Asthma, Pediatric, Emergency Medicine

Basics

Description

2.7 million children (<18 yr) affected in US
850,000 ED visits per year in US
Inflammatory events, usually viral, lead to bronchoconstriction:
- Compounded by hyper-reactivity of airways
- Mediators of the inflammatory cascade exacerbate symptoms
Airway obstruction produces increased airway resistance and gas trapping:
- Mucosal edema
- Bronchospasm
- Mucous plugging
Infants more vulnerable to respiratory failure:
- Increased peripheral resistance
- Decreased elastic recoil with early airway closure
- Unstable rib cage
- Mechanically disadvantaged diaphragm
Family history of allergy
Medical history of early injury to airway (bronchopulmonary dysplasia, pneumonia, intubation, croup, reflux, passive exposure to smoking), reactions to foods and drugs, other allergic manifestations
Environmental exposures such as pets, smoke, carpets, or dust may trigger or exacerbate

Etiology

Precipitating/Aggravating Factors

Infection:
- Viral
- Bacterial
Allergic/irritant:
- Environment: Pollens, grasses, mold, house dust mites, and animal dander
- Occupational chemicals: Chlorine, ammonia-food and additives
- Irritants: Smoke, pollutants, gases, and aerosols
- Exercise
- Cold weather
- Emotional: Stress, phobia
- Intoxication: β-blockers, aspirin, NSAIDs

Diagnosis

Signs and Symptoms

General

Fatigue, somnolence
Diaphoresis, agitation
Hypoxia, cyanosis
Tachycardia
Dehydration
Pulsus paradoxus

Respiratory

Wheezing, rales, rhonchi
Cough, acute or chronic
Tachypnea
"Tight chest"�
Dyspnea, shortness of breath with prolonged expiratory phase
Retractions, accessory muscle use, nasal flaring
Hyperinflation
Often a history of recurrent episodes and chronic restrictions
Complications:
- Recurrent pneumonia, bronchitis
- Atelectasis
- Pneumothorax, pneumomediastinum
- Respiratory distress/failure/death

History

Precipitating events or known triggers
Chronicity of symptoms
Comorbid illnesses
History of disease:
- Previous hospitalizations for asthma
- Previous intubations and intensive care
- Regular and sporadic medications

Physical Exam

Vital signs, including oximetry and respiratory status
Wheezing: Absence of wheezing may be associated with markedly impaired air movement and decreased breath sounds
Signs of hypoxia
Skin and nail bed color bluish
Signs of respiratory fatigue, distress, or failure:
- Use of accessory muscles of respirations or retractions
- Lethargy or confusion

Essential Workup

Clinical diagnosis based primarily on physical exam and history; assess ventilation by observation for retractions and use of accessory muscles as well as auscultating for air exchange.
Follow response to bronchodilator therapy with present illness and past episodes.
Exclude other differential considerations.
Pulse oximetry:
- Initial SaO2 <91% (sea level) associated with significant illness: Admission, relapse, prolonged course
Peak flow meters in cooperative patients (usually >5 yr old)
- <50-70% predicts moderate to severe obstruction.
- >70-90% associated with mild to moderate obstruction
- >90% considered normal

Diagnosis Tests & Interpretation

Lab

Arterial blood gas (ABG) may be an adjunct to pulse oximetry to measure oxygenation and clinical exam to assess ventilation; not mandatory or routinely done.
CBC as a nonspecific marker of infection
Theophylline level: Only for patients on theophylline (not recommended)

Imaging
Chest radiograph considered in the following patients, esp. focusing on the presence of infiltrates, bronchial wall thickening, or hyperexpansion. �

<1 yr of age to exclude foreign body or atelectasis
First episode of significant wheezing (suggested to assess chronicity of illness and assist in excluding other conditions)
Increasing respiratory distress or minimal response to therapy
Respiratory distress/failure
Shortness of breath in the absence of wheezing

Diagnostic Procedures/Surgery
Peak flow measurement (see above) �

Differential Diagnosis

Infection/inflammation:
- Bronchiolitis: Clinically difficult to differentiate except by age and clinical history.
- Pneumonia: Viral, bacterial, chemical, or hypersensitivity
- Aspiration
- Retropharyngeal/mediastinal abscess/mass
- Anaphylactic reaction
Anatomic:
- Pneumothorax
- Foreign body
Vascular disorder:
- Compression of trachea by vascular anomaly
- Pulmonary embolism
- CHF
Congenital disease:
- Cystic fibrosis
- Tracheoesophageal fistula
- Bronchogenic cyst
- Congenital heart disease
Intoxication: Metabolic acidosis
Neoplasm
Vocal cord dysfunction (VCD)
Pulmonary edema-cardiogenic or noncardiogenic
Gastroesophageal reflux

Treatment

Pre-Hospital

Oxygen and oxygen saturation monitoring
Nebulized β-adrenergic agonist: Albuterol
Intubate for respiratory failure or severe fatigue.
IV fluids if evidence of dehydration
Rapid transport and good communication with ED

Initial Stabilization/Therapy

Maintain SaO2 >90-95%.
β-adrenergic nebulizer(s): Albuterol
Intubate for respiratory failure.
20 mL/kg 0.9% NS bolus if evidence of dehydration.

Ed Treatment/Procedures

Assess patient for signs of potential respiratory failure:
- Cyanosis
- Severe anxiety or irritability
- Lethargy, somnolence, fatigue
- Persistent tachypnea
- Poor air entry, ventilation
- Severe retractions
Monitor oxygenation; titrate oxygen saturation to SaO2 >95% (sea level).
β-adrenergic nebulizer: Albuterol:
- Frequent or continuous for severe asthma
- Levalbuterol may require less frequent dosing and may be associated with less side effects.
Ipratropium bromide may be added as adjunct to β-adrenergic agonists. Most effective when combined with 1st 3 doses of β-adrenergic agent in moderate to severely ill children
Steroid therapy:
- Oral for moderate exacerbations in those able to take oral meds
- IV for severe exacerbations or in those unable to take oral meds
- 1 dose of dexamethasone may be equivalent to traditional steroids
SC epinephrine or terbutaline for severe or refractory asthma (rarely used)
Magnesium sulfate may be useful in severe disease following standard therapy.
Intubate for respiratory failure:
- Ketamine is a useful induction agent.
20 mL/kg of 0.9% NS bolus if evidence of dehydration
Heliox (oxygen and helium) may be useful but studies are inconclusive

Medication

Albuterol (0.5% solution or 5 mg/mL):
- Nebulizer: 0.15 mg/kg per dose, up to 5 mg per dose, q15-30min PRN
- Metered-dose inhaler (MDI) (with spacer) (90 μg/puff): 2 puffs q5-10min, max. 10 puffs
- Also available for nebulizer as 0.083% solution or 2.5 mg/3 mL
Dexamethasone 0.3 mg/kg/dose (max.: 16 mg)
Epinephrine (1:1,000) (1 mg/mL): 0.01 mg/kg SC, up to 0.35 mL per dose, q20min for 3 doses
Ipratropium bromide: Nebulizer (0.02% inhaled sol 500 μg/2.5 mL), 250-500 μg per dose q6h
Ketamine (for intubation): 1-2 mg/kg IV as induction agent
Levalbuterol (0.63 and 1.25 mg vials): q6-8h by nebulizer
Magnesium sulfate: 25 mg/kg per dose IV over 20 min; max. 1.2-2 g per dose
Methylprednisolone: 1-2 mg/kg per dose IV q6h; max. 125 mg per dose
Prednisolone: 1-2 mg/kg per dose PO q12h (available as 15 mg/5 mL)
Prednisone: 1-2 mg/kg per dose PO q6-12h; max. 80 mg per dose
Terbutaline/(available as 1 mg/1 mL) (0.01%): 0.01 mL/kg SC q15-20min up to 0.25 mL per dose, q20min for 2 doses

First Line

Albuterol
Steroids
Ipratropium

Second Line

Epinephrine or terbutaline
Magnesium sulfate

Follow-Up

Disposition

Admission Criteria

Need to individualize based upon subjective and objective assessment
Persistent respiratory difficulty:
- Persistent wheezing
- Increased respiratory rate/tachypnea
- Retraction and use of accessory muscles
SaO2 <93% (sea level) on room air
Peak expiratory flow rate (PEFR) <50-70% predicted levels
Inability to tolerate oral medicines or liquids
Prior ED visit in last 24 hr
Comorbidity:
- Congenital heart disease
- Bronchopulmonary dysplasia
- CF
- Neuromuscular disease
Concomitant illness:
- Pneumonia or severe viral infection

Intensive Care Unit Criteria

Severe respiratory distress
SaO2 <90% or PaO2 <60 mm Hg on 40% oxygen
PaCO2 >40 mm Hg
Significant complications:
- Pneumothorax
- Dysrhythmia

Discharge Criteria

Good response to therapy. Observe in ED 60 min after last treatment before discharging:
- PEFR >70% predicted based on age/height
- SaO2 >93% on room air (sea level)
- Respiratory rate normal
- No retractions
- Clear or minimal wheezing
- No or minimal dyspnea
Good follow-up and compliance. Reduce exposure to irritants (smoking) or allergens
Discharge treatment:
- Intensive β-adrenergic regimen for 3-5 days
- Short course (3-5 days) of steroids (2 mg/kg/day) for those presenting with moderate symptoms with consideration of ongoing therapy using nebulized or MDI routes. Patients with moderate or severe exacerbations should have arrangements made for inhaled steroids over a 1-2 mo period such as fluticasone, budesonide, or beclomethasone
- Follow-up appointment 24-72 hr
- Instructions to return for shortness of breath refractory to home regimen
- Long-term therapy should be considered for children with recurrent episodes, persistent symptoms, or activity limitations.

Followup Recommendations

Primary care physician for maintenance therapy, often including nebulized or MDI steroid therapy and education about acute rescue management. �

Pearls and Pitfalls

Rapid treatment with continuous re-evaluation to detect any progression of disease is essential.
When admitting patients, assure that β-adrenergic agent therapy is not interrupted.

Additional Reading

Krebs �SE, Flood �RG, Peter �JR, et al. Evaluation of a high dose continuous albuterol protocol for treatment of pediatric asthma in the emergency department. Pediatr Emerg Care. 2013;29:191-196.
National Heart, Blood and Lung Institute; National Asthma Education and Prevention Program. Guidelines for the diagnosis and management of asthma. Bethesda, MD: NIH; 2007.
Robinson �PD, Van Asperen �P. Asthma in childhood. Pediatr Clin North Am. 2009;56(1):191-226.
Scarfone �RJ, Friedlaender �E. Corticosteroids in acute asthma: Past, present, and future. Pediatr Emerg Care. 2003;19(5):355-361.

Codes

ICD9

493.00 Extrinsic asthma, unspecified
493.02 Extrinsic asthma with (acute) exacerbation
493.90 Asthma, unspecified type, without mention of status asthmaticus
493.10 Intrinsic asthma, unspecified
493.01 Extrinsic asthma with status asthmaticus
493.0 Extrinsic asthma

ICD10

J45.901 Unspecified asthma with (acute) exacerbation
J45.902 Unspecified asthma with status asthmaticus
J45.909 Unspecified asthma, uncomplicated
J45.90 Unspecified asthma

SNOMED

195967001 Asthma (disorder)
233678006 childhood asthma (disorder)
389145006 allergic asthma (disorder)
31387002 Exercise-induced asthma (disorder)
266361008 Non-allergic asthma (disorder)

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