Desflurane
Desflurane is a halogenated volatile inhalant anesthetic with a chemical structure nearly identical to isoflurane, differing only by the substitution of a fluorine atom for chlorine at the alpha-ethyl carbon. **Key Clinical Features:** * **Extremely Rapid Kinetics:** Its very low blood/gas partition coefficient (0.42) allows for exceptionally fast induction and recovery times compared to other inhalants. * **Specialized Equipment Required:** Because its boiling point (22-23°C) is near room temperature, desflurane requires a specific, electrically heated, and pressurized vaporizer, which can be expensive. * **Airway Irritant:** Unlike sevoflurane, desflurane has a pungent odor and is a respiratory irritant, making it poorly suited for mask inductions (can cause breath-holding, salivation, and laryngospasm). * **Minimal Metabolism:** It is highly resistant to biodegradation (only 0.02% metabolized), minimizing the risk of hepatotoxicity or nephrotoxicity.
Mechanism: While the exact mechanism of inhalant anesthetics remains incompletely understood, desflurane is believed to produce general anesthesia by interacting with the **lipid matrix of neuronal membranes** and modulating multiple ligand-gated ion channels in the central nervous system. **Mechanistic Pathways:** * **GABA_A and Glycine Receptors:** Potentiates inhibitory neurotransmission → CNS depression. * **NMDA Receptors:** Inhibits excitatory glutamatergic transmission. **Minimum Alveolar Concentration (MAC) in Oxygen:** * Dogs: 7% * Cats: 9.8% * Horses: 7.23% * Rabbits: 8.9% * Alpacas/Llamas: 7.8-8.0% *Note: Desflurane causes dose-dependent cardiovascular (hypotension) and respiratory depression, but does not sensitize the myocardium to catecholamine-induced arrhythmias.*
Dosing by species
- General Anesthesia (Clinically useful concentrations) · Induction = 8-15%; Maintenance = 5-9% · Inhalation · Continuous · As needed
- General Anesthesia (Emergency patients) · 6% · Inhalation · Continuous · As needed · Approximate MAC for emergency patients
- General Anesthesia (Following IV induction) · start with a vaporiser setting of about 8% (around MAC in most animals), increasing the concentration as required. · Inhalation · Continuous · As needed
- General Anesthesia (Clinically useful concentrations) · Induction = 8-15%; Maintenance = 5-9% · Inhalation · Continuous · As needed
- General Anesthesia (Emergency patients) · 6% · Inhalation · Continuous · As needed · Approximate MAC for emergency patients
- General Anesthesia (Following IV induction) · start with a vaporiser setting of about 8% (around MAC in most animals), increasing the concentration as required. · Inhalation · Continuous · As needed
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Routes of administration
Contraindications
- Hypersensitivity to desflurane or other halogenated anesthetic agents
- History of or predilection towards malignant hyperthermia
Adverse effects
- Hypotension (dose-dependent)
- Respiratory depression (dose-dependent)
- Respiratory irritation and salivation (especially with mask induction)
- Sympathetic stimulation (tachycardia/hypertension) with rapid increases in concentration
- Malignant hyperthermia (in susceptible individuals, though incidence may be lower than other halogenated agents)
- Transient increases in glucose and white blood cell count
Drug interactions
- ACE Inhibitors or other hypotensive agents · Concomitant use may increase risks for severe hypotension.
- Non-depolarizing neuromuscular blocking agents · Additive neuromuscular blockade may occur.
- Succinylcholine · May induce increased incidences of cardiac effects (bradycardia, arrhythmias, sinus arrest, apnea) and trigger malignant hyperthermia in susceptible patients.
Monitoring
- Respiratory rate, rhythm, and ventilatory status (capnography)
- Cardiac rate and rhythm (ECG)
- Arterial blood pressure
- Level of anesthetic depth (jaw tone, palpebral reflex)
- Body temperature
- Neuromuscular function
Overdose
In the event of an overdosage, immediately **discontinue desflurane**. Maintain a patent airway and provide positive pressure ventilation with 100% oxygen. Support cardiovascular function with intravenous fluids and sympathomimetics as necessary.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.