Electrocardiographic registers: A simultaneous 12-lead
standard electrocardiogram (ECG) was obtained before and
after the haemodialysis, which registered: cardiac frequency,
rate, P-wave, PR-interval, duration and amplitude of complex
QRS, T-wave and arrhythmias.
All ECGs were read by one of the investigators who had no
prior knowledge of the serum potassium level, and the amplitude
of T-wave was measured, in each patient, before and
after HD. Later, the difference between the different waves
was reduced before the HD and after the same HD. The derivations
in intercostal spaces were conserved to avoid a different
positioning and, as consequence, a different morphology that
contaminated the changes in the layouts that might have
appeared, which is why we used self-adhesive electrodes
throughout the treatment.