Q. Why do I need oxygen?
A. Patients with ILD may need supplemental oxygen because of the inflamed or scarred alveolar-capillary membrane, or the interstitial space in the lungs. This makes it more difficult for the oxygen to move from the airsac across the airsac wall and enter the bloodstream, particularly during exertion when the demand for oxygen becomes higher. If your oxygen saturation falls below 89%, this qualifies you for Medicare and other insurers' coverage for oxygen. 'Normal' oxygen saturations are between 97%-99%; in general patients are advised to keep saturations above 88-90%.
Q. What are the benefits of oxygen?
- decreased shortness of breath
- decreased strain on the heart (lower heartrate, prevention of pulmonary hypertension)
- increased activity level
- improved sleep quality
- increased ability to be involved in activities outside of the home
Using oxygen may not make your shortness of breath go away; your breathlessness can be due to low oxygen levels, however, even if your oxygen levels are normal, you may still get breathless with activity. This is because of the increased stiffness of the lung due to the inflammation or scarring which creates more 'work of breathing' which you sense as uncomfortable breathing or dyspnea. Other causes of breathlessness include deconditioning and loss of muscle, or excessive body weight.
Q. What if my physician prescribes oxygen but I choose not to use it?
A. You may experience different symptoms depending on how low your oxygen saturations are, including increased heart rate with activity, increased breathing rate, increased pressure in the lung's blood vessels (pulmonary hypertension) or worsening shortness of breath with activity.
If your oxygen levels are below 89% at rest, there is evidence that using oxygen over 15 hrs/day may improve survival. So if you have low oxygen levels at rest it is important for you to use oxygen as prescribed. If you only have low oxygen levels when you exert yourself, the benefits may vary between patients. There is very little data or research on the long term effects for patients with ILD who do not use supplemental oxygen during episodic or intermittent periods of low oxygen levels, such as during daily exercise. Patients with ILD vary a great deal in terms of how much they desaturate with exertion; some patients do not need supplemental oxygen and others need very high levels. If your oxygen saturations are right around 88% with activity you may not feel the symptoms that another ILD patient might feel with saturations around 80%.
Some patients experience significant benefit to their breathlessness, activity levels, and general quality of life when using oxygen while others may not. This is an important discussion to have with your healthcare providers in order to make the decision for using oxygen and to have realistic expectations for this treatment. Physically managing the equipment, using oxygen in public and around family, and the impact on your day to day life can be significant. However the benefit of staying active, being able to exercise, travel, and be mobile outside of your home can be significant.
Q. What kinds of oxygen are available?
A. Oxygen is available in three forms:
- Compressed gas: This form of oxygen comes in hard, green, metal cylinders. These cylinders come in multiple sizes (C, D, or E) tanks, or very small cylinders around the size of a wine bottle ( M4, M6, M9, or ML4, ML6). The smaller ones can be carried in a backpack or purse; the larger ones (E tanks) are pulled on a wheeled trolley. When using a compressed gas cylinder, a regulator is attached to it that allows you to turn it on and off and to set the flow rates. Some regulators can switch between intermittent (pulse) and continuous flow (discussed below).
- Liquid oxygen (LOX): This is a form of oxygen that has been super cooled until it becomes a liquid and is then stored inside a large reservoir tank; smaller portable canisters are filled as needed from this large tank. When this liquid oxygen is exposed to air it changes to a gaseous form. Compared to compressed gas cylinders, portable liquid oxygen canisters can hold more oxygen due to its concentrated form. The smaller portable devices are also capable of providing high continuous flow (>4 Liters/min). Liquid oxygen is not as readily available from Durable Medical Equipment (DME) companies as the compressed gas cylinders and concentrators, primarily due to its higher cost of weekly deliveries, the need for special equipment, and servicing.
- Oxygen Concentrators: Oxygen concentrators, both the stationary and small portable types, take oxygen from the air around you ("room air") and draw that air in through special sieves, or filters, that remove the nitrogen and produce 'concentrated' oxygen. The concentration of the oxygen in the air that we breathe at sea level is 21%; an oxygen concentrator can purify that oxygen to about 94-97%. The in-home concentrators (stationary) plug into the wall and use electricity, while the portable oxygen concentrators (POCs) use a battery that is rechargeable, and can be plugged into a wall outlet to charge. POCs vary in that some can switch between pulse and continuous flow, while others are only pulse flow. POCs are limited in continuous flow and currently only go to 3 liters/minute on continuous flow, whereas metal canisters can go up to 10 L/min. or more. Stationary concentrators are available in two capacities; one goes up to 5L/min and the high-flow ones can go up to 10 L/min).
Q. What are the different types of flows on oxygen equipment?
A. There are two basic types of flow on oxygen devices:
- Continuous flow (CF): This type of oxygen flow means that oxygen is flowing at the same rate the entire time that you are breathing, whether you are inhaling or exhaling. It is ordered in liters per minute or L/min. Continuous flow is always used during sleep, although recently there are some POCs with pulse flow that are described as being sensitive enough to trigger during sleep. All stationary concentrators only use continuous flow. Some POCs and compressed gas canisters can be switched between pulse flow and continuous flow. Some POCs only provide intermittent flow.
- Pulse flow (intermittent or demand flow): On this setting, oxygen only flows during the inspiratory (inhalation) phase of your breathing- the device is triggered to deliver oxygen by each of your breaths. While you exhale no oxygen is flowing. Some pulse devices are set to deliver the same pulse dose of oxygen for each breath no matter how fast you are breathing (number of breaths per minute), while other pulse devices are set to deliver a set volume of oxygen each minute. In the latter, the faster you breathe per minute, the lower dose of oxygen you get with each breath. Pulse devices do not deliver L/min, but instead use number settings of 1, 2, 3, etc...Pulse can be used with compressed gas cylinders, liquid oxygen canisters, and also with POCs. The advantage of pulse devices is that they conserve oxygen by allowing the tank or POC battery to last longer as they are only delivering oxygen during inspiration.
Q. What are the advantages of using a device with pulse or intermittent flow?
A. The main advantage is that pulse devices prolong the time that either a tank or a POC battery will last. Using pulse settings on compressed gas cylinders makes them last longer when you are out of the house. Using pulse on POCs will make the battery last longer compared to using that POC on a CF setting. POCs can be charged anywhere by plugging into the wall (or even a car lighter), and don't 'run out' of oxygen, but the higher the setting on a POC, the shorter the battery life.
Q. What are the disadvantages of using a device with intermittent flow?
A. The disadvantage of using pulse settings is that in some patients this mode does not maintain oxygen saturations above 88-90%. Pulse devices are often not adequate to keep saturations >88% in patients who need oxygen >4 L/min CF, and during times of rapid respiratory rates when the POC may not ‘trigger’ properly.. Currently the highest pulse flow available on POCs is 6, but patients may find that their saturations with exertion on 6 pulse are lower than when using oxygen at 6 L/min on a CF device. Another potential disadvantage of pulse is that during exertion or episodes of breathlessness when you may breathe with a very rapid but shallow breathing pattern, the pulse device may not consistently trigger.
Q. How do I know if the oxygen device I receive or choose is effective for me?
A. The most important thing to remember is that no matter what type of oxygen device you receive or choose from your Durable Medical Equipment (DME) oxygen company, you need to be tested on that device both at rest sitting quietly, and also during periods of exercise or activity, to make sure that the equipment is adequate for you and keeps your oxygen saturations above 88-90%. Always take your portable equipment with you to your doctor's appointment; the physician, nurse or medical assistant can walk you and check your oxygen saturations on your equipment. You should also do this yourself at home when you exercise or walk. Make a note of what setting your equipment is on and check your pulse oximeter readings when resting, and again during or immediately after periods of exercise or exertion. Share this information with your healthcare provider, especially if you note any significant changes.