A 10-year-old boy in respiratory distress arrives late in the evening to the emergency department (ED); he has a 2-hour history of rapid breathing and a complaint that his chest hurts. His mother gave him two nebulizer treatments without improvement. She tells you that this is the fourth time in 3 months that he has required ED visits for similar symptoms. Your initial examination reveals an afebrile male with a respiratory rate of 60 breaths per minute and a heart rate of 120 beats/min (bpm). You note that his pulse varies in amplitude with respiration. His blood pressure is normal, but his capillary refill is somewhat sluggish at 4 to 6 seconds. He is pale, appears drowsy, has mild perioral cyanosis, and is using accessory chest muscles to breathe. You hear only faint wheezing on chest auscultation.
What are the initial steps in evaluating this patient?
What is the most likely diagnosis?
What is the next step in evaluation?
ANSWERS TO CASE 20: Asthma Exacerbation
Summary: A 10-year-old boy with a multiple episodes of respiratory difficulty presents with tachypnea, perioral cyanosis, pulsus paradoxus, use of accessory muscles of breathing, slight wheezing, delayed capillary refill, and drowsiness.
• Initial steps: Treating this patient’s respiratory distress is of immediate concern. The airway is evaluated first, followed by an evaluation of breathing, and finally assessment of the circulatory status (the “ABCs”). Initial management includes administration of oxygen, an inhaled β-agonist, and a systemic dose of prednisone. Intravenous administration of fluids and medications is indicated for a patient with this degree of distress. A stat blood gas determination and monitoring oxygen saturation levels will aid further management.
• Most likely diagnosis: Asthma exacerbation.
• Next step in evaluation: After initial stabilization, past medical and family histories (medications, triggers, frequency and severity of previous episodes, previous hospitalization or intensive care unit admissions) and a review of systems are obtained. The physical examination, blood gas report, and response to initial treatments will determine subsequent management.
1. Know the acute management of asthma exacerbation.
2. Know how to classify the severity of an asthma exacerbation.
3. Know the approach to long-term management of asthma and prevention of exacerbations.
This child’s history of ED visits for respiratory difficulty and his presenting symptoms point to asthma as the most likely diagnosis; less likely conditions include cystic fibrosis, foreign-body aspiration, and congestive heart failure. The National Institutes of Health, National Heart, Lung, and Blood Institute (NHLBI) asthma guidelines suggest this child’s exacerbation is severe and requires immediate, intensive treatment. His drowsiness is of particular concern, indicating impending respiratory failure; his respiratory and circulatory status must be assessed frequently. The paucity of wheezes results from severe airway obstruction and reduced air movement; wheezing is likely to increase as therapy allows more air movement.
ASTHMA: The diagnosis when: (1) episodic symptoms of airflow obstruction are present; (2) airflow obstruction is at least partially reversible; and (3) alternative diagnoses are excluded.
ASTHMA EXACERBATION: Characterized by the triad of bronchoconstriction, airway inflammation, and mucus plugging.
PULSUS PARADOXUS: A blood pressure that varies more widely with respiration than normal. A variance of greater than 10 mm Hg between inspiration and expiration suggests obstructive airway disease, pericardial tamponade, or constrictive pericarditis.
SPIROMETRY: A test of pulmonary function. For patients with asthma, this test demonstrates airflow obstruction and reversibility, and can be used to determine an individual’s response to treatment.
Asthma accounts for approximately three million visits to pediatricians per year in the United States. The median age at onset is 4 years, but 20% of children develop symptoms within the first year of life. Atopy and a family history of asthma are strong risk factors for its development, as is respiratory infection early in life; between 40% and 50% of children with respiratory syncytial virus (RSV) bronchiolitis later develop asthma. More than half of children with asthma have symptom resolution by young adulthood, but many have abnormal pulmonary function tests only to become symptomatic in later adulthood. Heavy exposure to pollution, allergens, or cigarette smoke makes resolution less likely. A chronic nighttime cough might be a harbinger of asthma.
Airway inflammation in asthma is a result of mast cell activation. An immediate immunoglobulin (Ig) E response to environmental triggers occurs within 15 to 30 minutes and includes vasodilation, increased vascular permeability, smooth-muscle constriction, and mucus secretion. Common triggers include dust mites, animal dander, cigarette smoke, pollution, weather changes, upper respiratory infections, certain drugs (ie, β-adrenergic antagonists, and some nonsteroidal anti-inflammatory agents), and exercise (particularly when performed in a cold environment). Two to four hours after this acute response, a late-phase reaction (LPR) begins. The LPR is characterized by infiltration of inflammatory cells into the airway parenchyma; it is responsible for the chronic inflammation seen in asthma. Airway hyperresponsiveness may persist for weeks after the LPR.
Asthma management involves classifying the disease severity and identifying and minimizing exposure to triggers. Severity is defined as either intermittent or persistent; persistent asthma is further divided into mild, moderate, or severe. Allergy testing can be helpful in some situations. Pharmacotherapy for the child’s asthma symptoms follows NHLBI guidelines (available at http://www.nhlbi.nih.gov/guide-lines/asthma/asthsumm.pdf). Adequate long-term management depends on reinforcement with the patient and family of the goals of therapy. Repeat objective assessment of lung function is achieved with spirometry performed in the clinic and peak expiratory flow measurements obtained at home.
Pharmacotherapyfor asthma includes β-adrenergic agonists, anticholinergics, anti-inflammatory agents, and leukotriene modifiers. The NHLBI guidelines provide a stepwise approach to administration of these medications.
β-Adrenergic agonists (ie, albuterol) rapidly reverse bronchoconstriction via β2-receptors on bronchial smooth muscle cells; they do not significantly inhibit the LPR. These agents also can be used immediately prior to exercise or exposure to allergens to minimize the acute asthmatic response. Toxicity includes tachycardia and muscle tremor. Increased levels of drug are delivered to the lungs and toxicity is decreased when these medications are delivered through inhalation routes (nebulizer or inhaler) as compared to the oral route. When inhalers are used, a reservoir device (“spacer”) is used to maximize drug delivered to the lungs. Patients must not over-rely on short-acting inhalers because this practice is associated with death in severe asthma attacks.
Anticholinergics may be useful in the acute management of asthma exacerbation but are of little value in chronic therapy; they work by inhibiting the vagal reflex at smooth muscles.
Cromolyn and nedocromil, anti-inflammatory drugs that act by reducing the immune response to allergen exposure, become effective after 2 to 4 weeks of therapy; they are successful in only 75% of patients. Leukotriene modifiers are safe and effective anti-inflammatory medications for long-term control for some patients. The most potent available anti-inflammatory drugs are corticosteroids,which are useful for acute exacerbations (oral or intravenous prednisone, prednisolone) and for chronic therapy (inhaled corticosteroids).
20.1 A 12-year-old asthmatic girl presents to the ED with tachypnea, intracostal retractions, perioral cyanosis, and minimal wheezing. You administer oxygen, inhaled albuterol, and intravenous prednisone. Upon reassessment, wheezing increases in all fields, and the child’s color has improved. Which of the following is the appropriate explanation for these findings?
A. The girl is not having an asthma attack.
B. The girl is not responding to the albuterol, and her symptoms are worsening.
C. The girl is responding to the albuterol, and her symptoms are improving.
D. The girl did not receive enough albuterol.
E. The albuterol was inadvertently left out of the inhalation treatment, and the girl received only saline.
20.2 A previously healthy 2-year-old girl presents with the complaint of acute-onset wheezing. Her mother denies previous wheezing episodes and denies a family history of asthma or atopy. The mother says that she left the child playing in her older brother’s room. Approximately 20 minutes later she heard the child coughing and wheezing. Which of the following is the best next step in management?
A. Determining what the girl was playing with and ordering a chest radiograph
B. Referring the child to a pulmonologist
C. Prescribing antibiotics for a likely pneumonia
D. Administering an injection of intramuscular prednisone and sending her home
E. Accusing the mother of poor supervision of her child’s health, because this obviously is not the first time the child has experienced these symptoms
20.3 A well-developed 4-month-old boy presents to the ED on a cold winter’s night with the complaint of worsening respiratory distress and decreased oral intake. His parents report that he was well until yesterday, when he developed upper respiratory symptoms and a low-grade fever. Upon examination of the child, you note pallor and perioral cyanosis, a respiratory rate of 65 breaths/min, and tight wheezes throughout the chest. An arterial blood gas shows a pH of 7.15, a PCO2 of 65 mm Hg, and a serum bicarbonate of 20 mmol/L. Which of the following is the most likely explanation regarding the child’s condition?
A. The child most likely has bronchiolitis and is at risk of respiratory failure.
B. The child most likely has bronchiolitis, and his symptoms should resolve in the emergency department with additional albuterol treatments.
C. The child should undergo upper endoscopy, as you suspect a tracheoesophageal fistula.
D. The child most likely has gastroesophageal reflux and has aspirated.
E. The child has a metabolic acidosis that is most likely due to bacterial sepsis.
20.4 A 15-year-old adolescent male uses his albuterol inhaler shortly after he mows the lawn because of a mild feeling of chest “tightness.” He later returns home early from dinner at a friend’s house when he has the sudden onset of wheezing, cough, and chest pain. Which of the following is the most likely explanation for these circumstances?
A. He likely aspirated a piece of grass.
B. His albuterol inhaler must be empty.
C. His albuterol inhaler must be outdated.
D. He is having a late-phase reaction.
E. He has been exposed to a new allergen that is more irritating than grass.
20.1 C. This child presented in severe respiratory distress. Her improved color indicates reversible symptoms, confirming the diagnosis of asthma. Increased wheezing is auscultated after albuterol treatment because lung areas previously obstructed are now opening, allowing additional airflow. Less-experienced examiners may misinterpret lack of air movement as “clear” breath sounds, further delaying appropriate medical management.
20.2 A. Young children, generally between 4 months and 3 years of age, normally put objects in their mouth, and they are prone to developing foreign-body aspirations. A pulmonologist ultimately may be needed to retrieve the object, but this would not be a first step.
20.3 A. The differential diagnosis for a wheezing baby is extensive. However, the sudden onset of respiratory symptoms in a previously healthy infant, particularly in association with fever, is most consistent with the diagnosis of bronchiolitis. Initial treatment for this baby includes oxygen and a trial of nebulized albuterol or epinephrine. A blood gas measurement should be obtained immediately for any patient who presents in severe respiratory distress. This child’s blood gas indices show a marked respiratory acidosis. He will likely require mechanical ventilation and monitoring in an intensive care setting until his symptoms improve. Infants with wheezing caused by bronchiolitis do not always respond to β-agonists. Chest radiographs in infants with bronchiolitis typically show hyperinflated lungs with areas of atelectasis. Respiratory syncytial virus (RSV) and influenza A are common causes of bronchiolitis in infants in the wintertime, but several other viral causes are also possible. A careful history should be obtained to rule out less common causes of wheezing in an infant, such as recurrent aspiration or a congenital anomaly.
20.4 D. A late-phase reaction typically occurs 2 to 4 hours after an initial wheezing episode. It is caused by accumulation of inflammatory cells in the airway.
The prevalence of asthma in Western countries has been increasing steadily, making this the most frequent admission diagnosis for children in many urban hospitals.
Atopy and a family history of asthma are risk factors for development of asthma; exposure to pollutants including cigarette smoke makes resolution less likely.
The late-phase reaction begins 2 to 4 hours after allergen exposure and is responsible for the chronic inflammation seen in asthma.
Acute and long-term management of asthma is guided by recommendations published by the National Heart, Lung, and Blood Institute.
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National Heart, Lung and Blood Institute. National Asthma Education and Prevention Program, Expert Panel Report 3: guidelines for the diagnosis and management of asthma, 2007. Available at: http://www.nhlbi.nih.gov/guidelines/asthma/asthsumm.pdf. Accessed April 23, 2012.