Vol. XI: Vaporizers: Know What You Give, Know What You Get

There is no doubt that the anesthetic vaporizer is the most important component on the anesthetic machine. It determines the “dose” of anesthetic that is being administered to the patient and therefore it must be functioning properly. The vaporizer is also the component most readily blamed if problems with anesthesia are encountered. This is most often done by those who do not understand the function of all the components of the anesthetic machine. What often happens as a result of this “blame game” is that the vaporizer is switched or swapped by a representative that regularly calls on the practice. The following scenario illustrates what usually happens.

Scenario: The Vaporizer Exchange Process

A representative of company A to Z calls on a practice and one of the staff comments that they have been having problems keeping patients anesthetized. The rep explains that A to Z can exchange the vaporizer and that will probably take care of the problem. The staff member gets authorization and the exchange takes place. Sometimes the rep does the exchange at that time or A to Z may send the vaporizer to the clinic. In either case, the original vaporizer will probably not be returned.

Key Questions Raised by the Exchange Process

This scenario is common in veterinary practice and raises several questions:

1. Did the rep verify the calibration of the vaporizer before it was removed from the machine?
2. Were the other components of the anesthetic machine verified?
3. How does the cost of the vaporizer exchange compare to having a reputable service company verify and test the entire machine, including the vaporizer?
4. Was there calibration documentation provided for the vaporizer that A to Z provided?

The Importance of Calibration and Verification

If the rep did not verify the calibration on the vaporizer that was removed, the exchange may not be necessary. In a retrospective study of all vaporizers that Veta mac verified in 2014, only 3.8% were out of tolerance and needed to be cleaned and recalibrated. The tolerance used by Veta mac in the field is ±20% of the setting on the dial.1 Vaporizers that are disassembled, cleaned and recalibrated in Veta mac’s vaporizer lab have a tolerance of ±15%.

Common Causes of Anesthesia Problems

Most often problems with anesthesia are a result of the delivered anesthetic concentration being diluted by a leak in the breathing system or components not functioning properly, namely one way valves. Without a systematic evaluation and verification of all the components of the machine, exchanging the vaporizer may in fact not solve the problem.

Comparing Costs: Exchange vs. Service Company Verification

The cost to have a reputable service company verify and test the anesthetic machine and the vaporizer is going to be $150-200. This is less than most vaporizer exchange programs. The service company will supply printed records of the service provided and also a certificate of compliance. If requested by the practice, a certificate of liability insurance should be provided. All of Veta mac’s service representatives have performed anesthesia and received service training on most brands of veterinary anesthesia machines.

Benefits and Drawbacks of Vaporizer Exchange Programs

The benefit of this exchange program is solely to A to Z. Only one trip is required to each practice since it is an exchange and not a “loaner” vaporizer. If it is shipped there is no need to ship vaporizers twice. And no inventory of “loaner” vaporizers is needed. The vaporizers that were among the 3.8% that were out of tolerance in 2014 were cleaned and recalibrated by offering the use of a “loaner” to the client while their vaporizer was being cleaned and recalibrated. The client’s vaporizer was then returned to the client and the loaner was returned to Vetamac.

Another disadvantage of the exchange program is you know what you’re giving away but you don’t know what you are receiving. You may have a vaporizer that is only 2 years old and you receive in exchange a vaporizer that might be 10 years old. The 2 year old vaporizer is verified and then the next client will receive a vaporizer that is 2 years old.

The Value of Regular Service and Verification

There is no better way to know the working condition of your anesthetic machine than to have a reputable service company performing regular service and providing assistance when there are problems.