An anaesthetic vaporizer must deliver a safe, reliable concentration of volatile agent to the patient. Anaesthetists should understand the basic principles of. Vaporizers are an integral part of modern-day anaesthesia, allowing the delivery of safe concentrations of volatile anaesthetic agent. Over time, vaporizer design. Anaesthesia vaporizers for inhalational anaesthetic agents. Principal, classification, types, hazards.

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Each pin has an O-ring at the base that makes the seal with the vapouriser. Understanding vaporizers; continuing education in anesthesia. This page was last edited on 29 Septemberat InClover invented an ether inhaler with a water jacket, and by the late alternatives to ether came to the fore, mainly due to the introduction of spinal anaesthesia.

Physics All Journals search input. The splitting ratio of these two flows depends on the ratio of resistances to their flow, which is controlled by the concentration control dial, and the automatic temperature compensation valve.

Anaesthetic vaporizer

Vaporizer and Selectatec leaks. Additionally, on a very warm day, all the desflurane would boil, and very high potentially lethal concentrations of desflurane might reach the patient.

Every 2 ml of incoming gas picks up 1 ml of vapour. This is a minor effect. None the less, the order should be: The clever bit was how to make it work reliably, knowing that Desflurane can boil so close to room temperature.

Processing: Vaporizers

The most common such vaporizer is the Ohmeda Tec 6, designed specifically for use with desflurane. Reprinted with permission of Elsevier. The cassette includes magnets to ID the agent to the machine on insertion, an electrical connection to an internal temperature sensor, and self-sealing ports for gas in and out, but no other electronics. Regulation Variable Bypass, fully saturated vapour chamber Mechanical: It can also be seen that a plenum vaporizer can only work one way round: The fresh gas flow from the flow meters enters the vapouriser and is split into two streams, one stream flows into the fresh gas bypass circuit and the other stream flows through the vapourising chamber where it is enriched with the vapour of the liquid anaesthetic naaesthesia.


These factors are described below. For Sevoflurane and Enflurane, with lower anaestbesia pressures: At or below this critical temperature, it can exist in both its liquid and gaseous forms; the latter is called a vapour.

The vapourising module is agent specific and is connected to a storage tank. Modern plenum vaporizers produce an accurate concentration of agent at flow rates between 0.

Heats agent to 39 degrees C, which produces a vapor pressure of around mm Hg. Cardiothoracic Geriatric Oral sedation dentistry. Output decreased due to cooling after induction. Powell JF, Morgan C. Gas in the vaporising chamber becomes fully saturated with volatile anaesthetic vapour.

Vaporizers | Anesthesia Equipment Simplified | AccessAnesthesiology | McGraw-Hill Medical

The vapouriser has two independent gas circuits arranged in parallel. Anesthetic equipment History of anesthesia Drug delivery devices Dosage forms. The Aisys has low agent alarms on all vaporizers. Click on the thumbnail, or on the underlined text, to see the larger version.

Plenum vaporizers have a much higher internal resistance, requiring fresh gas at above atmospheric pressure. The Aladin will not deliver volatile agent without mains power or battery backup, and adequate oxygen or air pressure.


The safe delivery of volatile anaesthesia today is due in part to the development of increasingly anasthesia vaporizers.

For a study of this vaporizer’s anafsthesia, see Anesth Analg ; It is tippable and robust. Flow reversal through the anaesthetic machine back bar: The cassette holds up to ml when full. Footnotes Source of Support: In addition, the resistance generated by the flow splitting valve becomes more significant at low flow rates—this results in more gas bypassing the vaporizing chamber.

Vapor pressure Molecules escape from a volatile liquid to the vapor phase, creating a “saturated vapor pressure” at equilibrium. Another failure anaesthwsia Selectatec block. When the ball in the sight tube is at the bottom, the cassette contains 80 ml or less.

Actually the dissolved Desflurane ‘dilutes’ the Sevoflurane appreciably and the net anaesrhesia may be almost none. The output of older vaporizers varies slightly with changes in fresh gas mixture, whereas the Aladin compensates for this automatically.

Gas cans nowadays are made out of plastic, not metal like in the past. Saturated vapour pressure for any one agent varies with temperature, and plenum vaporizers are designed to operate within a specific temperature range.

An unusual assembly fault. Modern vaporizers are temperature compensated hence the Tec series. Gregory Rose, and J. One of these streams passes straight through the vaporizer in the bypass channel. The cassettes for halothane, enflurane and isoflurane have keyed fillers or the Easy-fil system. Why does output rise with altitude?