Altitude, Oxygen Levels and Oximetry

By Mary Burns, RN, BS
PERF Executive Vice President

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 you take in less oxygen with each breath, because the air pressure decreases, making the air “thinner” than at sea level.. That means that your arterial blood oxygen, and your oxygen saturation, also decrease. Pulmonary patients, who already have low blood oxygen at sea level, may have a problem at altitudes as low as 3,000 feet where barometric pressure is 10% lower than at sea level. (Remember that planes are pressurized at about 5,000 to 8,000 feet 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.

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.

Your physician might know from experience what your oxygen needs may be at higher altitudes. A walking test to see if you desaturate, (if your oxygen level decreases) and how much you desaturate when walking, can help with this estimate of your oxygen needs at various altitudes. For some individuals, when there is concern about the safety of going on a long trip, a HAST (High Altitude Simulation Test) might be ordered. This provides accurate information on what your oxygen saturation will be at about 8,000 feet and is easily done in a pulmonary function lab, where you will be tested while you breathe air containing 15% oxygen.

If you do need oxygen when flying, make sure you contact your airline company well in advance! Make sure you understand what their rules are for oxygen use, or taking along your equipment! If they want an oxygen prescription from your doctor, bring at least one duplicate!

Oximeters – Oximetry

Many patients, who have gone through pulmonary rehab programs and gotten sophisticated about understanding the importance of their oxygen saturation, purchase their own oximeter. If you obtain your doctor’s prescription, you should be able to deduct it from your income tax. On rare occasions, an insurance company will reimburse the purchase cost if you get a prescription. It is worth checking on. However, many oximeters are now available in sports stores or online.

If you wish to purchase an oximeter, there are several on the market. For many years we’ve had the best experience with the little Nonin Go2 Achieve sports model. It can be purchased online from Nonin or Amazon; cost runs from $80 to $100. It comes with a lanyard so it can be worn around your neck like a pendant. The oximeter shows your heart rate in addition to your oxygen saturation. Don’t get them mixed up!

Oximeters are great for patients who have gone through pulmonary rehab and are knowledgeable about oxygen, oxygen saturations and oximeters. Their physicians are sometimes comfortable with having their patients titrate their oxygen according to their saturations, especially when traveling to different altitudes. If, however, you haven’t gone through rehab, or your program hasn’t taught you about 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.

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 arm. However, oximeter readings are a lot less difficult (and less painful!) to obtain, great for providing trends. They 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, we think you shouldn’t waste your time and money buying an oximeter! The oximeter can’t tell the difference between the oxygen (O2) and the carbon monoxide (CO) in your blood, thus giving you a falsely high indication of the amount of oxygen circulating in your blood if you have been smoking!

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 a higher altitude. In Denver (5,000 feet altitude), a normal saturation is about 90%.

You should aim to 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 and 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 will 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 big difference in your oximetry levels.

Breathing Techniques

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. Using good pursed-lip breathing (PLB) can 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 slowly usually helps also.

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 quickly able to increase their saturations up to 93% with good PLB technique. We’ve seen some superstars get all the way up to 98%, higher than the saturations they have on 2 liters per minute of oxygen!

WARNING! If you work too hard at your breathing techniques, you will see that you may actually lower your saturations! So, relax and don’t be an overachiever!

Why would you want to 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 great value for those of you who have compromised oxygen levels with activity or at high altitude.

Remember that each person is different! Please be sure to discuss these breathing techniques and the use of an oximeter with your doctor, who will be able to give you advice regarding their use.

Do you have a question about respiratory disease that has been bothering you? If so, feel free to write and ask us, either through our web site or by mail. We answer all of your letters.

Note: This article was updated in September 2016.