Anesthetic vaporizers are used in the administration of volatile anesthetics. The device works by controlling the vaporization of the liquid anesthetic agent and delivering a reliable concentration to the subject. These devices manage the delivery of the anesthetic concentration by taking into account the varying ambient temperature, fresh gas flow, and agent vapor pressure.
Modern vaporizers have come a long way since their initial open mask design. Classification of vaporizers can be based on many factors such as the method of output regulation and method of vaporization; however, in clinical research, the primary interest is in the deliverance of precise concentration of the anesthetic agent. Vaporizers that allow accurate selection of the final concentration of the agent are known as precision vaporizers.
Apparatus and Equipment
Conduct Science’s vaporizer system has 120 cc liquid capacity with a large sight glass to allow liquid level monitoring at-a-glance. The apparatus has automated flow rate (0.2 to 10,000 cc/min) and temperature compensation (10° to 35° C) capabilities and is equipped with a 50kPa pressure tolerance tanks. To prevent unintentional engagement, the system comes with an integrated safety lock. These vaporizers are designed to be used with isoflurane (0 to 5% output) and sevoflurane (0 to 8% output) and are available as pour-fill and easy attachment-fill style.
The vaporizer system is composed of concentration control dial, the bypass chamber, the vaporizing chamber, the filler port and filler cap.
Vaporizers are designed to be used with specific anesthetic agents and are equipped with filling systems to enforce the same. The filler tubes are agent specific. The fittings on the vaporizer and the collar of the bottles are specific to the agent too. This precaution is built into the design to prevent mixing of the anesthetic agents.
Most modern vaporizers can be seen fitted to the back bar of the anesthetic machines using special mounting systems. These set-ups allow a quick and easy exchange of vaporizers between anesthetic machines. Although multiple vaporizers can be fitted to the anesthetic machine, as a cautionary measure most back bar systems restrict usage to only one vaporizer at a time.
Mode of Operation
The variable bypass vaporizers are the most commonly used vaporizes. Their working principle involves splitting the fresh gas flow and saturating a small portion completely with the volatile anesthetic before recombining into the main gas flow. This process is achieved by setting of the anesthetic concentration using the control dial and the pressurized chamber of the plenum vaporizers. These devices are also equipped with thermo-compensation capabilities for a steady vaporizer output.
To ensure the appropriate working of the plenum vaporizer systems, it is important that the system is supplied with pressurized gas. The vaporizer must be correctly attached, and locking mechanisms must be fully engaged to avoid any leakage of the agent and the gas. Vaporizers must not be overfilled or underfilled to prevent failure of the vaporizer systems. It is also important to ensure that the correct anesthetic agent is used to prevent over- or under-dosing the subject. Regular servicing of the vaporizer is also critical for its proper functioning.
Chakravarti S, Basu S (2013). Modern anaesthesia vapourisers. Indian J Anaesth. 57(5):464-71. doi: 10.4103/0019-5049.120142.
Fish, R. E. (2008). Anesthesia and analgesia in laboratory animals. Amsterdam: Elsevier.
Flecknel, P. (2009). Laboratory Animal Anaesthesia. Elsevier.