[Influence of hyperkalemia on clinical decision making]

In our hospital, extreme values are promptly reported in routine test, one of three kinds of reporting system. We investigated the influence of hyperkalemia on clinical decision making and discussed critical levels of hyperkalemia and the significance of prompt report of it.

One hundred eighty six patients with more than 6 mmol/l of blood potassium detected during 1993 were studied. Each episode in a patient with different causes was classified as a separated case and finally 194 cases were studied. Cause of hyperkalemia, clinical symptoms, electrocardiogram, outcome and treatment were investigated.

The mortality was 14% in 6 approximately 7 mmol/l, 42% in 7 approximately 8 mmol/l and 100% in more than 8 mmol/l. Electrocardiograms showed high peaked T wave in 6 approximately 7 mmol/l, widening of QRS complex and bradycardia in 7 approximately 8 mmol/l, and ventricular fibrillation and flatter in more than 8 mmol/1. These results supported that 7 mmol/l was acceptable as a critical value. One hundred percent of outpatients and 79% of inpatients undergoing emergency tests were promptly treated by doctors, and 61% and 35% undergoing urgent tests, and 52% and 30% undergoing routine tests (prompt report) were done respectively. Prompt reports of extreme values were more useful in decision making for outpatients than inpatients. Urea-N was more important than potassium as a factor influencing decision making in both patients, because most patients had renal failure or heart failure.

The mortality and electrocardiogram studies supported that 7 mmol/l was an acceptable critical value. Prompt reports of hyperkalemia were more significant to clinical decision making for medical care for outpatients than for inpatients.