Pediatric Respiratory Emergencies: Lower Airway Obstruction

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Chapter 169

Pediatric Respiratory Emergencies

Lower Airway Obstruction



Introduction and Epidemiology

Asthma, the most prevalent chronic disease of childhood, affects almost 7 million children in the United States.1 In the past 25 years, childhood asthma prevalence rates have more than doubled.1 The public health burden posed by this disease, as assessed by emergency department (ED) visits, hospitalizations, and deaths, remains at a historically high level. About 3% of all ED visits among children are for asthma, which accounts for 750,000 such visits annually.1 Similarly, about 3% of all hospitalizations for children are due to asthma, totaling about 200,000 per year.1 In addition, there are astonishing racial disparities among children with this condition. Compared with white children, black children have a 60% higher prevalence rate, a 260% higher ED visit rate, a 250% higher hospitalization rate, and a 500% higher death rate due to asthma.1

Thus asthma is one of the few chronic diseases of childhood for which there have been increases in prevalence, morbidity, and mortality in recent decades. These trends are occurring despite unprecedented investments in terms of money, preclinical and clinical research, and national focus. The reasons for these trends are no doubt multifactorial and are beyond the scope of this discussion. This portion of the chapter focuses on the recognition, evaluation, and clinical management of children in the ED with acute asthma.

Distinguishing Principles of Disease

Anatomy and Physiology

Asthma, a lower airway disease marked by bronchoconstriction, mucosal edema, and pulmonary secretions, may lead to respiratory failure if it is not treated in a timely or effective manner. Important anatomic and physiologic differences exist between children and adults that may hasten the development of respiratory failure, mandating that clinicians quickly recognize and take appropriate measures to reverse respiratory distress.

An upper respiratory infection (URI) associated with copious rhinorrhea, a common trigger of an asthma exacerbation, may significantly increase airway resistance. Further, a small decrease in the internal diameter of the upper airway causes a greater increase in resistance for the young child compared with the adult. In fact, just 1 mm of edema can decrease the cross-sectional area of the infant’s airway by 75%.

Regarding the thorax, the young child has a compliant chest wall and horizontally located ribs. These factors limit use of the thorax to increase tidal volume; instead, ventilation is dependent on diaphragmatic movement. However, abdominal distention as might occur with crying or swallowing of air will impede diaphragmatic breathing. With the inability to significantly increase tidal volume, minute ventilation becomes rate dependent, quickly leading to fatigue.

An infant younger than 12 months has an oxygen consumption index that is double that of an adult because of a higher rate of metabolism. Increased airway resistance and chest wall compliance necessitate more rapid breathing and increased energy expenditure. Increased work of breathing may account for as much as 15% of total oxygen consumption, at a time when oxygenation is poor. As a result, the child will have hypoxemia rapidly in response to respiratory disease. The child with significant respiratory distress and inadequate oxygenation may become bradycardic, leading to cardiopulmonary arrest within minutes if appropriate interventions are not undertaken.

Clinical Features


In evaluating the child with acute wheezing, the treating physician should obtain a concise history, perform a brief and focused physical examination, determine the initial degree of illness, and initiate appropriate therapy. After therapy has begun, a more comprehensive history and physical examination can be conducted. The initial history should include questions about the child’s age, duration and severity of symptoms, possible choking episode (foreign body aspiration), and recent medication use. The parents should be able to relate how the severity of this attack compares with that of previous exacerbations. A history of difficulty in sleeping, eating, or speaking as a result of this attack suggests a moderate to severe exacerbation. The names, doses, and frequency of administration of asthma medications recently received should be noted. A child who has been receiving aggressive therapy with short-acting beta2-agonists (SABAs) just before ED arrival may not respond favorably to that same therapy in the ED. Any comorbidities should be identified early in the clinical course.

A more comprehensive history should include questions about asthma triggers, such as URIs, cigarette smoke, allergies, or exercise. Inquiries about fever and hydration status should be part of a complete review of systems. A past medical history of frequent asthma exacerbations, ED visits for asthma, or hospitalizations to either the general ward or the intensive care unit would raise the concern for poorly controlled asthma. The impact that asthma has on the child’s life may be gauged by the monthly frequency of daytime or nighttime symptoms, such as cough, wheezing, shortness of breath, or chest tightness, as well as missed days of school or restricted activity. Persistent asthma has been defined as having at least 3 days per week of symptoms or use of SABA or awakening at night with asthma symptoms several nights per month.2 Conversely, some will consider any child treated for an asthma exacerbation in the ED to have persistent asthma. A child who meets criteria for persistent asthma should be receiving daily anti-inflammatory therapy, and those older than 5 years should be monitoring symptoms with a peak flow meter.2 If the child is wheezing for the first time, inquiries about other possible causes of wheezing (see Differential Considerations) should be made. Family and social histories should focus on asthma, cystic fibrosis, or atopic disease and the adequacy of support systems at home.

Physical Examination

In the initial focused physical examination of the wheezing child, vital signs should be obtained and the level of consciousness assessed. A child who is anxious, restless, or lethargic may be hypoxemic. No single asthma score has been universally adopted to assess degree of illness or treatment responses.3,4 Most asthma scores include key clinical factors, such as respiratory rate, degree of wheezing, inspiratory to expiratory ratio, use of accessory muscles, and oxygen saturation in room air.4 Such scores can assist in the assessment of the pretreatment degree of illness at ED triage and in tracking of the child’s response to therapy.

For a child with severe disease, wheezing may be audible without a stethoscope, or no wheezing may be detected if aeration is extremely poor. Asymmetrical wheezing suggests pneumonia, pneumothorax, or the presence of a foreign body. Palpation of the chest and neck may reveal subcutaneous air associated with a pneumomediastinum or pneumothorax. After this initial assessment, the remainder of the physical examination may be performed. The most anxiety-provoking aspects of the examination, such as otoscopy, should be delayed until after treatment is well under way.

Diagnostic Strategies

Pulse Oximetry and Arterial Blood Gas Analysis

Adjunctive studies, such as arterial oxygen saturation measured by pulse oximetry, may assist in determining the initial degree of illness.5 Pulse oximetry is noninvasive and inexpensive, and it provides objective data about the degree of illness of a wheezing child. The oxygen saturation of any child with respiratory distress should be determined soon after ED arrival, and supplemental oxygen should be provided if the oxygen saturation is 92% or less.

With the widespread use of pulse oximetry, physicians rarely need to obtain an arterial blood gas (ABG) analysis, especially if the sole purpose is to determine the partial pressure of oxygen. The acquisition of an ABG analysis should be reserved for the child with severe disease to measure the extent of respiratory acidosis and hypercapnia. The timing of this test is important. For a severely ill child requiring admission to the intensive care unit, it may be helpful to obtain this test after ED therapy has been initiated when a clinical plateau has been reached. ABG results can then be used as a baseline that may be compared with subsequent results during the hospitalization. An apparently normal partial pressure of carbon dioxide (PaCO2) or pH may actually reflect severe disease. For example, a “normal” PaCO2 of 40 mm Hg in a child with extreme tachypnea and retractions suggests impaired ventilation and impending respiratory failure.

Chest Radiographs

URIs marked by low-grade fever and coughing are common triggers of asthma exacerbations. These signs overlap with those found among children with pneumonia, making it difficult to determine the necessity of obtaining a chest radiograph in the evaluation of an acutely wheezing child. No set of predictors has been found that can accurately identify children likely to have abnormalities on chest radiography.6 Hyperinflation, interstitial markings, and atelectasis are common radiographic findings that may be seen in a wheezing child, but these should not result in initiation of antibiotic therapy or other changes in management. More serious conditions associated with asthma, such as pneumonia, pneumomediastinum, and pneumothoraces, are much less common. Rarely is an unsuspected diagnosis made on the basis of a chest radiograph in an acutely wheezing child, even if the child has never wheezed before.7

It should not be a routine practice to obtain chest radiographs for all wheezing children, even those who are wheezing for the first time or those who are being hospitalized.7 Chest radiographs should be considered for those with focal chest findings, fever, extreme distress, subcutaneous emphysema, or a history of choking. Reassessment after treatment to evaluate for the resolution of focal findings may further decrease the need to obtain a chest radiograph. This selective approach will be more cost-effective and lessen unnecessary radiation exposure and overuse of antibiotics. On the other hand, clinicians may have a lower threshold to obtain chest radiographs for infants with first-time wheezing because of a slightly greater likelihood of uncovering an anatomic abnormality.

Differential Considerations

Although most children with wheezing have asthma, other conditions should be considered. A differential diagnosis for childhood asthma is listed in Table 169-1. Of these conditions, bronchiolitis, laryngotracheobronchitis (croup), pneumonia, and gastroesophageal reflux are those that clinicians will encounter most often. Bronchiolitis is the one disease that is most commonly confused with asthma. Although the viruses associated with bronchiolitis infect children of all ages, clinical bronchiolitis marked by wheezing is seen almost exclusively in those younger than 12 months. Patients with bronchiolitis typically present between November and March. There is much clinical overlap between asthma and bronchiolitis, and the two cannot be distinguished by physical examination findings alone. A complete discussion of bronchiolitis is included later in this chapter.

Table 169-1

Differential Diagnosis of Asthma

Bronchiolitis Infant, preceding upper respiratory infection, seasonal, no history of atopy, no family history of asthma
Laryngotracheobronchitis (croup) Inspiratory stridor, barky cough, fever, response to humidified air
Pneumonia Focal wheezing, rhonchi, rales, grunting, fever
Tuberculosis Diffuse adenopathy, weight loss, prolonged fever
Bronchiolitis obliterans Prolonged cough or chest pain, inhalational exposure to toxin
Anatomic or Congenital  
Gastroesophageal reflux Frequent emesis, weight loss, aspiration
Cystic fibrosis Diarrhea, weight loss, chronic cough, salty sweat
Congestive heart failure Rales, murmur, gallop, hepatosplenomegaly, cardiomegaly or pulmonary vascular congestion on chest radiograph
Tracheoesophageal fistula Choking, coughing, cyanosis with feeds
Mediastinal mass Chest pain, mediastinal density on chest radiograph
Vascular ring Stridor, cyanosis, apnea, high-pitched brassy cough, dysphagia
Foreign body aspiration History of choking, toddler, asymmetrical pulmonary examination, unilateral hyperinflation on chest radiograph
Anaphylaxis Abrupt onset, urticarial rash, angioedema, history of allergies

Croup may have a viral or allergic etiology and affects children from infancy through early school age. The hallmark of the disease is inflammation of the upper airway, resulting in a harsh, barky cough and inspiratory stridor. Symptoms are often worse at night. Asthma will not be manifested with stridor alone, but a subset of children with croup may present with both stridor and wheezing and may be misdiagnosed with asthma.

Children with pneumonia may sometimes present with a component of wheezing, although respiratory rales and rhonchi are the usual auscultative findings. Infants and young children may also have high fever, cough, grunting, nasal flaring, or retractions, whereas more classic asymmetrical pulmonary findings are more easily detected in older children.

In addition to asthma, gastroesophageal reflux can account for recurrent wheezing in infants. In these children, poor lower esophageal sphincter function results in regurgitation and aspiration of gastric contents, leading to reflex bronchospasm. Young infants with recurrent wheezing, frequent “spitting up” of feeds, or failure to thrive should be referred for a diagnostic workup.


For purposes of patient management, it is best to stratify children by degree of illness on the basis of the initial clinical assessment (Fig. 169-1). This will help ensure the timely initiation of an appropriately aggressive approach for sicker children while minimizing adverse effects from unnecessary therapy among those with milder exacerbations. Of course, during the ED stay, the illness severity may change, making frequent examinations to assess response to therapy essential.

Mild Exacerbation

A mild exacerbation is characterized by alertness, slight tachypnea, expiratory wheezing only, mildly prolonged expiratory phase, minimal accessory muscle use, and oxygen saturation of greater than 95%. Children who are able to provide a PEFR should have a value greater than 70% of personal best. Patients with a mild exacerbation, especially those who were not receiving any asthma therapy before the ED visit, will usually require SABA therapy only. The Expert Panel of the National Heart, Lung, and Blood Institute (NHLBI) recommends that patients receive therapy every 20 minutes in the first hour of care.2 Children with mild exacerbations often improve promptly with just one or two SABA treatments. Many of these patients are managed without systemic corticosteroids. However, systemic corticosteroids may be given to those who are already undergoing a course of treatment with them before ED arrival or to those who do not respond promptly to SABA therapy (see later section on moderate exacerbation).

Because of its rapid onset of action, relatively long duration of action, and good safety profile, racemic albuterol has become the SABA of choice for treatment of children with acute asthma. Options for mode of delivery include small-volume nebulizers (NEBs) and the metered-dose inhaler with a spacer (MDI-S), and studies have assessed the use of levalbuterol in this setting.

Nebulizers versus Metered-Dose Inhalers with Spacers.: There is considerable debate about the optimal method for delivery of SABAs to children with acute asthma. About three fourths of pediatric emergency medicine physicians report using NEBs to administer SABAs, regardless of illness severity.8 NEBs provide a passive means of receiving aerosolized medication. Precise coordination between respiration and aerosol delivery is not needed, and medications such as anticholinergics as well as humidified oxygen may be delivered concurrently with the SABA. However, delivery is inefficient, with only about 10% of the drug in the reservoir delivered to the small airways.9,10 In addition, administration takes about 10 minutes, increasing respiratory therapy time and costs, and an external power source is needed, limiting portability.

On the other hand, spacers used with MDIs provide a reservoir of medication that is available to be inhaled. Therefore, precise coordination between actuation and inhalation is not needed, and there is no need for breath-holding. Drug deposition in the oropharynx and systemic absorption are reduced with the use of a spacer.11 The decreased administration time associated with MDI-S use may result in reduced costs.1214 A recent cost analysis determined that the use of MDIs with spacers in place of NEBs to treat children with mild to moderate asthma exacerbations in the ED could yield significant cost savings.15 The portability of the MDI-S allows older children to use it during the school day. Face mask–equipped spacers are available for children too young to use the spacer’s mouthpiece, although mouthpieces are preferable for older children to decrease nasal filtering of drug, which may reduce lung deposition. After each actuation, children should take five to eight breaths to completely empty the spacer.

These NEB disadvantages along with the development and widespread use of spacers have led investigators to assess the role of MDI-S for delivery of SABAs in the ED. Numerous clinical trials and meta-analyses have consistently demonstrated that delivery by MDI-S is at least as effective as delivery by NEBs.11,1623 Among children 1 to 4 years old, MDI-S use was associated with a greater reduction in wheezing and a lower hospitalization rate.14 One systematic review evaluated trials in which a total of 2066 children with acute asthma were randomized to receive SABAs by one of these two methods.17 Those children treated with MDI-S had shorter ED length of stay and a reduced hospitalization rate that was not statistically significant. The American College of Chest Physicians and American College of Asthma, Allergy, and Immunology concluded that both the NEB and MDI-S are appropriate for the delivery of SABA in the ED.24 Thus, compared with NEBs, MDI-S administration has been shown to be equally effective for children of all ages,14,16 with a wide range of illness severity and by multiple outcome measures.

Typically, when racemic albuterol is administered by intermittent nebulization, a dose of 0.15 mg/kg is placed in the reservoir of a NEB. This dose is well established as one that is both effective and safe.25,26 Optimal dosing for albuterol administered by MDI-S is not as well defined. A review assessed 10 randomized controlled trials comparing MDI-S with NEBs for delivery of SABAs to children with acute asthma.11 In some studies, up to seven times more drug was placed in the NEB reservoir compared with that released by MDI-S, yet outcomes were similar. This reflects the inefficiency inherent with NEB delivery, with much drug being lost to the environment. Multiple puffs of SABAs delivered by MDI-S seem to be well tolerated, even by young children.14,16 In one trial, children 1 to 4 years old treated with six puffs of albuterol by MDI-S had less tachycardia than did those treated with 2.5 mg of albuterol by NEB.14 The 2007 NHLBI guidelines state that “equivalent bronchodilation can be achieved either by high doses (4-12 puffs) of a SABA by MDI with a valved holding chamber  …  or by nebulizer”; they suggest a dose of four to eight puffs.2 Table 169-2 provides recommended SABA doses stratified by the patient’s weight.

Racemic Albuterol versus Levalbuterol.: Another consideration in the use of SABAs is the potential role of levalbuterol. Racemic albuterol is an equal mix of the active R-albuterol and the inactive S-albuterol. R-Albuterol produces bronchodilation as well as side effects such as tachycardia and tremors. S-Albuterol was long thought to be inert. However, there is some evidence that S-albuterol may increase reactivity to histamine, have proinflammatory effects, and exhibit “characteristics of a typical contractile agent.”27–33 Further, there seems to be preferential retention of S-albuterol in the lungs of healthy volunteers3436; this may account for diminished effectiveness with frequent dosing. Levalbuterol is pure R-albuterol without the S component. In theory, levalbuterol should be more effective than racemic albuterol at half the dose because there are no competing harmful effects from the S-isomer.

Studies assessing the use of levalbuterol for treatment of children with acute asthma have not consistently demonstrated this theoretic advantage. In the first of these clinical trials, levalbuterol (1.25 mg) was compared with racemic albuterol (2.5 mg) in the ED treatment of more than 500 children with acute asthma.37 The use of levalbuterol was associated with a decreased need for hospitalization. However, the baseline hospitalization rate in this study was high even though patients with all degrees of illness severity were enrolled. Subsequently, three other randomized trials comparing the ED use of the two drugs have failed to find a levalbuterol benefit.3840 These three studies analyzed children with a wide range of illness severities and baseline hospitalization rates and used various outcome measures, such as asthma scores, pulmonary function test results, and hospitalization rates. Racemic albuterol was demonstrated to be as effective as levalbuterol under each of these circumstances.

Similarly, a clinical trial failed to demonstrate a benefit with the use of continuously nebulized levalbuterol.41 Children who failed to respond to ED treatment and required hospitalization were randomized to receive either continuously nebulized levalbuterol or albuterol. There were no differences in the two groups with respect to time that continuous therapy was needed or time to discharge home. The acquisition cost of levalbuterol is more than 10 times greater than that of racemic albuterol.40 Until there are more compelling data to demonstrate conclusively that the additional costs of levalbuterol are offset by the need for fewer nebulizations, decreased length of ED or hospital stay, or decreased need for hospitalization, racemic albuterol should remain the drug of choice for children with acute asthma exacerbations.

Disposition.: Most children with a mild exacerbation will be able to be discharged home. Those sustaining clinical improvement 60 minutes after the most recent SABA treatment may be discharged. SABAs should be continued for the next 3 to 10 days. If systemic corticosteroid therapy was administered in the ED, it should also be continued for 3 to 10 days; 2 mg/kg/day of oral prednisone is recommended. Children should continue all other asthma controller medications, including inhaled corticosteroids (ICS).

For those who are not already receiving ICS, it is unclear if prescribing them at ED discharge leads to improved short-term outcomes. Among adult asthmatics discharged from the ED after acute asthma exacerbations, the addition of inhaled flunisolide did not lead to improved outcomes.42 Of note, though, compliance with the inhaled medication was low, and many patients were lost to follow-up. On the other hand, adults randomized to inhaled budesonide after ED discharge had a marked decrease in relapse rates, frequency of SABA use, and asthma symptoms.43 A review concluded that there is “insufficient evidence that ICS therapy provides additional benefit” when it is added to systemic corticosteroids at ED discharge.44 Pediatric emergency medicine physicians rarely prescribe ICS at ED discharge, even to children who have persistent asthma.45

Rather than prescribing ICS to prevent ED relapse, emergency physicians should consider longer term goals for those with persistent disease. National guidelines state that ICS are the medications of choice when long-term controller therapy is initiated for children with persistent asthma.2 These drugs are safe and well tolerated at recommended doses. Longitudinal studies show that daily use of ICS may decrease growth velocity, but these changes are small and reversible.46,47 Therefore, emergency physicians should identify children who, during the preceding month, have had frequent asthma symptoms, nighttime awakenings, and the need for frequent use of SABAs for asthma control. As stated by national asthma guidelines, initiation of ICS therapy at ED discharge “should be considered” for these patients.2 Those already taking low doses of daily ICS may benefit from an increase in dosing. Initiation or increase of ICS would be in addition to the 3- to 10-day course of systemic corticosteroids after ED discharge.

In addition to prescribing medications, emergency physicians should also provide asthma education at discharge. Some EDs provide standardized information to families with a video or DVD while they undergo ED therapy. This education should include a description of how to identify and to avoid asthma triggers, a written asthma action plan explaining proper steps to take in response to an asthma flare, a review of discharge medications, and instruction on proper MDI-S use. Also, follow-up asthma care within 1 to 4 weeks should be arranged.

Summary.: For children with mild asthma exacerbations, racemic albuterol should be administered every 20 minutes, as needed (see Fig. 169-1). Most children will respond promptly to therapy and be well enough to be discharged home after one or two treatments. Systemic corticosteroids may be considered for those who exhibit a suboptimal response to SABAs (see later section on moderate exacerbation). NEBs and MDI-S are each reasonable options for delivery of SABAs intermittently. Table 169-2 lists recommended doses for SABAs and other asthma medications in the ED, and Table 169-3 provides a recommended strategy for SABA administration. Rather than base the method of delivery on the issue of efficacy, clinicians should assess other factors. Determination of the number of treatments a child is likely to need, the anticipated cooperation with a given delivery method, the need to deliver concurrent medications, and costs will help guide decision-making.

Moderate Exacerbation

Children who are alert but very tachypneic and have wheezing throughout expiration, an inspiratory-expiratory ratio of 1 : 2, and significant use of accessory muscles are experiencing a moderate asthma exacerbation. Typically, the oxygen saturation will be 92 to 95% and the PEFR will be 41 to 70% of the personal best. As with children experiencing milder attacks, the cornerstone of therapy is aggressive SABA therapy. In addition, other medications such as ipratropium bromide (IB) and corticosteroids should be added, and consideration should be given to delivery of SABAs continuously.

Anticholinergics.: Stimulation of airway cholinergic receptors results in reflex bronchoconstriction, which may be blocked with the use of anticholinergic agents such as IB. This medication is available as an MDI and as a solution for nebulization that may be mixed directly with racemic albuterol. The MDI formulation should not be given to patients with allergy to peanut or soy because it contains soya lecithin; this is not a concern with the solution for nebulization.

Studies have shown that use of SABAs with IB is more effective than SABAs alone.47,48 In a randomized, double-blind clinical trial, three doses of IB administered concurrently with the first three SABA treatments were shown to be superior to just one dose of IB.49 In another study, more than 400 children were randomized to receive racemic albuterol and prednisone alone or that therapy plus IB.48 Those judged to be moderately ill did not experience an IB benefit. However, among those with an initial PEFR less than 50% predicted, the use of IB resulted in a significantly lower hospitalization rate. A systematic review and meta-analysis compared the use of SABAs plus anticholinergics with SABAs alone among children older than 18 months.50 In the 16 trials assessed, combination therapy was associated with significantly lower hospitalization rates and improvements in asthma scores and pulmonary function test results. These investigators concluded that multiple doses of IB added to SABAs should be standard treatment of children with moderate to severe asthma exacerbations.

Clinical benefits after IB use may be delayed for up to 60 minutes.49 However, it is inexpensive, and because less than 1% is absorbed systemically, it is virtually free of adverse effects.50 IB should be administered to children with moderate to severe exacerbations. Three doses may be mixed with racemic albuterol and delivered concurrently and continuously by NEB in the first hour of care (see Table 169-3). This means of administration, although not superior to delivery by MDI-S, will help ensure compliance with the goal of the equivalent of three albuterol treatments in the first hour of care.2 Alternatively, four to eight puffs of IB may be given every 20 minutes in the first hour of care,2 but these children will also need to receive a substantial number of puffs of SABAs, and as clinicians care for other patients, there may be delays in receiving appropriately aggressive therapy. In summary, sicker patients require three albuterol treatments soon after ED arrival. Continuous delivery by NEB during 1 hour may be preferred to intermittent MDI-S, not for superior efficacy but to help ensure timely medication delivery.

Systemic Corticosteroids.: There are compelling data to show that the prompt use of corticosteroids can decrease the need for hospitalization and that they should be used routinely for patients with moderate disease.4,5156 Clinicians must decide the optimal agent and route of administration.

Oral versus Parenteral.: Two early clinical trials established the efficacy of parenterally administered corticosteroids in the ED. Compared with those treated with placebo, adults treated with intravenous methylprednisolone had a lower hospitalization rate,51 as did children treated with intramuscular methylprednisolone.52 Scarfone and colleagues were the first to demonstrate the efficacy of orally administered corticosteroids in this setting.4 Children treated with frequent SABAs and oral prednisone had a reduced need for hospitalization compared with those treated with SABA therapy alone. Further, a meta-analysis determined that compared with placebo, oral corticosteroids were effective in reducing the need for hospitalization among children with acute asthma exacerbations.55

There have been few clinical trials directly comparing oral and parenteral therapy. In one small study, there were no differences in any outcome measures for children in the ED with moderate to severe asthma who were treated with equal doses of either intravenous or oral methylprednisolone.57 The most recent NHLBI guidelines recommend oral administration of corticosteroids because this is less invasive and the benefits seem to be equivalent to those of parenteral therapy.58,59 Further, oral corticosteroid therapy is inexpensive, the drugs are rapidly and completely absorbed, and this mode of administration provides the potential for out-of-hospital administration either at home or in a physician’s office.