Apnea is defined as the cessation of spontaneous respiration. While it can occasionally be transient and self-limited—as observed in abnormal respiratory patterns like Cheyne-Stokes and Biot’s respirations—it more commonly represents a life-threatening emergency requiring immediate intervention to prevent hypoxic injury and death.

Pathophysiology and common mechanisms

Apnea arises due to disruption in one or more of six fundamental pathophysiologic mechanisms:

1. Airway obstruction: Physical blockage or compression of the trachea or bronchi (e.g., foreign body aspiration, bronchospasm).

2. Brain stem dysfunction: Damage or pathology affecting respiratory centers in the medulla or pons, impairing respiratory drive.

3. Neuromuscular failure: Impaired function of respiratory muscles or their innervation.

4. Parenchymatous lung disease: Diseases causing fluid accumulation or loss of alveolar function, impairing gas exchange.

5. Pleural pressure gradient disruption: Injuries that impair normal pleural mechanics, such as flail chest.

6. Pulmonary capillary perfusion decrease: Circulatory compromise limiting effective pulmonary perfusion, such as in cardiac arrest or massive pulmonary embolism.

Etiology (Selected causes)

• Airway obstruction: Asthma, bronchospasm, foreign body aspiration, COPD exacerbation, mucus plugs, upper airway tumors, obstructive sleep apnea.

• Brain stem dysfunction: Trauma, hemorrhage, infarction, tumors, infections (meningitis, encephalitis), increased intracranial pressure, CNS depressant overdose.

• Neuromuscular failure: Amyotrophic lateral sclerosis, Guillain-Barré syndrome, myasthenia gravis, spinal cord injury, botulism, phrenic nerve paralysis.

• Parenchymal lung disease: ARDS, pneumonia, pulmonary edema, emphysema, near drowning.

• Pleural pressure gradient disruption: Flail chest, open chest wounds.

• Pulmonary capillary perfusion decrease: Cardiac arrest, myocardial infarction, pulmonary embolism, shock states.

• Infectious causes: Respiratory syncytial virus (RSV) in infants can cause apnea due to airway edema and obstruction.

• Drug-induced: CNS depressants (benzodiazepines, opioids), neuromuscular blockers causing respiratory muscle paralysis.

• Sleep-related apneas: Obstructive and central sleep apnea syndromes.

Emergency interventions

• Airway management: Immediately secure a patent airway. Position patient supine; use head-tilt, chin-lift maneuver unless cervical spine injury is suspected, in which case use jaw-thrust technique to avoid neck hyperextension.

• Assess breathing: Quickly look, listen, and feel for spontaneous respirations.

• Artificial ventilation: If apnea persists, initiate rescue breathing or mechanical ventilation until spontaneous breathing resumes.

• Circulation: Assess carotid pulse (brachial pulse in infants/children). If absent, begin cardiopulmonary resuscitation (CPR) immediately.

• Continuous monitoring: Monitor cardiac and respiratory function vigilantly to detect recurrent apnea or cardiac arrest.

History and Physical Examination

• History: Obtain onset and circumstances of apnea, preceding symptoms (headache, chest pain, dyspnea), history of respiratory, cardiac, neurologic conditions, drug use, allergies.

• Inspection: Check for trauma signs, facial burns, oral/nasal secretions indicating pulmonary edema or airway obstruction.

• Auscultation: Evaluate lung fields for crackles, rhonchi; assess heart for murmurs, arrhythmias, pericardial rub.

• Neurologic exam: Assess consciousness level, orientation, cranial nerve function, motor strength, reflexes, and sensation.

• Other signs: Look for cyanosis, pallor, jugular venous distension, peripheral edema.

Special Populations

• Pediatrics: Premature neonates prone to apnea due to CNS immaturity; common causes include sepsis, intracranial hemorrhages, RSV bronchiolitis, SIDS risk. In toddlers, airway obstruction from foreign body aspiration is a leading cause.

• Geriatrics: Increased sensitivity to sedatives and analgesics may precipitate apnea even at therapeutic doses.

Patient Counseling and Education

• Discuss etiology and treatment plan clearly.

• Teach safety strategies to prevent aspiration.

• Encourage family/caregivers to learn CPR to respond promptly to apnea episodes.

References

1. Leger D, Bayon V, Laaban JP, Philip P. Impact of sleep apnea on economics. Sleep Med Rev. 2012;16:455–462.

2. Philip P, Sagaspe P, Lagarde E, et al. Sleep disorders and accidental risk in regular highway drivers. Sleep Med. 2010;11:973–979.