Usefulness of ABPM and bioimpedance for the treatment and control of hypertension in patients on chronic haemodialysis

Nefrologia (Engl Ed). 2021 Jan-Feb;41(1):17-26. doi: 10.1016/j.nefroe.2020.06.019. Epub 2021 Mar 10.

Abstract

Introduction: Hypertension is very common in haemodialysis (HD) patients, and is associated with increased morbidity and mortality rates. The goals of our research were to: 1. Measure blood pressure (BP) during HD sessions; 2. Study BP in between HD sessions with 44-h Ambulatory Blood Pressure Monitoring (ABPM); 3. Evaluate changes in treatment after the ABPM; 4. Perform bioimpedance spectroscopy (BIS) on all patients and, in those hyper-hydrated or hypertensive according to ABPM, assess for changes in BP after adjusting the dry weight; 5. Identify factors associated with average systolic and diastolic BP measured by ABPM.

Material and methods: Prospective observational study, which included 100 patients from our dialysis unit. We measured BP before and after the HD sessions for two weeks and then, mid-week, we attached the ABPM device to the patients for 44 h. Before starting the following dialysis session, we performed BIS. A second ABPM was performed on hyper-hydrated patients and patients hypertensive according to ABPM to evaluate changes in BP values.

Results: According to the ABPM, 65% of patients had daytime BP > 135/85 mmHg, 90% night-time BP > 120/70 mmHg and 76% average BP > 130/80 mmHg; 11% had a dipper pattern, 51% non-dipper and 38% riser. The average systolic and diastolic BP readings were 4.7 mmHg (3.8%) and 1.1 mmHg (1.64%) higher on the second day. The dose of antihypertensive medication had to be lowered in 6% of patients, 9% had to stop taking it, 28% needed increased doses and 17% had to add a new drug. The pre-HD diastolic BP best matched the ABPM. After performing the bioimpedance and adjusting dry weight, there was a statistically significant decrease in all BP values. The univariate analysis showed that the average systolic BP was higher in patients with a high-calcium dialysis bath, more antihypertensive drugs and higher doses of EPO. The multivariate analysis showed significant association for EPO and number of drugs (p < 0.01). The average diastolic BP was higher in younger patients and patients with lower Charlson index, lower body mass index and less diuresis, those on higher doses of EPO and non-diabetics. The linear regression study showed age (p < 0.005), body mass index (p < 0.03) and EPO (p < 0.03) as significant variables.

Conclusions: Our study shows: 1. The variability of hypertension criteria according to use of BP values from during the HD session or ABPM; 2. The variability of BP in the interdialysis period; 3. That the pre-dialysis diastolic BP best corresponds with the ABPM. 4. That the use of both BIS and ABPM improves the control of BP; 5. That the dose of EPO is the most important factor associated with hypertension in our patients.

Keywords: Ambulatory blood pressure monitoring; Bioimpedance spectroscopy; Haemodialysis; Hemodiálisis; Hipertensión arterial; Hypertension; Monitorización ambulatoria de la presión arterial; bioimpedancia espectroscópica.