What happens if during hemodialysis (HD) for End-Stage Renal Disease (ESRD), dialysis lines become clotted and you are unable to return blood to the patient?

Emergency Management of Clotted Hemodialysis Lines with Inability to Return Blood

Immediate Clinical Consequences

When dialysis lines become clotted during hemodialysis and blood cannot be returned to the patient, the patient loses the blood volume trapped in the extracorporeal circuit (typically 200-300 mL), which can precipitate acute hemodynamic instability, particularly in volume-depleted or cardiovascularly compromised patients. 1

Critical Immediate Actions

• Stop the blood pump immediately to prevent further complications and clotting of the remaining circuit 1
• Do not attempt to force blood return through a clotted line, as this risks dislodging thrombus and causing pulmonary embolism 2
• Assess hemodynamic stability - monitor blood pressure, heart rate, and symptoms of hypovolemia 3
• Administer IV fluid resuscitation through a separate peripheral or central line if hypotension develops 3

Blood Volume Loss and Patient Impact

The trapped blood volume represents a significant acute loss that compounds the already compromised cardiovascular status of ESRD patients:

• Hypovolemia risk: The 200-300 mL blood loss can trigger intradialytic hypotension, which occurs in 15-50% of HD treatments and is associated with vascular access thrombosis, inadequate dialysis dose, and increased mortality 3
• Inadequate dialysis delivery: The premature termination results in reduced treatment time and inadequate urea clearance, contributing to underdialysis 1
• Anemia exacerbation: Repeated blood loss from clotted circuits worsens the baseline anemia in ESRD patients 4

Management Algorithm

Step 1: Stabilize the Patient

• Fluid replacement: Administer 250-500 mL normal saline IV through alternative access to replace lost blood volume 3
• Monitor vital signs continuously for 30-60 minutes post-event 5
• Assess for symptoms of air embolism (chest pain, dyspnea, cardiac arrest) if any air entered the circuit during the clotting event 5

Step 2: Address the Clotted Access

• Do not attempt thrombolytic therapy through the clotted dialysis lines during an active session 6
• Clamp all lines to prevent any potential air entry or further complications 1
• Document the effective dialysis time accurately, excluding the period after clotting occurred, as this impacts adequacy calculations 1

Step 3: Establish Alternative Dialysis Access

• Place a temporary dialysis catheter if the patient requires immediate continuation of dialysis to achieve adequate treatment time 1
• Preferred site: Internal jugular vein (recirculation 0.4%) over femoral vein (recirculation 13.1%) for optimal dialysis delivery 1
• Catheter length: Use catheters >20 cm to minimize recirculation (8.3% vs 26.3% for shorter catheters) 1

Step 4: Definitive Access Management

• Thrombectomy within 24-48 hours: Early intervention on the thrombosed access optimizes long-term patency 1
• Endovascular approach preferred: Mechanical thrombectomy combined with balloon angioplasty has 75-94% clinical success rates 1
• Surgical consultation: Consider if endovascular declotting fails or if thrombosis recurs >2 times within one month 1

Prevention of Recurrence

Monitoring for Access Dysfunction

• Blood flow rate <300 mL/min is the primary warning sign of impending thrombosis 1
• Prepump arterial pressure <-250 mm Hg indicates significant inflow obstruction 1
• Venous pressure >250 mm Hg suggests outflow stenosis 1
• Progressive decline in URR <65% (or Kt/V <1.2) indicates inadequate dialysis delivery from access dysfunction 1

Anticoagulation Strategy Optimization

• Regional citrate anticoagulation is preferred over systemic heparin for patients with recurrent clotting, as it provides superior circuit anticoagulation without systemic effects 7, 8
• Avoid heparin-free dialysis as routine practice, as it increases circuit clotting risk 7
• Adequate heparin dosing: Ensure appropriate anticoagulation protocol is followed, as dialyzer clotting reduces effective surface area and treatment adequacy 1

Common Pitfalls to Avoid

• Never attempt to "push through" clotted lines: This can cause pulmonary embolism, which has been reported as fatal in dialysis patients 2
• Do not underestimate blood loss: The trapped volume may seem small but is clinically significant in ESRD patients with limited cardiovascular reserve 3
• Avoid delaying access evaluation: Waiting until complete thrombosis occurs makes salvage more difficult; intervene at first signs of dysfunction 1
• Do not ignore inadequate dialysis delivery: Document reduced treatment time and adjust subsequent sessions to compensate for missed dose 1
• Never reuse a clotted dialyzer: Clotting reduces effective surface area and clearance, even if partially patent 1

Documentation Requirements

• Record exact time dialysis was terminated due to clotting 1
• Calculate actual effective treatment time excluding the period after clotting 1
• Document blood flow rates achieved before clotting occurred 1
• Note estimated blood loss (circuit volume) for anemia management 4
• Report as a quality assurance event to track access complication rates 1, 3