Blood Pressure and Weight Trends over the First 12 Weeks of Haemodialysis: A Retrospective Incident Cohort Study
Optimal blood pressure control (BP) in haemodialysis populations is achieved by reduction of extracellular fluid volume (measured by weight). This study examines BP and weight changes after initiation of haemodialysis.
Methods: Patients commencing haemodialysis with permanent intent at the Christchurch Home Haemodialysis Training Centre between 1995 and 2004 were included. Outcomes were hospitalisation, and weight and BP during the first 12 weeks of dialysis. Paired data were compared using t-tests expressed as mean ± SD.
Results: The 151 patients received 3-4 haemodialysis sessions over 5 weekdays (5 hours/session) through the observation period. Twenty-nine patients (19%) continued on antihypertensive treatment after starting haemodialysis (compared with 94% at baseline, P <0.001). The predialysis mean arterial blood pressure (MAP) was lower at the end of week dialysis compared with the predialysis MAP at the start of the week (mean decrease each week ranged from 3.64-6.67 mmHg, P < 0.0004). Following the 2-day weekend without dialysis the predialysis MAP returned to baseline values. The mean predialysis weight also fell over each week but rose during each weekend. The predialysis MAP for patients continued on antihypertensive drugs was 102.6 ± 15.8 mmHg compared with 106.4 ± 14.0 mmHg where medications were withdrawn (P=0.28). Ten patients (6.6%), all remaining on antihypertensive treatment, were hospitalised for cardiovascular events.
Conclusions: Frequent haemodialysis improves control of BP and weight even with withdrawal of antihypertensive medication. During the weekend “gap” BP control regresses to baseline. This suggests that more frequent dialysis may be beneficial in the first weeks of dialysis.