Laurie Soroken, Annette McDonough Asthma that is not appropriately managed may lead to exacerbations requiring emergent care.1 Bronchospasm, a symptom of asthma, is also referred to as bronchial spasm. Bronchospasm is defined as a sudden constriction of the muscles of the bronchial walls that leads to a temporary narrowing of the bronchi. When muscle tightening and inflammation occur, coughing, wheezing, shortness of breath, and thicker mucus production develop.2 The actual incidence of bronchospasm is difficult to determine because many cases are intermittent and the conditions that cause bronchospasm are multiple. It is estimated that 39.5 million Americans have been diagnosed with asthma. Females have higher prevalence rates than males, by 14%. The 2011 prevalence rate for blacks was higher than for whites by 36.9%.3 Acute bronchospasm is responsible for an estimated 10.6 million physician office visits, 1.2 million hospital outpatient department visits, 2.1 million emergency department visits, 500,000 hospital admissions, and 4000 deaths annually.3–6 In addition, young adults have been identified as a population at risk, because these individuals are reported to have a high incidence of asthma and less access to primary and preventive care and are most likely not to fill their asthma medication prescriptions.1 Bronchospasm usually occurs as a response to a specific trigger, the most common being identified as asthma. Clinical conditions that are associated with bronchospasm include anaphylactic reactions to medications or other allergens, asthma, chronic obstructive pulmonary disease, congestive heart failure, exercise, lower respiratory tract infection, mechanical airway obstruction by anatomic changes or tumor, pulmonary embolism, and vocal cord dysfunction.4,6 Allergic triggers include “pet dander, dust mites, pollen or mold.”2 Exposures to smoke, pollution, cold air, and changes in weather are examples of nonallergic triggers.2 Bronchospasm results when hyperreactivity of the airways, caused by inflammatory substances, produces airway bronchoconstriction, edema, and obstruction. On exposure to causative agents, substances that are released from basophils or mast cells lead to an allergic reaction that causes constriction and inflammation.7 Airway hyperresponsiveness (AHR) occurs along with inflammation. AHR is the contraction of small muscles surrounding the airways, and this can limit the individual’s ability to move air throughout the lungs.8 The bronchospasm may be intermittent and resolve without treatment, or the obstruction may progress to respiratory arrest, with its potential for death. Patient presentations can vary from mild anxiety to acute respiratory distress. Symptoms may occur spontaneously or be precipitated by a trigger.5,6 The most common symptom of bronchospasm is wheezing. However, the patient with acute bronchospasm may have breathlessness, chest tightness, and coughing. Symptoms may vary in degree of severity. A repetitive, spasmodic cough may be the only sign of bronchospasm. The patient’s inability to speak a full sentence without pausing to breathe indicates severe bronchospasm. Patients’ psychological states vary according to their previous experience with this condition and the severity of symptoms. Patients with a history of asthma may have experienced bronchospasm frequently and may even have come to accept this as a usual daily pattern, whereas patients who experience their first episode or a severe episode may understandably be anxious. The skin color of a patient with acute bronchospasm may be normal, flushed, or pale. The presence of pruritus or a rash suggests an allergic cause. In addition, the patient may have tachypnea, tachycardia, and a normal or slightly elevated blood pressure. Hypotension occurs in an allergic reaction with anaphylaxis. Pulsus paradoxus of greater than 25 mm Hg is a uniform indicator of severe respiratory compromise.7 The use of accessory muscles is noted as a sign of more severe bronchospasm. Wheezing may be audible or detected during auscultation on inspiration or expiration. The finding of a silent chest indicates severe spasm and is an ominous sign. With audible wheezing, the trachea should be auscultated to discern whether these sounds are indicative of laryngospasm or partial airway obstruction with a foreign body. Peak flow measurements will be less than expected for the patient’s age and height or reduced from the patient’s baseline. Pulse oximetry values below 90% in adults indicate more severe bronchospasm. ABG analysis is best performed in an emergency department. Chest radiographs may assist in determining the cause of the bronchospasm. With asthma or allergy, the chest radiograph can be normal or show hyperinflation. Serology may reveal eosinophilia and elevated immunoglobulin E levels, suggesting an allergic cause.
Acute Bronchospasm
Definition and Epidemiology
Immediate emergency department referral or physician consultation is indicated for patients in acute respiratory distress. During a severe exacerbation, arterial blood gases (ABGs) need to be monitored for hypoxemia, hypercapnia, and respiratory acidosis. Recommendations are that PaO2 be kept above 60 mm Hg. An arterial saturation greater than 90% is needed to prevent tissue hypoxia and to preserve tissue cellular oxygenation.6
Physician consultation is indicated for patients with an SaO2 of less than 92% on room air and failure to improve with nebulizer treatment given three times or epinephrine injection administered three times or to a peak flow of greater than 80% of predicted.
Pathophysiology
Clinical Presentation
Physical Examination
Diagnostics
Acute Bronchospasm
Chapter 24
