- Presence of a pacemaker, internal defibrillator or other implantable electronic devices j. Active respiratory infection within the past 4 weeks k. COPD exacerbation within the past 4 weeks l. Myocardial infarction (MI) within the last 6 months m. Unstable or life threatening arrhythmia within the last year n. Malignancy treated with radiation or chemotherapy within the last 2 years o. Documented history of other respiratory diseases (cystic fibrosis, tuberculosis, vocal chord dysfunction, Churg-Strauss syndrome, allergic bronchopulmonary aspergillosis)