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 (not routine) (PaO2/PCO2) ❑ Order additional test if needed

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 or PEF ≥ 40-60%

Severe exacerbation FEV1 or PEF ≤ 40%

Imminent or ongoing respiratory arrest

❑ Administer oxygen to reach a target SaO2 ≥ 90% ❑ Administer inhaled SABA by nebulizer or metered dose inhaler (MDI), maximum 3 doses in 1st hour ❑ Administer oral corticosteroid if no response or recent intake of oral steroid

❑ Administer oxygen to reach a target SaO2 ≥ 90% ❑ Administer high dose inhaled SABA plus ipratropium by either nebulizer of by MDI with valve holding chamber ♦ Every 20 minutes, OR ♦ For 1 continuous hour ❑ Administer oral corticosteroids

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

Reassess the patient: ❑ Patient's subjective response ❑ Physical findings ❑ FEV1 and PEF ❑ Oxygen saturation ❑ Order additional tests if needed

Moderate exacerbation: ❑ FEV1 or PEF 40-69% predicted ❑ Moderate signs and symptoms on physical exam

Severe exacerbation: ❑ FEV1 or PEF 40-69% predicted ❑ High risk patient ❑ Severe signs and symptoms on physical exam ♦ Severe symptoms at rest ♦ Chest retraction ♦ Use of accessory muscle

❑ Administer inhaled SABA every 60 minutes ❑ Administer oral corticosteroids ❑ Treat for 1-3 hours ❑ Take a decision on whether to admit the patient or not within the first 4 hours based on the patient's improvement status

❑ Administer oxygen ❑ Administer nebulized SABA and ipratropium continuously or every hour ❑ Administer oral corticosteroids ❑ Consider adjunct therapy

Reassess the patient

Good response: ❑ FEV1 or PEF ≥ 70% ❑ Absence of distress ❑ Stable after 60 minutes of treatment ❑ Normal physical exam

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

Poor response ❑ FEV1or PEF < 40% ❑ PCO2 ≥ 42 mm Hg ❑ Confusion and severe symptoms

Admission to ward: ❑ Administer oxygen ❑ Administer inhaled SABA ❑ Administer oral or IV corticosteroids ❑ Monitor the patient

Admission to ICU: ❑ Administer oxygen ❑ Administer inhaled SABA continuously or every hour ❑ Administer IV corticosteroids ❑ Consider adjunct therapies Intubate the patient in case of: ❑ Inability to speak ❑ Altered mental status ❑ Progressing fatigue ❑ Intercostal retraction ❑ Increasing PaCO2 above 42 mmHg ❑ Apnea ❑ Coma

Improvement

Patient discharge: ❑ Continue treatment with inhaled SABA ❑ Continue course of oral steroids ❑ Continue/initiate inhaled corticosteroids ❑ Educate the patient ❑ Schedule a follow up visit

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 minutes up to 4 hours, then every 1-4 hours as needed.
Levalbuterol a) Nebulizer solution b) MDI	♦ 1.25-2.5 mg every 20 minutes for 3 doses, then 1.25-5 mg every 1-4 hours as needed. ♦ 4-8 puffs every 20 minutes upto 4 hours, then every 1-4 hours as needed.
Anticholinergics
Ipratropium bromide a) Nebulizer solution b) MDI	♦ 0.5 mg every 20 minutes for 3 doses, then as needed. ♦ 8 puffs every 20 minutes 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 minutes for 3 doses, then as needed. ♦ 8 puffs every 20 minutes as needed for 3 hours
Systemic corticosteroids
Prednisone, prednisolone, methylprednisolone	♦ 40-80 mg/day in 1 or 2 divided doses until peak expiratory flow (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 such as pneumonia, pneumomediastinum and pneumothorax.
• Administer oxygen through nasal cannula or a mask with a target of SaO₂ >90%, except for pregnant women and patients with heart disease for whom the target oxygen saturation should be more than 95%.

Ordering labs:

• Ordering additional labs should not hinder administering treatment.
• Measure serum theophylline concentration in patients who have taken theophylline before presentation.
• Order ABG in patients with severe respiratory distress or suspected hypoventilation.
• Measure serum electrolytes in patients who have been taking diuretics regularly and in patients who have coexistent cardiovascular disease.
• Obtain chest radiography for patients with suspected congestive heart failure, pneumothorax, pneumomediastinum, pneumonia, or lobar atelectasis.
• Obtain electrocardiograms in patients older than 50 years of age with evidence of heart disease or COPD.
• Order a CBC in patients presenting with elevated temperature.

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, further 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.
• Use permissive hypercapniap or pcontrolled hypoventilation as a ventilator strategy.
• Have a low threshold for intubation because the intubation of asthmatic patients can be complicated.
• Consider administering IV magnesium sulfate or heliox-driven albuterol nebulization when the intubation of an asthmatic patient is difficult.

Discharge:

• Educate the patient by reviewing the list of home medications, the appropriate technique used for the inhaler and the importance of follow up visits.
• 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
• IV isoproterenol
• Leukotriene modifiers
• Antibiotics including macrolides (except for comorbid conditions)
• Excessive hydration
• Mucolytics
• Chest physical therapy
• Non invasive ventilation