Patients will need rapid and aggressive management using oxygen, bronchodilation, and steroid treatment. Close observation is also key. If the patient does not respond to the management of inflammation and bronchoconstriction, expert consultation and further treatment are mandatory.

Related Video: How to Manage Life-Threatening Asthma

Oxygen 

Begin with 4L/min in severe asthma. The goal is a SaO₂ over 90%.

Oxygen should be supplemented simultaneously with beta 2 agonist therapy. Provide oxygen even if SaO₂ is above 90%. 

This is because beta 2 agonist therapy can lead to initially worsened hypoxemia due to its effect on pulmonary bronchodilation and vasodilation. As blood flow is increased to the lung, there is right to left shunting of poorly oxygenated systemic blood passes through the pulmonary system and remains poorly oxygenated at arrival at the left atrium. 

Provide high flow oxygen if needed

Monitor patients continuously

Beta 2 Agonist Inhalation

Two common inhalers used for acute asthma attacks are albuterol or levalbuterol. As beta 2 agonists, they relax the smooth muscles of the bronchial tree, thereby rapidly reducing bronchospasms with little significant side effects. Inhaled therapy is more effective than systemic therapy, and the same dose can be given to most adult patients. Albuterol is the gold standard of asthma treatment, and levalbuterol has similar safety and efficacy.

Albuterol is a beta-2 agonist.

MDI or nebulizer

Studies indicate that continuous or intermittent nebulized albuterol is equivalent in routine treatment of asthma; however, there may be a benefit to continuous therapy in severe cases. Overall, research suggests there is no difference in treatment outcomes between the MDI using a spacer and nebulizers. Nebulizer treatment is most common in the ED setting. For albuterol nebulizers, use 2.5-5mg at 20-minute intervals three times or a continuous nebulizer with 10-15 mg over an hour. Doses can be increased with more severe disease. When using MDI of 90 mcg each puff, use 4-8 puffs at 20-minute intervals as long as four hours then at 1-4 hour intervals.

Child Using a Nebulizer

Corticosteroids

Systemically given corticosteroids treat the inflammation associated with asthma but usually take about 6-12 hours to take effect. Their use has been shown to decrease the need for hospitalization, length of stay, complication, and return ER visits. Treatment should begin as quickly as possible with a dose of IV 125 mg methylprednisolone (ranging between 40-250mg). Subsequent doses (methylprednisolone, prednisolone, or prednisone) are 40-80 mg divided into 1-2 doses over the 24 hours with a goal PEF over 70% predicted.  

There is no good evidence indicating that inhaled steroids should be used in acute severe asthma treatment.

Additional treatments

Anticholinergic

Anticholinergic treatment is associated with an increased lung function when administered with albuterol. Nebulized 0.5 mg ipratropium bromide is usually given. The effect onset is about 20 minutes, with maximum effect at 1 -1.5 hours. It has minimal side effects and is usually given once but can be repeated. In this case, repeating a 0.25 or 0.5 mg dose at 20-minute intervals can be considered.

Additionally, it can be repeated at 4-6 hour intervals. It is recommended in patients with FEV1 or PEF under 80% predicted.

Ipratropium bromide is chemically similar to atropine and causes dilation of the bronchial tree via inhibition of the vagal associated constriction. It is less potent and slower to act than beta 2 agonists. 

Ipratropium bromide is beneficial in severe cases of life-threatening episodes of asthma when given with beta 2 agonists compared to beta 2 agonists alone. It should not be used following admission to the hospital.  

Magnesium Sulfate

Magnesium sulfate given systemically can increase lung function when given with beta 2 agonist and corticosteroids. Magnesium helps to relax the smooth muscle of the bronchial tree separate from serum magnesium. It has minimal adverse events (i.e., lightheadedness and flushing) and has been shown to decrease admission to the hospital. It did not have as much impact if the FEV1 was over 25 % of predicted. IV 2 g magnesium is given for 20 minutes with beta 2 agonist and corticosteroid treatment. 

Some studies have looked at nebulized magnesium and showed an associated increase in FEV1 as well as SpO₂. However, only a trend for improvement was seen in a meta-analysis. 

Heliox

This is combined oxygen (30%) and helium (70%). The combination is not as dense as room air. It helps to improve the efficacy of nebulized albuterol by augmenting delivery. It has been associated with a decreased need for intubation. Research indicates it should only be used in refractory asthma cases. Due to the need for 70% helium, there is an associated decrease in maximum oxygen supplementation, which may be harmful to asthmatic patients.  

Systemic adrenergic medications

Epinephrine or terbutaline can be given to patients with severe asthmatic attacks. These beta-adrenergic medications relax the smooth muscle of the bronchial tree rapidly. Epinephrine is a non-selective beta-agonist, while terbutaline is selective for beta 2 receptors. The epinephrine dose is 0.3-0.5mg at 20-minute intervals, while the terbutaline dose is 0.25 mg at 20-minute intervals. Both can be repeated three times. It is most common to give this to pediatric patients. However, there is a 4% risk of major side effects. Additionally, there is no evidence of the superiority of epinephrine compared to the inhalation of beta 2 agonists. 

Typically, IV epinephrine is used in young patients who are unable to use inhaled beta 2 agonists effectively. If the symptoms are too severe, these patients may be unable to inhale and gain adequate delivery of beta 2 agonists into the lungs. As it can cause tachycardia, hypertension, and increased cardiac oxygen demand, it is best to use it in patients who are otherwise healthy without major comorbidities.  The subcutaneous alternative is better tolerated and may be given to older patients with asthma. 

Terbutaline is also given via an IV or subcutaneous route. It is slower to work (5-30 minutes), has a longer time to the maximal effect (1-2 hours), and a longer duration (3-6 hours) than epinephrine. Consequently, it is usually not used in the acute management of severe asthmas. Some research shows a benefit in managing wheezing in children compared to epinephrine. 

Other treatments

Ketamine

This systemic anesthetic with dissociative properties leads to the dilation of the bronchial tree as well as bronchial secretion stimulation. There are mixed reports as to its efficacy; however, it can be useful in patients who need anesthetic for advanced airway placement. 

Methylxanthines

These medications were traditionally used in asthma care; however, due to lack of research efficacy as well as unstable pharmacokinetics, they are no longer recommended in the acute treatment of asthma.

Leukotriene receptor agonist

These medications augment lung function and minimize the need for long-term therapy with short-acting beta-agonists. While there is some evidence that it may be beneficial in acute treatment, more research is required for recommendations. 

Inhaled anesthetic

Some research suggests a benefit to inhaled anesthetics such as isoflurane and sevoflurane in treating status asthmaticus that is refractory to maximal treatments. These medications work to dilate the bronchial tree. They may also decrease oxygen demands, production of carbon dioxide, and patient antagonism to the ventilator settings.