When is The Optimal Time to Measure Blood Pressure in Hemodialysis Patients?
The management of hypertension is difficult in hemodialysis patients. This is due to significant variability of blood pressure between pre, post and inter-dialytic periods that correlates to their respective intravascular status. The intravascular status can be assessed by measuring inferior vena cava (IVC) diameter using ultrasound. However, the exact time that IVC starts to become euvolemic post-hemodialysis was not known. This study aimed to determine the optimal time to measure blood pressure post-hemodialysis based on euvolemic state. A cross-sectional study involving 14 end-stage renal failure (ESRF) patients on regular hemodialysis was conducted in HUSM Hemodialysis Unit. Hourly blood pressure was taken using ambulatory blood pressure monitoring (ABPM) device. The ABPM was applied for 24 hours inclusive of 5 hours post-hemodialysis, (total of 24 readings). Serial ultrasonographic IVC diameter and blood pressure measurements were done at 10, 30 and 60 minutes post-hemodialysis. Median IVC diameter at 10 minutes was 1.33 cm (0% of the IVC diameter normalized), at 30 minutes was 1.55 cm (50% of the IVC diameters normalized) and at 60 minutes was 1.62 (64.3% of the IVC diameters normalized). The mean systolic blood pressure difference at 10, 30 and 60 minutes were 2.64, 0.64 and 2.79 mmHg respectively. The median diastolic blood pressure difference at 10, 30 and 60 minutes were -5.00, -.4.50 and 2.00 mm Hg respectively. An appropriate timing for blood pressure measurement is critical for optimum blood pressure control as it significantly affect the mortality of ESRF patients. From this study, the recommended post-hemodialysis blood pressure measurement in ESRF patients was at 60 minutes and should not be earlier than 30 minutes.