In Reply:—

Thank you for allowing us to respond to the article “Oxygen Flush Valve Booby Trap.” The authors describe an intermittent dilution of the breathing circuit gases from a broken flush valve. Although Datex-Ohmeda (Madison, WI) was not advised of this event before notification by Anesthesiology, and our service staff did not have the opportunity to examine the valve in question, we can suppose that the valve fault described would be consistent with the clinical findings observed by the authors.

It is important to point out that this type of failure, when the “fracture” is displaced, will fail the Food and Drug Administration Preoperative Checkout Procedure during both the high pressure leak test, recommended once per day, and the low pressure leak test, recommended before each anesthetic. This failure, when “reduced” will likely pass the same Food and Drug Administration checkout procedure. This makes the fault difficult to identify, and Datex-Ohmeda commends the biomedical staff for isolating the probable cause of this event.

With respect to the statement regarding the sevoflurane vaporizer, we must suggest the authors’ statement is incorrect. As described by the authors, there is no evidence that the “sevoflurane vaporizer also failed to deliver expected concentrations of vapor.” It would be more accurate to state that the described fault permitted oxygen to dilute the vaporizer concentration within the fresh gas flow pathway. This comment notwithstanding, both the unexpectedly high Fio2and the unexpectedly low inspired agent concentration do serve to emphasize another topical issue, the need for constant clinical vigilance. There are many causes of circuit gas dilutions that produce such variations. The anesthetic agent analyzer is the best method to assure the desired concentration of all gases is achieved.

Finally, Datex-Ohmeda strongly urges all members of the anesthesia community to report suspected issues to Datex-Ohmeda. Without such information, we are unable to see the entire picture as relates to the ongoing operation of our equipment. This is especially true for those departments who benefit from an internal biomedical department; although these departments may be very adept at the ongoing maintenance, Datex-Ohmeda continues to request users notify the company directly when events such as that described in the letter occur.

Datex-Ohmeda (now a part of GE Medical Systems), Madison, Wisconsin.