Total conductivity remained within range because decreased sodium in the batch offset the increased potassium. The conductivity meter displayed normal values while delivering lethal potassium concentrations.
Na⁺ decreased + K⁺ increased = Total conductivity unchanged → MACHINE SAYS "PASS" — PATIENT DIES
When multiple patients exhibit unexpected symptoms, the common element — machine, room, or concentrate batch — must be suspected immediately.
Conductivity monitoring verifies total ionic strength, not individual ion composition. It cannot detect dangerous substitutions of one electrolyte for another.
Acute irritability, cramps, or hypotension during dialysis without clear cause should prompt immediate electrolyte testing and consideration of dialysate composition error.
Transferring a symptomatic patient to a proven-stable system is a critical diagnostic and therapeutic step that can confirm equipment-related causation.
New lots of concentrate should be introduced in a controlled manner, with enhanced monitoring of the first patients treated using that batch.
Machines fail. Displays lie. Patients tell the truth. Clinical observation remains the most essential safety layer in hemodialysis.
This event demonstrates that clinical observation remains an essential safety layer in hemodialysis. Equipment alarms and displays cannot replace trained assessment of patient response.
When unexplained adverse events occur, particularly in multiple patients, systematic investigation of water and concentrate must be initiated immediately — regardless of normal machine readings.
The machine said "PASS." The patient almost died. Trust your eyes, not the screen.