How Should a Child Who Presents to the Emergency Room With Wheezing Be Assessed and Treated?
The first consideration when evaluating a wheezing child is whether the wheezing is likely to be asthma or, in the case of a child without prior wheezing, bronchospasm. Some focused questions will allow one to quickly assess the likelihood that the wheezing child is experiencing asthma or bronchospasm:
- Has the child had previous similar episodes? Recurrent episodes of wheezing are very suggestive of asthma.
- Do other family members have asthma? A family history of asthma is suggestive of asthma.
- Was this episode preceded by upper respiratory symptoms? Most asthma attacks are triggered by upper respiratory illnesses.
- Did the symptoms come on very rapidly, or did they follow an episode of choking or gagging? Rapid onset of wheezing or difficulty breathing may suggest an allergic reaction or, especially with a history of choking or gagging, foreign-body aspiration.
- Is there a history of cardiac disease or failure to thrive? Congestive heart failure and cystic fibrosis may present with wheezing and may also cause failure to thrive.
Once it is felt the symptoms are due to asthma or bronchospasm, the assessment of the wheezing child is almost exclusively clinical. The first step is to determine the degree of respiratory distress present, as this will dictate how rapid any interventions must be. Respiratory failure, or impending respiratory failure, must be addressed immediately and aggressively. Agitation or lethargy, dusky mucous membranes, minimal air movement, marked accessory muscle use, and oxygen saturation below 90% may all be signs of respiratory failure. In patients without respiratory failure, it is useful to classify patients by degree of severity, as this will also help to tailor management. Table 33-1 shows a useful clinical classification for asthma severity.1 Scoring systems, such as the Pulmonary Index,2 have been developed to assign a numerical score based on clinical parameters, including some of those found in Table 33-1. In the Pulmonary Index, a score of less than 6 represents a mild asthma exacerbation, while a score of more than 10 represents a severe exacerbation. Scoring systems are most frequently used in research studies to assess severity, but also can be used to develop treatment algorithms and monitor response to therapy.
A peak flow meter may be used to objectively assess airflow obstruction. In general, children ages 6 years and older are cooperative enough and can be instructed in how to perform peak expiratory flow rates (PEFR). This measurement is most useful in patients who perform them regularly at home so that measurements taken during an acute attack can be compared to their personal best PEFR when healthy. There are predicted values available based on gender and height that can be used for children who have not done PEFR or cannot remember their personal best.
There is little role of ancillary testing in wheezing patients. Chest radiographs do little to change management in the asthmatic patient. They should be considered in patients with high fever and focal findings (persistent focal wheezing, focal rales, or decreased breath sounds) that may suggest pneumonia and in patients where there is concern for pneumothorax or pneumomediastinum (severe disease or persistent decreased breath sounds). Chest radiographs should also be considered in first-time wheezing patients, especially when an alternative diagnosis (see Question 34) is being strongly considered. Similarly, arterial blood gas sampling has little value in the emergent management of the wheezing child. Oxygenation can be assessed noninvasively with pulse oximetry. PaCO2 is often elevated in severe illness early in the course of therapy, and its measurement at that time is unlikely to affect management. Although it can be used over time to track deterioration, the decision to intubate is made on a clinical basis.
Once the severity of the episode has been determined, treatment can be tailored appropriately. The mainstay of any wheezing episode thought to be due to bronchospasm is inhaled beta-agonist therapy, such as albuterol. In mild cases, this may be given as individual doses, with reassessment after the doses to determine effect. The dose of nebulized albuterol is generally quoted as 0.15 mg/kg per dose. Many institutions, however, dose albuterol according to broader weight ranges, with children less than 20 kg receiving 2.5 mg per dose and children over 20 kg receiving 5 mg per dose. In moderate to severe cases, which require multiple doses, these doses should be given as either 3 back-to-back treatments over 45 to 60 minutes or as a continuous nebulization over 60 minutes (10 mg/hr in patients 5 to 10 kg, 15 mg/hr in patients 10 to 20 kg, and 20 mg/hr in patients over 20 kg). Moderate to severe cases should also receive two to three doses of inhaled ipratropium bromide, an anticholinergic bronchodilator, over this time period as well. The use of ipratropium bromide in moderate to severe asthma exacerbations has been shown to decrease the need for hospitalization.3 Traditionally, beta-agonist therapy has been given by nebulization. There is, however, strong evidence that delivery by metered-dose inhaler with spacer (MDI-S) in children is just as effective as nebulization. This route may certainly be used for mild cases. For moderate cases, MDI-S may theoretically be used, although given the need to give ipratropium bromide (which can be given concomitantly with nebulized albuterol), nebulization is often more practical. Another advantage of nebulizer delivery is that, for children with oxygen saturations less than 92%, oxygen can be delivered along with nebulized medications. In the most severe cases, when there is concern about delivery of nebulized medication due to inadequate air movement, subcutaneous terbutaline may be given at a dose of 0.01 mg/kg (maximum 0.4 mg).
Along with initial bronchodilator therapy, moderate to severe cases should receive a dose of steroids. Oral steroids have been shown to be as effective as intravenous steroids and reduce the need for hospitalization. Oral prednisone or prednisolone are given at doses of 1 to 2 mg/kg. Dexamethasone phosphate is an alternative, given at a dose of 0.6 mg/kg (maximum 10 to 12 mg). It may be advantageous to use prednisolone, as the IV formulation (10 mg/mL) can be given orally in a smaller volume, and it has a longer half-life (36 to 72 hours) than prednisone or prednisolone, with similar efficacy. In cases of severe respiratory distress or vomiting, intravenous methylprednisolone should be given at a dose of 1 to 2 mg/kg (maximum 125 mg).
The majority of moderate to severe asthma patients will respond to the measures discussed. For those who do not, there is some evidence that intravenous magnesium sulfate 50 to 75 mg/kg (maximum 2 g) can reduce the need for hospitalization.4 In the severe cases not responding to continuous inhaled beta-agonist, intravenous terbutaline can also be initiated. This is started with a 5 to 10 mcg/kg bolus followed by a 0.3 to 0.5 mcg/kg/min infusion titrating to effect to a maximum of 5 mcg/kg/min. For the
most severe patients who are deteriorating despite maximal therapy, noninvasive positive pressure ventilation may be useful to avoid intubation.
Most acute episodes of wheezing are due to flares of pre-existing asthma often associated with a respiratory viral infection or exposure to another known trigger. Careful history and physical examination can guide the need for additional testing in a patient with previously diagnosed asthma, and this testing can often be deferred. A new-onset episode of wheezing requires more careful consideration while treatment is initiated. Aggressive medical therapy, as outlined previously, and supplemental oxygen if necessary are often all that are needed to address the flare, and the majority of patients can be discharged home with close clinical follow-up.
1. Stevenson MD, Ruddy RM. Asthma and allergic emergencies In: Fleisher GR, Ludwig S, Henretig FM, eds. Textbook of Pediatric Emergency Medicine. 6th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2009.
2. Becker AB, Nelson NA, Simons SE. The pulmonary index. Assessment of a clinical score for asthma. Am J Dis Child. 1984;138:574-576.
3. Qureshi F, Pestian J, Davis P, Zaritsky A. Effect of nebulized ipratropium on the hospitalization rates in children. N Engl J Med. 1998;339:1030-1035.
4. Chuek DK, Chau DC, Lee SL. A meta-analysis on intravenous magnesium sulphate for treating acute asthma. Arch Dis Child. 2005;90:74-77.