Answer:
The reason this age restriction was placed as a protective variable, to help identify those individuals for which treatment may be beneficial, while reducing the risk of harm. There has been a significant increase in use of IM epinephrine within the bronchoconstriction medical directive in patients who do not meet the indications whereby the potential for significant morbidity may result from its administration.
The differential diagnosis for wheeze on auscultation and respiratory distress includes: COPD, CHF, Asthma exacerbations, Anaphylaxis, Pneumonia, Pneumothorax and Pulmonary Embolism (note this is not an exhaustive list).
Of these, the only conditions that benefit from epinephrine are anaphylaxis and potentially, as a last-ditch effort, asthma exacerbation (although the evidence is quite sparse for asthma exacerbation1, 2). Other conditions on this list, including CHF and patients with a history of cardiovascular disease are at risk of harm from epinephrine administration, with no benefit. Similarly, many patients with COPD can develop pulmonary hypertension and the use of epinephrine in these patients can lead to acute morbidity.
Epinephrine administration causes adrenergic surge from both alpha and beta-adrenergic receptor activation. This surge will worsen afterload (and thus cardiac strain) in CHF, leading to worsening pathophysiology and acute compensation, even death. In patients with cardiovascular disease, this surge can cause ischemia from increased cardiac demand and vasoconstriction. Therefore, giving epinephrine to these patients causes harm, with no benefit.
Differentiating these conditions based on symptoms and history can be challenging in the prehospital environment. For example, many patients state they have “COPD/Asthma”. Overlap in these conditions does exist. However, those that are 50 or older likely have predominantly COPD and whose age puts them at risk of the cardiovascular side effects of epinephrine administration, without benefit3.
In order to help risk stratify those patients who could benefit from epinephrine in the setting of bronchoconstriction with history of asthma and cough, an age restriction was added to this COVID-19 pandemic management consideration (link).
The OBHG MAC is reviewing the directive to ensure that the correct patients with acute bronchoconstriction (acute asthma) that could benefit from IM epi and those that do not benefit from it and in which it could cause harm (COPD, CHF etc) can be identified.
For more info on this topic, check out the SWORBHP Podcast with Dr. David Morden that was recorded Jan 8, 2020 (link to Podcast page).
- Cydulka R et al. The use of epinephrine in the treatment of older adult asthmatics. Ann Emerg Med: 1988 Apr;17(4):322-6.
- Zaidan MF et al. Management of acute asthma in adults in 2020. JAMA; 323(6):563-564.
- Global Intiative for Chronic Obstructive Lung Disease (GOLD). Global strategy for the diagnosis, management, and prevention of chronic obstruction pulmonary disease: 2021 report. Global initiative for chronic obstructive lung disease , inc. 2020. https://goldcopd.org/wp-content/uploads/2020/11/GOLD-REPORT-2021-v1.1-25Nov20_WMV.pdf