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What This Guide Helps With
Troubleshooting elevated PEEP or incomplete exhalation caused by circuit restrictions, valve problems, scavenging issues, moisture, accessories, or incorrect ventilation settings.
Step-by-Step Troubleshooting
1. Ensure Patient Safety First
Do not perform extended troubleshooting while the Carestation 600 Series is supporting an active patient.
If expiratory pressure remains elevated during a procedure:
- Notify the anesthesia provider immediately.
- Move the patient to another verified anesthesia machine or approved backup ventilation method.
- Maintain appropriate independent patient monitoring.
- Follow the facility’s anesthesia-machine failure procedure.
Expected: Patient ventilation no longer depends on equipment with unresolved elevated expiratory pressure.
Once the patient is safely supported by alternate equipment, continue troubleshooting in a controlled Clinical Engineering environment.
2. Confirm the Reported Condition
Review the alarm history and determine whether the issue involves:
- PEEP remaining above the selected value
- Airway pressure failing to return to baseline
- Continuous positive pressure between breaths
- Slow or incomplete exhalation
- Bellows or reservoir-bag behavior that appears abnormal
- The problem occurring only in a particular ventilation mode
- A specific displayed alarm or advisory message
Record the selected PEEP, measured PEEP, peak pressure, ventilation mode, breathing rate, and circuit configuration.
Expected: The reported condition can be reproduced and distinguished from a temporary clinical event or incorrect setting.
If the pressure returns to the selected baseline and the problem cannot be reproduced, complete the full system checkout before returning the device to service.
3. Verify Ventilator and Fresh-Gas Settings
Confirm that:
- The selected PEEP is appropriate for the test setup.
- The respiratory rate and inspiratory-to-expiratory ratio allow adequate exhalation time.
- Tidal volume or inspiratory pressure is not excessive for the test lung.
- Fresh-gas flow is not unnecessarily high.
- No alternate ventilation mode or previous case setting remains selected.
Use a manufacturer-compatible test lung rather than evaluating the condition on a patient.
Expected: Expiratory pressure returns to the selected PEEP level between breaths.
If correcting the settings resolves the issue, run the required checkout and stop troubleshooting.
4. Inspect the Patient Breathing Circuit
Trace the entire breathing circuit and check for:
- Kinked or compressed tubing
- Tubing trapped under equipment
- Blocked or contaminated connectors
- Incorrectly assembled circuit components
- Water accumulation in low points
- Occluded filters, heat-and-moisture exchangers, or airway adapters
- Accessories installed backward
- An undersized or incompatible breathing circuit
Remove unnecessary accessories and test with a known-good circuit and test lung.
Expected: Gas flows freely through the inspiratory and expiratory limbs, and pressure returns normally during exhalation.
If replacing the circuit or accessory resolves the problem, document the failed component and stop.
5. Check the Expiratory Path
Inspect the externally accessible expiratory components for:
- Moisture or contamination
- Misaligned breathing-system components
- Improperly installed expiratory flow-sensing components
- Damaged seals or connectors
- Debris that may restrict gas flow
- Components not fully seated after cleaning or reassembly
Do not force components into position. Follow facility infection-control procedures when handling contaminated breathing-system parts.
Expected: The expiratory path is correctly assembled, unobstructed, dry, and securely seated.
If reseating or replacing an approved external component resolves the issue, complete the system checkout and stop.
6. Inspect the Absorber and Breathing-System Assembly
Confirm that:
- The absorber canister is correctly installed.
- The canister and breathing-system assembly are fully latched.
- Disposable or reusable absorber components are compatible with the machine.
- No packaging, debris, or excess absorbent material is obstructing gas flow.
- Seals are present, clean, and undamaged.
- The breathing system was reassembled correctly after cleaning.
Use a known-good absorber assembly when available.
Expected: The breathing system passes checkout and allows unrestricted exhalation.
If the problem follows a particular absorber or external assembly, remove that component from service.
7. Evaluate the Scavenging System
Disconnect the machine from active patient use before changing scavenging connections.
Inspect the anesthetic-gas scavenging system for:
- A kinked or crushed transfer hose
- A blocked scavenging connection
- Excessive suction from the facility disposal system
- An incorrectly connected active scavenging interface
- A full reservoir bag or abnormal scavenging flow indication
- An adapter or hose restricting the exhaust path
Temporarily evaluate the machine using the approved facility method for isolating the external scavenging connection. Do not vent anesthetic gas into an occupied workspace.
Expected: Expiratory pressure remains stable when connected to a properly functioning scavenging system.
If the elevated pressure disappears when the facility scavenging connection is isolated, refer the terminal, hose, or disposal system for correction.
8. Check the Manual Ventilation Configuration
Place the machine in the appropriate nonclinical test configuration and inspect:
- Bag/ventilator mode selection
- Adjustable pressure-limiting valve position
- Reservoir bag and bag-arm connections
- Breathing-system selector operation
- External obstruction around movable controls
Confirm that the adjustable pressure-limiting valve is not incorrectly set during manual ventilation testing.
Expected: Pressure releases normally through the intended pathway in both manual and mechanical test configurations.
If the problem occurs only in one configuration, document that distinction for bench evaluation.
9. Compare With Known-Good External Components
Using compatible and approved parts, substitute one component at a time:
- Breathing circuit
- Test lung
- Filter or heat-and-moisture exchanger
- Sampling adapter
- Absorber assembly
- Scavenging hose
- Externally removable flow-sensing components
Avoid changing multiple components simultaneously because doing so may prevent identification of the actual cause.
Expected: The faulty or restrictive external component is identified.
If a substituted component resolves the problem, remove the suspect component from service and complete the required functional testing.
10. Restart and Perform the Complete System Checkout
With the machine removed from patient use:
- Power the system down normally.
- Allow the shutdown sequence to complete.
- Verify that all external components are correctly installed.
- Restart the machine.
- Perform the complete pre-use or system checkout.
- Test ventilation with a compatible test lung.
- Confirm that measured PEEP returns to the selected value across several breaths.
- Verify operation in applicable ventilation modes.
Do not return the machine to service solely because the alarm cleared after restarting.
Expected: The machine passes checkout without pressure, flow, valve, leak, or ventilation failures.
If the issue is resolved and all required tests pass consistently, document the findings and return the device according to facility policy.
If the Problem Persists
If elevated expiratory pressure continues after settings, circuits, accessories, breathing-system assembly, absorber components, and scavenging connections have been ruled out, the cause is likely internal.
Possible internal areas may include the expiratory valve mechanism, ventilator control system, internal pneumatic pathways, pressure sensing, or electronic control components.
The anesthesia machine should be:
- Removed from service
- Labeled Out of Service
- Sent for qualified repair or bench evaluation
- Evaluated using the manufacturer’s service documentation and approved test equipment
Do not continue repeated clinical testing or perform unauthorized internal adjustments. Knowing when to stop and escalate is proper troubleshooting.
Clinical Use Tip
Never troubleshoot persistent elevated PEEP on an active patient. Move the patient to verified equipment first, then reproduce the issue with an approved test lung in a controlled environment.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Anesthesia staff reported that airway pressure remained above the selected PEEP and did not return to baseline during mechanical ventilation."
Cause
What was observed during troubleshooting.
Example:
"A water-filled filter in the expiratory circuit restricted exhaled gas flow and caused elevated expiratory pressure."
Resolution
What action was taken.
Example:
"Replaced the restricted filter, installed a known-good breathing circuit, completed the system checkout, and verified that measured PEEP returned to the selected value."
Helpful Details to Include (If Known)
- Patient removed from the affected machine
- Exact alarm or advisory displayed
- Selected and measured PEEP values
- Ventilation mode and respiratory rate
- Peak airway pressure
- Whether the condition occurred in bag, ventilator, or both modes
- Breathing circuit inspected or replaced
- Filters and accessories removed or exchanged
- Absorber assembly inspected
- Scavenging hose and terminal evaluated
- Moisture or contamination found
- Checkout results
- Whether the issue was reproducible
- Final device status
Final Thought
Elevated expiratory pressure can create a serious ventilation hazard. Begin with patient safety, then evaluate settings, circuit restrictions, breathing-system components, and scavenging before suspecting an internal failure. Careful testing and complete CCR documentation support both safe escalation and reliable repair.
That is successful troubleshooting.