Calcium and Hyperkalemia

“Calcium Chloride/Gluconate are used during Hyperkalemia induced ECG changes to reduce Serum Potassium.” The answer is:    False! The majority of Potassium in our body is found intracellular. Only a very small percentage (about 2%) is found extracellular, ranging between 3.5- 5.5 mEq/L. As extracellular Potassium levels increase, the action potential threshold decreases, for example, instead of -90mV, now its -80mV. Remember, the Sodium-Potassium ATPase pump controls these ions, so as Hyperkalemia worsens, the amount of Sodium influx also decreases. All of these factors lead to decreased ventricular conduction, causing  shorter QT Intervals, ST-T wave abnormalities and wide QRS complexes on the ECG. You will not always get the classic “Peaked T” waves or bizarre QRS complex morphologies, but this does not mean that there is no Hyperkalemia, or there is no life threat. Normal Action Potential (AP) Phases: In the beginning of the AP (Phase 0), Sodium channels open, with rapid Sodium influx.   While Sodium moves into the cell, a small amount of Potassium exits the cell (Phase 1).   This triggers Calcium influx (Phase 2), which maintains depolarization, conductivity and cardiac contractility.   During repolarization (Phase 3), slow Sodium efflux occurs, while Calcium channels close, and Potassium continues to leave the cell.   The period where the cell remains inactive is the Resting Membrane Potential (Phase 4).   During...
Source: EMS 12-Lead - Category: Cardiology Authors: Tags: Hyperkalemia Pharmacology Source Type: research