Breathing that slows down or stops from any cause is called apnea.

Apnea can come and go and be temporary. This can occur with obstructive sleep apnea, for example.

Prolonged apnea means a person has stopped breathing. If the heart is still active, the condition is known as respiratory arrest. This is a life-threatening event that requires immediate medical attention and first aid.

Prolonged apnea accompanied by lack of any heart activity in a person who is not responsive is called cardiac (or cardiopulmonary) arrest. In infants and children, the most common cause of cardiac arrest is respiratory arrest. In adults, the opposite usually occurs: Cardiac arrest leads to respiratory arrest.

Apnea can occur for many different reasons. The most common causes of apnea in infants and small children are generally quite different from the most common causes in adults.

Common causes of apnea in infants and young children include:

• Asthma
• Bronchiolitis
• Choking
• Encephalitis
• Gastroesophageal reflux (heartburn)
• Holding one's breath
• Meningitis
• Pneumonia
• Premature birth
• Seizures

Common causes of apnea in adults include:

• Asthma or other lung diseases
• Cardiac arrest
• Choking
• Drug overdose, especially due to alcohol, narcotic painkillers, barbiturates, anesthetics, and other depressants (See: Drug abuse first aid)
• Obstructive sleep apnea

Other causes of apnea include:

• Head or brain-stem injury
• Irregular heartbeat (See:arrhythmias)
• Metabolic disorders
• Near-drowning
• Stroke and other neurological disorders

See immediate medical attention or call your local emergency number (such as 911) if a person with any type of apnea:

• Becomes limp
• Has a seizure
• Is not alert (loses consciousness)
• Remains drowsy
• Turns blue

If a person has stopped breathing, call for emergency help and perform CPR (if you know how). When in a public place, look for an Automated External Defibrillator (AED) and follow the directions.

CPR or other emergency measures will be done in an emergency room or by an ambulance EMT (emergency medical technician).

Once the patient is stable, the health care provider will do a physical exam, which includes listening to heart sounds and breath sounds.

Questions will be asked about the person's medical history and symptoms, including:

• Time pattern
  • Has this ever happened before?
  • How long did the event last?
  • Has the person had repeated, brief episodes of apnea?
  • Did the episode end with a sudden deep snorting breath?
  • Did the episode occur while awake or asleep?
• Recent health history
  • Has there been any recent history of an accident or injury?
  • Has the person been ill recently?
  • Had there been any breathing difficulty before the breathing stopped?
  • What other symptoms have you noticed?
  • What medications does the person take?
  • Does the person use street or recreational drugs?

Diagnostic tests that may be done include:

• Arterial blood gas
• Chest x-ray
• ECG
• Other blood tests

Gausche-Hill M. Sudden infant death syndrome and apparent life-threatening events. In: Marx J, ed. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 6th ed. St Philadelphia, Pa: Mosby Elsevier; 2006:chap 175.