COPD and SUPPLEMENTAL OXYGEN - what’s the scoop?

In using pulse oximetry, I wish I could count on hand the amount of times I have heard a patient disappointed to find out their SpO2 is 91%, 92%, or even 93% when according to the patient, they are normally more like 97% or 98%. This has been concerning to me as many people consider their SpO2 to be their lungs grade on a report card. This is just not the case and should be corrected whenever possible. Our bodies rely on relative increases in the level of carbon dioxide in order to remind our bodies to breathe. COPD is a disease that consists of “a combination of chronic airway inflammation and remodeling…that results in airway narrowing, parenchymal destruction, and pulmonary vascular thickening.”1 As a result, during exhalation (normally a passive process), air is trapped in the distal aspects of the lungs due to this narrowing and premature closure of airways.2 Thus, the problem is getting the carbon dioxide out, not necessarily the need for cramming more oxygen into an already congested and dilated primary airspace. Strategies that include pursed lip breathing could provide the alveolar backpressure required to keep more of these airways open and get more carbon dioxide out. However, in COPD this extra carbon dioxide that is trapped in airways/airspaces is not stimulating the patient to breathe. In this scenario, “the patient relies on low level of oxygen in the tissues, i.e., hypoxia, to breathe.”2Unfortunately sometimes we find patients using oxygen outside the bounds of the order from their pulmonologist, potentially decreasing respiratory drive.2 It is in these instances that it is incumbent upon us as their home health team to educate them that their SpO2 is not their report card, 100% is not the goal, and that a relative level of hypoxia is important for the patient to maintain breathing appropriately. Of course, most of our patients have a parameter to maintain SpO2 greater than 88% or 90% at rest depending on the case. However, it is important for us to think smart and maintain contact with their pulmonologist to ensure good patient care and hopefully keep them out of the hospital when preventable. References: 1. O’Sullivan SB, Schmitz TJ, Fulk GD. Physical Rehabilitation. Philadelphia: F.A. Davis Company; 2014. 2. Hillegass E, Fick A, et al. Supplemental oxygen utilization during physical therapy interventions: Evidence based recommendations from the Cardiovascular and Pulmonary Section Task Force on Supplemental Oxygen. Cardiopulm Phys Ther Jl. 2014:25(2):38-49