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What This Guide Helps With
Troubleshooting failure to deliver an indicated shock caused by AED analysis state, electrode contact, depleted battery, accessories, controls, or device faults.
Step-by-Step Troubleshooting
1. Ensure Patient Safety First
Do not perform extended troubleshooting during an active cardiac arrest when the LIFEPAK CR2 is not delivering expected therapy.
Immediately continue CPR according to the clinical response protocol and obtain another verified defibrillator/AED without delaying resuscitation.
Expected: Patient care is transferred to functioning emergency equipment while resuscitation continues.
Why it matters: A suspected therapy-delivery failure is a critical equipment condition. Troubleshooting must never delay CPR or access to another defibrillator.
If another device restores access to defibrillation therapy, remove the affected LIFEPAK CR2 from clinical use and continue evaluation in a controlled Clinical Engineering environment.
2. Confirm Whether a Shock Was Actually Advised
Review the reported event carefully before concluding that the CR2 failed to deliver a shock.
Determine whether the device:
- Announced that a shock was advised
- Announced that no shock was advised
- Continued CPR prompts without entering a shock sequence
- Began charging but did not complete the sequence
- Reached a shock-ready state but did not deliver therapy
- Restarted, shut down, or produced an error during analysis or charging
Expected: Clinical Engineering distinguishes a true failure from normal AED operation when the analyzed rhythm does not meet the device’s criteria for shock therapy.
Why it matters: An AED is not expected to shock every cardiac arrest rhythm. “No shock delivered” alone does not prove equipment failure.
If the event was consistent with a normal “no shock advised” sequence and no device fault is present, document the findings and stop.
3. Identify the Device Configuration and Expected Shock Action
Verify whether the specific LIFEPAK CR2 configuration is semi-automatic or fully automatic.
For a semi-automatic configuration, confirm whether the expected user shock action occurred after the device reached the appropriate shock-ready sequence.
For a fully automatic configuration, do not interpret the absence of a manual shock-button action as a defect.
Expected: The reported behavior is compared with the actual configuration of the device.
Why it matters: A configuration misunderstanding can be reported as “shock would not deliver” even when the unit is functioning as designed.
If the complaint is explained by the device configuration, document the finding and stop.
4. Check the Readiness Condition Before Further Testing
Inspect the LIFEPAK CR2 for its normal readiness indication and any attention condition.
Check for:
- Missing normal readiness indication
- Audible alert tones
- Device-not-ready status
- Visible damage
- Signs of recent drop or impact
- Evidence of fluid intrusion
- Unusual heat
- Burn odor or electrical smell
Expected: A ready-state device shows no unresolved attention condition or obvious physical damage.
Why it matters: A device already indicating a readiness problem should not be trusted for therapy until the underlying condition is resolved.
If abnormal heat, odor, liquid intrusion, or significant impact damage is present, stop testing, remove the unit from service, and escalate for evaluation.
5. Inspect the QUIK-STEP Electrode Assembly
Verify that the installed electrode assembly is the correct compatible type for the LIFEPAK CR2.
Check:
- Expiration date
- Package integrity
- Evidence the electrode package has been opened
- Torn, punctured, or compromised packaging
- Dried or contaminated adhesive gel
- Damaged electrode leads
- Physical damage to the tray or assembly
- Signs the electrodes were previously deployed or used
Expected: The electrode assembly is compatible, within expiration, intact, and suitable for service.
Why it matters: Damaged, expired, opened, or compromised electrodes can interfere with dependable patient contact and therapy readiness.
If the electrode assembly is questionable, replace it with an approved compatible set, restore the unit to the proper ready condition, and reassess. If the issue is resolved, stop.
6. Check Electrode Contact as a Possible Cause of the Reported Event
For an actual clinical event, determine from staff reports and available device/event information whether the CR2 repeatedly prompted for pad attachment or better contact.
Ask whether:
- Pads were fully removed from their backing
- Both pads were applied to the patient
- Placement followed the device prompts
- The chest was excessively wet
- Heavy chest hair prevented adhesion
- A pad lifted during CPR
- Pads were placed over clothing
- Movement disrupted contact
Expected: No evidence suggests that inadequate electrode contact prevented progression through analysis and therapy.
Why it matters: Poor pad contact may interrupt rhythm analysis or prevent the device from progressing normally toward shock delivery.
Do not attempt to reproduce a patient-contact problem on a person. Use only approved test methods in the Clinical Engineering environment.
If pad contact explains the event and the device subsequently passes required evaluation, document the cause and stop.
7. Inspect the Battery Installation and Condition
Inspect the LIFEPAK CR2 lithium battery externally.
Check for:
- Battery fully seated
- Loose installation
- Cracked housing
- Swelling or deformation
- Contamination at accessible contact areas
- Corrosion
- Evidence of leakage
- Known replacement-due condition
- Recent battery alert or replacement message
Reseat or replace the battery only according to the approved maintenance process using the correct compatible battery.
Expected: The correct battery is secure, undamaged, and does not produce a low-battery or attention condition.
Why it matters: Defibrillator charging requires dependable power. A degraded or poorly seated battery can contribute to startup, charging, or therapy-sequence problems.
If an approved replacement battery restores normal readiness and the device passes required verification, document the correction and stop.
8. Perform a Controlled Power-Cycle Check
In a controlled Clinical Engineering environment and after ensuring no patient is connected:
- Turn the device off.
- Inspect the battery and electrode installation.
- Restore the components correctly.
- Restart the device.
- Observe prompts, indicators, and any abnormal alert.
Expected: The CR2 initializes normally without repeated fault indications or abnormal restart behavior.
Why it matters: A controlled restart can identify a persistent startup or readiness fault without assuming internal failure.
If the unit continues to indicate a fault, repeatedly restarts, or cannot reach a normal ready condition, stop and escalate.
9. Evaluate Whether Charging Was the Actual Failure
Review the reported sequence and determine whether the CR2:
- Never announced or indicated a shockable condition
- Began a shock sequence but failed to become ready
- Took abnormally long to progress
- Restarted during charging
- Produced a device fault
- Became ready but then aborted the sequence
Expected: Clinical Engineering isolates the complaint to analysis, electrode contact, charging, user interaction, or actual energy delivery.
Why it matters: “Would not shock” can describe several different failures. Correct isolation prevents unnecessary parts replacement and improves escalation documentation.
If the device consistently fails during the charging portion of the sequence, remove it from service and proceed to authorized evaluation.
10. Inspect the External User Controls
For configurations that use a manual shock action, inspect the accessible control area for:
- Cracking
- Sticking
- Contamination
- Physical obstruction
- Impact damage
- Abnormal tactile response
Do not disassemble the control panel or attempt internal switch repair.
Expected: External controls are intact and operate normally during approved functional evaluation.
Why it matters: Physical damage or contamination can interfere with control actuation, but internal control repair is beyond external troubleshooting.
If the control is mechanically abnormal or fails an approved functional check, remove the device from service and escalate.
11. Perform Approved Functional Verification
Only qualified Clinical Engineering personnel should perform therapy verification using:
- An approved defibrillator analyzer or test load
- Facility-approved procedures
- Current manufacturer service information
- The correct test setup for the specific CR2 configuration
Do not discharge the LIFEPAK CR2 into open air, loose electrodes, a person, or an improvised load.
Verify, as permitted by the approved procedure:
- Normal startup
- Readiness status
- Electrode recognition
- Analysis sequence
- Charge progression
- Shock sequence
- Delivered-energy performance where authorized
- Absence of device faults
Expected: The unit completes the approved verification sequence and meets applicable acceptance criteria.
Why it matters: A reported shock-delivery failure cannot be safely cleared by visual inspection alone when therapy performance remains in question.
If the device passes all required testing and the original complaint is explained by an external cause, document the findings and return it to service according to facility policy. If the failure is reproduced or results are questionable, stop.
12. Review Available Event and Device Information
When available through the facility’s approved workflow, review relevant event data, service information, or AED program-management records.
Look for evidence of:
- Shock advised versus no shock advised
- Pad-contact interruptions
- Battery warnings
- Device-not-ready condition
- Restart behavior
- Fault indication
- Incomplete therapy sequence
Expected: Objective device information supports or narrows the reported complaint.
Why it matters: Event evidence may distinguish device failure from rhythm analysis, poor electrode contact, battery condition, or an incomplete user sequence.
If the information identifies and resolves an external cause and the unit passes required verification, document and stop.
13. Make the Final Service Decision
Return the LIFEPAK CR2 to service only when:
- The complaint has been explained or corrected
- Correct compatible electrodes are installed
- Battery condition is acceptable
- No unresolved readiness alert exists
- No physical safety concern remains
- Required functional verification passes
- Final status is documented
Expected: Only a verified, ready device is returned to emergency service.
If any doubt remains about shock charging or therapy delivery, do not return the unit to service.
If the Problem Persists
If the LIFEPAK CR2 still will not complete an expected shock sequence after electrode condition, battery installation, readiness status, device configuration, external controls, and approved functional testing have been checked, common external causes have been ruled out.
The fault may involve an internal condition such as:
- High-voltage charging circuitry
- Energy-storage circuitry
- Internal therapy switching
- Control-input circuitry
- Electrode sensing circuitry
- Internal power distribution
- Processor or system-control fault
The device should be:
- Removed from service
- Labeled Out of Service
- Sent for authorized repair or bench evaluation
Do not perform unapproved internal high-voltage troubleshooting or board-level repair.
Knowing when to stop is proper troubleshooting. A defibrillator with unresolved therapy-delivery performance must never be returned to clinical service based only on intermittent normal operation.
Clinical Use Tip
Never troubleshoot a suspected shock-delivery failure on an active patient.
During a resuscitation, continue CPR according to protocol and obtain another verified defibrillator immediately. Troubleshoot the affected LIFEPAK CR2 only after patient care has been transferred and the device is in a controlled environment.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Clinical staff reported that the LIFEPAK CR2 announced a shockable sequence but did not deliver the expected shock."
Cause
What was observed during troubleshooting.
Example:
"Inspection found the installed QUIK-STEP electrode assembly compromised and the device could not complete the expected therapy sequence during initial evaluation."
Resolution
What action was taken.
Example:
"Replaced the electrode assembly with an approved compatible set, restored normal readiness, completed approved functional verification, and confirmed acceptable operation before return to service."
Helpful Details to Include (If Known)
- Active patient event or bench complaint
- Shock advised or no shock advised
- Semi-automatic or fully automatic configuration
- Readiness indication observed
- Audible attention tones present
- Electrode type verified
- Electrode expiration checked
- Electrode package integrity checked
- Pad-contact prompts reported
- Battery seating checked
- Battery replaced or swapped
- Device restarted during sequence
- Charging behavior observed
- Fault message or alert recorded
- External control condition checked
- Event information reviewed
- Approved analyzer verification completed
- Delivered-energy verification result, if authorized
- Unusual heat or smell noted
- Final device status documented
Final Thought
A reported failure to deliver a shock requires disciplined troubleshooting because the absence of a shock may reflect normal AED analysis, poor electrode contact, battery condition, an incomplete therapy sequence, or a true internal failure. Protect the patient first, verify external causes logically, use approved test equipment, and escalate immediately when therapy performance remains uncertain. Clear CCR documentation preserves the evidence needed for both patient safety and effective repair decisions.
That is successful troubleshooting.