Bio-impedance monitoring in patients with intradialytic hypertension

Abstract

The current guideline for target blood pressure (BP) in patients with chronic kidney disease (CKD) according to the Kidney Disease: Improving Global Outcomes (KDIGO, 2012b) guidelines is 130/80mmHg (non-diabetics) and 140/90mmHg (diabetics). Haemodynamic instability is a common complication in haemodialysis (HD); however, the focus is mostly on intradialytic hypotension rather than intradialytic hypertension (IDH), giving one a good idea of how the scales tip in terms of prevalence, awareness and general knowledge of IDH among the dialysis community. Currently there is no standard definition of IDH. Definitions vary widely. Chazot et al. (2010) define IDH as systolic BP rise of ≥10mmHg from start to finish of HD, rise in mean arterial pressure (MAP) during dialysis of 15mmHg or hypertension that appears resistant to ultrafiltration (UF) during or immediately after dialysis. Locatelli et al. (2010) suggest that the prevalence of IDH among HD patients varies between 5% and 15%. Simply put, IDH is the paradoxical rise in BP during or immediately after HD. Inrig et al. (2007) and Inrig et al. (2009) showed that IDH increased the risk of hospitalisation and death, as reported in the Crit-Line Intradialytic Monitoring Benefit study and the United States Renal Data System HD study. The pathogenesis of IDH is unclear. A number of factors have been implicated and could be responsible, acting collectively or separately. Factors that might have an impact include subclinical volume overload, as indicated by Agarwal et al. (2010), activation of the sympathetic system and the renin-angiotensin-aldosterone system (RAAS), endothelial cell dysfunction, sodium gain during dialysis, use and route of administration of erythropoietin-stimulating agents and possible removal of antihypertensive agents during dialysis. The literature suggests that the management of IDH relies heavily on fluid dynamics and control of sodium in terms of diet as well as interdialytic management. Contradicting this statement, though, were the findings published by Van Buren et al. (2011); there was no difference in interdialytic weight gain (IDWG) between the IDH group and the control group in their study. This poses the following question: Is there a difference in hydration status between patients who develop IDH compared to patients with stable BP on dialysis?