Real-life evaluation of an alert system to detect the risk of unreported dyskaelemia in haemolysed blood samples from a hospital emergency department

Abstract

Background

In vitro haemolysis is a recurrent problem in emergency department samples. Potassium is one of the most critical tests and sensitive to increasing levels of in vitro haemolysis. Haemolysis results in a large number of invalidated potassium test results.

Methods

We set up an alert system to detect the risk of dyskalaemia based on potassium value and haemolysis index (HI). We retrospectively evaluated the effectiveness of the alert system for haemolysed blood samples from the emergency department.

Results

54 605 samples were included. Women more frequently had a sample with a high HI value, resulting in the invalidation of a potassium test result (3.22% vs 2.35%, P < 0.001). In the case of haemolysed samples, the frequency of alerts for hyperkalemia risk was similar in women and men. Hypokalaemia was significantly more frequent in women than in men (12.71% vs 9.38%, P < 0.001). Among the haemolyzed samples, no hypokalaemia risk alerts were observed and 42 patients had a hyperkalaemia risk alert. For these patients, the potassium value of a second sample was significantly higher in patients with an alert on the first sample (4.85 mmol/L vs 4.0 mmol/L, P < 0.001), with a higher rate of hyperkalaemia (57.14% vs 4.76%, P < 0.001) and critical hyperkalaemia (17.86% vs 0.3%, P < 0.001). Negative predictive value and positive predictive value to detect hyperkalaemia were 90.4% [89.6–91] and 41.3% [25.5%–59.1%].

Conclusions

Our alert system was effective to detect the risk of hyperkalemia, and could help clinicians to better target patients requiring repeat sampling for potassium.