ECG Based Serum Potassium Estimation

Potassium is the most commonly found cation inside the human body and is more concentrated intracellularly than in extracellular components. The homeostasis of Potassium in the blood is maintained by dietary intake and excretion through urine, stool and sweat. In between this, it is primarily stored in muscles and bones. When the blood levels of Potassium start to fluctuate, its effects are found all over the body including skeletal, gastrointestinal and cardiac muscles. However, blood reports usually detect the serum level changes quite late, the process being time consuming, minimally invasive and requires the expertise of phlebotomy every time. We have identified a method of estimating Serum Potassium levels from 12- lead ECGs. Every 0.2mV (2 small squares) increase in T-wave height in a 12-lead ECG corresponded with approximately 0.7mEq/L increase in Serum Potassium levels; conversely 0.2mV (2 small squares) decrease in T-wave height corresponded with approximately 0.7mEq/L decrease in Serum Potassium levels. These equations were tested with 695 and 611 patients respectively, showing a p value of <.00001 (significance interval = 0.01) in both cases. This method of calculating Serum Potassium levels from T-wave heights in ECGs is not only extremely accurate but also non-invasive and less time-consuming. Utilizations of these equations can be most useful in cardiac monitored beds (eg. ICU, CCU, HDU etc) where Potassium levels can be continuously displayed without any extra hardware, any expertise or any invasive procedures. This can help clinicians assess very subtle changes in Serum Potassium levels as and when they occur.