Lower Respiratory Tract Infections: AECOPD, Aspiration, and Pneumonia in the COVID-19 Era (Chapter 2)

5 December, 2022

Now, measuring COPD similarly can be approached at multiple levels. Taking a history is important – asking about habits like smoking, or occupations like mining or exposure to toxic gases, determining how limited a patient is and activities; can they walk up a flight or two stairs? Are they limited even walking on level ground? These things give an idea of how impacted they are by COPD. Examination as we’ve mentioned is important. You may hear diminished respiratory sounds and patients with significant lung obstruction or lung tissue damage. They may take a tripod posture, using accessory muscles and leaning forward to assist in respirations; some may have signs of chronic smoking like tobacco staining. You can ask them what makes symptoms worse – we find that patients who are requiring supplemental oxygen either as needed or chronically show significant impairment of lung function. You can measure lung function with tests such as the pulmonary function tests for FEV1 divided by Forced Vital Capacity (FVC) – recall that this requires some degree of instrumentation, and sometimes trained personnel to achieve. Diffusing capacity is another test that can be useful to follow the progression of COPD and determine stability versus worsening; however, it requires a laboratory. In many cases, particularly acutely will obtain arterial blood gases which do require a laboratory and are somewhat uncomfortable. With the advent of COVID-19 and the widespread availability of portable pulse oximetry monitors, we’re finding these more widely available, both in the office setting and for home use. So it’s relatively easy to obtain a pulse oximeter, which has some limitations to accuracy, but if used properly can be very helpful. Radiologic tests like Chest X-rays (CXR) and CT scanning have their place in evaluating the COPD patient. All of these combined can be used to ‘stage’ patients. For example, the Global Obstructive Lung Disease (GOLD) initiative has graded COPD on a stage from A to D. And this is one way to document level of function and progression in the chart.

Now, what causes worsening of dyspnea in COPD? Well, an exacerbation has multiple components –  patients may complain of a cough which has increased in frequency or increased in severity. The amount of sputum and the quality is important. It often is minimal or white, or clear at baseline but with an exacerbation, it increases in quantity and frequently becomes colored. Many patients will present with shortness of breath as their main complaint about AECOPD. Now, respiratory infections probably are associated with about 70% of exacerbations. Aspiration is important to consider both as a cause and later on, we’ll see as something leading to pneumonia. And it’s not only the overt aspiration, which you can see in a hospitalized patient with diminished mental status, which you can also occur you can also encounter it sub clinically in patients who have regurgitation or chronic gastro esophageal reflux with aspiration of stomach acid into the lungs. In the differential of shortness of breath and COPD are the older patients with congestive heart failure, who suffered from fluid or salt overload. Allergen exposure may be important for individuals who have an allergic and immunologic cause of shortness of breath. Pulmonary hypertension and it’s worsening may lead to shortness of breath. And of course, many of our patients forget to take their medications or are resistant to taking their medications, which can trigger an exacerbation and an office visit.


Now looking at the differential diagnosis of a COPD from early COVID-19. The history is very important. Obviously COVID-19 can strike young otherwise healthy individuals and progress fairly rapidly. These individuals will not have a history of COPD or lung disease. On the other hand, probably half of the admissions or visits to the emergency department are older patients with risk factors which may include COPD, and there you’re put to the test of determining early COVID-19 versus AECOPD. We did find that one interesting factor in our patients who are in the emergency department awaiting admission, even the young ones who had progressive or impending severe COVID-19 would not complain significantly shortness of breath and rest despite significant hypoxemia on laboratory tests whereas the patients with AECOPD were generally complaining of shortness of breath as one of their major complaints. And finally, remember we now have compared to almost three years ago when the epidemic was starting fairly rapid tests for the COVID 19 virus. Some of these, including the rapid tests will yield results within an hour and are fairly accurate. And in addition to test specifically for COVID 19, we have tests for other viruses, notably influenza in season, RSV, adenovirus, and some of the other pathogens, which, if you make a diagnosis can help to decide how to treat the patient in what setting to treat the patient and perhaps exclude COVID-19 as a differential.