Hypokalaemia often causes muscle fatigue, weakness and lethargy. In severe cases low potassium will lead to constipation, arrhythmias (flattened T waves and prominent u waves) and a weak cardiac contraction. Those most at risk are NG free drainage/vomiting , diarrhoea and people on diuretics with out taking potassium supplements. Look at your patients on diuretics and check their K | ECT4Health- Nurse/Paramedic Education