Missed critical value callbacks due to middleware flaw

Objectives: In 2018, our clinical laboratory was alerted to back-to-back plasma sodium critical value callback failures on the same patient, occurring on different shifts and involving different technologists. Therefore, we set forth to investigate the root cause for the critical value callback failures. Design and methods: We conducted a thorough investigation focused on the processes associated with critical value identification and notification for plasma sodium measurement performed on the Siemens Vista. Results: Our investigation uncovered a flaw in the Siemens CentraLink middleware software. A default dark blue bar in the top row of the results review display was determined to obscure the red color which highlights critical values for lab staff identification. Sodium was disproportionately impacted by this flaw, as it is commonly ordered as part of metabolic panels, and is listed first among the panel analytes in the top row of the CentraLink display. Retrospective data review comparing critical callback failure rates for sodium to potassium and hemoglobin confirmed that sodium had significantly higher critical callback failure rates than these other analytes. After alerting the product manufacturer, Siemens programmed the CentraLink display so that the top row was blank and devoid of patient results, so that the blue color in the top row would no longer obscure the red visual cue of a patient's critical result. Sodium critical value callback failures were reduced to 0% after this middleware display correction. Conclusions: Middleware design flaws can have unexpected consequences on clinical laboratory operations. We encourage clinical laboratories to closely examine user interfaces utilized by laboratory staff, and be wary of potential impacts that the display format may have on results reporting.