Sevoflurane
**Sevoflurane** is a highly volatile, halogenated inhalational anesthetic widely used in veterinary medicine for the induction and maintenance of general anesthesia. Key pharmacological characteristics include: * **Low Blood:Gas Partition Coefficient (0.6)**: This allows for exceptionally rapid alveolar-to-arterial equilibration, resulting in much faster induction and recovery times compared to isoflurane or halothane. * **Non-pungent Odor**: Unlike isoflurane, sevoflurane is not irritating to the airway, making it the preferred agent for **mask or chamber inductions** in exotic species, fractious felines, and pediatric patients. * **Hemodynamic Stability**: It tends to cause less profound hypotension than isoflurane, making it particularly useful in debilitated or geriatric patients. **Clinical Pearl**: Because anesthetic depth can change very rapidly with sevoflurane, vigilant monitoring is required to prevent accidental anesthetic overdose during maintenance.
Mecanismo: The precise mechanism of inhalant anesthetics remains incompletely elucidated, but they primarily act by disrupting synaptic transmission within the central nervous system. * **Lipid Matrix Interaction** → Alters the function of neuronal membrane proteins. * **GABA_A Receptors** → Potentiates inhibitory neurotransmission, leading to profound CNS depression. * **NMDA Receptors** → Antagonizes excitatory glutamatergic signaling. * **Glycine Receptors** → Enhances inhibitory signaling in the spinal cord, contributing to skeletal muscle relaxation. Due to its **low solubility in blood**, minimal amounts of sevoflurane need to dissolve before alveolar partial pressures equilibrate with arterial partial pressures, driving its rapid onset and offset of action.
Dosificación por especie
- Anesthesia Induction (Mask/Chamber) · starting at a concentration of around 4-4.5%. Maximum concentration (8%) · Inhalation · Once · Until loss of consciousness · Reduce concentration as soon as the animal loses consciousness.
- Anesthesia Maintenance (Circle System) · vaporizer setting of 3% for a circle system is a reasonable initial concentration · Inhalation · Continuous · Duration of procedure · MAC is reported as 2.58%
- Induction of anaesthesia (unpremedicated) · 6-8% inspired concentration · Inhalational · continuous · until induced · Dose should be adjusted according to individual requirement and concurrent drugs.
- Maintenance of surgical anaesthesia · MAC is approximately 2.5% (expired concentration) · Inhalational · continuous · duration of surgery · Adjust concentration according to clinical assessment of anaesthetic depth. Administration of other anaesthetic agents and opioids reduces the dose requirement.
- Anesthesia Maintenance · MAC = 1.97-2.66% · Inhalation · Continuous · Duration of procedure · Monitor closely for malignant hyperthermia.
- Anesthesia · Titrate to effect · Inhalation · Continuous · Duration of procedure · Can cause temporary decreases in erythrocyte and white cell counts and total protein (reverses within 2 hours post-discontinuation).
Vías de administración
Contraindicaciones
- Patients with a history or predilection towards malignant hyperthermia
- Known hypersensitivity to sevoflurane or other halogenated anaesthetics
- Known or suspected susceptibility to malignant hyperthermia
Efectos adversos
- Dose-dependent hypotension
- Dose-dependent respiratory depression
- Gastrointestinal effects (nausea, vomiting, ileus)
- Myocardial depression and bradycardia (less than halothane)
- Malignant hyperthermia (rare but life-threatening)
- Temporary decreases in erythrocyte, white cell counts, and total protein in ferrets
- Agitation or excitement during rapid recovery
- Neonatal depression (crosses the placental barrier)
Interacciones farmacológicas
- Aminoglycosides, Lincosamides · May enhance neuromuscular blockade
- Barbiturates (phenobarbital, pentobarbital) · May increase concentrations of inorganic fluoride
- Non-depolarizing neuromuscular blocking agents (atracurium, pancuronium, vecuronium) · Additive neuromuscular blockade may occur
- Isoniazid · May increase concentrations of inorganic fluoride
- Midazolam · May potentiate sevoflurane effects; decrease MAC
- Opiates · May potentiate sevoflurane effects; decrease MAC
- St. John's Wort · Increased risk for anesthetic complications; recommend discontinuing 5 days in advance of surgery
- Succinylcholine · Sevoflurane may enhance effects
- Sympathomimetics (dopamine, epinephrine, norepinephrine, ephedrine) · Sensitizes the myocardium to sympathomimetics (less than halothane); arrhythmias may still result
- Tramadol · May decrease MAC requirements
- Verapamil · May cause cardiodepression
- Sedatives (e.g., alpha-2 agonists, phenothiazines) · Reduces the concentration of sevoflurane required to achieve surgical anaesthesia (MAC reduction). · major
Monitorización
- Respiratory rate, rhythm, and ventilatory status (capnography recommended)
- Cardiac rate and rhythm (ECG)
- Blood pressure (especially in 'at risk' or geriatric patients)
- Level of anesthetic depth (jaw tone, palpebral reflex, eye position)
- Body temperature (monitor for hypothermia or sudden spikes indicating malignant hyperthermia)
- Respiratory rate, rhythm, and depth (Capnography/ETCO2 highly recommended)
- Arterial blood pressure (hypotension is dose-dependent)
- Heart rate and rhythm (ECG)
- Anaesthetic depth (jaw tone, palpebral reflex, eye position)
- Pulse oximetry (SpO2)
- Body temperature
Sobredosis
In the event of an overdosage, **immediately discontinue sevoflurane administration**. * Maintain a patent airway. * Flush the breathing circuit with 100% oxygen. * Support respiratory function with positive pressure ventilation if necessary. * Support cardiac function and treat severe hypotension with IV fluids and sympathomimetics as clinically indicated.
La referencia de fármacos de VetSheet está destinada a veterinarios colegiados como apoyo a la decisión clínica, no sustituye el juicio profesional ni la ficha técnica vigente del fabricante.