Monday, 1 April 2013

( Hypokalemia )

Hypokalemia is a disorder characterized by electrolyte
Plasma concentrations of potassium
below 3.5 mEq/L.1Cerca of 98% of potassium (K +) body is in the intracellular compartment, and 78% of this muscle. Only 2% of the body's extracellular ie 70 mEq of
which 0.4% or 15 mEq of K + total body can be measured in the plasma.2
The incidence of this disorder in hospitalized patients can reach 20%, 2.3 Figure hyponatremia
as the most common electrolyte disorder in hospitalized patients, with incidence of 2% 4.5
Among the most common causes of hypokalemia are reported in the literature renal losses
and gastrointestinal diseases, in 40% of cases, especially secondary to treatment with diuretics
thiazide and losses diarrea.6 patients
trauma are at increased risk of hypokalaemia, with incidence of 45-68% in some centers hospitalarios.2 renal potassium excretion depends mainly on three factors: loss of sodium and water by the distal collecting tubules, action aldosterone and serum potassium mismo.6
Hospitalized patients with hypokalemia are at increased risk of dysrhythmias and death due to
heart failure, hypertension and ischemic cerebrovascular events and hemorrhagic
9The gicos.3 ,7-clinical manifestations of hypokalemia directly relate the intra and extracellular potassium due to changes in the electrical potential of the membrane resting
cell, leading to their hyperpolarization and consequent action potential prolongation. The systems affected by the decrease in serum potassium are: cardiovascular, musculoskeletal, gastrointestinal and renal. Most patients who present with mild hypokalemia (serum potassium levels between 3.0 and 3.5 mEq / L) are asymptomatic, while the most common signs and symptoms in
with moderate hypokalemia (K + concentrations between 2.5 and 3.0 mEq / L) consist of dysrhythmias
heart, weakness, muscle paralysis, twitching, ileus and nephrogenic diabetes insipidus.
Patients who progress to severe hypokalemia (K + concentrations below 2.5 mEq / L)
manifest rhabdomyolysis, myoglobinuria, symmetrical ascending paralysis and cardiac respiratorio.1, 2.10
Due to changes in cell membrane potentials and potential prolongation
action, hypokalemia causes electrocardiographic changes, where the findings
most common are the PR segment extension, the appearance of U waves occasionally prominent
can mimic T waves, ST segment depression and increased investment and T-wave amplitude
Sometimes the appearance of U wave stands with the T wave, which simulates the extended segment QT.11 Patients with mild to moderate hypokalemia and cardiovascular disease or recent myocardial infarction, have increased risk of ventricular dysrhythmias ventricular fibrillation.

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