What is the cause of intradialytic hypertension (high blood pressure during dialysis)?

From the Guidelines

Intradialytic hypertension is primarily caused by volume overload due to excessive sodium and water intake, which can be managed by optimizing dry weight through ultrafiltration and educating patients on fluid and sodium restrictions. The underlying mechanisms of intradialytic hypertension are complex and multifactorial, involving sympathetic nervous system activation, renin-angiotensin system stimulation, endothelial dysfunction, and removal of antihypertensive medications during dialysis 1.

Key Factors Contributing to Intradialytic Hypertension

• Volume overload due to excessive sodium and water intake, leading to expansion of the extracellular fluid (ECF) volume 1
• Poor volume control, which can exacerbate hypertension and its detrimental effects on the cardiovascular system 1
• Inadequate ultrafiltration during dialysis, resulting in insufficient removal of excess fluid 1

Management Strategies

• Optimizing dry weight through ultrafiltration to minimize volume overload 1
• Educating patients on fluid and sodium restrictions between dialysis sessions to prevent volume overload 1
• Using lower dialysate sodium concentration (135-138 mEq/L) and extending dialysis time to allow for gentler fluid removal 1
• Considering pharmacological treatment with short-acting antihypertensives like nifedipine or captopril, and long-acting agents such as carvedilol or amlodipine for persistent cases 1

Importance of Regular Blood Pressure Monitoring

Regular blood pressure monitoring before, during, and after dialysis sessions is essential, as intradialytic hypertension is associated with increased cardiovascular morbidity and mortality 1. By prioritizing volume control and optimizing dialysis prescription, healthcare providers can help mitigate the risks associated with intradialytic hypertension and improve patient outcomes.

From the Research

Causes of Intradialytic Hypertension

• Intradialytic hypertension is a complex condition with multiple underlying causes, including:
  • Chronic extracellular volume excess, despite small interdialytic weight gains 2
  • Intradialytic vascular resistance surges, which may be driven by mediators other than endothelin-1 2, 3
  • Subclinical volume overload, sympathetic overactivity, activation of the renin-angiotensin system, endothelial cell dysfunction, and specific dialytic techniques 4
  • Activation of the renin-angiotensin-aldosterone system and sympathetic nervous system, volume and sodium overload, and endothelial dysfunction 5
• The pathophysiology of intradialytic hypertension is multifactorial and not fully understood, but it is associated with increased cardiovascular morbidity and mortality rates 5

Role of Dialysate Sodium Concentration

• Low dialysate sodium concentrations have been shown to decrease systolic blood pressure and ameliorate intradialytic hypertension 6
• The effect of dialysate sodium concentration on endothelial-derived vasoregulators, such as endothelin 1 and nitric oxide, is unclear and requires further study 6

Patient Characteristics

• Patients with intradialytic hypertension tend to have lower albumin and predialysis urea nitrogen levels, and smaller interdialytic weight gains 2
• Intradialytic hypertension is more common in older patients, those with lower dry weights, and those prescribed more antihypertensive medications 4