1 What is the best clinical indicator of airway obstruction in children with asthma?

There is no single best indicator of obstruction. It is generally true that, in younger children, observation is often more revealing than auscultation; it is hard to listen for wheezes in a crying child. Signs of airway obstruction include:

2 What is the pulmonary index?

The pulmonary index is one of many clinical scores used in the evaluation of acute asthma severity (Table 41-1). Although no single score has been shown to be superior, the pulmonary index has been used widely in asthma research. Also, there is not universal agreement on how to interpret the score. As a general guide, a score < 6 is considered mild, while a score > 10 is considered severe.

Becker AB, Nelson NA, Simons FER: The pulmonary index: Assessment of a clinical score for asthma. Am J Dis Child 138:574–576, 1984.

3 Describe the role of measuring peak expiratory flow rate during acute asthma exacerbations in children

Clinical assessment, while helpful, may underestimate the degree of airway obstruction in a child with acute asthma. The most commonly used pulmonary function test in pediatric acute care is the pulmonary expiratory flow rate (PEFR), which is the maximal rate of airflow during forced exhalation after a maximal inhalation. It is easily measured using an inexpensive, handheld metering device. Children as young as 4 or 5 years old can be taught how to perform PEFR, although it is more difficult to learn in the setting of an acute exacerbation. Advantages of PEFR include ease of performance, low cost, and ability to track changes during therapy. However, PEFR is effort-dependent and cannot be performed by very young children. In addition, PEFR measures function in medium and large airways, while much of the pathology in asthma occurs in medium and small airways; thus, even PEFR can underestimate the severity of disease. Normal values depend on the age and height of the child (a table is usually included with the meter), as well as the severity of the underlying lung disease, so results should be expressed as a percentage of predicted value, or of the patient’s usual best value if known. PEFR of at least 80% of predicted indicates mild disease, 50–80% of predicted is considered moderate, and less than 50% of predicted constitutes severe disease. Failure to achieve PEFR of at least 50% of predicted is one indication for hospital admission.

Gorelick MH, Stevens MW, Schultz TR, Scribano PV: Difficulty in obtaining peak expiratory flow measurements in children with acute asthma. Pediatr Emerg Care 20:22–26, 2004.

4 How should pulse oximetry be interpreted in acute asthma?

“Normal” values vary considerably between institutions and practitioners. An SaO₂ (saturation of O₂ measured by pulse oximetry) of 95% correlates with a PaO₂ of around 75, while an SaO₂ of 90% is close to a PaO₂ of 60, at the top of the steep portion of the oxygen desaturation curve. Most clinicians set a cut-off for normal somewhere in between. Remember that while a low saturation is worrisome, a normal oxygen saturation does not rule out severe disease.

Keahey L, Bulloch B, Becker AB, et al: Initial oxygen saturation as a predictor of admission in children presenting to the emergency department with acute asthma. Ann Emerg Med 40:300–307, 2002.

5 Why does hypoxemia sometimes increase paradoxically after treatment with inhaled bronchodilators?

Hypoxemia in asthma is due to ventilation–perfusion mismatch. The acute deleterious effects of bronchodilators on oxygenation are believed to be due to their effects on the circulation rather than on the airways. After treatment, particularly when administered with high concentrations of oxygen, there is improvement in local alveolar oxygenation. This, in turn, causes a reversal of hypoxia-induced pulmonary vasoconstriction, with the result that areas previously neither ventilated nor perfused are now perfused but not ventilated, increasing the mismatch.

6 What is Poiseuille’s law?

where n = viscosity coefficient of the gas, l = length of the tube, and r = radius of the tube. Thus, resistance to airflow increases in inverse proportion to the fourth power of the radius of the air passages. The take-home message is that a little narrowing goes a long way toward blocking air flow.

7 What are the indications for obtaining arterial blood gas (ABG) analysis in a patient with asthma?

Since oxygenation can be measured noninvasively, ABG is useful primarily for monitoring carbon dioxide concentration and acid–base status. In deciding whether to obtain an ABG, it is worth considering that hypercarbia generally only develops when the PEFR is < 20–25% of predicted. Moreover, the decision to intubate a patient with asthma is rarely made on the basis of ABG results alone. Thus, ABG is usually reserved for the following patients:

8 What is pulsus paradoxus?

Pulsus paradoxus is an exaggeration of the normal decrease in systolic blood pressure during inspiration. In acute asthma, it has been shown to correlate well with pulmonary function tests, and it can be useful in assessing asthma severity and response to treatment. A pulsus paradoxus < 10 is considered normal; 10–20 indicates moderate obstruction; and > 20 indicates severe obstruction.

To measure pulsus paradoxus, inflate the cuff of a manual sphygmomanometer, then auscultate as pressure is gradually released. Initially, Korotkoff sounds are heard only during expiration and disappear with inspiration. The difference between the pressure at which the sounds are first heard and the pressure at which they cease to disappear with expiration is the pulsus paradoxus.

Other conditions that may cause an elevated pulsus paradoxus include severe pneumonia, pericardial effusion, constrictive pericarditis, and conditions affecting myocardial compliance (e.g., amyloidosis, endomyocardial fibroelastosis).

9 A 6-year-old with asthma is treated for acute wheezing in the ED with only partial relief and needs to be admitted to the hospital. Should a chest x-ray be obtained?

Chest radiography is of limited value in the evaluation of the patient with acute asthma. It may be useful in identifying those patients with airleak (i.e., pneumothorax or pneumomediastinum) or a concomitant pneumonia. However, routinely obtaining radiographs in all patients with acute asthma, or even all patients with exacerbation serious enough to require hospital admission, rarely leads to an unexpected finding that changes management. In patients with known asthma, chest radiographs should be limited to cases where there is clinical suspicion of a radiographic abnormality, such as persistent rales or asymmetry of breath sounds, high fever, crepitus in the neck, or very poor response to therapy or deterioration after initial therapy.

10 What is the value of radiography in children with a first episode of wheezing?

Routine use of radiography in such children is of relatively low yield. However, most authorities recommend obtaining an x-ray in a child with a first episode of wheezing. A number of conditions other than reactive airways disease may present with wheezing, and these should be ruled out before a diagnosis of asthma is made (Table 41-2). Radiography is probably not necessary in children with clinical bronchiolitis of mild-to-moderate severity, or in older children with a family history of asthma who respond completely to inhaled bronchodilators; however, in most cases of first-time wheezing, a chest x-ray is prudent.

Table 41-2 Other Causes of Wheezing

Roback MG, Dreitlin DA: Chest radiograph in the evaluation of first time wheezing episodes: Review of current clinical practice and efficacy. Pediatr Emerg Care 14:181–184, 1998.

11 What is the role of exhaled nitric oxide (NO) measurement in the assessment of asthma?

NO is generated from the action of nitric oxide synthase on L-arginine in the lung. NO synthase activity increases during the inflammatory process, producing increased concentrations of NO in exhaled air. Measurement of exhaled NO levels has been shown to be a sensitive, noninvasive means of measuring the degree of airway inflammation in adult and pediatric patients, and it correlates well with other markers of chronic asthma severity. Available data suggest, however, that exhaled NO levels correlate poorly with acute severity in ED patients.

Gill M, Walker S, Khan A, et al: Exhaled nitric oxide levels during acute asthma exacerbation. Acad Emerg Med 12:579–586, 2005.

12 What is the preferred initial treatment for children with acute asthma?

Treatment is tailored to the severity of the exacerbation, but treatment with inhaled bronchodilators is the mainstay of initial therapy for all patients. Those with moderate to severe exacerbation (as determined by clinical status or PEFR) should receive 3–4 doses of an inhaled bronchodilator in the first hour of treatment until there is good response; those with more mild disease may require less aggressive treatment. In addition, systemic steroids should be given immediately in severely ill patients, to those who are symptomatic despite appropriate bronchodilator therapy at home, and to all patients who fail to show complete response to one or two inhalation treatments in the ED.

Expert Panel on Management of Asthma: Guidelines for the Diagnosis and Management of Asthma: Clinical Practice Guidelines. Available at: http://www.nhlbi.nih.gov/guidelines/asthma/asthgdln.htm

13 Isn’t nebulization a more effective means of delivering inhaled beta-agonists than a metered dose inhaler (MDI)?

Several studies and meta-analyses have shown that nebulizer and MDI are clinically equivalent, provided that an appropriate dose is given and that a spacer device is used with the MDI. Standard doses of nebulized beta-agonist (0.15 mg/kg per dose, maximum 5 mg) are substantially higher than for MDI. However, the particles produced by the MDI deliver medication far more effectively to the lungs. Current recommendations of ED dosages of albuterol for acute asthma are for 2–4 puffs of albuterol for young children, 4–6 puffs for older children, and 4–8 puffs for adolescents and adults. Spacer devices (e.g., Aerochamber^®) are available in a variety of sizes and configurations and can be used successfully even in young infants. In one sense the delivery systems are not equivalent: Studies have shown that use of MDI is less expensive and leads to shorter ED stays.

Cates CJ, Bara A, Crilly JA, Rowe BH. Holding chambers versus nebulisers for beta-agonist treatment of acute asthma. Cochrane Database of Systematic Reviews 2003, Issue 2. Available at: http://www.cochrane.org/cochrane/revabstr/AB000052.htm

14 What are the adverse effects of albuterol?

Note that even with high-dose therapy, while mild degrees of hypokalemia are common (one-third of children in one study), symptomatic hypokalemia requiring treatment is rare. Patients receiving high-dose continuous albuterol for more than 6–8 hours should have serum potassium monitored.

15 What is levalbuterol?

Racemic (standard) albuterol is a mixture of two isomers. Levalbuterol (Xopenex) is the pure R-isomer, which is responsible for bronchodilation. Although some authors suggest that levalbuterol produces fewer side effects, particularly tachycardia and jitteriness, than albuterol, most of the clinical evidence supports the notion that equipotent doses of albuterol and levalbuterol have similar bronchodilator efficacy and side effect profiles for acute use. There is some evidence that the S-isomer may increase airway reactivity, suggesting that levalbuterol may be preferred for chronic use.

Qureshi F, Zaritzky A, Welch C, et al: Clinical efficacy of racemic albuterol versus levalbuterol for the treatment of acute pediatric asthma. Ann Emerg Med 46:29–36, 2005.

16 What is the mechanism of action of ipratropium?

Ipratropium bromide binds to cholinergic receptors, located primarily in the medium and large airways, leading to bronchodilation. Because vagally mediated bronchodilation is much less marked than that produced by adrenergic stimulation, ipratropium is a much less potent bronchodilator than albuterol and should not be used alone. However, the concomitant administration of both leads to a synergistic effect. Ipratropium is structurally related to atropine, but it is a quaternary compound, and therefore is poorly absorbed. Thus, systemic side effects are minimal.

17 Which patients should receive ipratropium?

Ipratropium bromide binds to cholinergic receptors in the airways; concomitant administration with beta-agonists leads to a synergistic bronchodilator effect. Pediatric studies are fairly convincing that addition of ipratropium to albuterol leads to significant improvement in patients with severe asthma exacerbation. The benefit in those with more moderate disease is less clear. However, ipratropium has very little downside; costs and adverse effects are both minimal. It should be given to those patients with severe disease at presentation and those who fail or have failed to respond well to beta-agonists alone.

Plotnick LH, Ducharme FM: Combined inhaled anticholinergics and beta2-agonists for initial treatment of acute asthma in children. Cochrane Database of Systematic Reviews 2000, Issue 3. Available at: http://www.cochrane.org/cochrane/revabstr/AB000060.htm

18 What is the optimum dose of ipratropium?

This has not yet been well established. Young children (< 10 kg) should get 250 μg (one-half vial) per dose; larger children can get 500 μg per dose. While multiple doses have been shown to be better than a single dose, the optimum schedule is not known. Most authorities recommend adding ipratropium to two or three of the first three doses of albuterol given in the ED, then every 2–4 hours.

19 When should steroids be administered?

The sooner, the better. Asthma is an inflammatory disease. Bronchodilators control only the symptoms, not the underlying pathology. Therefore, nearly all children with acute asthma should receive systemic corticosteroids, preferably at the start of their ED treatment. That said, there is a trade-off in that too-frequent steroid administration may lead to problems. Patients with particularly mild disease, who require no or only a single treatment in the ED and have complete relief of symptoms with infrequent (no more than three to four times a day) treatments at home, may be managed without steroids.

20 What are the actions of corticosteroids in acute asthma?

Steroids have multiple actions, including:

The last two help explain the observed onset of clinical effect within 2 hours of administration—during the time course of a typical ED visit. Peak effect of steroids requires interference with cellular synthetic pathways and occurs after 6–12 hours.

21 When are IV steroids preferred over the oral route?

Almost never. There are several pediatric studies, and more from the adult literature, showing oral and IV corticosteroids to be equally effective, even among severely ill patients. The IV route should be reserved for those unable to take oral medicine (persistent vomiting, severe respiratory distress) and perhaps those patients ill enough to be admitted to an intensive care unit.

Barnett PL, Caputo GL, Baskin M, Kuppermann N: Intravenous versus oral corticosteroids in the management of acute asthma in children. Ann Emerg Med 29:212–217, 1997.

22 How can steroids be given to the child who is vomiting but does not require hospital admission?

Although pediatric data are sparse, a short course of high-dose inhaled steroids may be a useful alternative in children with mild-to-moderate exacerbation. Another option is the intramuscular route using dexamethasone. Two studies in children support this; one used a dose of 0.3 mg/kg, and the other used 1.7 mg/kg.

Edmonds ML, Camargo CA Jr, Brenner BE, Rowe BH: Inhaled steroids for acute asthma following emergency department discharge. The Cochrane Database of Systematic Reviews 2000, Issue 3: http://www.cochrane.org/cochrane/revabstr/AB002316.htm

23 What are the contraindications to systemic steroids?

Note that concomitant bacterial infection (e.g., otitis media, pneumonia) is not a contraindication to the use of steroids.

24 Describe the role of magnesium sulfate in acute asthma

Magnesium sulfate produces bronchodilation via direct effect on smooth muscle because of calcium antagonism. It may provide added benefit when adrenergic and vagal receptors have been saturated. In children with severe exacerbations, the addition of magnesium sulfate to aggressive beta-agonist therapy and systemic steroids leads to greater clinical improvement and improved pulmonary function and SaO₂. The effectiveness in patients with less severe illness is equivocal.

Rowe BH, Bretzlaff JA, Bourdon C, et al: Magnesium sulfate for treating exacerbations of acute asthma in the emergency department. Cochrane Database of Systematic Reviews 2000, Issue 1. Available at: http://www.cochrane.org/cochrane/revabstr/AB001490.htm

25 What is the dose of magnesium sulfate for asthma?

50–100 mg/kg (maximum 2–2.5 g) administered intravenously over 20–30 minutes.

26 What is heliox?

Heliox is a mixture of helium and oxygen, usually in a ratio of 60–70% He:30–40% O₂. Because helium is a smaller molecule than either nitrogen (the major component of air) or oxygen, heliox is less viscous than air. According to Poiseuille’s law, gas flow is inversely proportional to viscosity; thus, heliox may be better able to diffuse past constricted air passages than air mixtures or pure oxygen. The evidence for its effectiveness in status asthmaticus is mixed. Case series and uncontrolled trials have shown improvement among severely ill patients given heliox. However, controlled clinical trials have failed to show significant benefit in terms of pulmonary function or clinical score. Among the disadvantages are the relatively low oxygen concentration permitted and the need for a tight-fitting mask (which may limit compliance in younger children). It remains an investigational agent but may be considered in patients with severe illness that fails to respond to other treatment.

Rodrigo G, Pollack C, Rodrigo C, Rowe BH: Heliox for nonintubated acute asthma patients. Cochrane Database of Systematic Reviews 2003, Issue 2. Available at http://www.cochrane.org/cochrane/revabstr/AB002884.htm

27 What are the indications for endotracheal intubation and mechanical ventilation in a patient with asthma?

28 Which medications should be used during endotracheal intubation of an asthmatic patient?

Rapid sequence induction, including sedation and neuromuscular blockade, should be used. Ketamine is a good choice as a sedating agent because of its intrinsic bronchodilating properties. However, because it also increases airway secretions, it should be used in combination with an anticholinergic agent such as atropine or glycopyrrolate. Some medications, including opiates (morphine, meperidine) and muscle relaxants (curare, atracurium), potentiate histamine release and may worsen bronchospasm.

29 What are the two most common complications of mechanical ventilation?

30 What is bronchiolitis?

Bronchiolitis is a viral infection of the upper and lower respiratory tract (medium and small airways). The peak incidence is in the winter. Children less than 2 years of age are most commonly affected. Respiratory syncytial virus accounts for approximately 80% of cases; parainfluenza, human metapneumovirus, adenovirus, influenza, and other respiratory viruses are less common causes.

31 Is there a test for respiratory syncytial virus (RSV)? How good is it?

RSV can be identified in nasal secretions by viral culture. Rapid antigen testing is also widely available in many hospital laboratories. The sensitivity of the commercially available tests is generally in the range of 80–90%, and specificity is greater than 90%. However, the clinical utility of these tests is limited, since treatment is directed toward the clinical manifestations rather than the etiologic agent; treatment generally is the same regardless of the results of the test.

Bordley WC, Viswanathan M, King VJ, et al: Diagnosis and testing in bronchiolitis: A systematic review. Arch Pediatr Adolesc Med 158:119–126, 2004.

32 What are the clinical characteristics and natural history of bronchiolitis?

Bronchiolitis begins as an upper respiratory infection, with coryza and cough. (In older children and adults, as well as many infants, RSV infection remains confined to the upper respiratory tract.) Over a period of several days, the lower tract becomes involved, with the development of wheezing and rhonchi, as well as signs of respiratory distress. Typically, signs and symptoms peak in severity on the third to fifth day of illness and then begin to wane. The total duration of illness is generally 10 to 14 days, although some infants may have a prolonged course. In one study, 18% of children were still symptomatic at 3 weeks. Central apnea can occur in young infants, usually at the onset of illness, before respiratory signs manifest.

Swingler GH, Hussey GD, Zwarenstein MZ: Duration of illness in ambulatory children diagnosed with bronchiolitis. Arch Pediatr Adolesc Med 154:997–1000, 2000.

33 Who is at risk for severe disease?

Among the risk factors for severe illness are very young age, prematurity, underlying cardiac or pulmonary disease, and immunodeficiency. Most previously healthy infants have mild to moderate disease and do not require hospitalization. However, several clinical features are predictive of development of more serious illness (Table 41-3). A score of 3 or more has a sensitivity and specificity of approximately 80% for severe disease (defined as needing hospitalization).

Shaw KN, Bell LM, Sherman NH: Outpatient assessment of infants with bronchiolitis. Am J Dis Child 145:151–155, 1991.

34 What is the role of albuterol in the management of bronchiolitis?

Because wheezing is a clinical hallmark of bronchiolitis, inhaled beta-agonists are often administered. However, multiple clinical trials, summarized in two meta-analyses, have shown mixed results. On average, the benefit of beta-agonists is small. It appears that a subset of infants responds well, while a larger group responds minimally or not at all. It is not currently possible to predict responsiveness; therefore, a trial of albuterol, either 0.25–0.5 ml of a 0.5% solution via nebulizer or 2 puffs from an MDI with spacer/mask is warranted. Those children who respond are candidates for further treatment. It is not necessary to continue treatment in the absence of clinical responsiveness. Oral albuterol has not been shown to be efficacious.

King VJ, Viswanathan M, Bordley WC, et al: Pharmacologic treatment of bronchiolitis in infants and children: A systematic review. Arch Pediatr Adolesc Med 158:127–137, 2004.

35 A 3-month-old child with bronchiolitis has moderate distress and a pulse oximetry of 93% in room air. She does not respond to inhaled albuterol. Is there any other effective treatment?

Although several studies have found a superior clinical benefit of inhaled epinephrine compared to albuterol, more recent literature has shown that epinephrine and albuterol are similarly effective. It is not customary to administer inhaled epinephrine on an outpatient basis; a trial of epinephrine may be considered in those patients with more severe illness who are likely to require hospitalization. The usual dose is 3 ml of a 1:1000 solution via nebulizer.

Hartling L, Wiebe N, Russell K, et al: Epinephrine for bronchiolitis. Cochrane Database of Systematic Reviews 2004, Issue 1: http://www.cochrane.org/cochrane/revabstr/AB003123.htm

36 Is there a role for corticosteroids in bronchiolitis?

Most studies to date have shown no benefit of corticosteroids, either systemic or inhaled, in the treatment of bronchiolitis. One study by Schuh et al (J Pediatr 140:27–32, 2002) found that a single dose of dexamethasone decreased hospital admission by more than 50%; this finding has not yet been confirmed in larger, multicenter studies. Steroids may be of benefit in selected children with wheezing suspected of having intrinsic reactive airways disease, such as those with a prior history of wheezing, or strong family or personal history of atopy and good response to inhaled beta-agonists.

Patel H, Platt R, Lozano JM, Wang EEL: Glucocorticoids for acute viral bronchiolitis in infants and young children. Cochrane Database of Systematic Reviews 2004, Issue 3. Available at: http://www.cochrane.org/cochrane/revabstr/AB004878.htm

37 What is ribavirin?

Ribavirin is an antiviral agent with activity against RSV. Although previously recommended for patients with or at risk for severe RSV infection, experts have recommended more recently that ribavirin not be used routinely, even in severe cases.

38 What is palivizumab?

Palivizumab (Synagis) is a humanized mouse monoclonal antibody against RSV. Palivizumab prophylaxis has been shown to reduce the incidence and severity of RSV bronchiolitis in high-risk patients. It is administered as a monthly intramuscular injection.

39 What is croup? How is it diagnosed?

Croup is a viral infection of the upper respiratory tract lasting 7–10 days. It is the most common cause of stridor in a febrile child. Parainfluenza virus can be recovered from the nasopharynx in over 90% of cases. The rest of the cases are caused by influenza, respiratory syncytial virus, measles, or adenovirus. It is most often seen in the fall months with a peak in October, and it typically affects children between the ages of 6 and 36 months.

Croup usually begins with a fever (temperature 38–39° C) and rhinorrhea. The cricoid cartilage causes the mucosal swelling to occur inwards, encroaching on the airway. A harsh, barky, “seal-like” cough begins within 12–48 hours. There may be associated tachypnea, stridor, and subcostal retractions in the more severe cases. The symptoms may be relieved by cool or humidified air and are exacerbated by crying.

40 What is the differential diagnosis of croup?

Conditions that may be mistaken for croup include bacterial tracheitis, retropharyngeal abscess, and epiglottitis (Table 41-4). The last is a much less common entity since 1990, with the introduction of the Hib vaccine. In a 6- to 24-month-old afebrile child, an index of suspicion should be kept for an aspirated foreign body. Often a clear history of choking is not obtained.

41 When are diagnostic tests indicated (or of value) in croup?

Croup is diagnosed on the basis of presenting signs and symptoms. Children with characteristic disease do not require further diagnostic testing. Anteroposterior and lateral radiographs of the neck may be indicated in children with atypical features (e.g., age less than 6 months, recurrent or prolonged croup, toxicity on exam). The typical radiographic findings are shown in Table 41-4.

42 How do you assess the severity of croup?

Several scoring systems have been devised to assess croup severity. The most commonly used is the modified Westley score (Table 41-5). A score of < 4 indicates mild disease, 4–6 indicates moderate disease, and a score of 7 indicates severe disease.

Super DM, Cartelli NA, Brooks LJ, et al: A prospective randomized double-blind study to evaluate the effect of dexamethasone in acute larygotracheitis. J Pediatr 115:323–329, 1989.

43 What are indications for admission?

A child with a croup score = 7, significant respiratory compromise, dehydration, unreliable caretaker, or lack of adequate follow-up should be admitted to the hospital. For those severely ill patients not responding to therapy, an ABG may be helpful in deciding admission to the general ward versus the pediatric ICU.

44 Is there any scientific evidence that humidified air is beneficial in the treatment of children with croup?

No. In theory, the humidified air moistens secretions and soothes the inflammation of the mucosa. However, despite the ubiquitous recommendations for the use of “the steamy bathroom” and “misty ox,” controlled trials have failed to demonstrate a clinical benefit.

Nieto GM, Kentab O, Klassen TP, Osmond MH: A randomized controlled trial of mist in the acute treatment of moderate croup. Acad Emerg Med 9:873–879, 2002.

Scolnik D, Coates AL, Stephens D, et al: Controlled delivery of high vs low humidity vs mist therapy for croup in emergency departments: A randomized controlled trial. JAMA 295:1274, 2006.

45 Is there any scientific evidence that steroids are beneficial in the treatment of croup?

Yes. Although many of the randomized trials involving the use of steroids in croup have involved relatively small numbers of patients, meta-analyses of these trials have shown significant decreases in clinical croup scores and decrease in risk of intubation in patients with croup who receive steroids. In addition, one study has also demonstrated that steroids reduce symptom duration even in children with mild symptoms. In general, patients with more than minimal symptoms (e.g., a croup score = 1) should be treated with steroids.

Bjornson CL, Klassen TP, Williamson J, et al: A randomized trial of a single dose of oral dexamethasone for mild croup. N Engl J Med 351:1306, 2004.

Russell K, Wiebe N, Saenz A, et al: Glucocorticoids for croup. Cochrane Database of Systematic Reviews 2004, Issue 1. Available at: http://www.cochrane.org/cochrane/revabstr/AB001955.htm

46 Which method of corticosteroid delivery is better: intramuscular, oral, or nebulized? What is the ideal dose?

Both dexamethasone (given orally or intramuscularly) and the newer synthetic glucocorticoid budesonide (inhaled) have been shown to be effective in the treatment of croup, although recent studies have suggested that systemic dexamethasone is superior. Comparisons of oral and intramuscular dexamethasone have found similar rates of clinical improvement. The usual dose of dexamethasone for croup has traditionally been 0.6 mg/kg IM or PO, though doses of 0.15 and 0.3 mg/kg have been shown to be similarly effective.

47 Is racemic epinephrine superior to “regular” L-epinephrine in the treatment of croup?

Nebulized epinephrine has been shown to provide short-term benefit in the treatment of croup, presumably by reducing tracheal secretions and mucosal edema. Racemic epinephrine has been advocated traditionally, based on the belief that a mixture of D– and L– isomers would lead to less tachycardia. However, in a randomized trial directly comparing the two drugs, they were equivalent in terms of efficacy and side effects. A dose of 5 ml of L-epinephrine 1:1000 is equal to 0.5 ml of the racemic (2%) mixture.

Kunkel NC, Baker MD: Use of racemic epinephrine, dexamethasone, and mist in the outpatient management of croup. Pediatr Emerg Care 12:156–159, 1996.

48 Do patients who receive nebulized epinephrine in the ED require admission to the hospital?

Because of the “rebound phenomenon”—a tendency to return to the baseline clinical picture after the epinephrine wears off—administration of nebulized epinephrine to children with croup in the ED became a major reason for admission to the hospital in the 1980s and early 1990s. However, studies have demonstrated a lack of adverse outcome in children who are discharged after a period of observation (typically 2–4 hours) after epinephrine. To be safely discharged, it is recommended that the child remain clinically stable (no stridor at rest, normal air entry and oxygen saturation), and that the child receive a dose of dexamethasone prior to discharge.

49 How reliable are signs and symptoms in diagnosing pneumonia in young children?

Infants and young children with pneumonia often have subtle and nonspecific pulmonary findings. The issue of “occult” pneumonia—pneumonia in the absence of any pulmonary findings—has been a controversial one. Several authors have found that the risk of pneumonia is very low in the absence of any findings, but they caution that tachypnea may be a sole finding. Tachypnea, in fact, has the greatest negative predictive value. A study of highly febrile children with leukocytosis (WBC > 20,000) found that 26% of such children in whom pneumonia was unsuspected clinically had infiltrates on chest x-ray. However, tachypnea in this study was evaluated qualitatively.

50 What are the most common bacterial causes of pneumonia in children?

See Table 41-6.

Table 41-6 Most Common Bacterial Causes of Pneumonia In Children

* In unimmunized populations.

51 What organisms are most commonly associated with pleural effusion?

Pneumococci, S. aureus, and M. tuberculosis are the most common causes of effusion in children with pneumonia.