
ISOFLURANE
Inhalation
Small mood changes for 6 days
Organofluoride compound
Fast onset 7-10 minutes
Low blood solubility
Unique by non-pungent musty ethereal smelling
Relaxes muscles
Anesthetic lasting 15-30 minutes
Nonflammable
Elimination 95% by exhalation
Here are some key points about isoflurane that might help with your board exam review:
Class: Inhalation anesthetic, specifically a halogenated ether.
Pharmacokinetics:
- Delivered as a gas to the lungs, then to the arterial vascular system, and crosses the blood-brain barrier.
- Intermediate solubility and high potency allow for easy regulation of anesthesia depth.
- Metabolized mostly in the liver, with some in the kidneys. Only 0.2% is metabolized, with the rest eliminated through the lungs.
- Rapid induction and emergence, with patients typically awakening within 10 minutes and becoming coherent within 15-30 minutes.
Mechanism of Action:
- Effects: Produces amnesia, skeletal muscle relaxation, and hypnosis. It blocks pain perception and may amplify the effects of inhibitory neurotransmitters like GABA and glycine.
- Receptors: Acts on GABA receptors in the brain (causing loss of consciousness and amnesia) and glycine receptors in the spinal cord (causing immobility). It also antagonizes excitatory NMDA receptors.
Clinical Effects:
- Cardiovascular: Causes a dose-dependent decrease in blood pressure and may increase heart rate. It preserves carotid baroreflexes, allowing compensatory heart rate adjustments.
- Respiratory: Increases respiratory rate but decreases tidal volume, leading to an overall decrease in minute ventilation. It also produces moderate bronchodilation.
- Neuromuscular: Causes progressive skeletal muscle relaxation, enhancing the action of neuromuscular blocking agents.
Additional Points:
- MAC (Minimum Alveolar Concentration): 1.15%.
- Vapor Pressure: 240 mmHg at 20°C2.
- Blood:Gas Partition Coefficient: 1.4, indicating moderate solubility.
- Metabolite: Trifluoroacetic acid, with minimal nephrotoxicity and uncommon hepatotoxicity.
For more anesthesiology mnemonics check this mnemonic book.
This post covers the points you need to know for your board exams as well as for teaching residents on the daily rounds. Medical professionals can't use the information here to treat their patients nor people can use the information her to treat themselves. If you are having any medical issues, contact your local emergency services or your primary care provider. Please refer to your doctor for medical advice.