CHAPTER 13 Dyspnea

Dyspnea, or shortness of breath, is a subjective sensation of air hunger that results in labored breathing. True dyspnea results from three general causes: (1) an increased awareness of normal breathing, such as with hyperventilation; (2) an increase in the work of breathing, such as in airway obstruction or restricted volume; and (3) abnormalities in the ventilatory system, such as in neurological disorders, diseases of the muscles, and chest wall abnormalities. In disease states it is usually a result of pulmonary or cardiac pathology. When eliciting the history, it is helpful to determine if this is new-onset acute dyspnea, chronic progressive dyspnea, or chronic recurrent dyspnea. Carefully directed questioning will provide essential clues for identifying the differential diagnoses. In children younger than 3 years, who usually cannot express the sensation, caregivers can observe tachypnea, retractions, stridor, nasal flaring, or feeding difficulty.

Diagnostic reasoning: focused history

Is this an emergency?

Severe dyspnea is a medical emergency. If not treated immediately, respiratory failure and death can occur. Assess the adequacy of the airway first. Emergency measures should be instituted to establish ventilation. When the patient is stabilized, search for the underlying cause of the dyspnea.

Key questions

Did this occur suddenly, or has it been developing gradually? Over what period of time (hours, days, weeks) has it developed?

What were you (or the child) doing just before having difficulty in breathing?

Do you (or the child) have other symptoms, such as itching or swelling?

Onset

New-onset acute dyspnea in a patient in acute distress can signal a life-threatening problem. In the patient with no previous history of heart or lung disease, dyspnea can indicate several conditions that require immediate treatment, such as aspiration of a foreign body, anaphylaxis, pulmonary embolism (PE), and pneumonia. A common cause of acute-onset dyspnea is left ventricular dysfunction.

Acute upper or lower airway obstruction in children has the greatest potential to cause serious morbidity or mortality and therefore must initially be ruled out. The most serious problem is hypoxemia caused by the inability to transport oxygen past a blocked upper airway, such as with epiglottitis, croup, or a foreign body.

Acute dyspnea requires immediate assessment of the airway and ventilatory status with oxygen and cardiac monitoring. Often this must occur before a definitive diagnostic evaluation has been completed.

Acute epiglottitis in children is caused by Haemophilus influenzae. Inflammation of the epiglottis causes edema that obstructs the tracheal airway. The onset is sudden and the course of the disease is rapid. The patient’s presenting symptoms usually include drooling, dysphonia, dysphagia, and respiratory distress with inspiratory stridor. The child looks anxious and sits up and forward with the jaw open to assist in air intake.

Status asthmaticus is a progressive bronchospasm from an increase in airflow resistance in children who are having an asthma event that does not respond to pharmacological intervention. Fever can be present, and pulse rate and respirations are increased. The use of accessory respiratory muscles is seen. Sometimes wheezing is not heard because of lack of air movement. The combination of hypoxia, hypercapnia, and acidosis can result in cardiovascular depression and cardiopulmonary arrest.

Foreign body aspiration

The adult patient with foreign body aspiration reports that dyspnea occurred while eating solid foods or drinking large amounts of alcohol. Children who put small objects in their mouth are at risk for aspiration of the object into the airway and subsequent airway obstruction. The patient or the care provider gives a history of sudden onset of choking, coughing, or wheezing, without preceding upper respiratory tract infection. Often the child has been playing on the floor or outside at the time of the onset of symptoms.

Anaphylaxis

Anaphylaxis can follow insect bites or the ingestion of medication or other potential allergens (e.g., shellfish, peanuts). Primary symptoms include flushing, generalized pruritus, fear, faintness, and sneezing. An allergic response can lead to shock, cardiac arrythmia, laryngeal edema, and death within minutes. The sooner the symptoms occur, the more severe the reaction.

Is the dyspnea caused by a secondary obstruction in the lower respiratory tract?

Key questions

Have you had cough or recent cold?

Do you have a history of asthma?

Is there a family history of asthma?

Cough

Secondary partial airway obstruction caused by small airway disease contributes to hypoxemia via intrapulmonary shunting. The pulmonary obstruction can be intraluminal (distal foreign objects, asthma); intramural (edema, bronchomalacia, bronchiolitis); or extramural (compression from tumor, lymph nodes). The narrowing increases both airway resistance and turbulence of airflow. The imbalance between pulmonary ventilation and perfusion affects oxygen exchange. This causes the patient to work harder to maintain adequate ventilation, resulting in dyspnea.

History of asthma

Both adults and children can experience airway obstruction caused by reactive airways disease or asthma. Personal or family history of asthma increases the risk of dyspnea from acute bronchospasm.

Is the dyspnea caused by trauma to the chest?

Key question

Have you experienced any trauma to the chest?

Trauma

Limitation of motion of the thoracic cage because of pain and/or trauma can be associated with severe alveolar hypoventilation and subsequent dyspnea.

Pneumothorax occurs most frequently in young persons during strenuous activity. Spontaneous pneumothorax results in sudden loss of lung volume, hypoxia, hypercapnia, and significant shortness of breath (SOB). Blunt chest trauma can be caused by a fall or motor vehicle accident.

Is the dyspnea caused by a pulmonary embolus?

Key questions

Have you recently been confined to bed or been sitting for a long period of time?

Have you had recent surgery?

Have you recently sustained a fracture?

Are you taking birth control pills or estrogen?

Do you smoke?

What medications are you taking?

Are you feeling anxious or scared?

The person with PE is usually in acute distress and reports significant SOB, localized pleuritic chest pain, apprehension, bloody sputum production, diaphoresis, fever, and history of conditions causing risk for emboli. These risk factors include age of greater than 60 years, pulmonary hypertension, congestive heart failure, chronic lung disease, ischemic heart disease, stroke, and cancer. Predisposing factors that can contribute to thrombus formation include (1) venous stasis, (2) hypercoagulability, and (3) endothelial injury with inflammation to the vessel lining. Trauma, muscle spasm, or clot dissolution can cause the thrombus to dislodge, creating an embolus. Emboli circulate in the blood to the right side of the heart and enter the lungs via the pulmonary artery. If the clot is not dissolved within the lungs, it occludes the pulmonary artery and obstructs blood flow and perfusion of the lungs. Patients with suspected PE are referred for emergency pulmonary/vascular consultation.

Confinement, surgery, and fracture

Persons with a history of deep vein thrombosis or prolonged immobility are at greater risk for PE. Vascular lung disease is characterized by a decrease in the size of the pulmonary vascular bed. When emboli reach the pulmonary artery, the reduced blood flow through the lungs results in arterial hypoxemia and hypercapnia. These lead to symptoms of dyspnea. Dyspnea resulting from PE is usually accompanied by fever, chest pain, and restlessness.

Trauma to leg

There is an increased risk of PE in adolescents who have sustained traumatic injury to their lower limbs.

Anxiety

People with PE feel a sense of impending doom. Significant oxygen deprivation can contribute to this symptom.

Oral contraceptives/estrogen

The estrogen in oral contraceptives causes increased coagulation of red blood cells, which increases the risk for PE. In addition, the risk of PE increases with the combination of smoking and oral contraceptives, especially in women older than age 35.

Medications

A complete medication history can provide clues to a possible hypercoagulability state. Patients who are taking anticoagulants and are underdosed can be at risk for PE. Patients taking medication for heart failure, such as digitalis or angiotensin-converting enzyme (ACE) inhibitors, are at risk because of chronic heart failure. Serum estrogen receptor modulators (tamoxifen, raloxifene) increase the risk for PE.

Is the dyspnea related to a preexisting disease?

Key questions

Do you have a history of heart problems, lung problems (asthma), or anemia?

Do you have any numbness or tingling in your body? Where?

Have you noticed any other symptoms?

Past history of disease

History of coronary artery disease (CAD), heart failure, valvular heart disease, chronic obstructive pulmonary disease (COPD), or asthma should raise the level of suspicion for recurrence or complications of that disease. Myocardial infarction (MI) can cause sudden dyspnea in persons with or without prior history of CAD. Careful questioning regarding associated symptoms and risk factors can reveal characteristics of probable MI (see Chapter 7).

Progressively increasing SOB is frequently a symptom of worsening COPD. It is often associated with cough that is worse in the morning, clear to yellow color sputum, exercise intolerance, and fatigue. Chronic progressive dyspnea in the patient with a history of heart failure or cardiac valve disease is most frequently a symptom of heart failure. Associated symptoms include peripheral edema, ascites, cough possibly with frothy sputum production, chest pain, and fatigue. Orthopnea (difficulty breathing when lying flat) and paroxysmal nocturnal dyspnea (PND) (a sudden onset of SOB when lying flat) are most often associated with heart failure.

In children with heart disease, dyspnea occurs because of insufficient blood being pumped to the lungs as a result of congenital structural anomaly or pump failure or secondary to pulmonary hypertension. Simple respiratory tract infections can cause severe respiratory insufficiency in the child who has cardiopulmonary disease. Associated symptoms include retractions (including abdominal muscles), tachypnea, nasal flaring and grunting, peripheral edema, ascites, cough, and fatigue.

Chronic progressive dyspnea because of lung involvement can also be present in patients with a history of systemic illnesses, such as sarcoidosis, rheumatological disease (rheumatoid lungs), cystic fibrosis, or Goodpasture syndrome (a rare syndrome of progressive glomerulonephritis, hemoptysis, and hemosiderosis).

Periodic recurrent dyspnea is most often the result of bronchospasm and inflamed bronchi caused by asthma. Persons with asthma can be relatively symptom free between episodes and can often identify the cause of their SOB with little prompting. Symptoms are frequently associated with recent respiratory tract infection, exercise, or exposure to allergens. The patient or parent may report audible wheezes, decreased exercise tolerance, and frequent cough. Wheezing is extremely unusual in the neonatal period and implies intrathoracic airway obstruction due to intraluminal obstruction, fixed airway narrowing, variable narrowing, or external compression. All of these factors lead to turbulent expiratory flow and audible wheeze.

Hematological diseases can affect the oxygen-carrying capacity of the blood, resulting in tissue hypoxia and a decrease in arterial pH, which stimulates the central nervous system to cause the symptom of dyspnea. Severe anemia from any cause can result in this reaction. Also, whenever the oxygen-carrying capacity of the blood is decreased because of the inability of hemoglobin to bind oxygen, dyspnea can occur. Carbon monoxide poisoning, cyanide poisoning, and methemoglobinemia are examples.

The progressive dyspnea of anemia is usually associated with fatigue, palpitations, lightheadedness, or dizziness.

Hyperventilation

Hyperventilation syndrome, a nonemergent but frightening experience, is usually accompanied by paresthesias around the mouth and of the distal extremities. Anxiety-related dyspnea should not be diagnosed until one has ruled out more serious causes.

When dyspnea is caused by pulmonary or cardiac conditions, the SOB worsens with increasing activity and improves with rest. Dyspnea caused by anxiety does not improve, and can worsen, with rest.

What factors precipitate or aggravate the dyspnea?

Key questions

What activities are associated with shortness of breath?

Do you take any medication?

Do you have any known allergies (to trees, dust, pollen, animals)? Have you been exposed to these recently?

Is there anything you can do to help yourself feel less short of breath, such as sit up, stay indoors, lie down, or use medication?

Precipitating factors

Chronic dyspnea of pulmonary origin is most frequently precipitated and aggravated by exposure to smoke. This is true for both progressive and recurrent dyspnea. Progressive dyspnea manifested in COPD is often exacerbated by exertion and is alleviated or improved with rest. As the disease progresses, less and less intense exercise, even talking, can result in increased SOB. In addition, respiratory tract infections are frequent causes of increased SOB for these patients. Exercise-induced asthma will cause dyspnea related to activity and is relieved with rest or use of bronchodilators.

Medication use

The dyspnea related to asthma is relieved by use of bronchodilator agents and steroids.

Allergies

Exposure to cold and/or allergens, exercise, and viral respiratory tract infections frequently precipitate chronic recurrent dyspnea associated with asthma.

Recumbence, missed medications, high sodium intake, and exertion often precipitate chronic dyspnea associated with heart failure. This applies to both progressive and recurrent chronic dyspnea.

Alleviating factors

Alleviating factors for dyspnea include sitting upright, taking diuretic medications, using bronchodilators, and resting for a prolonged period.

Is the dyspnea caused by a neuromuscular problem?

Key questions

Are your immunizations up to date?

If a child: Has the child eaten any honey?

Do you live on a farm?

If a child: Is the child at risk for lead poisoning?

Do you have a headache, muscle weakness, or visual changes?

Neuromuscular effects

Abnormalities of neural or neuromuscular transmission to the respiratory muscles can result in paresis or paralysis, leading to alveolar hypoventilation. Direct involvement of the respiratory muscles affected by systemic musculoskeletal diseases can lead to reduction of vital capacity and total lung capacity and result in hypercapnic hypoventilation and dyspnea. Examples of neuromuscular health problems leading to dyspnea include infections, such as poliomyelitis or tetanus, or a central nervous system insult.

Immunizations

Lack of childhood or adult immunizations for poliomyelitis or tetanus can lead to paralysis or tetany of the respiratory musculature, resulting in dyspnea and subsequent respiratory distress.

Honey

Honey is a common source of contamination of Clostridium botulinum, which can cause respiratory distress in infants and small children. The incubation period is only a few hours. Nausea, vomiting, and diarrhea result, followed by cranial nerve involvement, diplopia, weak suck, facial weakness, and absent gag reflex. Generalized hypotonia and weakness then develop and can progress to respiratory failure.

Farm residence

Organophosphate chemicals that are commonly used as insecticides can cause a myasthenia-like syndrome in children exposed to these toxins. Children residing on farms are most at risk.

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