Author:
Roger M.Barkin
Nathan I.Shapiro
Description
- 2.7 million children (<18 yr) affected annually in the U.S.
- 850,000 ED visits per year in the U.S.
- Inflammatory events, usually viral, lead to bronchoconstriction:
- Compounded by hyperreactivity 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:
- Allergic/irritant:
- Environment: Pollens, grasses, mold, house dust mites, and animal dand er
- Occupational chemicals: Chlorine, ammonia - food and additives
- Irritants: Smoke, pollutants, gases, and aerosols
- Exercise
- Cold weather
- Emotional: Stress, phobia
- Intoxication: β-blockers, aspirin, NSAIDs
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
- 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
Diagnostic Tests & Interpretation
Lab
- Arterial blood gas (ABG) may be an adjunct to pulse oximetry to measure oxygenation and clinical exam to assess ventilation; not mand atory or routinely done
- CBC as a nonspecific marker of infection
- Theophylline level: Only for patients on theophylline (not recommended)
Imaging
CXR 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:
- 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
Prehospital
- 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 is isomer that is used by some clinicians
- Ipratropium bromide may be added as adjunct to β-adrenergic agonists. Most effective when combined with first 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 is equivalent to traditional oral steroids
- SC epinephrine or terbutaline for severe or refractory asthma (rarely used)
- Magnesium sulfate may be useful in severe disease following stand ard therapy
- Intubate for respiratory failure:
- 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 p.r.n
- Metered-dose inhaler (MDI) (with spacer) (90 mcg/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 mcg/2.5 mL), 250-500 mcg
- Per dose q6h
- Ketamine (for intubation): 1-2 mg/kg IV as induction agent
- 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 with good taste)
- 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
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:
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
- Compliant home environment
- Discharge treatment:
- Intensive β-adrenergic regimen for 3-5 d
- Short course (3-5 d) of steroids (2 mg/kg/d) 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 with inhaled steroids should be considered for children with recurrent episodes, persistent symptoms, or activity limitations. Growth should be monitored as well as adrenocorticotropic suppression. An integrated multilevel approach may improve asthma outcome
- Teach peak flow and use of MDI with spacer. Educate about asthma and avoidance of irritants
Follow-up Recommendations
Primary care physician for maintenance therapy, often including nebulized or MDI steroid therapy and education about acute rescue management
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- KrebsSE, FloodRG, PeterJR, 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. Available at www.nhlbi.nih.gov/health-pro/guidelines/current/asthma-guidelines.
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