#672 Intradialytic hypotension and adverse symptoms are not related
Authors: Chaara Sabrine , Rootjes Paul , Bergtop Miquéla , Grooteman Muriel , Liu Peiyun , Nubé Menso , Wijngaarden Gertrude , de Roij van Zuijdewijn Camiel 
Published: May 2024

Abstract

Background and Aims
Intradialytic hypotension (IDH) is the most common side-effect of intermittent hemodialysis (HD). Yet, its definition lacks consensus about the magnitude of blood pressure (BP) drops, occurrence of adverse symptoms (AS) and/or interventions. Generally, BP is measured twice/hour, while additional readings are carried out when AS arise. Consequently, AS became a prerequisite for the diagnosis of IDH, both in the National Kidney Disease Outcomes Quality Initiative (KDOQI) and in the European Best Practice Guideline (EBPG). Yet, a large study on the associations between 8 IDH definitions and mortality, showed that an absolute nadir systolic blood pressure (SBP) &lt;90 mmHg or &lt;100 mmHg (with a pre-dialysis SBP &lt; 160 mmHg or SBP ≥160 mmHg resp.) is most strongly associated with mortality. Neither AS nor interventions were related to outcome. Due to the absence of reliable studies, however, it is still unclear whether IDH and AS are related. Therefore, 1) the occurrence of (a)symptomatic IDH was evaluated according to the nadir-based definition; 2) relations between real-time AS and IDH were explored; 3) associations between IDH-susceptibility and physical intradialytic patient-reported outcome measures (PID-PROMS) were analysed.

Methods
Forty HD patients were cross-over randomized to standard HD (S-HD), cool HD (C-HD), low-(LV) and high-volume (HV) hemodiafiltration (HDF), each for two weeks. Every second week, BP was measured every 15 minutes during treatment. While AS were monitored real-time, PID-PROMS were documented after each modality with a modified dialysis symptom index [mDSI] questionnaire. The occurrence of symptomatic and asymptomatic IDH, defined as a SBP &lt; 90 or 100 mmHg (depending on the pre-dialysis SBP), was evaluated. For each presentation of AS, we assessed its association with blood pressure by examining concurrent IDH using both the KDOQI/EBPG definitions and the nadir-based definition (Fig. 2). Patients were stratified into tertiles of IDH (IDH-prone, IDH-intermediate and IDH-resistant). The frequency and severity of discrete symptoms, recovery time and total symptom-burden were compared using logistic regression models and Kruskal-Willis tests.

Results
In 458 sessions, 222 IDH-episodes occurred of which 98% were asymptomatic. While nursing records revealed 24 real-time AS, 54% was BP-related and 17% fulfilled the nadir-based criteria, leaving 46% of AS unrelated to IDH (Fig. 2). IDH-prone patients experienced headaches more frequently (p = 0.01), and perceived dizziness (p = 0.05) and shivering (p &lt; 0.01) more severely. No associations were found between IDH-susceptibility and symptom-burden, recovery time, or other discrete side-effects.

Conclusions
1) Most IDH-episodes are asymptomatic; 2) Conversely, 46% of AS occur without IDH and (3) PID-PROMS are completely independent of IDH-susceptibility. 4) Symptom-based definitions severely underestimate IDH, when compared to a nadir-based IDH definition.