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Introduction
Sevoflurane is very similar to isoflurane but is less potent. However, it's odour is less pungent making it more suitable for mask induction, but can also be used as a maintentance agent. It is becoming more popular in veterinary anaesthesia.
Pharmacokinetics
Sevoflurane is also a halogenated ether. It is also stable and nonflammable. Alkaline carbon dioxide absorbents react with sevoflurane to produced a potentially toxic compound. This can be influenced by environmental temperature, sevoflurane concentrations, use of baralyme rather then sodalime, low flow rates and already exposed absorbents. The blood:gas partition coefficient is very low, meaning that has a rapid onset of action. It has a high tissue solubility however, which means that recovery is more prolonged compared to isoflurane or halothane. The MAC of sevoflurane is approximately 2.4% in dogs and 2.6% in cats and is therefore less potent the other agents. Sevoflurane undergoes a small amount of hepatic metabolism.
Adverse Effects
Central Nervous System
- Increases intracranial pressure due to cerebral vasodilation.
Cardiovascular System
- Mild myocardial contractility depression.
- Decreased arterial blood pressure and systemic vascular resistance.
Other Systems
- There is an increase in hepatic artery flow, but reduced in the hepatic portal vein, like isoflurane.
Contraindications
- It is advisable to avoid the use of sevoflurane in patients with renal disease as there is a potential for further renal damage.