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Long Interdialytic Gap Cardiovascular Risk — ESENeph MCQ

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EasyHaemodialysisLong Interdialytic Gap Cardiovascular RiskESENeph

A 55-year-old man with CKD G5D on HD has an interdialytic potassium of 5.8 mmol/L measured on Monday (he last dialysed on Friday). This is the 'long gap' potassium. Why is the long interdialytic interval clinically important?

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Correct answer: D — The long interdialytic gap (2 days vs 1 day between sessions in thrice-weekly HD) is associated with significantly higher rates of sudden cardiac death, cardiovascular events, and hospitalisations due to greater accumulation of potassium, fluid, and uraemic toxins

In thrice-weekly HD (Mon/Wed/Fri or Tue/Thu/Sat), the long interdialytic gap (Friday-to-Monday or Saturday-to-Tuesday = 2 days) results in greater potassium accumulation, fluid overload, and uraemic toxin buildup compared to the short gap (1 day). Registry data consistently shows increased sudden cardiac death and cardiovascular events on the day after the long gap. Strategies to mitigate long-gap risk include: strict dietary compliance over weekends, potassium binder use on non-dialysis days, additional dialysis sessions, or every-other-day or daily HD schedules. This is one argument for more frequent dialysis modalities.

Reference: Foley et al 2011 – Long Gap Mortality; ERA-EDTA 2019 – HD Schedule