Ventilator alarms: high and low pressure, low volume and apnoea, and what to do first
- Safe practice
Go to the patient first; if they are in distress and the cause is unclear, ventilate with a bag and oxygen while the ventilator is checked.
What it is
A ventilator alarm means that a pressure, volume, rate or supply value has crossed its limit. The alarm says where to look; the patient says how urgent it is. The WHO toolkit gives a fixed order of questions: is the tube in the trachea, is there a problem with the circuit or oxygen supply, does a suction catheter pass through the tube, are there breath sounds on both sides, is something else making the lungs or chest stiff, is the patient haemodynamically unstable, and is the patient agitated and out of synchrony with the ventilator. The nurse works through this order with the respiratory therapist and the doctor.
What it requires
- A bag-valve device with oxygen and a PEEP valve at the bedside.
- Suction ready and a closed suction catheter in place.
- Knowing the alarm limits set for this patient and the current settings.
- Knowing whom to call: the respiratory therapist, the nurse in charge and the doctor.
Components
- High airway pressure.
- Low airway pressure or low tidal volume.
- Low or high minute ventilation and high respiratory rate.
- Apnoea (no breath triggered in a spontaneous mode).
- Oxygen or gas supply failure.
How it is applied (and why)
- Go to the patient: chest rise, colour, SpO2 and distress — the alarm points the way; the patient sets the urgency.
- Read which alarm sounded and the current values — high and low pressure point to different causes.
- If the patient deteriorates and the cause is unclear, disconnect and bag with 100% oxygen while someone checks the ventilator.
- Check the circuit from end to end: connections, leaks, kinks and water — disconnection and leaks cause low-pressure alarms.
- Check tube depth, cuff and fixation; a large leak or no chest rise suggests a displaced tube — call for help to reintubate.
- Pass a suction catheter: if it will not pass, the tube is kinked, bitten or blocked; if it passes, suction the secretions.
- If the patient bites, insert a bite block as the protocol says; if they cough or fight the ventilator, assess pain and position.
- Listen to both sides: one silent side suggests a tube in one bronchus, collapse or pneumothorax; wheeze suggests bronchospasm.
- Check blood pressure and heart rate: severe hypotension with high pressure suggests tension pneumothorax or auto-PEEP — emergency call.
- Reconnect when safe, confirm settings and alarms, and record the alarm, the cause and the action.
First look by alarm type (WHO toolkit, tool 9.13)
| Alarm | Common causes | First nursing action |
|---|---|---|
| High pressure | Secretions, biting, coughing, kinked tube, water in circuit, bronchospasm, tube in one bronchus, pneumothorax | Assess the patient, pass a suction catheter, listen to both sides, call if not resolved |
| Low pressure or low volume | Disconnection, circuit leak, cuff leak, displaced tube | Check connections and cuff; large leak or no chest rise: bag with oxygen and call |
| Apnoea | The patient stopped triggering breaths in a spontaneous mode | Check consciousness and sedation, ventilate if needed, call the doctor |
In nursing practice
- Auto-PEEP (breath stacking), common in COPD and asthma, raises pressures and can cause severe hypotension.
- Abdominal distension makes the chest stiffer; draining the stomach through a nasogastric tube may help, as ordered.
- Agitation can be the cause or the result of another problem: rule out tube, circuit and lung problems before more sedation.
- Repeated alarms of the same type need a review of the settings and limits with the team.
Common mistakes
- Treating agitation with more sedation before ruling out a tube, circuit or lung problem.
- Waiting for a chest X-ray when a tension pneumothorax is suspected.
- Missing a displaced tube when a large leak appears.
- Leaving condensate in the circuit.
Test yourself
Think of the answer, then tap the question to see it.
What should the nurse do first when a ventilator alarms and the patient is deteriorating with no obvious cause?
Disconnect the patient and ventilate with a bag and 100% oxygen while another person checks the ventilator and circuit.
What does a suction catheter that will not pass through the endotracheal tube suggest?
That the tube is kinked, bitten or blocked by secretions. A bite block may help; a blocked tube may need to be replaced.
What does a high peak pressure with a normal plateau pressure suggest?
A resistance problem in the airway or tube, such as secretions, biting, a kink or bronchospasm, rather than stiff lungs.
Which common causes lead to a low-pressure or low-volume alarm?
Disconnection of the circuit, a leak in the circuit or around the cuff, and a displaced endotracheal tube.
Elsewhere in DurgiPedia
Connections
Educational content for students; it does not replace your institution's protocols, supervised clinical training or a prescriber's order. Dose-calculation examples use made-up numbers: they are educational, not a clinical order.
Sources: Clinical care for severe acute respiratory infection: toolkit, update 2022 (COVID-19 adaptation), tools 9.12 and 9.13 (World Health Organization, 2022); Clinical management of COVID-19: living guideline, 18 August 2023 (World Health Organization, 2023); Clinical review: liberation from mechanical ventilation (Critical Care (open access, PMC), 2008).
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