Blood pressure during the interdialytic period in haemodialysis patients: estimation of representative blood pressure values

Abstract

The estimation of representative blood pressure (BP) levels is difficult in haemodialysis (HD) patients as it is not known whether pre- or postdialytic blood pressure are predictive for the average interdialytic BP. Furthermore, the day-night BP rhythm can be disturbed in HD patients. Therefore, in this study, BP was measured during the interdialytic period using non-invasive ambulatory BP measurements in fourhypotensive, six normotensive, and 12 hypertensiveHD patients. It was assessed whether pre- or postdia-lytic BP was representative for the average interdia-lytic BP. Furthermore, the nocturnal BP reductionwas compared between HD patients, seven normotensive controls and eight treated subjects with essential hypertension. Postdialytic BP was superior topredialytic BP in predicting the average BP duringthe interdialytic period. BP did not differ significantly between day 1 and day 2 of the interdialytic period but increased rapidly in the hours before dialysis.Weight gain (corrected for actual body-weight) did not correlate significantly with the increment in sys-tolic BP (r=0.21; P = 0.2) or diastolic BP (r = −0.02; P = 0.5) during the interdialytic period. The nocturnaldecline in systolic BP was significantly attenuated(PPPPP<0.001) controls. We conclude that postdialytic BP is more representative for the average interdialytic BP than predialytic BP and should therefore be used to define hypertension in HD patients. BP increases rapidly in the hours before HD. Furthermore, the nocturnal reduction in BP is attenuated in HD patients, which might have consequences for the prescription of antihypertensive therapy.