On this page
Asset Type
Manufacturer
Model
What This Guide Helps With
Troubleshooting no breath, apnea, or unreliable respiration detection caused by patient condition, sampling line issues, setup problems, or monitor faults.
Step-by-Step Troubleshooting
Ensure Patient Safety First
Treat a no breath or apnea alarm as a patient safety alarm first, not an equipment problem.
Confirm clinical staff are assessing the patient immediately. Do not silence or dismiss the alarm until the patient’s breathing status is verified.
Expected outcome: The patient is assessed for apnea, airway obstruction, respiratory depression, ventilator disconnection, or other clinical concerns.
Why it matters: A no breath or apnea alarm may indicate the patient is not breathing or that ventilation is not being detected.
Remove the Device From Active Troubleshooting if Patient Monitoring Is Still Needed
If the patient still requires EtCO2 or respiration monitoring, move monitoring to another working device or approved backup method before continuing equipment troubleshooting.
Expected outcome: Patient monitoring continues safely without relying on a questionable monitor.
If this resolves the immediate risk, stop clinical use of the suspect device and continue evaluation off-patient.
Verify the Reported Alarm or Detection Problem
Confirm the exact alarm or behavior reported by staff. Look for messages such as no breath, apnea, missing respiration rate, intermittent respiration rate, weak capnogram, or absent CO2 waveform.
Note when the problem occurs:
- Immediately after connecting the patient
- After patient movement
- During transport
- Only with a specific sampling line
- Only on battery power
- Intermittently during monitoring
- After switching patient type or care area
Expected outcome: The reported issue is confirmed and the failure pattern is understood.
Why it matters: Intermittent breath detection problems are often caused by setup, sampling, moisture, obstruction, or patient interface issues.
Check the CO2 Waveform, Not Just the Numeric Respiration Rate
Observe whether the capnogram waveform is present, stable, weak, irregular, or completely absent.
Expected outcome: A consistent waveform should appear with valid breathing, and the respiration rate should update appropriately.
Why it matters: If the waveform is poor or missing, the monitor may not be receiving a usable breath signal.
Inspect the Sampling Line or Cannula Connection
Confirm the CO2 sampling line is fully seated in the monitor and properly connected to the patient interface.
Check for:
- Loose connection
- Kinked tubing
- Crushed tubing
- Disconnected cannula
- Sampling line pulled loose during movement
- Wrong or incompatible accessory
- Moisture, secretions, or blockage
Expected outcome: The sampling path is secure, open, and appropriate for the patient setup.
If reconnecting or correcting the sampling line restores waveform and respiration detection, stop.
Replace the Sampling Line or Cannula With a Known-Good Compatible Accessory
Use a new or known-good Medtronic-compatible CO2 sampling line or cannula.
Expected outcome: A blocked, contaminated, damaged, or incorrect sampling line is ruled out.
If respiration detection becomes stable after replacing the line, document the accessory issue and return the monitor only if all testing passes.
Check for Patient Interface Placement Issues
Confirm the cannula, airway adapter, or sampling connection is positioned correctly for the patient type and breathing route.
For nasal/oral cannulas, verify the cannula is not displaced from the nose or mouth. For intubated or ventilated patients, verify the airway adapter and circuit connection are secure.
Expected outcome: The sample source is correctly positioned to capture exhaled CO2.
Why it matters: The monitor cannot detect breaths reliably if the sample line is not receiving exhaled gas.
Check for Low or Absent EtCO2 Readings
Observe whether EtCO2 values are missing, very low, dashed out, or inconsistent.
Expected outcome: If EtCO2 is absent or unstable, the no breath/apnea alarm may be caused by lack of valid CO2 detection rather than a standalone respiration rate problem.
Why it matters: Respiration rate on a capnography monitor depends on breath detection from the CO2 waveform.
Confirm Alarm Settings and Patient Type
Check whether the apnea/no breath delay, respiration rate limits, and patient type are appropriate for the patient being monitored. Do not change clinical alarm settings without clinical approval.
Expected outcome: Alarm behavior matches the intended clinical setup.
Why it matters: Incorrect patient type or alarm delay settings can cause alarms to occur sooner, later, or differently than staff expect.
Check for Moisture or Contamination at the Sample Connection
Inspect the sampling inlet area and sampling line connection for visible moisture, residue, or contamination. Do not force fluid into or out of the device.
Expected outcome: No moisture or contamination is present at the external sample connection.
Why it matters: Moisture or contamination can interfere with sample flow and cause unreliable CO2 and respiration readings.
Restart the Monitor Only After Patient Safety Is Addressed
If the issue is not occurring on an active patient, power cycle the monitor and allow it to complete startup normally.
Reconnect a known-good sampling line and check whether the alarm or unreliable detection returns.
Expected outcome: Temporary software or startup communication issues clear after restart.
If the issue clears and does not return during testing, document the restart and final functional check.
Compare Against a Known-Good Monitor if Available
Using the same patient setup or a test setup when appropriate, compare behavior with another Capnostream 35 or approved capnography monitor.
Expected outcome: The issue follows either the patient/accessory setup or the suspect monitor.
Why it matters: This helps separate a device problem from a sampling line, setup, or clinical condition.
Perform a Basic Functional Check Off-Patient
Use site-approved procedures to verify that the monitor powers normally, recognizes the sampling line, displays CO2/respiration information as expected, and alarms appropriately.
Expected outcome: The monitor should detect valid breaths and alarm appropriately when no breath condition is simulated or present per site procedure.
Do not return the monitor to service unless the issue is resolved and the device passes functional verification.
If the Problem Persists
If the no breath/apnea alarm or unreliable respiration detection continues after patient condition, setup, sampling line, accessory, alarm settings, and basic functional checks have been ruled out, the issue may be internal to the CO2 monitoring system, sampling pump, sensor pathway, software, or related electronics.
Remove the Capnostream 35 from service, label it Out of Service, and send it for repair or bench evaluation.
Knowing when to stop is proper troubleshooting. Do not continue using a monitor that cannot reliably detect respiration during patient care.
Clinical Use Tip
Do not troubleshoot unreliable apnea or respiration detection on an active patient unless patient safety is already controlled. Move the patient to another working monitor first if EtCO2 or respiration monitoring is required.
Therapy and monitoring continuity come first. Once the patient is safely monitored by another device or approved backup method, continue troubleshooting the suspect monitor off-patient.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Clinical staff reported the Medtronic Capnostream 35 was alarming no breath/apnea and intermittently losing respiration rate during monitoring."
Cause
What was observed during troubleshooting.
Example:
"Found CO2 sampling line partially kinked near the patient connection, causing weak waveform and unreliable breath detection."
Resolution
What action was taken.
Example:
"Replaced sampling line, verified stable CO2 waveform and respiration rate, confirmed alarm cleared, and returned monitor to service after functional check."
Helpful Details to Include (If Known)
- Exact alarm message displayed
- Whether patient was transferred to another monitor
- CO2 waveform present, weak, intermittent, or absent
- EtCO2 value displayed or missing
- Respiration rate displayed or dashed out
- Sampling line inspected
- Sampling line replaced
- Cannula or airway adapter placement checked
- Alarm settings reviewed with clinical staff
- Patient type setting verified
- Moisture or blockage noted
- Power cycle performed
- Compared with known-good monitor
- Power behavior, including whether the issue occurred on AC power or battery power
- Environmental factors such as transport, movement, humidity, moisture, or location-specific conditions
- Indicator lights, screen messages, alarms, or displayed status information
- Final device status
Final Thought
No breath and apnea alarms must be treated as patient safety events first. Once the patient is safe, Clinical Engineering should work logically through sampling line condition, accessory setup, waveform quality, alarm settings, and functional verification before suspecting internal failure. Clear CCR documentation helps show what was checked, what was found, and why the device was either returned to service or escalated for repair.
That is successful troubleshooting.