Methods to identify saline-contaminated electrolyte profiles.

BACKGROUND: With providers becoming more selective in ordering daily chemistry profiles, it is critical that profiles ordered are accurate. Contaminated electrolyte profiles are an overlooked and potentially dangerous source of inaccurate clinical data. This study aimed to develop a method to accurately identify electrolyte profiles contaminated with normal saline to prevent reporting of erroneous measurements.
METHODS: We conducted a retrospective cohort study of 76,497 electrolyte profiles from 5032 patients in a deidentified clinical database of all patients in the electronic medical record at Vanderbilt University Medical Center. Five methods to identify errors in quantification based on either deviations from observed concentration distributions or expected numerical changes from saline contamination were developed and tested. Potentially contaminated measurements were validated based on changes in electrolyte concentrations observed in the subsequent sample.
RESULTS: Identification of erroneous electrolyte profiles based on absolute and percent deviations from normal variation rarely resulted in >50% of identified samples validated as contaminated. A targeted methodology based on expected changes in calcium and chloride concentrations due to saline contamination validated approximately 80% of identified samples when higher thresholds for changes in electrolyte concentration were used and 50% of identified samples when lower thresholds were used.
CONCLUSIONS: Targeted methodology based on changes in chloride and calcium successfully identified electrolyte profiles suspicious for contamination. Implementation of this methodology could prevent misinterpretation of a patient's clinical course, inappropriate interventions, and unwarranted changes in treatment strategy.