If treatment were required, the underlying cause should be addressed. Most cases of chronic hypokemia are well tolerated, and if the patient has no symptoms, I would not replace the K+ preoperatively unless the K+ were below 2.5 mEq/L. ECG changes include flattened T-waves, U-waves (due to prolonged Purkinje fiber repolarization), and prolonged QT. Patients can develop PAC, PVC, SB, PAT, JT, AVB, VT, and VF. Symptoms of hypokalemia include weakness (especially if K+< 2.5), myalgia, constipation, and rhabdomyolysis. Causes of redistribution (entry into cells) include β-agonists, insulin, Hypokalemic per paralysis. Causes of loss can be: (1) GI: Diarrhea, (2) Skin: Sweating, (3) Renal: Lasix, HCTZ, Amphotericine, Cisplatin, Hyperaldosteronism, Cushing’s disease, Bartter sundrome. Thus, hypokalemia lowers the RMP, making it harder to achieve threshold for depolarization and hyperkalemia raises the RMP, making it easier to achieve threshold.Ĭauses of hypokalemia include inadequate intake, loss, or redistribution. Since the potassium channel is the open at rest, changes in the internal or external K concentration may change the RMP according to the equation:ĮRMP ≈ E = - ln I/ o. Both these events produce a negative intracellular change and a negative RMP.
The resting membrane potential (RMP) of myocytes is determined by the Na+/K+-ATPase, which pumps 3 Na+ out for every 2K+ pumped and an open potassium channel that allows K to move outside the cell, down its concentration gradient. Fluids, Electrolytes, Nutrition ECG Changes with Hypo-/Hyperkalemia
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