Mechanical ventilation

Alarms and sudden deterioration (DOPES)

Reviewed Nov 2026·1 references
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If a ventilated patient suddenly desaturates or becomes hypotensive, take them off the ventilator and hand-bag with 100% O2, then work through DOPES: Displacement, Obstruction, Pneumothorax, Equipment, Stacking.

At the bedside

Timed steps
  1. 1

    Look at the patient, not the screen

    0 s

    Colour, chest movement, SpO2 trace quality, ETCO2 waveform, BP.

  2. 2

    Hand-bag on 100% O2

    0-30 s

    Disconnect from the ventilator and bag with a PEEP valve. Easy to bag and patient improves = equipment problem; hard to bag = patient or tube problem.

  3. 3

    Displacement

    D

    ETCO2 lost or reduced? Tube depth changed? Cuff leak, voice? Reintubate if displaced.

  4. 4

    Obstruction

    O

    Pass a suction catheter; secretions, blood, kinked or bitten tube. Change tube if it will not pass.

  5. 5

    Pneumothorax

    P

    Unilateral air entry, absent lung sliding, rising pressures, hypotension: needle or finger decompression, then drain.

  6. 6

    Equipment

    E

    Ventilator, circuit disconnection, O2 supply, HME blockage, wet filters.

  7. 7

    Stacking (auto-PEEP)

    S

    Obstructive disease, high rate: disconnect for 20-30 s, then reduce rate, increase expiratory time.

  8. 8

    Other causes

    Then

    Bronchospasm, PE, pulmonary oedema, mucus plug with lobar collapse, abdominal distension, patient effort/asynchrony, sedation wearing off.

Common alarms

AlarmLikely causesAction
High pressureSecretions, biting, kinked tube, bronchospasm, pneumothorax, coughing, asynchronySuction, bite block, bronchodilator, examine chest, sedation review
Low pressure / low Vt / disconnectCircuit disconnection, cuff leak, tube displacement, broncho-pleural fistulaCheck circuit, cuff pressure, tube depth
High RRPain, agitation, acidosis, hypoxaemia, auto-triggering from leak or waterTreat cause; check trigger sensitivity
Low minute volume / apnoeaOver-sedation on PSV, neuromuscular weaknessSwitch to assist-control; reduce sedation
High PEEP / auto-PEEPAir trappingLower rate, shorter Ti, bronchodilator
Red flag · call your senior now
Hypotension + rising pressures + unilateral silent chest: tension pneumothorax.
Red flag
Loss of ETCO2 waveform: assume displacement until proven otherwise.
Pitfall
Silencing an alarm without finding the cause.
Pitfall
Increasing FiO2 while a tube is blocked.
Pearl
Keep a bag-valve-mask with PEEP valve, suction and spare tube at every ventilated bed.

References

  1. 1

    Boles JM, Bion J, Connors A, et al. Weaning from mechanical ventilation. Eur Respir J. 2007;29(5):1033-1056

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Educational reference for trained clinicians. Check doses against your hospital protocol and the patient in front of you.