Five Things to Keep in Mind When Treating an Asthmatic

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Author: Puja Gopal, MD
Emergency Medicine Resident
University of Illinois at Chicago
AAEM/RSA Publications Committee Member

Asthmatic patients present along a broad spectrum of severity. There are those who present with mild wheezing, have complete resolution with a single neb treatment, and go home with a refill of their albuterol inhaler. And then there are those patients who present unable to speak or breathe and become increasingly agitated and altered. Though presentations of asthmatic patients may vary greatly, there are some key things you can keep in mind with the asthmatics you see.

1. Monitor the patient and the 5 key vital signs closely – temperature, pulse, respiratory rate, blood pressure and oxygen saturation. Heart rate above 120 and respiratory rate above 30 are concerning for a severe asthma exacerbation. Also note that a decreasing respiratory rate can be concerning for the inability to maintain respiratory effort and possible decompensation. An oxygen saturation <90% is hypoxemia and requires your attention. Monitoring your patient’s mental status is of utmost importance to ensure they don’t become agitated or altered – both of which can occur with hypoxia and/or hypercapnia.[1]
   
2. Start the key three therapies for asthma early: “SOB” – steroids, oxygen, and bronchodilators. Remember SOB in your patient with asthma who has shortness of breath. Bronchodilators like albuterol are our first line therapy, and may be combined with an anticholinergic such as ipratropium; this dual therapy is commonly referred to by the trade name DuoNeb.[1] Oxygen is essential – start your patient on nasal cannula, non-rebreather, or, if they are really sick, non-invasive ventilation (we’ll talk more about this below). Start them on systemic steroids early. This is especially important in critically ill patients, because while steroids will work to decrease inflammation, they don’t work immediately. In pediatric patients with moderate to severe asthma, steroids actually reduce admission rates and length of treatment.[2] IV or PO steroids may be used depending on the situation; both are effective.[3]
   
3. IM/IV meds – IV Magnesium has been found to be beneficial in severe asthma. Its mechanism of action is to cause relaxation of bronchial smooth muscle.[4] IM or subcutaneous epinephrine has also been shown to be effective and is thought to cause bronchodilation and decrease bronchial edema. Another consideration is terbutaline. Methylxanthines were used in the past, however, are now rarely used due to very narrow therapeutic range. These therapies tend to be used in severe cases when established therapies (i.e. bronchodilators) aren’t working.[1, 3]
   
4. Non-invasive ventilation is a method of oxygen delivery via a positive pressure mask that is used in severe exacerbations and can be a means of delaying or even preventing intubation in patients with respiratory failure. It decreases a patient’s work of breathing and is very useful in patients who you think may require intubation. It allows you to possibly prevent an intubation or, if need be, provides additional time to prepare to intubate (i.e. gather equipment, dose medications). If the patient doesn’t improve with a trial of non-invasive ventilation you can go ahead and intubate, but if the patient does improve you can continue to monitor. Monitoring a patient on non-invasive ventilation includes examining the work of breathing/respiratory effort, watching for signs of agitation or altered mental status, and performing blood gas analysis with initiation of therapy and every 1-2 hours until the patient is stable.[5] Non-invasive ventilation has been studied rigorously in COPD and pulmonary edema, but not as well in asthma. A meta-analysis conducted in 2012 on non-invasive ventilation and asthma didn’t show a decrease in intubation rates or mortality, but did show improved ICU and total hospital lengths of stay.[6, 7] Of note, non-invasive ventilation has been shown to be safe, effective (leading to clinical improvement), and well-tolerated in the pediatric population.[8]
   
5. Intubation – this is a very serious decision and should be made when you have exhausted all other routes of medical management. Ensure once more that all other therapies have been given before you take control of the airway. Intubation in asthmatics is a very high-risk procedure, because these patients are at high risk of decompensation during intubation and high risk for death as a result of the intubation.[9] Ventilator settings are of utmost importance. Initial settings in the assist/control -mode include: RR of 10 breaths/min, tidal volume of 7-8 mL/kg (ideal body weight), inspiratory flow at 80-90 L/min, FiO2 of 100%, and PEEP of 0. A lower respiratory rate will allow for prolonged expiration time and decreased hyperinflation and auto-PEEP.[9] The two key things to keep in mind are: 1) prevent hyperventilation and thus breath stacking and barotrauma. To ensure the plateau pressure isn’t above 30, which poses risk for barotrauma, you can use the inspiratory hold button on your ventilator and then decrease the respiratory rate as necessary. Another option is to increase the inspiratory flow rate to maximize time for expiration.[5] The main complication of hyperventilation that we’re concerned about are tension pneumothorax and cardiac arrest. 2) Oxygenation is a primary focus and thus hypercapnia can be okay in these patients (aka permissive hypercapnia). Studies have shown patients can tolerate a pH down to 7.1.[3,5] Be very cognizant of the vent settings and make sure to check on your patient frequently after intubation!

Remember to closely monitor the sick asthmatic patients from the moment of their arrival in the emergency department because there is risk for rapid and unpredictable decompensation. Tailor your strategy for each individual patient, especially in your pediatric population.

Hope this helps guide you with your next asthmatic patient!


Sources:

1) Acute Asthma. World Allergy Organization. http://www.worldallergy.org/professional/allergic_diseases_center/asthma/index.php?mode=print#treatment. Published September 2004. Updated July 2015. Accessed August 31, 2015.

2) Bhogal SK, Mcgillivray D, Bourbeau J, Benedetti A, Bartlett S, Ducharme FM. Early administration of systemic corticosteroids reduces hospital admission rates for children with moderate and severe asthma exacerbation. Ann Emerg Med. 2012;60(1):84-91.e3. PMID: 22410507

3) Guidelines 2000 for cardiopulmonary resuscitation and emergency cardiovascular care. Part 8: advanced challenges in resuscitation: section 3: special challenges in ECC. The American Heart Association in collaboration with the International Liaison Committee on Resuscitation. Circulation. 2000;102(8 suppl):I229–52. PMID: 10966677

4) Rowe BH, Bretzlaff JA, Bourdon C, Bota GW, Camargo CA Jr. Magnesium sulfate for treating exacerbations of acute asthma in the emergency department. Cochrane Database Syst Rev. 2002;(4):CD001490. PMID: 10796650

5) Mosier JM, Hypes C, Joshi R, Whitmore S, Parthasarathy S, Cairns CB. Ventilator Strategies and Rescue Therapies for Management of Acute Respiratory Failure in the Emergency Department. Ann Emerg Med. 2015;66(5): 529-41. PMID: 26014437

6) Soroksky A, Klinowski E, Ilgyev E, et al. Noninvasive positive pressure ventilation in acute asthmatic attack. Eur Respir Rev. 2010;19(115):39-45. PMID: 20956164

7) Lim WJ, Mohammed akram R, Carson KV, et al. Non-invasive positive pressure ventilation for treatment of respiratory failure due to severe acute exacerbations of asthma. Cochrane Database Syst Rev. 2012;12:CD004360. PMID: 23235608

8) Basnet S, Mander G, Andoh J, Klaska H, Verhulst S, Koirala J. Safety, efficacy, and tolerability of early initiation of noninvasive positive pressure ventilation in pediatric patients admitted with status asthmaticus: a pilot study. Pediatr Crit Care Med. 2012;13(4):393-8.

9) Brenner B, Corbridge T, Kazzi A. Intubation and mechanical ventilation of the asthmatic patient in respiratory failure. J Emerg Med. 2009;37(2 Suppl):S23-34.