The following is posted with the approval of it's author, Mary Burns, R.N. and Exec VP of PERF
Altitude, Oxygen Levels and Oximetry
Summer vacations are upon us and some of you have expressed concerns about going to higher altitudes, either by flying, or by driving up to the mountains. You may remember that as you ascend in altitude the available amount of oxygen in the air decreases. That means that your arterial blood oxygen, and your oxygen saturation, also decreases. Pulmonary patients, who already have low blood oxygen at sea level, may have a problem at altitudes as low as 3,000 ft. (Remember that planes are pressurized at about 5,000 to 8,000 ft and occasionally even higher!)
Before we get started with a discussion of oxygen needs, it is important to point out that many people with lung disease, even fairly severe disease, have been evaluated and found to have no significant problem with oxygen levels in their blood. If this is true for you, great! If not, read on.
High Altitude Simulation Test (HAST)
How can the doctor tell if you need to increase the liter flow of your oxygen, or if you need to be put on supplemental oxygen when you fly across the country, or drive up to the mountains? Needs vary with the individual and can be hard to estimate in the individual with lung disease.
Your doctor may refer to a nomogram, which provides an educated guess about your oxygen needs. He may order a HAST (High Altitude Simulation Test) which provides accurate information and is easily done in a pulmonary function lab. Another option is to perform a walking test to see if you desaturate, and how much, with walking. This can help him to estimate your oxygen needs at various altitudes.
Oximeters - Oximetry
Many patients, who have gone through pulmonary rehab programs and gotten sophisticated about their oxygen saturations, purchase their own oximeter. This usually requires obtaining a doctor's prescription and license number before your purchase from a medical supply company. On rare occasions, an insurance company will reimburse the purchase cost if you get a prescription. It is worth checking on.
If you wish to purchase an oximeter there are several small ones on the market. We've had the most experience with the little Nonin 9500 Onyx finger probe oximeter, which can be purchased for about $350.00, plus tax. But, we know other patients who have been price gouged for as much as $700.00! Shop around.
There are several places where you can now buy a small Nonin Onyx oximeter without a doctor's prescription. The Nonin 9500 is a little bigger than the size of a thimble and provides your heart rate in addition to your oxygen saturation. It comes with a long cord and can be carried around your neck like a pendant.
Richmark Medical Supplies sells the Nonin Onyx for $340.00 plus shipping if you live in IL, WI or IN. If you live in another state it is $359.00 plus shipping. Call 1-800-882-889 and ask for Tom.
Aeromedix sells their Nonin 9500 for $346.00* including shipping. Look up their website at http://www.aeromedixrx.com or make a toll free phone call to 1-888-362-7123 for further information. ( *Edited remark: Late note. If you mention EFFORTS or Pulmonary Paper, you can buy it at $340.00 )
Oximeters are great for patients who have gone through rehab and are very knowledgeable about oxygen, oxygen saturations and oximeters. Their physicians are often comfortable with having them titrate their oxygen according to their saturations. If, however, you haven't gone through rehab, or your program hasn't relied on oximetry, there are some concerns about using this technology without a thorough understanding of its limits. You should definitely get your physician's advice on this. Remember, oxygen is a drug, and the dose (the liter flow) should be prescribed by your doctor and changed only with your physician's advice and permission.
We are going to provide a little crash course on oximeters, dedicated to Iris Patton of Neff, Ohio who asked us to tell her know more about them.
- The first thing you need to remember is that the oxygen saturation provided by an oximeter does NOT have the accuracy of an arterial blood gas (ABG, a test done on blood usually taken from an artery in your wrist). However, oximeter readings are a lot less difficult (and less painful!) to obtain, are great for providing trends, and are certainly a lot less expensive.
- Several things can affect the accuracy of the reading that you get with a finger oximeter including some nail polishes, (especially blue, green, black or metallic ones), poor circulation, and having had a cigarette in the past few hours. If you smoke, don't waste your time and money buying an oximeter! The oximeter can't tell the difference between the oxygen (O2) in your blood, and the carbon monoxide (CO), thus giving you a falsely high indication of the adequacy of the amount of oxygen circulating in your blood if you have been smoking!
- Your oximeter will give you a heart rate as well as an oxygen saturation. Don't get the two confused.
- A normal saturation, at sea level, is about 98%. Many patients with COPD will have an oximetry reading in the mid or low 90's, but that is fine. People without pulmonary disease also have low oximeter readings when they go to altitude. In Denver (5,000 ft. altitude) a normal saturation is about 90%.
- You should have an oximetry reading above 88% but don't worry if it jumps around and briefly drops below that. It can be due to your activity or circulation, a bent finger or arm, cold hands, or even due to holding your breath rather than exhaling with effort. Consistently having levels drop below 88% is of concern and should be reported to your physician.
- Most physicians prefer that you maintain an oximetry reading of at least 90%, keeping it between 90-94%. The preferred level depends on your individual condition and the type of pulmonary problem that you have. This is where you turn to your pulmonary physician for advice specific to you. Remember, each of you is an individual with different needs.
- If you are observant, you will find that pacing yourself helps keep your oxygen level up.
- You'll probably find that your oximetry readings will be high, even "normal", when you are sitting, and that they will drop with activity. If you are really smart, you will find that your breathing pattern can make a significant difference in your oximetry levels.
- Those of you with restrictive disease will find that your oxygen saturations may plummet with activity if you don't carefully pace yourself and practice good breathing techniques.
- If you have COPD, when you breathe slowly, breathe out longer than you breathe in, and use pursed lip breathing (PLB) it can sometimes make the difference between a normal and an abnormal oximetry reading. If you have a form of restrictive disease, you may need to try different breathing techniques to see what works best for you. Slowing your breathing helps, and using PLB usually helps.
- If you are doing good pursed lip breathing you should be able to increase your oxygen saturation numbers while you are doing the PLB. The lower your saturation, the easier it is to "blow those numbers up". The closer your saturation is to normal, the better your technique needs to be in order to increase your saturation numbers. There are lots of patients with low oxygen saturations who are able to increase their saturations all the way up to 93% with good PLB technique. We've seen some super stars get all the way up to 98%, much higher than the saturations they have on 2 lpm of oxygen!
- WARNING! If you work too hard at your breathing techniques, you will see that you actually lower your saturations! So, relax and don't be an over achiever!
- Why would you want to do use PLB to increase your oxygen levels when you have oxygen prescribed for this very reason? For peace of mind! If you have confidence in your ability to keep your oxygen saturations at a safe level with your own breathing techniques you never have to panic if you temporarily run out of oxygen! Also, proper breathing techniques, including a slower breathing pattern, enable you to better utilize your prescribed oxygen and you may find you need a lower liter flow. Investing in an oximeter, if only to practice breathing techniques, may be of value for those of you who have compromised oxygen levels with activity or at altitude.
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Last Update 05/29/2009
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