Effect of Hyperkalemia on Twave duration in hemodialysis patients

ABSTRACT INTRODUCTION: Uremia is a state of systemic poisoning affecting the cardiovascular, gastrointestinal, hematopoietic, immune, nervous, endocrine systems, electrolyte and acid base abnormalities partly due to renal excretory dysfunction.1A high potassium concentration in the extracellular fluid is a dangerous and often early complication of renal failure.2 The classic electrocardiographic manifestations of hyperkalemia include peaked T waves, widening of the QRS complex, loss of the P wave, “sine wave” configuration, or ventricular fibrillation and asystole. Although, ECG is generally speculated as a reliable rapid method for detection of potentially lethal hyperkalemia, however in the presence of profound hyperkalemia, there may be only minimal or non-specific ECG changes in hemodialysis patients, suggesting that one cannot rely on ECG features of hyperkalemia in renal failure.3However hyperkalemia in patients on maintenance hemodialysis can cause a decrease in T-wave duration on ECG.4 OBJECTIVE OF THE STUDY: To determine the correlation between T-wave duration on ECG and predialysis serum potassium level in maintenance hemodialysis patients. STUDY DESIGN: Cross sectional survey SETTING: Department of Hemodialysis, Sheikh Zayed Hospital, Lahore. DURATION OF STUDY : 6 months from the approved date of synopsis (27/02/2013). SAMPLE SIZE: 150 patients were included in this study. Sample size of 150 cases was calculated with 5% type-I error and 10 % type-II error and taking expected correlation coefficient between pre dialysis serum potassium level and duration of T wave in hemodialysis patients i.e -0.315. SAMPLING TECHNIQUE: Non probability purposive sampling DATA COLLECTION PROCEDURE: 150 patients that fulfilled the inclusion and exclusion criteria were included in the study. Permission was taken from hospital ethical committee. Informed consent to participate in the study was taken from patients. Bio data of all patients was entered in the proforma. Pre-dialysis sample of blood for potassium was drawn by the researcher without applying tourniquet on the limb to avoid false values and sent to Biochemistry laboratory of Sheikh Zayed Hospital, Lahore. The laboratory provided the report within 30 minutes.ECG was recorded in all those patients who had hyperkalemia. The duration of T-wave was measured by using standard scale (1 small box = 0.04 second). All the data was entered into a pre designed Proforma. All statistical analysis was done by using Statistical Package of Social Sciences version 15.0. RESULTS: We studied 150 patients undergoing maintenance hemodialysis at Hemodiaysis Unit of Sheikh Zayed Hospital, Lahore. The patients had a mean age of 42.18±12.49.The age range varied from 18 years to 70 years. There were 98 male and 52 female patients. The Karl Pearson correlation coefficient was calculatedby using the Statistical Package for Social Sciences Version 15.0 to see the correlation between the raised serum potassium level and decreased T wave duration calculated from the ECG. The Karl Pearson correlation coefficient was found to be 0.791 which denotes a positive correlation between decreased T-wave duration and hyperkalemia. P value was found to be 0.00 which is significant (p<0.05) CONCLUSION: We concluded that there is a strong correlation between hyperkalemia and decreased T wave duration in patients on maintenance hemodialysis. KEYWORDS: Hyperkalemia, Maintenance Hemodialysis, T wave duration