Evita O2 sensor problems?

Lately I have experienced a number of ventilator problems. Here at Sunny Flats we use the Drager Evita ventilator, which up until now I have found to be an excellent piece of equipment. It’s reliable, user-friendly, and packed with all the modes and features an RT could dream of. It’s easy to find what you’re looking for and it’s easy to troubleshoot. The flow sensors(which are at the end of the exhalation line and use some kind of pisoelectric magic to calculate flow and volume)have a tendency to go out of calibration depending on factors like humidity, but that is easy to fix. Up until now the flow sensors fragility has been my only complaint about the ventilator.

Within the last week, however, I have had several ventilators which have had total failures of the O2 sensors. It usually begins with the sensor drifting too high which resolves after a couple of sensor calibrations. But the O2 sensors continue to drift, and finally they go completely out of calibration and will not recalibrate. Luckily the sensor derangements have mostly occurred during our pre-use ventilator testing, but I have had to physically remove two patients from the ventilator and get a new machine due to sensor failures. It seems like a little thing but it’s difficult to manage a ventilator when you do not know the FIO2.

The O2 sensor drift and derangement has become a big problem here. My question is: have any other Drager users out there experienced this problem, or is it something we’re doing to our ventilators that is making them go out of calibration?

All this being said I would like to point out that Ilovethe Drager. It has all the bells and whistles, but it also works just fine for simple mechanical ventilation. We use it for everything from neonates in the NICU to difficult-to-wean COPDers to our postoperative surgical and cardiac patients. We use it in the ER and the PACU and occasionally on the stepdown floor. It’s a great machine and I like it; I’m just wondering whether any other users have had this problem and what we can do to prevent or solve it. Any feedback is appreciated!