Desflurane
Suprane
Fully fluorinated halogenated methyl ethyl ether — volatile general anesthetic
Same multi-site mechanism as sevoflurane: GABA-A + glycine potentiation, NMDA + nicotinic ACh inhibition, K⁺ channel activation.
Indications
- •GA maintenance (favored for fast emergence in obese / outpatient / long cases)
- •Not recommended for inhalational induction (pungency)
Dosing
| Context | Adult | Pediatric |
|---|---|---|
| Maintenance (adult) | 3–8% inspired (1 MAC = 6.0% age 40; declines ~6%/decade) | — |
| Maintenance (pediatric) | 1 MAC age 1–5 y ≈ 8.6%; not used for mask induction (cough/breath-holding/laryngospasm) | — |
Pharmacokinetics
Lowest blood:gas partition coefficient of clinical volatiles: 0.42 (vs sevo 0.65, iso 1.4). Translates to fastest emergence — particularly meaningful in obese patients and long cases. Negligible metabolism (~0.02%) → no fluoride or hepatotoxic intermediate concerns. Vapor pressure 681 mmHg at 20°C (almost atmospheric) requires HEATED, PRESSURIZED Tec 6 vaporizer.
Hemodynamic effects
Dose-dependent ↓SVR + ↓MAP (similar to sevo). UNIQUE: rapid increases in inspired concentration (>6%) cause sympathetic stimulation → HR + BP spike (mediated by airway irritation activating tracheo-bronchial receptors). Mitigate by gradual increase or pretreating with opioid/β-blocker.
Respiratory effects
PUNGENT — causes coughing, breath-holding, laryngospasm if increased rapidly. Contraindicated for inhalational induction. Otherwise similar respiratory profile to sevo (↓TV, ↑RR, bronchodilator, blunted CO₂ response).
Side effects
- !Sympathetic stimulation with rapid inspired concentration changes (>6%) — ↑HR, ↑BP, can precipitate myocardial ischemia in CAD
- !Carbon monoxide formation in DESICCATED CO₂ absorbents (especially old Baralyme; minimized with modern absorbents kept hydrated, FGF cycled off overnight)
- !MH trigger
- !Emergence cough/agitation if not weaned smoothly
- !Highest greenhouse warming potential of clinical volatiles (~2540 GWP-100; ~25× sevo) — environmental consideration
Contraindications
- ×MH susceptibility
- ×Inhalational induction (pungency)
- ×Severe coronary disease (relative — sympathetic surge risk with rapid concentration changes)
Clinical pearls
- ★FASTEST emergence of any volatile — clinically meaningful for obese patients (where redistribution is slowed by adipose) and long surgeries.
- ★Increase concentration GRADUALLY: 1% increments every few breaths to avoid sympathetic surge.
- ★Tec 6 vaporizer is heated (39°C) and electrically controlled — different from variable-bypass vaporizers; needs power.
- ★CO formation risk: turn off FGF overnight only with fresh hydrated absorbent OR keep absorbent moist; modern Amsorb eliminates risk.
- ★Highest environmental impact volatile — many institutions favoring sevo for sustainability when fast emergence isn't critical.
Other drugs in Inhalation Agents
- Sevoflurane
Multi-site CNS depression: GABA-A potentiation, glycine receptor potentiation, NMDA + nicotinic ACh inhibition, two-pore K⁺ channel activation. Net: dose-dependent unconsciousness, amnesia, immobility, and analgesia (modest).
- Isoflurane
Volatile anesthetic. Multiple sites: potentiates GABA-A, antagonizes NMDA, activates two-pore-domain K⁺ channels, modulates glycine. Lower potency than sevoflurane but produces deeper unconsciousness per MAC. Pungent — not used for inhalation induction.
- Nitrous Oxide
NMDA-receptor antagonism (primary) + opioid/GABA effects → analgesia + amnesia. Weak anesthetic (MAC 104%) so used as an adjuvant, not a sole agent.
Browse all classes: /reference/drugs
Suggested reading
- •Stoelting & Hines, Pharmacology & Physiology in Anesthetic Practice, 6e
- •Miller's Anesthesia, 9e
- •FDA package insert