J EVANS2, R WALKER1,2, S WILSON1,2,3
1ALFRED HEALTH, Melbourne, Victoria; 2Monash University, Melbourne, Victoria; 3BAKER IDI, Melbourne, Victoria
Aim: To characterise intradialytic systolic blood pressure (SBP) changes across individual and sequential outpatient haemodialysis (HD) treatments.
Methods: Continuous beat-to-beat SBP monitored using SOMNOtouchTM NIBP in parallel to routine therapy in 17 stable HD outpatients (76% male, 41% diabetic, 17% vascular catheter, mean age 64 years (range 23-83 years), mean (+SD) dialysis vintage 59+48 months. 7 patients underwent sequential monitoring across 1 week of treatment. Following noise reduction by median-hybrid filter, the SBP signal was analysed by summative intradialytic range, start and end-HD SBP and overall variability. Sequential HD sessions were assessed intra-individually by repeated ANOVA and paired-matrix Kolmogorov-Smirnov distribution analyses.
Results: There were no symptomatic SBP events observed. On aggregate there was a net upward SBP trajectory 4+11mmHg from start-HD SBP to end-HD SBP with a large, asymptomatic intraHD-SBP peak-to-trough gap of 26+17mmHg (range 9-86mmHg). The greatest net SBP changes were associated with ACE inhibitor prescription (p<0.05). SBP variability as measured by standard deviation was positively associated with the presence of diabetes (p<0.05). Age was the strongest predictor of intradialytic SBP range (r2=0.6, p<0.05). Across serial HD each patient showed significant differences in SBP distribution patterns (p<0.001). Intraindividual mean (IQR) dispersal across start, end and intraHD-mean SBP was 12 (6-18mmHg), 12 (5-16mmHg) and 14 (9-18mmHg) respectively. There was no common pattern of summative or time-point SBP reduction over the course of 1 week.
Conclusions: Substantial asymptomatic SBP volatility is common during HD when characterised using continuous monitoring techniques and the pattern of SBP behaviour is inconsistent from one treatment to the next. These observations raise doubt about the usefulness of intermittent conventional recordings of SBP, particularly in guiding the personalisation of HD prescription.