Sevoflurane

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.