Nihon Kohden NKV-330

Asset Type

Ventilator

Manufacturer

Nihon Kohden

Model

NKV-330

What This Guide Helps With

This guide helps troubleshoot the High PEEP alarm on a Nihon Kohden NKV-330 ventilator. This alarm indicates measured PEEP is more than 5 hPa above the EPAP/CPAP setting. Possible causes include patient airway resistance, circuit restriction, water accumulation, blocked expiratory flow, incorrect settings, pressure or flow sensor line problems, calibration issues, or a ventilator delivery fault.

Step-by-Step Troubleshooting

Ensure Patient Safety First

• Confirm the patient’s respiratory status immediately.
• Have clinical staff assess the patient, airway, oxygenation, ventilation, and work of breathing.
• Provide alternate ventilation if the patient is unstable or if ventilation performance is in question.
• Do not continue troubleshooting on an active patient if the pressure condition is unresolved.
• Remove the ventilator from patient use if the alarm persists or pressure delivery appears abnormal.

Verify the Reported Alarm and Behavior

• Confirm the ventilator is displaying the High PEEP alarm.
• Check the measured PEEP value.
• Compare measured PEEP to the EPAP or CPAP setting.
• Note whether the alarm occurs during startup, active ventilation, after circuit changes, after patient interface changes, or intermittently during exhalation.
• Confirm the measured PEEP is more than 5 hPa above the EPAP/CPAP setting.

Check the Patient and Airway

• Have clinical staff assess for coughing, patient-ventilator fighting, breath stacking, secretion buildup, airway obstruction, or changes in lung compliance.
• Confirm the patient is not actively exhaling against the ventilator or creating elevated baseline pressure.
• Do not assume an equipment failure until patient and airway causes have been considered.

Check Control and Alarm Settings

• Verify the EPAP/CPAP setting.
• Confirm the active ventilation mode and pressure settings are appropriate.
• Check whether recent setting changes were made.
• Confirm alarm limits are appropriate for the patient and mode of ventilation.
• Correct any setting issue only under the direction of qualified clinical staff.

Inspect the Patient Interface

• Inspect the mask, airway adapter, ET tube connection, trach connection, or other patient interface.
• Look for kinks, occlusion, moisture, secretions, crushed tubing, or misconnections.
• Confirm the interface is not blocked or partially obstructed.
• Replace questionable external components if needed.

Inspect the Breathing Circuit

• Follow the circuit from the ventilator outlet to the patient and back through the expiratory path.
• Look for kinked tubing, water accumulation, blocked filters, crushed tubing, incorrect circuit setup, obstructed expiratory limb, or misconnected components.
• Drain or replace affected circuit components according to hospital procedure.
• Confirm the circuit is open, dry, correctly assembled, and free of restriction.

Check the Exhalation Port

• Confirm the exhalation port is present, correct, and unobstructed.
• Check for water droplets, contamination, secretions, coverings, or incorrect placement.
• Replace the exhalation port or related circuit component if blockage is suspected.
• Confirm exhaled gas can leave the circuit properly.

Check the Pressure Sensor Line

• Inspect the pressure sensor line for water droplets, kinks, clogging, blockage, loose connections, or disconnected tubing.
• Replace or clear the line according to hospital procedure if contamination or blockage is found.
• Confirm the pressure sensor line is clean, open, dry, and securely connected.

Check the Flow Sensor Line

• Inspect the flow sensor line for water droplets, kinks, clogging, blockage, loose fittings, or damaged tubing.
• Replace questionable tubing or accessories as needed.
• Confirm the flow sensor line is clear and properly connected.

Calibrate the Pressure Sensor and Breathing Circuit

• Remove the ventilator from patient use before calibration.
• Install the correct test circuit or approved breathing circuit setup.
• Perform pressure sensor calibration.
• Perform breathing circuit calibration.
• Confirm calibration passes without errors.

Recheck Operation After Corrective Action

• Reconnect the appropriate test setup.
• Run the ventilator and observe measured PEEP.
• Confirm measured PEEP remains close to the EPAP/CPAP setting.
• Confirm the High PEEP alarm does not return.
• If the alarm clears, complete normal safety and performance checks before returning the ventilator to service.

If the Problem Persists

If the High PEEP alarm continues after checking the patient, settings, patient interface, breathing circuit, exhalation port, pressure sensor line, flow sensor line, and calibration, external and common causes have been ruled out.

A persistent High PEEP alarm may indicate an internal breath delivery or pressure-control problem. The CD-358P breath delivery unit may be faulty.

• Remove the ventilator from service.
• Label it Out of Service.
• Do not return it to patient use.
• Send the ventilator for repair, bench evaluation, or vendor/service-level support.

Clinical Use Tip

Never troubleshoot a High PEEP alarm on an active patient if ventilation safety is uncertain. Move the patient to a backup ventilator or approved alternate ventilation method first, then continue equipment troubleshooting on the removed device.

Work Order Documentation (CCR Method)

CCR = Complaint, Cause, Resolution

Complaint

What was reported by the clinical staff.

Example:
"NKV-330 ventilator reported High PEEP alarm. Measured PEEP was more than 5 hPa above the EPAP/CPAP setting during ventilation."

Cause

What was observed during troubleshooting.

Example:
"Water droplets and partial blockage were found in the expiratory circuit and pressure sensor line, causing elevated measured PEEP."

Resolution

What action was taken.

Example:
"Removed affected circuit components, replaced contaminated tubing, verified exhalation port was clear, completed pressure sensor and breathing circuit calibration, and confirmed the High PEEP alarm did not return during testing."

Helpful Details to Include (If Known)

• Alarm behavior
• Accessories swapped
• Power behavior
• Environmental factors
• Indicator lights
• Final device status

Final Thought

A High PEEP alarm should be treated as a real pressure-retention concern until proven otherwise. Start with patient safety, confirm the measured pressure condition, check the circuit and sensing lines carefully, then calibrate and test. If the alarm persists after external causes are ruled out, remove the ventilator from service and escalate appropriately. Clear CCR documentation protects the patient, the technician, and the repair process.

That is successful troubleshooting.