Guideline for Evaluating Altered Mental Status During Hemodialysis

Immediate Life‑Threatening Causes

Intradialytic Hypotension

Intradialytic hypotension accounts for roughly 15 % of premature dialysis terminations and is a major driver of intradialytic symptoms【1】【2】.
It commonly results from excessive ultrafiltration rate, an inaccurate estimated dry weight, or rapid fluid removal【1】【3】.
Prolonged hypotension can exaggerate urea rebound and impair cerebral perfusion, heightening the risk of neurologic deterioration【2】.

Rapid Electrolyte Shifts & Dialysate Composition Errors

Hemodialysis patients experience wide fluctuations in potassium, ionized calcium, magnesium, and bicarbonate, creating a dysrhythmogenic and neurologically unstable milieu【4】.
These fluctuations are especially problematic with high‑efficiency dialysis or incorrect dialysate prescriptions (e.g., inappropriate sodium, potassium, calcium, or use of acetate buffer)【5】【4】【1】【6】【3】.
Use of acetate‑buffered dialysate (instead of bicarbonate) increases the risk of neurological symptoms【1】【6】.

Aluminum Neurotoxicity

Two distinct syndromes exist: acute aluminum neurotoxicity and chronic dialysis encephalopathy【7】【8】.
Acute form: plasma aluminum 400–1,000 µg/L; presents with agitation, confusion, myoclonic jerks, seizures, often progressing to coma and death【7】【8】.
Chronic form: plasma aluminum 150–350 µg/L; insidious onset after 12–24 months of dialysis with stuttering speech, personality changes, motor disturbances, and hallucinations【7】【8】.
Symptoms typically worsen shortly after dialysis【8】 and may arise from aluminum‑contaminated dialysate or aluminum‑containing phosphate binders, especially when citrate is co‑administered【7】【8】.

Cardiac Dysrhythmias

29 % of dialysis patients develop life‑threatening ventricular dysrhythmias and 36 % experience silent myocardial ischemia during or after treatment【5】【4】.
Key risk factors include compromised myocardium, prolonged QTc interval, electrolyte abnormalities, intradialytic hypotension, and left ventricular hypertrophy (present in ~80 % of patients)【5】【4】.
Atrial fibrillation occurs in about 10 % of maintenance hemodialysis patients【5】.

Systematic Evaluation During the Dialysis Session

Clinical Assessment

Immediately check vital signs and blood pressure; hypotension is present in the majority of intradialytic mental‑status events【1】【2】.

Review of Dialysis Prescription

Verify ultrafiltration rate, dialysate composition (sodium, potassium, calcium, bicarbonate vs. acetate), and blood flow rate to identify potential contributors【1】【6】【3】.

Equipment Check

Inspect extracorporeal circuit pressures, ensure no air in lines, and confirm blood pump calibration to rule out mechanical causes【1】.

Point‑of‑Care Laboratory Tests

Obtain rapid glucose and electrolyte measurements (potassium, calcium, magnesium) to detect metabolic contributors【4】.

Additional Laboratory Evaluation

Measure plasma aluminum levels in chronic dialysis patients (>12 months) or those using aluminum‑containing binders; levels >150 µg/L suggest toxicity【7】【8】.
Perform a 12‑lead ECG to detect dysrhythmias, given their high prevalence in this population【5】【4】.

Imaging

Non‑contrast head CT is indicated for acute focal neurological deficits to identify cerebral air embolism (air in cerebral veins/sulci)【9】.

Common Pitfalls & Preventive Strategies

Do not attribute all intradialytic mental‑status changes to “uremia.” This can delay recognition of treatable causes such as air embolism or aluminum toxicity.
Do not assume hypotension alone explains symptoms; concurrent dysrhythmias occur in roughly 76 % of dialysis patients and must be evaluated【5】【4】.
Do not overlook medication review; renally cleared drugs (e.g., acyclovir) can accumulate and cause severe neurotoxicity if not dose‑adjusted.
Prevent dialysis disequilibrium syndrome in high‑risk patients by employing slower initial dialysis prescriptions rather than relying on treatment after onset.

Evidence‑Based Critical Factors in Sudden Unresponsiveness During Hemodialysis

Dialysate Composition Errors

In hemodialysis patients, using acetate‑buffered dialysate instead of bicarbonate‑buffered solutions has been shown to increase neurological symptoms by causing inappropriate vasodilation and venous pooling, highlighting the need to verify dialysate composition before each session. 10
Reducing blood‑flow rate or ultrafiltration rate in the middle of a dialysis treatment in response to acute symptoms does not correct the underlying cause and may compromise dialysis adequacy; therefore, such adjustments should be avoided until the primary problem is identified. 10

Cardiac Mortality and Arrhythmia Timing

Among individuals with end‑stage renal disease on maintenance hemodialysis, cardiac etiologies account for at least 40 % of all deaths, and sudden cardiac death comprises roughly 20 % of these cardiac deaths, underscoring the importance of rapid cardiac assessment during intradialytic events. 11
Arrhythmias frequently arise during the dialysis session and can persist for 4–5 hours afterward, driven by hemodynamic shifts and electrolyte fluctuations; continuous cardiac monitoring is therefore recommended throughout treatment and the immediate post‑dialysis period. 11

Management of Sudden Unresponsiveness During Hemodialysis – Evidence‑Based Recommendations

Cardiac Dysrhythmias

In hemodialysis patients, life‑threatening ventricular dysrhythmias occur in ≈ 29 % of treatment sessions, and overall dysrhythmias are present in ≈ 76 % of patients, accounting for ≈ 61 % of cardiac deaths. Prompt 12‑lead ECG acquisition and immediate defibrillation are therefore critical. 12
When ventricular fibrillation or pulseless ventricular tachycardia is identified, each minute without defibrillation reduces survival by 7–10 %; therefore, on‑site automated external defibrillators (AEDs) should be readily available and used without delay. 13

Intradialytic Hypotension

Excessive ultrafiltration (fluid removal beyond the patient’s estimated dry weight) is the most common cause of intradialytic hypotension; reviewing ultrafiltration rate and dry weight should be the first corrective step. 14
If hypotension is confirmed, administration of a normal‑saline bolus of 100–250 mL together with positioning the patient in Trendelenburg can rapidly restore blood pressure. 14
A prepump arterial pressure > 200 mmHg in the extracorporeal circuit signals inadequate blood flow and should prompt immediate circuit assessment. 15

Dialysate Composition and Temperature

Use of acetate‑buffered dialysate is associated with increased neurological symptoms due to inappropriate vasodilation; bicarbonate‑based solutions are preferred. 14
Lowering dialysate temperature to 35–36 °C has been shown to reduce the incidence of hypotensive episodes during treatment. 14

Equipment Integrity

Routine inspection for air in the extracorporeal circuit and verification that air detectors are functional are essential to prevent venous air embolism. 15
Confirming blood‑pump calibration is necessary because calibration errors can cause actual blood flow to be substantially lower than displayed, risking hemodynamic instability. 15
Evaluating the dialyzer for clotting is important, as clotting reduces effective membrane surface area and may precipitate intradialytic hypotension. 15

Patient Positioning During Resuscitation

If a patient becomes unresponsive, repositioning to the supine position should not be delayed when the recovery (lateral) position hampers assessment of signs of life; supine positioning facilitates rapid evaluation and intervention. 16

Causes of Disorientation After Hemodialysis (Cited Evidence)

Hemodynamic Factors

Rapid fluid shifts that exceed the vascular refilling capacity—especially when ultrafiltration rates are aggressive—produce intradialytic hypotension and transient cerebral hypoperfusion, a common trigger of post‑dialysis disorientation. 17, 18
A subset of patients develop paradoxical increases in blood pressure during fluid removal; both hypertensive and hypotensive episodes in these individuals can precipitate disorientation despite otherwise appropriate ultrafiltration. 18

Metabolic and Toxic Factors

Acute aluminum neurotoxicity occurs when plasma aluminum concentrations reach 400–1,000 µg/L, leading to agitation, confusion, myoclonic jerks, seizures, and potentially progression to coma and death. 19
Sources of toxic aluminum exposure include dialysate contaminated with 150–1,000 µg/L aluminum and the concurrent use of aluminum‑containing phosphate binders with citrate salts, which markedly increase intestinal aluminum absorption. 19
Chronic dialysis encephalopathy is associated with plasma aluminum levels of 150–350 µg/L after 12–24 months of dialysis; patients present with speech dysfluency, personality changes, spatial disorientation, motor disturbances, hallucinations, and paranoid behavior that worsen shortly after treatment, and most untreated individuals die within 6–12 months. 19
A plasma aluminum concentration > 150 µg/L should prompt evaluation for aluminum toxicity in chronic dialysis patients, particularly those receiving aluminum‑based binders. 19

Inadequate Dialysis Delivery

Technical problems such as access recirculation, insufficient blood flow, dialyzer clotting, pump calibration errors, and dialysate‑flow miscalibration diminish effective urea clearance, contributing to persistent uremic encephalopathy and disorientation. 20
Interruptions of treatment caused by clinical complications, equipment alarms, or premature termination reduce actual dialysis time, further risking ongoing uremic neurotoxicity manifesting as post‑dialysis disorientation. 20