Three Patients, One Carbon Tank, and a Chlorine Reading of 0.35

Immediate actions:

1. Stop dialysis on stations 1–3. Stop UF and blood flow. The priority is to stop further exposure.
2. Assess and support the affected patients - vital signs, oxygen, symptoms, and urine color. Treat chest pain and hypoxia seriously. Draw labs for hemolysis: plasma free hemoglobin, LDH, haptoglobin, bilirubin, and a CBC. Monitor for anemia and hyperkalemia.
3. Do not restart that loop until the water is verified safe.
4. Notify the medical director, the technician or water-treatment responsible person, and unit leadership. Document times, readings, and actions.
5. Preserve evidence: repeat chlorine testing at multiple points, record the meter and lot, and save the log.

Protecting stations 4–6:

• Confirm that the second loop is truly independent and that its chlorine result is acceptable.
• Test the second loop before continuing.
• If independence or test results are uncertain, stop all stations.

Returning blood: with suspected hemolysis, return blood cautiously and only per protocol; do not discard a patient's blood reflexively, but do not prolong exposure.

Chlorine/chloramine exposure:

• Cluster of patients on a shared water loop, with onset after treatment starts.
• Nausea, vomiting, chest tightness, metallic taste, and headache.
• Hemolysis signs: back pain, dark urine, falling hematocrit, and jaundice later.
• No fever initially; the water test is abnormal.

Dialyzer reaction:

• Usually one patient at a time, often with a new dialyzer or a first use.
• Fever, chills, flushing, itching, urticaria, chest tightness, and hypotension.
• Symptoms begin shortly after the start and improve when the circuit is stopped; the water test is normal.

Air embolism:

• Sudden dyspnea, chest pain, cyanosis, neurological signs, or cardiovascular collapse.
• Often associated with a visible air source, a disconnected line, or a chamber that ran dry.
• Does not produce a cluster tied to one water loop and does not cause dark urine.

The cluster pattern and the chlorine result make water contamination the leading explanation, but each patient still needs individual assessment.

Corrective actions:

• Replace or regenerate the carbon media as indicated; backwashing alone may not restore chlorine removal capacity.
• Inspect the pretreatment chain: softener, carbon tanks in series, and the RO.
• Verify the chlorine test method and meter against a known standard.
• Check whether the backwash procedure or timing allowed channeling or exhaustion.

Before resuming:

• Total chlorine at the post-carbon port must be within the unit's acceptable limit, typically below 0.1 mg/L, on repeated tests.
• Test at multiple points and at the start of the shift, not just once.
• Confirm RO water quality is within limits.
• Obtain medical director or responsible-person approval.
• Document the incident, the corrective action, and the verification results.

Patient follow-up:

• Repeat hemolysis labs and CBC; watch for delayed anemia.
• Report the event through the unit's incident and regulatory channels.
• Review water-treatment logs and staff competency.

Reasoning: conductivity and RO performance do not rule out chlorine breakthrough; carbon performance is verified by chlorine testing, not by conductivity.