An update review of intradialytic hypotension: concept, risk factors, clinical implications and management

Abstract

Intradialytic hypotension (IDH) is a frequent and serious complication of chronic haemodialysis, linked to adverse long-term outcomes including increased cardiovascular and all-cause mortality. IDH is the end result of the interaction between ultrafiltration rate (UFR), cardiac output and arteriolar tone. Thus excessive ultrafiltration may decrease the cardiac output, especially when compensatory mechanisms (heart rate, myocardial contractility, vascular tone and splanchnic flow shifts) fail to be optimally recruited. The repeated disruption of end-organ perfusion in IDH may lead to various adverse clinical outcomes affecting the heart, central nervous system, kidney and gastrointestinal system. Potential interventions to decrease the incidence or severity of IDH include optimization of the dialysis prescription (cool dialysate, UFR, sodium profiling and high-flux haemofiltration), interventions during the dialysis session (midodrine, mannitol, food intake, intradialytic exercise and intermittent pneumatic compression of the lower limbs) and interventions in the interdialysis period (lower interdialytic weight gain and blood pressure-lowering drugs). However, the evidence base for many of these interventions is thin and optimal prevention and management of IDH awaits further clinical investigation. Developing a consensus definition of IDH will facilitate clinical research. We review the most recent findings on risk factors, pathophysiology and management of IDH and, based on this, we call for a new consensus definition of IDH based on clinical outcomes and define a roadmap for IDH research.

Keywords: cardiovascular event; haemodialysis; intradialytic hypotension; roadmap; ultrafiltration.

FIGURE 1

Approaches to prevent and treat intradialysis hypotension. Approaches in which a safety signal has been described suggesting that outcomes may be impaired are indicated by the red 'Safety signal'.

FIGURE 2

IDH roadmap 2020. Roadmap towards a risk-based consensus definition of IDH based of BP values that predict outcomes and allow large-scale analysis of risk factors, impact on outcomes, selection of high-risk populations for interventional studies and assessment of impact of interventions. Different BP-related variables should be explored as predictors of outcomes and thus as potential components of the IDH definition. These include threshold for SBP, BP nadir, percentage change below baseline BP and others, including MAP values. Thresholds to grade the severity of the episodes should also be defined in a similar manner as we have different categories of AKI or CKD according to severity. In addition, the number of such IDH episodes per time period that is clinically relevant for outcomes risk should also be defined.