Oxygen

Who Needs Oxygen?

Chronic obstructive pulmonary disease, or COPD, refers to a series of chronic lung diseases in which breathing becomes slow or forced, and which are often the result of cigarette smoking. COPD affects more than 15 million people in the United States, but only a small minority with severe disease will require home oxygen therapy. However, whether or not they will need oxygen therapy is one of the main questions patients ask me when I diagnose them with COPD.

What Will Happen If I Have Low Oxygen Levels?

As COPD progresses, many changes occur in your lungs. You may have excessive mucus or sputum produced in your airways that can result in narrowing, or even closing of the airways. Lung tissue is often destroyed by cigarette smoke. Both the narrowing of the airways and damage to the lung tissue contribute to poor gas exchange in the lung. Narrowed airways make it hard for you to breathe oxygen into the areas where it can reach the blood. Areas of destroyed lung tissue reduce the area for gas exchange to occur. When these processes become severe enough, the lungs are not able to provide enough oxygen for the body's needs. Since this occurs very gradually, you may not realize if your blood oxygen level is lower, however you may notice decreased exercise tolerance because your muscles are not receiving enough oxygen. Your body responds in many ways to oxygen deficiency.

Pressure in the lungs and heart: The arteries that carry blood from the right side of the heart into the lungs sense low oxygen levels and constrict in an effort to direct that blood to more normal areas of the lung. This causes pressure in the pulmonary arteries to rise and this pressure, in turn, is transmitted back to the right side of the heart. The right side of the heart cannot handle increased pressure very well. In response, it dilates and contracts ineffectively and eventually the heart will fail. One of the most common signs of this circumstance is swelling or edema of the legs. Additionally, less blood will be delivered to the left side of the heart, and it will have less blood to pump to the rest of the body.

Raised levels of hemoglobin: Over time, other changes can occur. Hemoglobin, which carries oxygen in the blood, may increase to compensate for a chronically low supply of oxygen. This response, called secondary polycythemia can make the blood thick, and impair its ability to flow easily. If this happens, intellectual functioning may suffer or, rarely, you could suffer a stroke. To prevent these problems, your doctor will monitor your hemoglobin levels and, if the levels become dangerously elevated, your doctor will arrange for you to have blood removed just as if you were donating blood.

Poor sleep: Patients who have low or borderline-low oxygen levels when they are awake may develop dangerously low oxygen levels when they are asleep. People generally breathe less deeply when they are asleep, so it is normal for oxygen levels to drop slightly during this time. For those without lung disease, this does not cause a problem. But if you have COPD and your oxygen levels are already low, these levels may drop precipitously during sleep. This sends a signal to the brain to wake up and correct the problem. These "microarousals" can result in poor quality sleep.

What Are The Benefits Of Oxygen Therapy?

Studies have shown that the use of supplemental oxygen in COPD patients with low oxygen levels prolongs their lives. It has also been established in studies that using oxygen for part of the day has some benefit, but people who wear it all day benefit the most. This makes sense - if you wear oxygen 12 hours a day, you are removing the strain from your heart for only half of the day. The rest of the time, your heart is fighting an uphill battle just to do its job. A common misconception among people with COPD is that they can "store" oxygen. That is not possible. You use oxygen as you breathe. Once you leave your supplemental oxygen, your blood oxygen level will fall.

Who benefits the most?
People who are short of breath at rest will usually feel better shortly after starting supplemental oxygen. Often people will notice that exercising is easier, as more oxygen is getting to the muscles. Those with sleep disruption due to low oxygen levels at night will usually sleep better with supplemental oxygen. The long-term effects on the heart also slowly start to reverse.

Measuring the oxygen levels
There are two different ways your doctor can measure your oxygen levels.

The first is by directly measuring the oxygen in your blood through a test called an arterial blood gas (ABG). This is the most accurate method and most doctors will do this at least once, usually on an initial visit. However, since drawing blood is uncomfortable, if repeated measurements are necessary, a finger or ear probe can be used to measure the percent of hemoglobin saturated with oxygen. The blood drawing method measures the partial pressure of oxygen in the blood and the probe method measures oxygen saturation in the blood. The numbers will not be the same and are not directly comparable, so don't get worried if the values are very different from each other. Based on these test results, your doctor will know whether or not you will need supplemental oxygen.

How Much Does Oxygen Cost?

Oxygen can be very expensive, but Medicare and many other insurance companies will cover most of the cost of your oxygen if you meet specific criteria. Medicare has very specific criteria for determining who qualifies for supplemental oxygen and most insurance carriers adhere to these criteria.

Medicare
To be eligible for Medicare coverage for oxygen, you must have a measured blood oxygen of 55 millimeters of mercury (mmHg) or less, or a saturation of 88 percent. These measures must be taken at a time when you are awake, at rest, on room air, and when your disease is stable.

If your blood oxygen only drops to these levels during sleep or exercise, you may still meet the criteria. If your measured blood oxygen is between 56 and 59 mmHg and your saturation is 89 percent, you will meet the reimbursement criteria only if you have one of the following symptoms:

  • edema (swelling).
  • high pressure in your pulmonary arteries.
  • right heart failure.
  • secondary polycythemia.

If your numbers are higher than these, you will not qualify for Medicare criteria.

Is Supplemental Oxygen Safe For My Body?

Oxygen therapy is generally safe. Oxygen does produce free radicals (unstable molecules that react with proteins and other molecules to form more stable compounds), which can damage the lung. However, this is usually seen at higher oxygen concentrations than are required by most COPD patients. Those with severe COPD sometimes have increased levels of carbon dioxide in their blood and these levels may increase even further when supplemental oxygen is used. If the carbon dioxide levels become too high, it can cause sleepiness and sometimes even failed breathing. For this reason, if you have severe disease you should increase your supplemental oxygen only with your doctor's advice and only in a monitored setting. Usually carbon dioxide levels are not a major problem when low concentrations of supplemental oxygen (1 or 2 liters per minute) are used.

To ensure that you get adequate amounts of oxygen, never use more than 50 feet of tubing, as excessive tubing can decrease the oxygen concentration. Also, protect yourself against sudden loss of supply if you have an electrically-dependent concentrator system by keeping a portable tank for back up.

Is Oxygen Safe in My Home?

Just like many other substances, you need to take certain precautions to ensure your and your family's safety. However, if you follow the instructions of your supplier and doctor carefully, you have no cause to worry. A major concern with oxygen therapy is that oxygen is highly flammable. Fires and explosions have occurred, so unless you want this to happen to you, YOU (And the people around you) MUST NOT SMOKE! While the materials used to deliver the oxygen are fire resistant, the stream of oxygen can ignite when exposed to a cigarette or lit match. Similarly, oxygen should not be stored near furnaces, water heaters or other sources of heat or flame. You should have a functioning smoke detector and fire extinguisher available. Other precautions include:

  • Keep the oxygen system away from aerosol cans.
  • Don't use cleaning products with flammable components on or near the oxygen system.
  • Don't carry liquid oxygen in an enclosed bag like a backpack.
How Is Oxygen Supplied?

There are three types of oxygen systems available:

  • Liquid oxygen systems
  • Compressed gas systems
  • Oxygen concentrators

The oxygen from these systems is usually delivered into the body by nasal cannula (a tube with special prongs to fit into the nostrils), but can also be delivered by different types of face masks or by a small tube placed through the skin of the neck directly into the main breathing tube, the trachea. This is called transtracheal oxygen therapy. Oxygen masks and transtracheal oxygen are used for people who require a lot of oxygen.

The oxygen concentrator: The most commonly used system at home is the concentrator, which concentrates the oxygen from the air. It is not, however, portable and you would require a separate small, portable tank to take with you when you go out. Both compressed and liquid oxygen are available in portable tanks.

Compressed oxygen cylinders: Compressed oxygen cylinders are very convenient. They are small enough to be carried in small side packs, and weigh less than 10 pounds. The oxygen supply in these cylinders can last anywhere from 4 to 8 hours, depending on your oxygen requirements.

Liquid oxygen systems: Liquid oxygen systems weigh as little as 5.5 to 11 pounds and can supply oxygen for 8 hours or longer, again depending on the rate of oxygen flow you need. If you require many hours of portable oxygen supply, there are also some special nasal cannula and other devices which "save" oxygen by allowing you to use less oxygen per breath without lowering your blood oxygen level.

These small systems are widely available and should allow you to maintain a normal lifestyle. You can go exercising, shopping, to work, to dinner or anywhere else! In fact, it is very important that you do these things because moving around means you're getting exercise, and exercise keeps your body in shape, allowing you to do more, and feel better. Your doctor will determine your oxygen needs both at rest and with exercise. If you need more oxygen as you exercise, simply turn up the flow rate on your oxygen while you work out.

Can I Become Addicted To Oxygen?

Some patients ask me if they can become addicted to oxygen. They may have friends or loved ones with severe lung disease who have needed to progressively increase their amount of oxygen. In a sense, we are all addicted to oxygen - no one can live without it. But your body only needs as much oxygen as is needed for your muscles and vital organs to perform their jobs. It is not like alcohol or narcotics where larger and larger amounts are needed to obtain the same effect. Unfortunately though, COPD is a slowly progressive disease. As it gets worse, your lungs don't do their job as well as they once did, and you may need more supplemental oxygen to make up for what your lungs can no longer do.

Will I Always Need Oxygen?

Most patients who need supplemental oxygen will continue to need it if they have a chronic progressive disease like COPD. But there are exceptions. If you did not have proper medications when you started with supplemental oxygen, or if you were just overcoming an infection, it is possible that once you are adequately treated and stable, you will no longer need the oxygen. Roughly 20% of patients who are started on home oxygen therapy will no longer need it 1 to 3 months later. It is important to remember to have your oxygen saturation level checked both at rest and during exercise every few months to make sure you are getting the right amount of oxygen.

Conclusion

Think of supplemental oxygen as one of the many treatments available for COPD. Like any drug treatment, some patients need it, and some don't. If you have COPD and need extra oxygen, do not despair. Receiving supplemental oxygen can help you feel better, stay active, and live longer. Oxygen delivery systems are constantly being made smaller, lighter, and more portable, and you don't need to let oxygen therapy stop you from doing the things you want to do. In fact, to get the most out of your oxygen therapy, and to feel as good as you want to feel, it's important that you keep as active as possible.

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