What are the possible causes of a blood pressure of 180/100 mmHg observed during the final 30 minutes of a hemodialysis session?

Hypertension (180/100 mmHg) During Final 30 Minutes of Hemodialysis

The most likely cause of hypertension developing during the last 30 minutes of hemodialysis is intradialytic hypertension driven by volume overload, sympathetic nervous system activation, and renin-angiotensin system stimulation—this phenomenon affects 5-15% of dialysis patients and signals inadequate volume control requiring reassessment of dry weight. 1

Primary Pathophysiologic Mechanisms

Intradialytic hypertension is defined as a blood pressure increase of >10 mmHg from pre- to post-dialysis, and this pattern identifies patients with persistently elevated interdialytic blood pressure and associates with increased hospitalization and mortality. 1

The underlying mechanisms include:

• Volume excess is the dominant driver—inadequate ultrafiltration leaves the patient above their true dry weight, triggering compensatory vasoconstriction and hypertension as dialysis progresses. 1, 2

• Sympathetic nervous system activation occurs as a compensatory response to perceived volume depletion, even when total body volume remains excessive. 1, 3

• Renin-angiotensin system stimulation contributes to inappropriate vasoconstriction during ultrafiltration in patients with volume overload. 1, 3

• Endothelial stiffness and arterial rigidity prevent normal vascular accommodation to volume changes during dialysis. 1

Critical Diagnostic Approach

When blood pressure rises to 180/100 mmHg during the final 30 minutes of dialysis, you must systematically evaluate:

• An SBP increase of >10 mmHg from pre- to post-dialysis into the hypertensive range in at least 4 of 6 consecutive dialysis treatments mandates extensive evaluation of blood pressure and volume management, including out-of-unit home blood pressure measurements and critical reassessment of dry weight. 1

• Interdialytic weight gains exceeding 4.8% of body weight indicate excess sodium and fluid intake and are independently associated with increased mortality when adjusted for comorbidity. 4

• Physical examination should assess for peripheral edema, elevated jugular venous pressure, and signs of volume overload that indicate the current dry weight target is set too high. 1, 4

Management Algorithm

Step 1: Reassess Dry Weight Target

• The primary intervention is to lower the dry weight target gradually over 4-12 weeks (or even 6-12 months in some patients), reducing by 0.1 kg per 10 kg body weight per dialysis session when attempting to achieve euvolemia. 4

• Volume overload underlies most cases of blood pressure elevation in dialysis, and nonpharmacologic treatments directed at volume control should be the first-line approach before initiating or escalating antihypertensive medications. 1

Step 2: Modify Ultrafiltration Strategy

• If the patient has clear signs of volume overload but develops intradialytic hypertension, the issue is ultrafiltration rate tolerance, not total volume status—consider extending dialysis time rather than abandoning the dry weight goal. 4

• Lengthening dialysis sessions or adding additional treatments can lower ultrafiltration rates below 10 mL/h/kg while achieving the same total volume removal, which is the most effective strategy to manage volume without precipitating complications. 4

Step 3: Sodium Management

• Dietary sodium restriction to <2 g/day can reduce interdialytic weight gains and facilitate sodium removal without stimulating thirst. 4

• Avoid high dialysate sodium concentrations or sodium profiling because they increase thirst, lead to greater interdialytic weight gains, and may paradoxically worsen blood pressure control. 1, 4

• Sodium ramping (starting with dialysate sodium of 148 mEq/L early in dialysis, then decreasing) may be associated with increased weight gain and variable increase in interdialytic blood pressure, making it inappropriate for patients with intradialytic hypertension. 1

Step 4: Antihypertensive Medication Adjustment

• If blood pressure is well controlled and antihypertensive medications interfere with ultrafiltration, reducing medications to allow for enhanced ultrafiltration is reasonable. 1

• When antihypertensive medications are already being used for blood pressure control and cardioprotection, it is reasonable to continue them unless they interfere with targeting euvolemia. 1

Common Pitfalls to Avoid

• Do not attribute rising blood pressure during dialysis to "inadequate ultrafiltration" and respond by increasing the ultrafiltration rate—this creates a vicious cycle where excessive ultrafiltration rates (>10 mL/h/kg) trigger compensatory hypertension while causing end-organ ischemia. 4, 5

• Do not abandon volume control goals when intradialytic hypertension occurs—instead, extend dialysis time to achieve the same total volume removal at a slower, better-tolerated rate. 4

• Do not rely solely on intradialytic blood pressure measurements—out-of-unit home blood pressure monitoring and ambulatory blood pressure monitoring better predict outcomes and should guide management. 1, 2

Long-Term Cardiovascular Implications

• Intradialytic hypertension with an SBP increase of >10 mm Hg from pre- to post-dialysis demonstrates an association with hospitalization and mortality. 1

• Achieving euvolemia through gradual dry weight reduction provides optimal blood pressure control without need for antihypertensive drugs and leads to regression of left ventricular hypertrophy, prevention of heart failure, and ultimately reduced cardiovascular mortality. 5

• The goal is to achieve normal extracellular fluid volume and blood pressure over the long term, even if this requires 6-12 months of gradual adjustment in patients with diabetes or cardiomyopathy who have impaired compensatory mechanisms. 4, 5