Status asthmaticus medical therapy

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Initial severity assessment is evaluated using arterial blood gas and pulmonary function test and aggressive therapy is initiated to prevent progression to respiratory failure.

Medical Therapy

• Non-invasive ventilation using C-PAP or tight-fitting face mask may be used to reduce the work of breathing without intubation.

• Endotracheal intubation and mechanical ventilation should be used with caution in asthmatics who are non-responsive to medical therapy or non-invasive methods of ventilation, due to the substantial risk of barotrauma. Common indications include impending respiratory arrest, severe hypoxia non-responsive to supplemental oxygen, CO2 retention with PaCO₂ greater than 50 mmHg, acidosis and/or altered mental status.

• Supplemental oxygen via nasal canula or face mask is recommended to alleviate severe hypoxia. Oxygen saturation is maintained above 92% and is monitored using pulse Oximetry

• Helium with oxygen mixture has shown to reduce airway resistance and thereby reduce the work of breathing and also improve bronchodilator efficacy.

• Use of magnesium sulphate administered either IV or nebulized in addition to β2-agonists remains controversial.

• Mainstay drugs for the management include nebulized β2-agonists such as albuterol, salbutamol or terbutaline, parenteral steroids such as hydrocortisone or prednisolone and theophylline

• Anti-cholinergics such as ipratropium bromide may be indicated in patients who are unable to tolerate inhaled β2-agonists.

• In patients non-responsive to nebulized bronchodilator, IV-aminophylline or oral-leukotriene inhibitor may be used.

Therapy Based on the Severity of the Disease Assessed by Arterial Blood Gas Analysis

Stage 1

• Hyperventilation with normal PO₂
• No hypoxemia
• Patients may benefit from nebulized ipratropium used adjunctive to β2-agonist therapy

Stage 2

• Hyperventilation with hypoxemia (low PO₂ and PCO₂)
• Patients may require corticosteroids in addition to bronchodilator therapy

Stage 3

• CO2 retention due to respiratory muscle fatigue
• Markedly elevated PCO2 levels are an indicator for mechanical ventilation
• Aggressive β2-agonist therapy along with parenteral steroids and/or theophylline is indicated

Stage 4

• Severe hypoxia with markedly elevated PCO₂
• FEV1 lower than 20% predicted is suggestive of an impending respiratory arrest that may require intubation and mechanical ventilation
• Metered-dose inhalation of β2-agonist and anticholinergics are recommended. Administration of parenteral steroids and/or theophylline has also shown to be beneficial.