How to manage blood pressure during dialysis if the dialysis machine cannot monitor blood pressure?

Managing Blood Pressure During Dialysis Without Machine Monitoring

If the dialysis machine cannot monitor blood pressure, you must implement manual blood pressure measurements at minimum twice per session (pre- and post-dialysis) using a validated manual sphygmomanometer with proper technique, and increase measurement frequency to every 30-60 minutes during the session for patients at risk of intradialytic hypotension. 1

Minimum Required Manual Measurements

When machine monitoring is unavailable, establish this baseline protocol:

• Measure blood pressure at least 5 minutes before vascular access needle placement, as needle insertion causes substantial stress-induced elevation that does not reflect true blood pressure status 1
• Obtain both seated and standing measurements at the start and end of each session to detect orthostatic hypotension (≥15 mmHg systolic or ≥10 mmHg diastolic drop after 2 minutes standing) 1, 2
• Patient must sit quietly for 5 minutes with feet flat on floor and arm supported at heart level before each measurement 1

Technical Requirements for Accurate Manual Measurement

Manual measurements require strict adherence to technique to avoid the systematic overestimation seen with poorly validated automated devices (which can overestimate by 14/7 mmHg): 1

• Use auscultatory method with Korotkoff sounds for diastolic pressure determination 1
• Ensure cuff bladder encircles at least 80% of arm circumference 1
• Avoid caffeine, exercise, and smoking for at least 30 minutes before measurement 1
• Regularly validate equipment, as inaccurate devices are a major source of error 1

Increased Monitoring Frequency for High-Risk Patients

For patients experiencing hypotensive episodes or requiring vasopressor support to maintain mean arterial pressure ≥65 mmHg, increase manual blood pressure measurements to every 30-60 minutes throughout the dialysis session. 1, 2 This is critical because intradialytic hypotension can cause end-organ ischemia and increased mortality risk. 2

The evidence shows that pre- and post-dialysis measurements alone are imprecise estimates of interdialytic blood pressure and have either no association or U/J-shaped associations with mortality, making intradialytic monitoring essential for hemodynamic stability. 3

Alternative Measurement Sites

When bilateral arm access limitations exist:

• Measure blood pressure in thighs or legs using appropriately sized cuff in supine position only 1
• Critical caveat: Lower limb systolic blood pressure can be 30% higher than brachial pressure in young patients, making standard 140 mmHg targets invalid for leg measurements 1

Practical Algorithm for Manual Monitoring Schedule

Standard-risk patients (no history of intradialytic hypotension):

• Pre-dialysis: seated and standing measurements 1
• Mid-dialysis: one measurement at approximately 2 hours 1
• Post-dialysis: seated and standing measurements 1

High-risk patients (history of intradialytic hypotension, requiring vasopressors, or mean arterial pressure concerns):

• Pre-dialysis: seated and standing measurements 1
• Every 30-60 minutes during treatment 1, 2
• Post-dialysis: seated and standing measurements 1

Beyond In-Center Measurements

Home blood pressure monitoring or 44-hour ambulatory blood pressure monitoring provides more accurate assessment of true blood pressure burden than in-center measurements alone and has superior risk prediction for all-cause and cardiovascular mortality. 3, 1 When available, implement home blood pressure monitoring twice daily covering interdialytic days over 1-2 weeks or twice daily for 4 days following midweek treatment. 3, 1

Critical Pitfalls to Avoid

• Never measure blood pressure immediately after needle insertion, as this causes stress-induced elevation that does not reflect true status 1
• Never rely on isolated pre- or post-dialysis readings alone for diagnosing or managing hypertension, as they correlate poorly with interdialytic ambulatory blood pressure 1
• Do not use unvalidated automated devices without proper calibration, as they systematically overestimate blood pressure in dialysis patients 1
• Do not continue aggressive ultrafiltration in hypotensive patients requiring vasopressors, as this causes end-organ ischemia 2

Managing Intradialytic Hypotension Without Continuous Monitoring

When hypotension occurs during manual monitoring:

• Maintain mean arterial pressure ≥65 mmHg to ensure adequate tissue perfusion 2
• Consider increasing target dry weight by 0.5-1.0 kg if patient cannot tolerate current ultrafiltration goals even with vasopressor support 2
• Limit ultrafiltration rate to <6 mL/h/kg to reduce mortality risk 2
• Lower dialysate temperature to 35-36°C (instead of 37°C) to increase peripheral vasoconstriction and reduce hypotensive episodes 2