To maintain confidence in vaporizer performance, it must be both inspected and maintained regularly. Primary Medical, like such manufacturers as Ohmeda recommends frequent inspections in situ and annual maintenance in a calibration laboratory. Inspection can be performed in the hospital without removing the vaporizer from the machine. It includes visual examination and testing with a portable instrument such as the Riken to determine gross performance. In addition to inspection by resident biomedical personnel, those responsible for maintaining anesthesia machines may also examine the vaporizers mounted on them. Unfortunately, that inspection is no substitute for preventive maintenance. Maintaining a vaporizer consists of several operations which must be carried out in a laboratory. One indicator that a vaporizer has been serviced, instead of merely being inspected, is that it has been removed from the hospital and reinstalled. An even clearer indication is a service sticker affixed to the vaporizer itself, attesting to its having undergone a thorough preventive maintenance program.
One of the stickers we use at Primary Medical is shown in the above Figure; every competent service facility applies such a sticker to each unit it maintains. On request, Primary Medical will also provide a certificate attesting that we have serviced that unit and specifying its serial number and service date.
Disassembly
The first step in servicing a vaporizer is disassembly, in which the components are separated for examination. Only through such break-out can the technician locate wear, corrosion, or other causes of impending failure. Disassembly requires a laboratory if only to maintain tracking of the numerous small parts.
Cleaning
All parts are cleaned to facilitate thorough examination and to evaluate wear and corrosion. The unit is cleaned in a laboratory to ensure that any cleaning agent or vaporizer contaminant is evacuated safely.
Renewal and Lubrication
Wicks and seals such as o-rings degrade with time and with use. They must be replaced periodically to minimize the risk of sudden failure. Some components also require precise lubrication. Here, a laboratory environment is required to preclude contaminating the replacement part with materials present in the hospital environment.
Assembly and Re-calibration
The unit is reassembled and calibrated with precise instrumentation not only to ensure that it performs adequately, but also to determine that its profile of operation is consistent with that of a fully functional machine. That testing requires a controlled environment for testing and precise instrumentation. For example, Primary Medical uses two different chromatographs to calibrate vaporizers, and only checks performance with the relatively imprecise Riken as a final confirmation of performance.
In summary, frequent inspection of each vaporizer is a commendable field process, but it is no substitute for preventative maintenance. Vaporizer service cannot be performed in the field, and is recommended by manufacturers and by Primary Medical for your protection and for the protection of your patients.