Note: This is the first part of a two-part series written in collaboration with respiratory therapist Mark W. Mangus Sr., RRT, RPFT, FAARC, and oxygen expert Ryan Diesem.
One of the more hotly debated topics in the treatment of respiratory disease is supplemental oxygen use. Participants in the debate often include patients, clinicians, caretakers, suppliers, advocacy groups, and even politicians. In my experience, the information regarding when and how to use supplemental oxygen ranges in quality from the good, the bad, and in keeping with our western theme, the complete bull. It is my hope that I can help clear the air. That’s my third and final western pun. Thank you very much. I’ll be here all week.
For this column, I have asked two people, from whom I have learned a tremendous amount about proper oxygen supplementation, to join me in this endeavor: a man I call Respiratory Therapist-Laureate, Mark Mangus, and Oxygen Super-Guru and author of the Pulmonary Paper’s Portable Oxygen Concentrator (POC) Guide, Ryan Diesem.
What, me oxygen?
At the most basic level, your body’s ability to use oxygen is based upon three main factors:
- how well your lungs move air, and consequently oxygen in and carbon dioxide out
- how well your heart pumps said oxygen-rich blood
- how efficiently your muscles utilize that oxygen
How well your body takes up and utilizes oxygen is based upon supply and demand. The good news is that all three of these factors can improve with exercise and activity and all three typically get worse with inactivity. As I say over and over again, exercise is like pushing a car uphill. As soon as you stop pushing, you start rolling back downhill, only much more quickly. I am sure that most of us have experienced this at one time or another, so as Nike says, “Just do it!”
For people living with chronic obstructive pulmonary disease (COPD), pulmonary fibrosis (PF), and pulmonary hypertension (PH), it is not uncommon for one or more of these above-named factors to be impaired, causing hypoxemia and hypoxia, low oxygenation in the blood and tissues.
How much oxygen a person has in their blood can be determined by one of two tests, either by arterial blood gas (ABG) or via pulse oximetry.
Normal partial pressure of oxygen, as measured via ABG, ranges from about 75-100 millimeters of mercury (mmHg). Values of 60 or less indicate the need for supplemental oxygen.
Oxygen saturation, measured by either ABG or pulse oximetry, is considered normal when it is 95 percent or above. Values of 90 or less indicate the need for supplemental oxygen, although many insurance companies (including Medicare) require a saturation of 88 percent or less to cover supplemental oxygen.
Often, a patient will undergo a six-minute walk test to determine whether or not they desaturate with activity in order to qualify them for supplemental oxygen. However, wide variation in testing protocols from facility to facility, among other limitations, can lead to imperfect patterns of oxygen prescription and usage.
Shortness of breath does not equal saturation (SaO2%)
As I say over and over (and over) again, breathing is multifactorial, meaning there are many, many factors besides just the respiratory system and pulmonary function that can affect how well or how poorly we breathe. These include things such as cardiovascular health, level of conditioning (or deconditioning), medications, emotional state, and weather, among others.
Shortness of breath does not always indicate that you are hypoxic. In other words, your level of dyspnea, or air hunger, does not always correlate with your oxygen saturation.
This means that you can be short of breath, even extremely short of breath, even in the presence of normal oxygen saturation. Conversely, you can be hypoxic even if you are not particularly short of breath or disproportionately to your shortness of breath. Let’s examine what this means to you.
Why am I so short of breath if my oxygen is OK?
One of the most common questions that I am asked is how a person can be so short of breath and yet have a normal oxygen saturation (see above: “Breathing is multi-factorial”). In the case of the individual who is short of breath but has a normal oxygen saturation, supplemental oxygenation will not help you. I repeat, if your oxygen saturation is normal, supplemental oxygen will provide little, if any benefit, other than what EMTs and paramedics often refer to as “psychological first aid” or what some medical professionals refer to as “Obecalp” (read it backwards). So, what should you do instead?
In my book, Ultimate Pulmonary Wellness, I describe in detail a technique that we call “Recovery from Shortness of Breath.” In a nutshell:
- Stop what you are doing. Nobody ever becomes less short of breath by continuing the activity that made them short of breath in the first place. You either have to reduce your demand for air or increase your supply. The best way to reduce the demand is to stop whatever it is you’re doing.
- Talk to yourself, reminding yourself that you know what to do. Self-talk can be very empowering in high-stakes situations like these (assuming that you do actually know what to do). If you don’t know, I would strongly recommend enrolling in either an in-person or online pulmonary rehabilitation program.
- Assume the position. There are certain positions we call “recovery positions” that will help you to regain control of your breathing. These include several variations of bending over or leaning forward, resting your arms on your thighs or on a stationary object or wall. This allows the abdominal contents to drop forward, improving respiratory mechanics.
- Begin controlled breathing techniques (CBT). These include controlled breathing techniques such as diaphragmatic and pursed-lip breathing, among others. Again, if you are not familiar with these techniques, I would strongly recommend enrolling in a pulmonary rehabilitation program, either in person or online.
- Reassess and adapt. Now that you’ve caught your breath, reassess the situation and continue the activity (if you can) using the controlled breathing techniques and modifying the activity.
- In addition to the above, if you have not already done so, now might be a good time to consider using your rescue inhaler (with your doctor’s blessing) to further increase your air supply. In an ideal world (and with your doctor’s blessing), you might consider pre-medicating approximately 15 minutes before activity.
How can my oxygen be so low if I am not even short of breath?
In the case of the individual who is not particularly short of breath but who is hypoxic as measured either by ABG or pulse oximetry, they need oxygen. Again, if your ABG or pulse oximeter indicate you are hypoxic, you need oxygen whether you are short of breath or not. Hypoxia, even in the absence of significant shortness of breath, increases your risk of coronary insufficiency/ischemia, arrhythmia, pulmonary hypertension, and heart failure, among other potential hazards to your health, so as Lung Man says: “Use your oxygen, dammit!”
Rely on your instruments!
Although many people are convinced they can tell their own oxygen saturation based on how they feel, particularly as it relates to shortness of breath, I liken this to the “Guesser” who purports to guess your age, weight, or birth month at the carnival. Keep in mind that in the case of oxygenation, the stakes are much higher than a stuffed animal. And in the same way a SCUBA diver must rely on their depth gauge or a pilot relies on an altimeter, I always advise people to rely on their instruments, not the way they feel.
When (and how often) should I measure my oxygen?
The goal of measuring your oxygen is not to turn you into an obsessive measurement freak. The goal is to make sure you are sufficiently oxygenated both at rest and at all levels of activity. This means that at least until you start to understand how your body responds to increasing activity and how much oxygen it takes to keep you saturated, you will have to take more frequent measurements. You might even consider keeping a journal for a while until you can fully assess your body’s needs. As you start to understand your body’s trends, you can measure less frequently or if you are in distress.
This goes for pulmonary rehabilitation programs as well. I hear from people all the time about rehab programs that measure your oxygen before and after exercise but crickets during exercise. Again, if we want to assess a plane’s performance in the air, we have to take our measurements in the air; not just before takeoff and after landing.
Myths and misconceptions
Let’s also take a few moments to address some of the other myths, misconceptions, misinformation, and miseducation, as well as that famous river in northeast Africa (De Nile).
For the patient that only uses oxygen at home but not when they are out: Many people use their oxygen at home but do not take it with them when they leave the house. This is completely counterintuitive. Again, keeping in mind the principle of supply and demand, the times you need it most is when you are active and most likely to desaturate and contrary to what some people believe, you cannot somehow store oxygen in your body for use at a later time. If — and this is a big IF — you want to “experiment” by not using your oxygen (with your doctor’s blessing), the time to do it is when you are at home where the environment is controlled and while you are at rest and the demand is low.
For the patient who “only goes down to 88 percent”: When it comes to oxygen saturation, each percentage point is not created equal. Due to the way our hemoglobin takes on and gives up oxygen (as evidenced by the S-shaped oxygen-hemoglobin dissociation curve), as you drop below 90 percent, the magnitude of oxygen change in your bloodstream is greater than when you are between 90 and 100. Think about it like this: You want to take a photo with the Grand Canyon in back of you. You are 10 feet from the edge of the canyon. You can go anywhere between 1 and 10 feet with no ill effects, BUT, if you go that 11th foot — you get the idea. It is a similar principle with oxygen saturation. In addition, if we consider the plus or minus 3 percent (or more) error range of most pulse oximeters, a reading of 90 percent can actually be as low as 87 percent (or less).
For the patient whose oxygen “only goes down for a few minutes” or “recovers quickly”: I told you before that hypoxia increases the risk of many problems including coronary insufficiency/ischemia, arrhythmia, pulmonary hypertension, and heart failure. The risk increases the lower you go, the longer you stay there, and the more frequently you desaturate. But think of it like this. Imagine sitting in a glass booth that suddenly fills up with smoke, but don’t worry — it clears very quickly. I think most of us would agree it would be better if it never filled up with smoke in the first place. Well, that is how your brain, heart, and other vital organs feel about hypoxia, so as Lung Man says: “Wear your oxygen, dammit!”
Finally, for the patient who is worried about getting “too much oxygen”: It is for all of these previously mentioned reasons that I like my patients to stay at 93 percent or greater during activity. This includes patients with COPD, PF, and PH including people who are “CO2 retainers.” Every time I say this, people bring up the concept of hypoxic drive and the concern that the patient will stop breathing if we give them too much oxygen.
Basically, the idea behind this theory is that when patients have chronically high levels of carbon dioxide and/or prolonged periods of pH imbalance, they switch over to “hypoxic drive.” In other words, instead of responding to high levels of CO2 or changes in acid-base chemistry, which are the normal stimuli for respiration, they now respond to low oxygen and if we give them “too much oxygen,” they will stop breathing all together.
Now again, this is a call that needs to be made by your physician, BUT I can say that in my more than 27 years as both a cardiopulmonary physical therapist and emergency medical technician in many, many different environments, I have never, ever, seen this happen. Neither has Mark. Neither has Ryan. Again, this is our experience, but you would think that in a few hundred thousand exercise sessions, one of us would have seen it at least once, especially in light of the abundance of supplemental oxygen we use.
In next month’s column, we will discuss the various devices, accessories and best practices used in the delivery and usage of supplemental oxygen.
Dr. Noah Greenspan, DPT, CCS, EMT-B, is a board-certified Clinical Specialist in Cardiovascular and Pulmonary Physical Therapy, with more than 25 years of cardiopulmonary physical therapy and rehabilitation experience. His book “Ultimate Pulmonary Wellness” — a continuing source of pride — was published in 2017, and he has made it available for all to read online free-of-charge using that link or by going to the center’s website, www.PulmonaryWellness.com. His “Ultimate Pulmonary Wellness” Lecture & Webinar Series is also open to attend free-of-charge on the website.
Dr. Greenspan founded the Pulmonary Wellness & Rehabilitation Center, a Manhattan-based physical therapy practice specializing in the care of patients with cardiovascular and pulmonary diseases, in 1998. Under his direction, the Center has conducted over 100,000 exercise sessions and has been named “Best of the United States” in the area of cardiovascular and pulmonary physical therapy.