Potassium in the perioperative period.

Potassium ions play a vital role at a cellular level. These ions are actively transported into cells, causing an electrical imbalance and a build up of potential energy. When this energy is released following correct stimulation, the cells perform their designated functions. When these functions relate mainly to the heart and skeletal muscles, nerve and renal activity, the importance of potassium in cell function becomes very clear indeed. The excitability of the cells is proportional to the ratio of intracellular to extracellular potassium concentrations [8, 29]. Consequently, any variations in this ratio will affect cellular function, result in dysfunction of excitable cell membranes and cause the signs and symptoms [39] that are associated with imbalances of potassium concentration.