Journal of Human Hypertension (2001) 15, 775–779 2001 Nature Publishing Group All rights reserved 0950-9240/01 $15.00 www.nature.com/jhh ORIGINAL ARTICLE Determinants of mean arterial pressure and pulse pressure in chronic haemodialysis patients AB Abdelfatah, G Motte, D Ducloux and JM Chalopin Department of Nephrology, Dialysis, and Renal Transplantation, Saint Jacques Hospital, Besanc¸on, France Hypertension is highly prevalent in the dialysis popu- 1.84; 95% CI, 1.07–3.18, for 1% increase in IWG), and lation, and has been implicated in the pathogenesis of current smoking (RR, 2.59; 95% CI, 1.13–5.92) and nega- the observed excess of cardiovascular morbidity and tively with Hb concentration (RR, 0.92; 95% CI, 0.84– mortality in these patients. Nevertheless, there are no 0.99, for a 1 g/100 ml in Hb). Mean predialytic MAP was -reports on the clinical and biochemical determinants of 98 ؎ 15 mm Hg and significantly decreased after dialy -both pulse pressure (PP) and mean arterial pressure sis (91 ؎ 16 mm Hg; P Ͻ 0.0001). In multivariate analy (MAP) in dialysis populations. A total of 541 haemodia- sis, a 10 mm Hg increase in MAP was positively associa- lysed patients from 11 dialysis centres were included ted with parathyroid hormone (PTH) (RR, 1.32; 95% CI, in the study. The demographic, clinical, and biological 1.15–1.6, for 50 ng/ml in PTH), erythropoietin (EPO) characteristics were recorded. Both pre- and post- treatment (RR, 1.09; 95% CI, 1.03–1.16), and current dialytic blood pressures (systolic and diastolic) were smoking (RR, 1.87; 95% CI, 1.39–2.41). PP and MAP are measured. PP and MAP were calculated. Mean predia- associated with different clinical parameters. Most of -lytic PP was 67 ؎ 17 mm Hg and significantly decreased these factors are potentially reversible. Smoking cess after dialysis (60 ؎ 18 mm Hg; P Ͻ 0.0001). In multivari- ation, correction of anaemia and limitation of IWG ate analysis, a 10 mm Hg increase in PP was positively should be important challenges for physicians in care associated with age (RR, 2.01; 95% CI, 1.35–5.01, for a of dialysis patients. 10-year increase in age), diabetes mellitus (RR, 1.08; Journal of Human Hypertension (2001) 15, 775–779 95% CI, 1.04–1.14), interdialytic weight gain (IWG) (RR, Keywords: mean arterial pressure; pulse pressure; haemodialysis Introduction (increased sympathetic activity, fluid retention, acti- vation of the renin-angiotensin axis, etc) have been Cardiovascular disease (CVD) is the major cause of incriminated. Moreover, some clinical and bio- mortality both in the general population and in chemical parameters, including age, interdialytic patients with end-stage renal disease (ESRD) weight gain, erythropoietin (EPO) treatment, and accounting for approximately 40% of all deaths in 1,2 hyperparathyroidism have been also associated with both demographic groups. Nevertheless, com- hypertension in this patient category.4 pared to the general population, dialysis patients Blood pressure consists of both a steady compo- have disproportionately high rates of arteriosclerotic nent (mean arterial pressure, MAP) and a pulsatile outcomes, and CVD mortality in this patient cate- component (pulse pressure, PP). Major determinants gory is 10 to 20 times higher than in the general 3 of MAP are ventricular ejection and peripheral vas- population. Hypertension is highly prevalent in the 7,8 1,4 cular resistance. PP, the difference between sys- dialysis population, and has been implicated in tolic blood pressure (SBP) and diastolic blood press- the pathogenesis of the observed excess of cardio- 5,6 ure (DBP), is also made up of two major vascular morbidity and mortality in these patients. components, one due to ventricular ejection inter- The pathophysiology of dialysis-associated acting with the viscoelastic properties of the large hypertension is multifactorial. Several mechanisms arteries and the other due to wave reflection.7,8 The distinction between the two components of blood pressure is clinically relevant because new evidence Correspondence: Dr Didier Ducloux, Department of Nephrology, Dialysis, and Renal Transplantation, Saint Jacques Hospital, suggest that PP is a more sensitive measure of car- Besanc¸on, France. E-mail: adjusyȰwanadoo.fr diovascular risk than other indices of blood pressure Received 14 November 2000; revised and accepted 19 June 2001 (DBP, SBP, and MAP).9 Moreover, arterial stiffening Determinants of MAP and PP in chronic haemodialysis patients AB Abdelfatah et al 776 is very pronounced in renal patients accounting for used in analyses were the means of all predialysis an increase in PP in this population compared to during 1 week. controls.10 Age, gender, dry weight, size, residual renal func- Nevertheless, there is no report on the clinical and tion, haemodialysis duration, weekly haemodialysis biochemical determinants of both PP and MAP in session duration, diabetes mellitus, smoking status, the dialysis population. Such a knowledge may help compliance, past history of cardiovascular events physicians in the comprehensive approach of hyper- (CVE), binephrectomy or parathyroidectomy, anti- tension in this patient category. We reported base- hypertensive drugs, and EPO use were assessed line data of a prospective survey study in 541 hemo- through anamnesis and medical records. dialysed patients. Blood pressure was measured and both PP and MAP were calculated to determine fac- Residual renal function: Data on estimated urine tors associated with the different components of volume were collected and reported as a dichot- blood pressure. omous variable, less than or greater than 200 ml/24- h. Patients with estimated urine output of less than Patients and methods 200 ml/24 h were considered to have lost their residual renal function (RRF) whereas patients with Patients characteristics estimated urine output greater than 200 ml/24 h A total of 541 patients with coronary heart disease were considered to have preserved RRF. were included in a prospective survey study of car- diovascular morbidity and mortality in April 2000. Compliance: Behavioural compliance was evalu- The demographic characteristics of the study popu- ated by physicians in each centre and categorised as lation are depicted in Table 1. All the dialysis good or moderate. centres in Bourgogne-Franche Comte´ were asked to participate in the study. The inclusion criteria Smoking behaviour: With respect to smoking included coronary heart disease for at least 3 months behaviour, subjects were categorised as current or and the absence of acute illness at the time of the former smokers and those who never smoked. study. Primary renal disease: Primary renal disease was Blood pressure assessed through medical records and categorised as chronic glomerulonephritis, chronic interstitial Predialytic blood pressure (SBP, DBP) was measured nephritis, polycystic kidney disease, diabetes mel- by a nurse using a semi-automatic device, based on litus, nephroangiosclerosis, or undetermined. an oscillometric method with the patient in a sitting position after resting for more than 5 min before Nutritional status: Normalised protein catabolism starting the dialysis session. Postdialytic blood rate (nPCR) and albumin concentration were pressure was measured using the same method determined. Body mass index (BMI) was calculated 10 min after the end of the dialysis session. Pulse (weight (kg)/height (m)2). pressure (SBP − DBP) was calculated. MAP was defined as DBP plus one-third of PP. The values Dialysis adequacy: Kt/V was assessed using Dau- girdas 2 formula. Weekly dialysis time was also recorded. Table 1 Demographic, clinical and biological characteristics of the study population Ultrafiltration: Ultrafiltration was calculated as the Age (years) 66 ± 13 patient’s weight at the beginning of each session Gender (M/F) 340/201 minus the weight after the session, divided by the Diabetes 19% nephrologist’s determined dry weight. Ultrafil- Past history of cardiovascular disease 51% Binephrectomy 3.6% tration was calculated on the basis of the average of Current smokers 26% all measurements in the study week. BMI 24 ± 4.1 Haemodialysis duration (months) 41 ± 44 Haemodialysis session duration (hour/week) 12.1 ± 1.1 Statistical analysis UF rate 3.6 ± 1.4 Kt/V 1.47 ± 0.33 Results are given as mean Ϯ s.d. nPCR 1.04 ± 0.24 Initially, univariate analyses were carried out in Albumin (g/l) 39 ± 4 Hb (g/100 ml) 10.7 ± 1.9 order to examine the relationship between predialy- PTH (ng/ml) 236 ± 248 sis PP (or MAP), and a number of potential inde- Predialytic PP (mm Hg) 67 ± 17 pendent variables. Among the latter, covariates to Postdialytic PP (mm Hg) 60 ± 18 enter multivariate analyses were selected as follows: Predialytic MAP (mm Hg) 98 ± 15 Postdialytic MAP (mm Hg) 91 ± 16 • Continuous variables were tested using Student’s t-test or Mann–Whitney’s non-parametric test. Journal of Human Hypertension Determinants of MAP and PP in chronic haemodialysis patients AB Abdelfatah et al 777 • Categorical variables were tested using Pearson’s Table 3 Factors associated with predialytic PP chi-square, or Fisher’s exact test. Parameter RR CI The alpha threshold for covariate selection was 0.20. Such variables linked with PP (or MAP) with P- Age (for a 10 years increase in age) 2.01 1.35–5.01 values less than 0.20 were retained for multivariate Diabetes mellitus 1.08 1.04–1.14 analyses, medical knowledge of the variables guid- IWG (for 1% increase in IWG) 1.84 1.07–3.18 Smoking status 2.59 1.13–5.92 ing the final choice. Selected covariates were Haemoglobin (for a 1 g/100 ml in Hb) 0.92 0.84–0.99 entered into stepwise multiple-regression analysis. Starting with as many covariates as were chosen (either statistically or otherwise), the software per- formed backwards stepwise selection, the limit to Mean arterial pressure remove a covariate being a P-value of 0.10.