Erroneous Glucose and Lactate Values on Epoc - Negative Interference?

We are currently experiencing an issue with erroneous results for glucose and lactate levels for the epoc blood analysis system in the CICU population (3 cases) across the past two months.  There appears to be something that may be interfering with the amperometry method (maybe something physiologically that is reducing the hydrogen peroxide) and it isn't giving an instrument error code.  The glucose level is being reported as <20 mg/dL, even if normal when measured against laboratory methods (Vitros, RapidPoint) and our other POC method Abbott FSPP.  We have reported all the issues to Siemens with accompanying data files, corresponding lab results and patient medication lists to aid in determining what may be causing the analytical error.  Siemen’s response was that there were abnormal wave patterns with the glucose sensor detected at the sampling phase, however, no abnormal waveforms in the calibration phase.  They believe that this is the possibility that the negative interference is either from an undetermined endogenous substance or a pharmacological byproduct resulting from combinations of medications taken. 

 

The care teams have been instructed to send the patient specimens to the laboratory for analysis.

 

I am wondering if any other epoc users have been experiencing this issue or similar issues with the epoc Blood Analysis System.

 

Thanks for your help, 
Lara