Apnea alarm overview

Mechanical ventilation	Apnea - pressure only
	False alarm – threshold set too high
	Breathing system leak
	Pressure sensor tube disconnect or obstruction
	Apnea - flow only
	False alarm – high threshold (eg, neonate)
	Malfunctioning flow sensor (eg, due to moisture or broken filament)
	Apnea-CO₂ only
	Capnometer sample line crack or disconnect
	Esophageal intubation
	Cardiac arrest
	Apnea-flow and apnea-CO₂
	Breathing system obstruction
	Large cuff leak (no exhaled gas into breathing system)
	Esophageal intubation
	Apnea-pressure and apnea-flow and apnea-CO₂
	Breathing system disconnect
	Ventilator turned off or cycling failure malfunction
	Lower airway suction (gastric tube in trachea, tracheal/bronchial suction)
Spontaneous or manual ventilation	Apnea-pressure only
	False alarm – When switching from mechanical to spontaneous ventilation (apnea-pressure not applicable in spontaneous mode)
	Apnea-flow only
	False alarm – high threshold (neonate)
	Incomplete endotracheal tube kink or obstruction
	Breathing system disconnect with patient still connected to CO₂ sampling site
	Malfunctioning flow sensor (eg, due to moisture or broken filament)
	Apnea-CO₂ only
	Capnometer sample line crack or disconnect
	Apnea-flow and apnea-CO₂
	Patient apnea
	Breathing system obstruction
	Airway (ETT or LMA) obstruction
	Breathing system disconnect
	Lower airway suction (gastric tube in trachea, tracheal/bronchial suction)
	Esophageal intubation
	Cardiac arrest

Differential diagnosis based on mode of ventilation and combination of alarms.

CO₂: carbon dioxide; ETT: endotracheal tube; LMA: laryngeal mask airway.

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