Hypoxia

The 2014 flying season is starting up with the opening of Sun ‘n Fun which means it is time to think about what makes our flying safer.

Hypoxia (low oxygen levels) continues to be a problem for pilots even at altitudes below the 12,500 foot MSL FAA requirement.  Many pilots, especially those with any underlying heart or pulmonary disease, who are obese, and even those who have had LASIK surgery, need oxygen below FAA mandated altitudes and there are simple ways to prove this to yourself.

My favorite example is to fly at night at 8,000 feet MSL or so for 30 minutes.  Look at the lights around you.  Then turn on some oxygen.  Two liters per minutes should do.  You will see the lights become brighter just like they were on a rheostat!

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The same is true for our brains. After a long flight, even in a pressurized aircraft, our brains do not function as well be subjected to “relative hypoxia.”  That is hypoxia that would not be clinically significant in a hospital setting but might make our thinking process or our reflexes not as good as they could be.  Unfortunately, increased age tends to make this effect more pronounced.

Have you had LASIK surgery?  Have you ever noticed that after a long flight, your vision does not seem to be quite 20/20?  This is due to the hypoxic effect directly on the cornea.  Unfortunately, this will not be improved with oxygen unless the mask covers your eyes as well.

Those big stomachs also get in the way of our breathing, especially when we are in a sitting position.  Thus, hypoventilation or not taking a deep breath can increase our susceptibility to hypoxia at lower altitudes.  Obviously, anyone with a history of heart or lung disease will have a lower tolerance to low ambient oxygen levels as well.

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Oxygen is cheap and usually readily obtainable.  Portable tanks can be filled at most gas or medical supply houses.  (I will provide a free prescription if some yahoo requires it to fill a tank.  Just email me at Aeromedix.com.)  Unfortunately, only an A&P is supposed to fill a built in aircraft oxygen system but many choose to ignore this.

Also, oxygen is oxygen.  It all comes from liquid sources now and there is absolutely no difference between medical oxygen and aviator’s oxygen.  Without getting into a long explanation of why, just believe me on this.  Oxygen is oxygen and it is all the same from an inhalation point of view so buy where ever you can find it.

The best way to know for sure what your oxygen level is by using a pulse oximeter.  These inexpensive fingertip devices show the percentage of oxygen in your blood stream.  The normal range for people who live at or near sea level is 95-100%.  For people who live at 6,000’ MSL, it is 90 to 95%.  My general recommendation for oxygen use is a person “should” use oxygen when their saturation drops by 5% from their home airport saturation and they “must” use oxygen if it drops by 10 percentage points.  When starting the oxygen, the pilot should titrate the flow of oxygen to raise their saturation back to their home airport baseline saturation.

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Remember that there is one thing that will “fool” a pulse oximeter and artificially raise your oxygen saturation reading—carbon monoxide.  Carbon monoxide can leak into the cabin through cracks in the firewall, wheel wells, door seals, and even the tail cone.  I recommend everyone carry a low level digital carbon monoxide detector.

Dr. Brent Blue is a Senior Aviation Medical Examiner based in Jackson Hole, Wyoming.  He can be reached at brent.blue@aeromedix.com.

 

 

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The ReliefBand® is back!

The ReliefBand® is back!  Available to consumers without the need for a prescription and at a new low price, the ReliefBand® Voyager is an FDA cleared nerve stimulation medical device that treats and relieves motion-sickness. It is safe, drug-free, highly effective and clinically proven solution without side effects associated with medication. The ReliefBand® Voyager does not cause drowsiness, interact with medications, interfere with alcoholic beverages or cause drug-like side effects.  Because it produces no side effects, the ReliefBand® Voyager is fully FAA-legal for pilot use, and is ideal for student pilots and aerobatic pilots who need relief from motion sickness as well as passengers.

Aeromedix only offers products that have been tested and approved by Dr. Brent Blue, a FAA Senior Aviation Medical Examiner and Board Certified physician.  If Aeromedix sells it, it works!The Reletex was released in 2011, replacing the original ReliefBand®. Many customers have asked what the difference is between the Reletex and the ReliefBand® Voyager.  The Reletex is a prescription only. The ReliefBand® is an over the counter (OTC) version of the Reletex. The ReliefBand’s® maximum output of 35mA is slightly less than the 40ma of the Reletex. The ReliefBand® will last up to 60 days (based on usage of the device for 2 hours at power level 3 or below). As with the Reletex, the battery life depends on the individual usage of the device. Unfortunately, The ReliefBand Voyager® does not have replaceable batteries, a popular feature of the first generation of ReliefBand® devices.

If you want to know more about the ReliefBand® Voyager or place an order for one, visit the ReliefBand® Voyager product page. As always you can call us as well at 1-888-362-7123.

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The FAA’s New Big Brother Approach to Your Health

The FAA’s New Big Brother Approach to Your Health
By Brent Blue MD
Senior AME

The Federal Air Surgeon recently announced that Aviation Medical Examiners would soon be required to screen for obstructive sleep apnea (OSA) on all pilots by measuring neck circumference and calculating body mass index. Anyone who meets the criteria, neck size of 17 inches or over and a BMI of 40 or over, will not be granted a medical until they have been tested by a “sleep specialist” and either do not have OSA or have it adequately treated.

(Federal Air Surgeon’s Medical Bulletin)

Since the FAA does not show any significant number of accidents caused by OSA, what are they thinking? Are they now responsible for the overall health of pilots? If that is true, let us consider some other issues.

Aviation Medical Examiners do not ask, nor does the 8500 application form ask, if the pilot uses tobacco products—the greatest cause of preventable medical disease in the world. In addition, AMEs cannot require cholesterol history, family history, or exercise frequency. When it comes down to longevity, family history is the number one predictor. Number two is tobacco use. Exercise and weight control are tied for three and four.

So a pilot can come into my office for an AME exam, be 50 pounds overweight, be a two pack a day smoker, have parents who died from heart disease in their 40s, have a cholesterol of 300, and never exercises and all I will know about is his weight. And there is no weight limit for pilot medical qualifications!

So let us say this pilot has a neck size over 17 inches and a body mass index (BMI) over 40. (BMI was developed and only supposed to be valid for use with populations of people, not individuals. Use with individuals has been shown not to be valid. Tom Cruise’s BMI is 26 putting him in the “fat” category. LeBron James is 27.5—fat as well!) Now the FAA says that I must delay his medical until he sees a “sleep specialist” and either does not have OSA or is treated successfully. Now in either of these situations, we may have solved his sleep problems and that does lower his risk of high blood pressure and heart disease but he is still a flying time bomb. Other than the OSA, as his AME, I do not know it nor can do much about these other serious risk factor since I have no authority to force an answer and even do anything with just a risk factor.

A “sleep specialist”, usually a pulmonologist or neurologist who are into the high profit sleep centers, will require a full sleep study in their center—usually starting at $2,000 a pop. The frustrating part is most sleep apnea can be screened with a $200 nocturnal pulse oximetry study ordered or administered by your primary care physician. If your oxygen level does not drop when you sleep, it is highly unlikely you have OSA. If the oxygen level does drop, it may indicate a full sleep study in the sleep center.

So now the FAA is taking on sleep apnea as a risk factor even though it is low down the totem pole of risks which pose a hazard to aviation. Where does the FAA decide to stop? General aviation is already in a crisis with the slow economic recovery and the cost of fuel. Are potential pilots now going to have to go through more testing due to risk factors than life insurance companies require? (By the way, I have never had to measure someone’s neck for any life insurance physical in over 30 years. However, some life insurances do rate applicants on the basis of their BMI.) The FAA may be just trying to bury general aviation.

I am liberal Democrat who supports the Affordable Care Act. However, the Civil Aerospace Medical Institute’s (CAMI) Office of Aerospace Medicine job is to make sure that pilots are “safe” and they will not become “suddenly incapacitated” while piloting an aircraft. They are not mandated to make sure pilots are healthy specimens across the board. This is clearly an overreach of the FAA’s purpose utilizing the excuse of promoting aviation safety.

Keeping patients healthy is my job as their primary care physician and I am as aggressive as any doctor. Keeping people healthy is not the FAA’s job.

What is even more disturbing is CAMI cannot keep up with the paperwork for all the current special issuances and other non-routine medicals. With new rules like this, this back log will only increase in an agency whose budget is tight and getting tighter.

Just make sure you are wearing a 16 ½ inch shirt next time you see your AME!

*Dr. Brent Blue is a Senior AME based in Jackson Hole, Wyoming. He introduced pulse oximetry and digital carbon monoxide to general aviation through his company, Aeromedix.com.

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Fainting – Who Will Do the Flying

There have been a couple of recent reports of pilots fainting on board commercial aircraft. When most people faint, it is not usually a problem. When a pilot faints in flight, it could be catastrophic.

Fainting, or syncope in medical lingo, occurs when the brain does not get enough oxygenated blood to support neurological functioning. Basically, when the brain determines it is not getting enough blood, it says to the body “if you do not get me enough blood, I am going to make you get me enough by making you lie down!”

Fainting most commonly is due to blood pooling in the lower extremities and abdomen so the heart does not have enough blood returning to pump out to maintain blood pressure. This can happen when someone is told bad news, has their blood drawn, has severe pain, and many other reasons. This most common cause of fainting is called a vasovagal response. In these situations, the blood vessels in the peripheral vascular system (e.g. arms, legs, and abdomen) dilate due to stimulation from the vagus nerve which controls much of the automatic nervous system (the part of the nervous system we cannot actively control like heartbeat and blood pressure). The vessels dilate, the blood pools, blood pressure drops, and our brain does not like it.

Dehydration is one of the most common causes of syncope. Dehydration can be from just not drinking enough fluid (to avoid having to urinate in the aircraft), viral stomach illnesses which cause vomiting and diarrhea, to taking a diuretic for high blood pressure which increases fluid loss. Also remember that flying at higher altitudes or in pressurized aircraft causes more dehydration due to low humidity of those environments. Almost any medication which has the side effect of sedation may also contribute to fainting.

Pilots in cockpits are also prone to fainting due to the sitting position which presses on the veins in the back of the leg causing further reduction of blood return to the heart. Anemia or low blood cell count will also predispose to fainting as will advanced age.

When a person faints, they may exhibit jerking movements similar to those seen in seizures. Unfortunately, due to these movements, many people who faint are incorrectly labeled as having had a seizure which has serious implications for driving and flying.

There are other reasons beside vasovagal syncope which can cause fainting such as certain irregular rhythms of the heart, low blood sugar, and panic attacks with hyperventilation. Thus, many emergency room visits and even hospitalizations occur to evaluate a fainting event- particularly when it happens the first time- to search for a cause besides vasovagal syncope. Doctors call vasovagal syncope a diagnosis of exclusion because vasovagal is what we call it when we cannot find another reason.

When a person faints, the best thing to do is to lie them down and raise their feet. This promotes blood return to their heart and raises blood pressure to the brain. A cool wet towel to the face helps but slapping them silly like I once saw another physician do is uncalled-for. Save that ridiculous technique for bad movies. If a person does not wake up spontaneously within a minute or so after lying down, immediate medical attention should be sought.

Prevention of fainting is relatively easy: hydration, hydration, and more hydration. Also, eating something salty can help. Without some salt, you will not retain fluid so all hydration will be lost more quickly. If you have high blood pressure, you should not use salt, but if you do not have hypertension, a bag of potato chips can raise blood pressure slightly to help prevent fainting. (We often see patients, who do not have high blood pressure, develop problems from restricting salt too aggressively!)

When a pilot asked himself if he is fit to fly, one of the important things to consider is whether he is hydrated or has other issues that might make him more prone to fainting. In the two pilot cockpit of an airliner, fainting may be a non event. In a single pilot cockpit, it could be disastrous.

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The FAA and Oxygen—Bringing the FAA into the 21st century kicking and screaming

I thought getting “through the fence” fixed with FAA opposition took a long time, but Gary Eaton has worked a couple of years to fix a FAA problem that had no opposition — that “oxygen is oxygen!”

We’ve all heard the ancient cry in the many FAA documents that we must fill our aircraft built in systems with Aviator Breathing Oxygen (ABO). This dates back to the 1950s and 1960s when oxygen came from different sources and was prepared differently. For instance, medical oxygen was forbidden by the FAA because at that time, water vapor was mixed into the oxygen tank for patient comfort and this vapor could freeze in an aircraft’s oxygen plumbing in cold weather and/or high altitudes.

This is a reasonable approach, but for the last forty plus years all oxygen has come from the same liquid oxygen sources and water vapor has not been added to medical oxygen for the same period. With this being the case, it might be time to change the verbiage in the FAA recommendations and documents. Thus was the mission of Mr. Eaton. After a barrage of letters to the FAA and his US Senator, the FAA has agreed to “update the publications” effective October 1, 2012, with each revision cycle (cycles for publications are measured in years, not days or months). As Mr. Eaton says “It may be a bit too early to raise our glasses for a toast. The FAA promised a fix back on October 18, 2007 and they did not make the corrections then.”

What is even more interesting, the FAA now states that their regulations “do not specify purity” and the “FAA Advisory Circulars (AC) are not regulatory and provide an acceptable means, but not the only means, of regulatory compliance” (emphasis mine). So for all these years, when our A&P fill our aircraft oxygen systems with ABO, high priced but identical to medical oxygen, all we were paying for was the name and additional testing to prove it did not have any water in it. It was not even regulatory!

Now, in correspondence to Mr. Eaton, the FAA states they will recommend that supplemental oxygen “meet or exceed the Society of Automotive Engineers International (SAE) Aerospace Standard AS8010 (as revised), Aviator’s Breathing Oxygen Purity Standard” but this is only a recommendation. Given past experience, no one will know what this standard is since the SAE website charges to download the
standard. For the most part, it basically says oxygen needs to be 99.5% pure which means that any modern oxygen source is in “compliance.”

Mr. Eaton’s victory means that finally we can go to our local gas supplier, rent some H cylinders of cheap “medical oxygen,” buy or borrow a two or three tank cascade system hookup, and have our A&P use it to fill our aircraft. (There still is that pesky little FAA regulation which states that only A&Ps can fill installed aircraft oxygen systems but who pays attention to that?”) Oxygen is dirt cheap. Most H cylinders cost about $30 for the oxygen plus tank rent (unless you buy it). A two H cylinder cascade system will fill about 60 average size portable systems or about a dollar a fill. The system should fill about 30 average size built in systems or about $2 a pop!

That brings us to the gas suppliers. If you take your portable oxygen system to you local supplier to fill, if you ask for medical oxygen, they may want a prescription. You can always ask for ABO but that will cost you more dollars. Most of the time, the supplier will not accept the “welding gas” request for filling portable systems. They are not quite that dumb.

Here is my solution: Send me an email with your name and address and I will mail you a prescription for medical oxygen – no charge. It is the least I can do to honor Mr. Eaton’s hard work!

This article was reprinted from the October 2012 edition of Aircraft Owner magazine.

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