Serial Ecg Frequency Serial Potassium Measurements

Ouellette Find this author on Google Scholar Find this author on PubMed Search for this author on this site Gregory K.

Buller Find this author on Google Scholar Find this author on PubMed Search for this author on this site.

In a prospective series, 46 of patients with hyperkalemia were noted to have electrocardiographic changes, but no clear criteria were presented.

Design, setting, participants, measurements: Charts were reviewed for patients who were admitted to a community-based hospital with a diagnosis of hyperkalemia.

Inclusion criteria were potassium 6 with a concurrent electrocardiogram.

Data were abstracted regarding comorbid diagnoses, medications, and treatment.

Coincident, baseline, and follow-up electrocardiograms were examined for quantitative and qualitative changes in the QRS and T waves as well as the official cardiology readings.

Results: Ninety patients met criteria; two thirds were older than 65, and 48 presented with renal failure.

Common medications included blockers, insulin, and aspirin; 80 had potassium Conclusions: Given the poor sensitivity and specificity of electrocardiogram changes, there is no support for their use in guiding treatment of stable patients.

Serial Ecg Frequency Serial Potassium Measurements

Without identifiable electrocardiographic markers of the risk for complications, management of hyperkalemia should be guided by the clinical scenario and serial potassium measurements.

Hyperkalemia is a common and a potentially life-threatening electrolyte disorder in patients in the hospital setting.

Exact incidence varies between surveys, with estimates ranging between 1.1 and 10 of hospitalized patients ( 1 4 ).

Such estimates are reinforced by reports that in patients who are treated with at least prophylactic doses of heparin, now standard of care for most hospitalized patients, the incidence of hyperkalemia is between 7 and 8 ( 5 ).

Although severe cases may be associated with paralysis and cardiac arrest, in the majority of cases, symptoms are most often nonspecific and may include muscle twitching, nausea, vomiting, and abdominal pain ( 6 ).

In experimental settings, hyperkalemia has been associated with a defined series of electrocardiogram (ECG) abnormalities, including shortening of QT interval, peaking of T waves, QRS prolongation, shortening of PR interval, reduction in amplitude of the P wave, loss of sinoatrial conduction with onset of a wide-complex sine-wave ventricular rhythm, and ultimately asystole ( 7 ).

Although no uniform threshold has been documented in animal models, the most severe cardiac manifestations have been shown to occur with serum potassium concentrations 9 mEqL ( 7 ).

On the basis of these experimental observations, commonly used clinical references recommend ECG assessment as an integral part of the evaluation of patients with hyperkalemia ( 8 ).

In clinical series, the relationship between serum potassium concentration and cardiac manifestations is less clear.

In one published series of 127 patients with serum potassium concentrations ranging between 6 and 9.3 mEqL, no serious arrhythmias were documented ( 9 ).

Only 46 of ECG were noted to have changes suggestive of hyperkalemia, including QRS widening, conduction deficits, and peaking of T waves ( 9 ).

There are multiple case reports of patients with renal failure who presented without significant ECG changes despite markedly elevated potassium levels ( 10, 11 ).

Other, less typical ECG presentations of hyperkalemia include ST elevations mimicking acute myocardial infarction and rate-dependent bundle branch blocks ( 12 17 ).