Asthma exacerbation resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Vidit Bhargava, M.B.B.S [2]; Abdurahman Khalil, M.D. [3]

Definition

Asthma exacerbations are acute or subacute episodes of progressively worsening symptoms of cough, wheezing and dyspnea accompanied by a measurable decrease in peak expiratory airflow.

Causes

Life Threatening Causes

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated. Asthma exacerbation is a life-threatening condition and must be treated as such irrespective of the causes.

Common Causes

• Viral infections

• Exposure to allergen

• Bacterial infections

• Environmental pollutants

• Occupational irritants and sensitizers

• Medications (aspirin)

Management

Diagnosis

Characterize the symptoms: ❑ Dyspnea ❑ Wheezing ❑ Chest tightness ❑ Cough

Obtain a focused history: ❑ Onset ❑ Severity compared to previous episodes ❑ Possible causes ❑ Current medications ❑ Time since the last dose of asthma medications ❑ Exacerbations in previous 1 year ❑ Concurrent illness

Examine the patient: ❑ Agitation ❑ Tachypnea ❑ Tachycardia ❑ Use of accessory muscles ❑ Speech (full sentences, words) ❑ Level of alertness ❑ Hydration status ❑ Cyanosis

Order labs: ❑ Spirometry (FEV1, Peak expiratory flow PEF)† ❑ O2 saturation (pulse oximetry) ❑ Arterial blood gas (ABG) (PaO2/PCO2)

Consider alternative diagnosis: ❑ COPD exacerbation ❑ Aspiration pneumonia ❑ Allergy or hay fever ❑ Vocal cord dysfunction

Classify the severity

Mild: Symptoms: ❑ Breathlessness while walking ❑ Speaks full sentences Signs: ❑ Tachypnea ❑ End expiratory wheezing ❑ Pulse < 100/min ❑ FEV1 ≥ 70% ❑ Pulse oximetry > 95 % ❑ ABG Normal

Moderate: Symptoms: ❑ Breathlessness at rest, prefers sitting ❑ Speaks phrases ❑ Usually agitated Signs: ❑ Tachypnea ❑ Using accessory muscles of respiration ❑ Expiratory wheezing ❑ Pulse 100-120/min ❑ Pulsus paradoxus may be present ❑ FEV1 40-69 % ❑ Pulse oximetry 90-95 % ❑ ABG: PaO2 ≥ 60 mm Hg PCO2 < 42 mm Hg

Severe: Symptoms: ❑ Breathlessness at rest, sits upright ❑ Speaks words ❑ Usually agitated Signs: ❑ Tachypnea ≥ 30/min ❑ Using accessory muscles of respiration ❑ Wheezing throughout inhalation and exhalation ❑ Pulse > 120/min ❑ Pulsus paradoxus present ❑ FEV1 < 40 % ❑ Pulse oximetry < 90 % ❑ ABG: PaO2 < 60 mm Hg PCO2 ≥ 42 mm Hg

Imminent respiratory arrest: Symptoms: ❑ Drowsy or confused Signs: ❑ Paradoxical thoracoabdominal movement ❑ Wheeze absent ❑ Bradycardia ❑ Pulsus paradoxus absent due to resp. fatigue ❑ FEV1 < 25 % ❑ < 10 % in FEV1 after treatment

† In the initial management of severe exacerbations FEV₁ and PEF are not included, and the treatment should begin on clinical grounds.

Treatment

Mild or moderate exacerbation FEV1/PEF ≥ 40-60%

Severe exacerbation FEV1/PEF ≤ 40%

Imminent respiratory arrest

❑ Oxygenate, target SaO2 ≥ 90% ❑ Inhaled SABA by nebulizer or MDI, 3 doses in 1st hour max. ❑ Oral corticosteroid if no response or recent intake of oral steroid

❑ Oxygenate, target SaO2 ≥ 90% ❑ High dose inhaled SABA/MDI plus ipratropium every 20 mins for 1 hour ❑ oral corticosteroids

❑ Intubate and mechanically ventilate with 100% O2 ❑ Nebulized SABA and ipratropium ❑ IV corticosteroids ❑ Consider adjunct therapies

Reassess for following: ❑ Patients subjective response ❑ Physical findings ❑ FEV1/PEF ❑ Pulse oximetry/ABG

Moderate exacerbation: ❑ Inhaled SABA every 60mins ❑ Oral corticosteroid ❑ Treat for 1-3 hours if improvement, admission decision at hours

Severe exacerbation: ❑ Oxygen ❑ Nebulized SABA + Ipratropium continuous ❑ Oral corticosteroids ❑ consider adjunct therapy

Good response: ❑ FEV1/PEF > 70% ❑ No distress ❑ Stable after 60 mins of treatment ❑ Normal physical exam

Incomplete response: ❑ FEV1/PEF 40-69% ❑ Mild-moderate symptoms

Poor response ❑ FEV1/PEF < 40% ❑ PCO2 ≥ 42 mm Hg ❑ Confusion and severe symptoms

Admit to ward: ❑ Oxygen ❑ Inhaled SABA ❑ Oral or IV corticosteroids ❑ Monitor

Admit to ICU: ❑ Oxygen ❑ Inhaled SABA horly or continously ❑ Consider adjunct therapies ❑ Possible intubation and mechanical ventilation

Improvement

Discharge ❑ Continue treatment with inhaled SABA ❑ Continue course of oral steroids ❑ Continue/initiate inhaled corticosteroids ❑ Educate patient ❑ Schedule follow up

The following guidelines are based on directives issued by 'National Asthma Education and Prevention Program, Third Expert Panel on the Diagnosis and Management of Asthma'.

Shown below is a table summarizing the dosage of drugs used to manage asthma exacerbation:

Drug	Adult dosage
Inhaled Short Acting β Agonists (SABA)
Albuterol/Bitolterol/Pirbuterol a) Nebulizer solution b) MDI	♦ 2.5-5 mg every 20 minutes for 3 doses, then 2.5-10 mg every 1-4 hours as needed or 10-15 mg/hour continuously. ♦ 4-8 puffs every 20 mins upto 4 hours, then every 1-4 hours as needed.
Levalbuterol a) Nebulizer solution b) MDI	♦ 1.25-2.5 mg every 20 mins for 3 doses, then 1.25-5 mg every 1-4 hours as needed. ♦ 4-8 puffs every 20 mins upto 4 hours, then every 1-4 hours as needed.
Anticholinergics
Ipratropium bromide a) Nebulizer solution b) MDI	♦ 0.5 mg every 20 mins for 3 doses, then as needed. ♦ 8 puffs every 20 mins as needed for upto 3 hours.
Ipratropium with albuterol a) Nebulizer solution (each 3 ml containing 0.5 mg ipratropium and 2.5 mg albuterol) b) MDI (each puff contains 18 mcg ipratropium and 90 mcg albuterol)	♦ 3 ml every 20 mins for 3 doses, then as needed. ♦ 8 puffs every 20 mins as needed for 3 hours
Systemic corticosteroids
Prednisone/Prednisolone/Methylprednisolone	♦ 40-80 mg/day in 1 or 2 divided doses until peak expiratory flowrate (PEF) reaches 70% of personal best.

• SABA:short acting beta agonist
• FEV1:forced expiratory volume for the for the first second
• PEF: Expiratory peak flow

Do's

• Use the percent predicted FEV1 and peak expiratory flow (PEF) as your main factors to classify the severity of asthma exacerbation.
• Initiate the treatment of asthma exacerbation as soon as possible while obtaining a brief history and examining the patient.
• Rule out on physical examination complications of asthma exacerbation sch as pneumonia, pneumomediastinum and pneumothorax.

Ordering labs: These should not hinder administering treatment.

• Measure serum theophylline concentration in patients who have taken theophylline before presentation.
• Measure serum electrolytes in patients who have been taking diuretics regularly and in patients who have coexistent cardiovascular disease.
• Obtain chest radiography for patients suspected of congestive heart failure, or pneumothorax, pneumomediastinum, pneumonia, or lobar atelectasis.
• Obtain Electrocardiograms in patients older than 50 years of age with evidence of heart disease or COPD.

Drug therapy:

• Use only selective β agonists to mitigate cardiac risks.
• Prescribe a 5-10 days course of corticosteroids to prevent early relapse.

Adjunct therapies:

• Adjunct therapies that may be considered: (Evidence not complete, futhere data is required.)

• Intravenous magnesium sulfate in patients who have life-threatening exacerbations and in those whose exacerbations remain in the severe category after 1 hour of intensive conventional therapy.
• Heliox-driven albuterol nebulization for patients who have life-threatening exacerbations and for those patients whose exacerbations remain in the severe category after 1 hour of intensive conventional therapy.
• Intravenous beta₂-agonists
• Noninvasive ventilation
• Intravenous leukotriene receptor antagonists

Intubation:

• Intubate patients presenting with apnea or coma immediately.
• Should be done by an experienced physician.
• Use 'Permissive hypercapnia' or 'controlled hypoventilation' as the recommended ventilator strategy.

Discharge:

• Ensure patient has medication to continue after discharge.
• Educate patient.
• Consider issuing a PEF meter.

Don'ts

• Don't measure FEV 1 and PEF in a patient presenting with severe asthma exacerbation and proceed directly to the initiation of the management.
• The following treatments are not recommended during hospitalization or emergency care settings:

• Methylxanthine
• Antibiotics(except for comorbid conditions)
• Excessive hydration
• Mucolytics
• Chest physical therapy
• Sedation