Circulation 80,350 • Volume 21, No. 2 • Summer 2006   Issue PDF

Vaporizer Draining Intervals

Numerous questions to the Committee on Technology are individually and quickly answered each quarter by knowledgeable committee members. Many of those responses would be of value to the general readership, but are not suitable for the Dear SIRS column. Therefore, we have created this simple column to address the needs of our readership.

Dear Q&A:

In our operating rooms, we are exclusively using Datex-Ohmeda vaporizers: isoflurane in Isotec 4 and 5, sevoflurane in Sevotec 5, and desflurane in Tec 6.

Obviously, the agent in the vaporizer should be in date, but our question concerns the draining of vaporizers at various intervals. The Datex-Ohmeda Tec 5 manual suggests draining the agent every 2 weeks or an unspecified interval for agents without additives. The Tec 6 apparently cannot be drained at all. We have never before drained our vaporizers and don’t know of any other anesthesia department following these guidelines. The effort, waste, and environmental issues are of concern to us, particularly in regards to the recommended high frequency of drainage.

Any help regarding this issue is greatly appreciated, as we are now required to create a policy for our vaporizer maintenance.

Jay Jordan, MSN, CRNA
Rowan Regional Medical Center
Salisbury, North Carolina

Dear Mr. Jordan:

We’ve discussed the issue of draining vaporizers with people here in Madison. While the desflurane vaporizers are not meant to be drained in the field, the other vaporizers may be drained. The User Reference Manual for Tec 5 and Tec 7 vaporizers states:

Maintenance intervals:

Prior to performing any maintenance procedures or returning to a service center for repairs, clean and disinfect the vaporizer.

Every 2 weeks:

When the agent is low, drain the contents of the vaporizer into an appropriately marked container and discard the agent. For halothane vaporizers check the output of anesthetic agent periodically with an agent monitor. See note below.


The decomposition of halothane causes the release of halides, which may corrode metal components particularly in the presence of moisture. Also, a preservative added to halothane by its manufacturers to impede decomposition can leave a residue, which may cause vaporizer components to stick. If halothane is used infrequently the vaporizer should be drained after use.

I’ve asked around and no one knows why the recommendation is the same for isoflurane, sevoflurane, and enflurane vaporizers as it should be for halothane, except the common practice some years back was to share vaporizers among many different machines and all the user reference manuals stem from one master manual addressing worst-case scenarios. With sharing vaporizers common and with the possibility than any given vaporizer may be sitting on a shelf someplace and not routinely used, draining remained recommended; the user would not know how long a vaporizer was standing idle so the recommendation was as stated above. Most departments today have sufficient vaporizers to supply 1 for each machine. The issue remains, however, what is the quality of the agent in the vaporizer? Draining them periodically and refilling them assures a more uniform product in the vaporizer. Of course the thymol issue with halothane makes draining these vaporizers advisable.

Thank you for your question.
The Committee on Technology

The information provided in this column is for safety-related educational purposes only, and does not constitute medical nor legal advice. Individual or group responses are only commentary, provided for purposes of education or discussion, and are neither statements of advice nor the opinions of APSF. It is not the intention of APSF to provide specific medical or legal advice or to endorse any specific views or recommendations in response to the inquiries posted. In no event shall APSF be responsible or liable, directly or indirectly, for any damage or loss caused or alleged to be caused by or in connection with the reliance on any such information.