Kinks in Hemodialysis Tubing and Hypotension
No, kinks in hemodialysis tubing do not cause hypotension (low arterial pressure) in the traditional sense—instead, they cause a characteristic decrease in both prepump arterial and venous circuit pressures, which can lead to hemolysis and life-threatening complications. 1
Understanding the Pressure Changes from Kinked Tubing
Kinked tubing creates a distinct pressure pattern that differs fundamentally from typical intradialytic hypotension:
Postpump tubing kinks cause sustained, significant decreases (>25 mmHg) in both prepump arterial and venous circuit pressures, which is the opposite of what occurs with access problems or other obstructions 1
The highly occlusive setting of the roller blood pump means that postpump obstructions may not cause noticeable changes to monitored pressures, making kinks potentially dangerous and difficult to detect 1
When postpump arterial tubing kinks occur, they decrease blood flow rate and can cause acute hemolysis, which was documented in 5 patients over 10 days (4 deaths) at one clinic 1
True Causes of Intradialytic Hypotension
The actual causes of low blood pressure during hemodialysis are unrelated to tubing kinks and include:
Excessive ultrafiltration volume and rate, which is responsible for 70% of premature dialysis terminations due to hypotension and cramping 2
Inadequate achievement of appropriate dry weight, where the target may be set too low, causing hypovolemia 2
Autonomic dysfunction and impaired cardiovascular compensation, particularly in high-risk ESRD patients 3, 4
Dialysate-related factors including acetate-containing dialysate (which inappropriately decreases vascular resistance) and elevated dialysate temperature 2
Critical Distinction: Circuit Pressures vs. Patient Blood Pressure
It is essential to understand that circuit pressure changes from kinked tubing do not equate to patient hypotension:
Prepump arterial pressure ≥200 mmHg indicates access problems, not tubing kinks 5
Decreased circuit pressures from postpump kinks primarily threaten the patient through hemolysis, not through systemic hypotension 1
Patient blood pressure during dialysis is monitored separately and responds to ultrafiltration, volume status, and cardiovascular factors 2
Prevention and Monitoring
To prevent complications from both tubing kinks and true hypotension:
Regularly check blood tubing sets for kinks throughout treatment, particularly at bend points like tubing support clips and dialyzer inlets 1
Monitor circuit pressures for atypical trends within and between treatments, recognizing that sudden sustained decreases may indicate postpump obstruction 1
Address true hypotension by slowing ultrafiltration rate, reassessing dry weight, increasing dialysate sodium to 148 mEq/L, reducing dialysate temperature to 34-35°C, and administering midodrine 30 minutes before dialysis 2, 6, 5, 3
Common Pitfall to Avoid
Do not confuse decreased circuit pressures from kinked tubing with patient hypotension—they are separate phenomena requiring different interventions. Kinked tubing requires immediate identification and correction to prevent hemolysis, while patient hypotension requires dialysis prescription modifications and potentially pharmacological support 1, 2.