Post-carbon chlorine result of 0.3 mg/L at shift change
It is 06:50 Monday at a 12-station unit. The PCT performing daily water checks records a total chlorine of 0.3 mg/L at the sample port after the secondary carbon tank. Your facility's action level is 0.1 mg/L. The primary carbon tank was rebed four weeks ago and the softener was regenerating normally overnight. The RO is running within range and conductivity is normal. Six first-shift patients are already on treatment; the second shift starts in 45 minutes. The tech who ran the test says, 'The reagent bottle might be expired, so it's probably a false reading,' and asks whether the six patients can just finish their runs.
1. What happens before any additional patient is put on, and what do you do about the six patients already running?
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Treat 0.3 mg/L as a real result until it is disproven. Chlorine and chloramine are not removed by the RO and cause dose-related hemolysis.
Immediately:
- Hold all new starts, including the entire second shift.
- Notify the charge nurse, the RN, the medical director and the water treatment operator.
- Retest properly - fresh, in-date DPD reagent, sample drawn from the same post-carbon port after adequate flush, read at the specified time in the colorimeter. Also test the post-RO/loop point.
- Do not resume until the source is corrected and consecutive tests at each carbon tank outlet and at the loop are below the limit.
The six running patients: monitor actively for hemolysis - low back or chest pain, dyspnea, chills, falling pressure, and dark red 'port-wine' blood in the arterial line. Assess and document each one; report any positive finding to the RN and the provider, and draw blood if symptomatic. Do not tell them nothing is wrong before you know. An expired reagent justifies a repeat test, never a decision to keep dialyzing.
2. If the result is confirmed on retest, where do you look for the cause before restarting the unit?
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Work upstream from the sample port.
- Carbon tank exhaustion. Verify the post-carbon sample point is genuinely downstream of both tanks, not one. Check whether the primary was properly rinsed and backwashed after the recent rebed; a rebed four weeks ago is a plausible link and worth documenting in the water log.
- Empty-bed contact time. Contact time falls as flow rises. Ask whether the unit added stations, opened an extra shift, or increased loop flow recently - more flow through the same beds can push breakthrough.
- Softener performance. Hardness breakthrough consumes carbon capacity faster. Check hardness results for the last several days, salt level, and regeneration log.
- Chlorine demand. Check whether the municipal supply changed (a system flush or a seasonal ammonia change shifts free chlorine to chloramine, which carbon adsorbs less effectively).
- Sampling technique and records. Review the prior week's chlorine log - were results trending up before today? Were samples taken from a stagnant line without flushing?
Document each check. The unit restarts only when both carbon outlets and the loop are below the action level, verified by two consecutive rounds.
3. Later that morning one of the six patients reports low back pain and his arterial line blood looks dark. How does this change your actions?
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You now have a probable clinical event, not just a water finding.
- Stop the treatment. Do not rinse back the blood - returning a hemolyzed circuit adds free hemoglobin and potassium to a patient who cannot clear them.
- Assess and support: vital signs, oxygen per protocol, notify the RN and provider immediately; be prepared for transfer if he is unstable.
- Draw the hemolysis workup - plasma free hemoglobin or visual pink/red plasma, haptoglobin, LDH, potassium, bilirubin, CBC - and save a pre-transfusion sample.
- Preserve evidence: dialysate sample from the machine, the water sample, the concentrate in use, and keep the machine out of service and tagged.
- Screen the other five patients for the same findings; chloramine exposure follows the water, not the person.
- Report: file the incident report, notify the medical director and water treatment operator, and follow your facility's adverse-event policy. Document objectively - times, symptoms, actions - and do not speculate about blame in the chart.