Anaes · Volatile & inhalational agents

Isoflurane

Also known as 1-chloro-2,2,2-trifluoroethyl difluoromethyl ether · Fluorinated methyl ether · Forane · Maintenance volatile agent · The workhorse volatile · Pungent volatile

Isoflurane is a fluorinated methyl ether and one of the three modern volatile anaesthetic agents, the stable and cheap workhorse volatile used for maintenance where its pungency makes it unsuitable for inhalational induction. The framework rests on four exam-critical ideas: a blood-gas partition coefficient of 1.4 (higher than sevoflurane 0.65 and desflurane 0.42) means a slower induction and recovery than the insoluble agents; a minimum alveolar concentration of about 1.15 percent in adults measures a potency intermediate between halothane and sevoflurane; it is the least metabolised of the volatiles at about 0.2 percent, with no compound A and negligible fluoride release; and it is a potent vasodilator and the historical subject of the coronary-steal debate, now judged clinically insignificant in well-managed coronary disease. Built on the isoflurane-ICU-sedation-in-children work (Biedermann 2026), the inhaled-anaesthetics-and-Alzheimer's review (Yang 2026), the anaesthetics-and-glial-cells review (Wang 2026), the anaesthetic-gas-emissions analysis (Dogar 2026), the isoflurane-versus-desflurane optic-nerve study (Rajmohan 2026), the CPB-EEG-burst-suppression study (Bao 2026), the TAP-block-isoflurane study (Guadix-Urena 2026), and the desflurane-versus-propofol elderly neurocognitive trial (Somnuke 2026).

high8 referencesUpdated 26 July 20267 min readVerification in progress

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Red flags

Isoflurane IS a trigger of malignant hyperthermia — like every volatile agent, it must never be given to the known or suspected MH-susceptible patient; use a total intravenous technique with a vapour-free machine.Isoflurane is pungent and airway-irritant — it provokes coughing, breath-holding and laryngospasm in the awake patient and is NOT suitable for inhalational induction. Induction must be intravenous; isoflurane is a maintenance agent only.Isoflurane is a potent vasodilator that reduces systemic vascular resistance and mean arterial pressure; in hypovolaemia or shock the fall in blood pressure is exaggerated and the effective potency rises — titrate down or choose an intravenous technique.Isoflurane is a coronary vasodilator and was historically avoided in severe coronary disease for fear of coronary steal; the modern consensus is that steal is clinically insignificant in well-managed patients, but the concern is still examined and the haemodynamics must be controlled.Prolonged exposure in the developing brain produces neurotoxicity and apoptosis in preclinical models, and postoperative cognitive dysfunction in the elderly is debated; avoid prolonged high-dose exposure where alternatives exist, especially in neonates.Isoflurane is a greenhouse gas with a measurable global-warming potential and atmospheric lifetime; theatre scavenging is mandatory and the agent should be used at low fresh-gas flows to reduce both emissions and cost.

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A 65-year-old man with three-vessel coronary disease comes for major abdominal surgery. A junior suggests avoiding isoflurane "because of coronary steal". The consultant keeps isoflurane and explains that the steal concern is historical — provided the blood pressure and diastolic coronary perfusion are held, isoflurane is safe in coronary disease, and it may even precondition the myocardium.[1]

The two questions that frame isoflurane are: why is it maintenance only? (it is pungent) and is the steal real? (no, not in well-managed disease). Hold those, and the vasodilation, the preconditioning and the kinetics all follow.[1]

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[1]Biedermann R, et al. Isoflurane for difficult sedation in critically ill children: a retrospective analysis in a mixed pediatric intensive care population Front Pediatr, 2026.PMID 42290746
[2]Yang L, et al. Inhaled General Anesthetics in Alzheimer's Disease Progression: Divergent Effects, Underlying Mechanisms, and Future Perspectives Mol Neurobiol, 2026.PMID 41915331
[3]Wang X, et al. The dual effects of anesthetics on glial cells: a review of neuroprotection and neurotoxicity Front Pharmacol, 2026.PMID 41669683
[4]Dogar SA, et al. Anaesthetic gas emissions in a tertiary hospital in Pakistan: Behavioural drivers versus technological solutions J Clim Chang Health, 2026.PMID 42292653
[5]Rajmohan N, et al. Comparison of the effects of isoflurane and desflurane on the optic nerve sheath diameter in elderly patients undergoing robotic-assisted laparoscopic radical prostatectomies in steep Trendelenburg position - A randomised controlled trial J Minim Access Surg, 2026.PMID 42085065
[6]Bao H, et al. A Systematic Review of How Cardiopulmonary Bypass Parameters Influence Electroencephalogram Signals Brain Sci, 2026.PMID 42041820
[7]Guadix-Ureña Z, Aprea F, Domínguez JM, et al. Analgesic efficacy of an ultrasound-guided three-points transversus abdominis plane (TAP) block in bitches undergoing laparoscopic ovariectomy Vet J, 2026.PMID 42248237
[8]Somnuke P, et al. Effect of desflurane versus propofol on perioperative neurocognitive disorders in older adults undergoing major urological surgery: a randomized trial BMC Geriatr, 2026.PMID 42321629

Isoflurane

Also known as 1-chloro-2,2,2-trifluoroethyl difluoromethyl ether · Fluorinated methyl ether · Forane · Maintenance volatile agent · The workhorse volatile · Pungent volatile

high8 referencesUpdated 26 July 20267 min readVerification in progress

Practise this topic

8 MCQs

Meet the patient

Anaesthesia Pro

You have read the opening of this topic. The complete unit — every section and its primary-source references — is part of the Anaesthesia fellowship atlas.

References8Show ledger

[1]Biedermann R, et al. Isoflurane for difficult sedation in critically ill children: a retrospective analysis in a mixed pediatric intensive care population Front Pediatr, 2026.PMID 42290746
[2]Yang L, et al. Inhaled General Anesthetics in Alzheimer's Disease Progression: Divergent Effects, Underlying Mechanisms, and Future Perspectives Mol Neurobiol, 2026.PMID 41915331
[3]Wang X, et al. The dual effects of anesthetics on glial cells: a review of neuroprotection and neurotoxicity Front Pharmacol, 2026.PMID 41669683
[4]Dogar SA, et al. Anaesthetic gas emissions in a tertiary hospital in Pakistan: Behavioural drivers versus technological solutions J Clim Chang Health, 2026.PMID 42292653
[5]Rajmohan N, et al. Comparison of the effects of isoflurane and desflurane on the optic nerve sheath diameter in elderly patients undergoing robotic-assisted laparoscopic radical prostatectomies in steep Trendelenburg position - A randomised controlled trial J Minim Access Surg, 2026.PMID 42085065
[6]Bao H, et al. A Systematic Review of How Cardiopulmonary Bypass Parameters Influence Electroencephalogram Signals Brain Sci, 2026.PMID 42041820
[7]Guadix-Ureña Z, Aprea F, Domínguez JM, et al. Analgesic efficacy of an ultrasound-guided three-points transversus abdominis plane (TAP) block in bitches undergoing laparoscopic ovariectomy Vet J, 2026.PMID 42248237
[8]Somnuke P, et al. Effect of desflurane versus propofol on perioperative neurocognitive disorders in older adults undergoing major urological surgery: a randomized trial BMC Geriatr, 2026.PMID 42321629