Apnea
Apnea: Excerpt from Professional Guide to Signs & Symptoms (Fifth Edition)
Apnea, the cessation of spontaneous respiration, is occasionally temporary and self-limiting, as in Cheyne-Stokes and Biot’s respirations. In most cases, though, it’s a life-threatening emergency that requires immediate intervention to prevent death.
Apnea usually results from one or more of six pathophysiologic mechanisms, each of which has numerous causes. Its most common causes include trauma, cardiac arrest, neurologic disease, aspiration of foreign objects, bronchospasm, and drug overdose. (See Causes of apnea, page 68.)
Emergency interventions
If you detect apnea, first establish and maintain a patent airway. Place the patient in a supine position, and open his airway using the head-tilt, chin-lift technique. (Caution:
If the patient has or may have a head or neck injury, use the jaw-thrust technique to prevent hyperextending the neck.) Next, quickly look, listen, and feel for spontaneous respiration; if it’s absent, begin artificial ventilation until it occurs or until mechanical ventilation can be initiated.
Because apnea may result from (or may cause) cardiac arrest, assess the patient’s carotid pulse immediately after you’ve established a patent airway. Or, if the patient is an infant or small child, assess the brachial pulse instead. If you can’t palpate a pulse, begin cardiac compression.
History and physical examination
When the patient’s respiratory and cardiac status is stable, investigate the underlying cause of apnea. Ask him (or, if he’s unable to answer, anyone who witnessed the
episode) about the onset of apnea and events immediately preceding it. The cause may become readily apparent, as in trauma.
Take a patient history, especially noting reports of headache, chest pain, muscle weakness, sore throat, or dyspnea. Ask about a history of respiratory, cardiac, or neurologic disease and about allergies and drug use.
Inspect the head, face, neck, and trunk for soft-tissue injury, hemorrhage, or skeletal deformity. Don’t overlook obvious clues, such as oral and nasal secretions (reflecting fluid-filled airways and alveoli) or facial soot and singed nasal hair (suggesting thermal injury to the tracheobronchial tree).
Auscultate over all lung lobes for adventitious breath sounds, particularly crackles and rhonchi, and percuss the lung fields for increased dullness or hyperresonance. Move on to the heart, auscultating for murmurs, pericardial friction rub, and arrhythmias. Check for cyanosis, pallor, jugular vein distention, and edema. If appropriate, perform a neurologic assessment. Evaluate level of consciousness (LOC), orientation, and mental status; test cranial nerve and motor function, sensation, and reflexes in all extremities.
Medical causes
Airway obstruction
Occlusion or compression of the trachea, central airways, or smaller airways can cause sudden apnea by blocking the patient’s airflow and producing acute respiratory failure.
Brain stem dysfunction
Primary or secondary brain stem dysfunction can cause apnea by destroying the brain stem’s ability to initiate respirations. Apnea may arise suddenly (as in trauma, hemorrhage, or infarction) or gradually (as in degenerative disease or tumor). Apnea may be preceded by decreased LOC and various motor and sensory deficits.
Neuromuscular failure
Trauma or disease can disrupt the mechanics of respiration, causing sudden or gradual apnea. Associated findings include diaphragmatic or intercostal muscle paralysis from injury, or respiratory weakness or paralysis from acute or degenerative disease.
Parenchymatous lung disease
An accumulation of fluid within the alveoli produces apnea by interfering with pulmonary gas exchange and producing acute respiratory failure. Apnea may arise suddenly, as in near drowning and acute pulmonary edema, or gradually, as in emphysema. Apnea also may be preceded by crackles and labored respirations with accessory muscle use.
Pleural pressure gradient disruption
Conversion of normal negative pleural air pressure to positive pressure by chest wall injuries (such as flail chest) causes lung collapse, producing respiratory distress and, if untreated, apnea. Associated signs include an asymmetrical chest wall and asymmetrical or paradoxical respirations.
Pulmonary capillary perfusion decrease
Apnea can stem from obstructed pulmonary circulation, most commonly due to heart failure or lack of circulatory patency. It occurs suddenly in cardiac arrest, massive pulmonary embolism, and most cases of severe shock; it occurs progressively in septic shock and pulmonary hypertension. Related findings include hypotension, tachycardia, and edema.
Other causes
Drugs
Central nervous system (CNS) depressants may cause hypoventilation and apnea. Benzodiazepines may cause respiratory depression and apnea when given I.V. along with other CNS depressants to elderly or acutely ill patients.
Neuromuscular blockers—such as curariform drugs and anticholinesterases— may produce sudden apnea due to respiratory muscle paralysis.
Sleep-related apneas
These repetitive apneas occur during sleep from airflow obstruction or brain stem dysfunction.
Special considerations
Closely monitor the apneic patient’s cardiac and respiratory status to prevent further apneic episodes.
Pediatric pointers
Premature neonates are especially susceptible to periodic apneic episodes because of CNS immaturity. Other common causes of apnea in infants include sepsis, intraventricular and subarachnoid hemorrhage, seizures, bronchiolitis, and sudden infant death syndrome.
In toddlers and older children, the primary cause of apnea is acute airway obstruction from aspiration of foreign objects. Other causes include acute epiglottitis, croup, asthma, and systemic disorders, such as muscular dystrophy and cystic fibrosis.
Geriatric pointers
In elderly patients, increased sensitivity to analgesics, sedative-hypnotics, or any combination of these drugs may produce apnea, even with normal dosage ranges.
Patient counseling
Educate the patient about safety measures related to aspiration of medications. Encourage cardiopulmonary resuscitation training for all adolescents and adults.
Pictures
Book Source Details
- Book Title: Professional Guide to Signs & Symptoms (Fifth Edition)
- Author(s): Springhouse
- Year of Publication: 2006
- Copyright Details: Professional Guide to Signs & Symptoms (Fifth Edition), Copyright © 2006 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
» Next page: Paroxysmal nocturnal dyspnea (Professional Guide to Signs & Symptoms (Fifth Edition))
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