It is important to note that the evidence for the use of IM epi in asthma exacerbations is very weak. Many asthma guidelines do not include IM epi within the treatment algorithm due to the lack of evidence and the potential harm it may cause if used in inappropriate situations.
There are key “take-home” points from this question that apply to a patient less than 50 years old with multiple comorbidities as described. A patient with asthma who is subsequently diagnosed with COPD has experienced an evolution to a new chronic illness. IM epi has no benefit in this patient population. The initial diagnosis of asthma becomes more of a historical past medical illness that no longer truly reflects the patients’ disease. Furthermore, the patient you describe also has a history of CHF. This indicates that they have heart disease secondary to coronary artery disease, pulmonary hypertension from their COPD, or a cardiomyopathy. As such, the risk of IM epi causing cardiac ischemia, tachydysrhythmias or lethal arrythmias is significantly increased Given the low evidence for IM epi in severe bronchoconstriction in asthma and the potential risk for serious adverse events, IM epi should be avoided in this patient.
Although a history of CHF is not a contraindication for the use of IM epi in a patient less than 50 with severe bronchoconstriction secondary to asthma, the ability to differentiate the two etiologies can be difficult in the prehospital setting where advanced imaging and diagnostics are not available. As such, given the potential adverse events associated with its use, paramedics must be very judicious in utilizing this medication in a patient who has a history of pure asthma (and not COPD) in addition to a history of CHF. This will be a very rare subset of patients.
Please see the SWORBHP Podcast on the reasoning behind this age cap here. Below this age cap (<50 years-old) paramedic clinical acumen should guide management.