Dr. Robert Kurrle, M.D., Senior AME
Part I: "How did I get it?"
This is a two-part article on blood pressure. The first part will cover some basic definitionsand causes of hypertension. The second part will cover treatment and the FAA Medical.
Our circulatory system consists of systemic and pulmonary circulation, which work in series. Each system has both arteries and veins. The arteries transport the blood under high pressure to the tissues where the capillaries exchange fluid, nutrients, electrolytes, and hormones between the blood and the cells. The veins transport the blood under low pressure back to the heart. The heart actually consists of two pumps. The right atrium/ventricle pumps blood to the lungs where carbon dioxide is exchanged for oxygen. The oxygen rich blood returns to the left atrium/ventricle where it is pumpedto the body's cells by way of the systemic circulation. Blood pressure readings represent the arterial side of the systemic system. The heart pumps about five liters of blood per minute.
Your heart expands and contracts as it pumps, changing your blood pressure. When the heart contracts, blood flows into your blood vessels increasing the blood pressure. This peak pressure is called the systolic pressure. When your heart relaxes between beats, the flow of blood lessens and the blood pressure drops. This trough pressure is called the diastolic pressure. This is why your blood pressure is recorded as two numbers. The first, higher number, is the systolic pressure and the second, lower number, is the diastolic pressure. Blood pressure is the pressure of the blood on the walls of the arteries. This is dependent upon the energy of the heart action, theelasticity of the artery walls, the resistance of the circulation system, and the volume and viscosity ofthe blood. The maximum systolic pressure occurs near the end of the stroke output of the heart. Theminimum diastolic pressure occurs late in the cycle when the heart is refilling.
Blood pressure is measured using a blood pressure cuff and a stethoscope. The cuff is placed around the upper arm and the stethoscope is placed over the antecubital artery. As long as the cuff pressure is low the artery remains open and no sounds are heard despite the fact that the blood within the artery is pulsating. The cuff is inflated to a reading above the systolic pressure and the brachial artery is collapsed with no blood flow and no sounds. As the cuff pressure is gradually reduced and falls below systolic pressure, blood starts flowing through the artery during the peak ofthe systolic pressure wave. This can be heard as a tapping sound with the stethoscope. The initialpressure is recorded as the systolic. As the pressure in the cuff is lowered more, it will pass the point where the artery will stay open under the cuff, and the tapping sound will stop. That lower pressure is recorded as the diastolic.
Hypertension is defined as persistently high arterial blood pressure. High blood pressure is caused by increased peripheral vascular resistance; increased cardiac output; or both. This is because blood pressure is equal to cardiac output (flow) times resistance. Normal blood pressure is usually considered 120/80. Generally, blood pressure readings above 140 mm Hg. systolic and 90mm Hg. diastolic are considered high. High blood pressure rarely has any symptoms. That is why itis such a dangerous condition. It is estimated 25% of adult Americans suffer from hypertension.Hypertension is the silent killer with organ damage often the first indication of its presence. This can take the form of kidney disease, stroke, heart disease, or even problems with the retina. Persistent high blood pressure puts undo stress on the heart, blood vessels, and organs.
Primary (essential) hypertension is of unknown etiology. Heredity is a predisposing factor but the exact mechanism is unclear. Ninety-five percent of hypertension patients suffer from essential hypertension, which means no cause can be found. Control of essential hypertension is a complex problem because there is no obvious reason. Secondary hypertension is associated with different systemic disorders and diseases as well as some medication and drugs. Some commoncontributors to high blood pressure include sedentary lifestyle, smoking, weight gain, diet, stress, and of course heredity. You can change your life style, but you cannot change your genes.
It is very important to your health to have your blood pressure measured regularly.Hypertension must first be diagnosed so that it may be treated. There are many treatment options available that can improve your health and quality of life. Next month, we will talk about treatment and the impact on the FAA Medical. Questions?- call 322-9030, Spruce Creek Flight Physicals PA, 140 Piper Blvd, Spruce Creek Fly-In, Daytona Beach, FL 32128.
HIGH BLOOD PRESSURE & THE FAA
Part II: "Passing the FM Medical"
Last month, we covered some basic definitions of the circulatory system. We learned what blood pressure is, how it is defined and measured. We also defined hypertension as persistently high arterial blood pressure, usually above 140 mm Hg systolic and 90 mm Hg diastolic. This article will talk about treatment and the implications on the FAA medical exam.
Measurement of blood pressure is an essential part of the FM medical certificationexamination. The average blood pressure while sitting should not exceed 155mm Hg systolic and 95mm Hg diastolic maximum for all classes. A medical assessment is required for all applicants who need or use antihypertensive medication to control blood pressure.
Now, what happens if a pilot comes in for his medical and his blood pressure is above the FAA limits? Of course, pressure can be elevated due to the "white coat syndrome", or from the anxiety associated with the exam itself. Caffeine from the morning coffee can also be a culprit. If the pressure is high, several readings can be taken. Often, after the pilot "passes" everything else and is allowed to relax, the blood pressure will drop back to his/her baseline. If it remains high, the application may be held. If a series of three normal readings over a seven-day period are made, the medical may be granted. Otherwise, the application must be deferred and evaluation by his/her medical doctor will be required.
Treatment for hypertension will be determined by your primary care physician. This may include lifestyle changes and/or antihypertensive medications. Selection of the initial medication will be guided by the age and race of the patient and by coexisting diseases or conditions thatmay represent a contraindication for certain drugs.
Medical certificates may be issued to all classes of pilots, if otherwise qualified, whose hypertension is adequately controlled with acceptable medications without adverse side effects. The initial application after starting on antihypertensive medication requires a current (within six months) cardiovascular evaluation by the applicant's attending physician. This must include pertinent history, risk factors, clinical exam including: three normal blood pressure readings, a resting EKG, and a blood workup. Specific mention must be made of the medications used, their dosage, and absence of side effects. If you are still on blood pressure medication at the time of your medical certificate renewal, a status report from the treating physician will be required. This should include a brief history, the current medication and dose, adequacy of control, and absence of side effects. The status report is required annually for first and second classes, and at the time of renewal for third class. These need to be brought to the AME at the time of the exam (or within two weeks of the exam) to be able to obtain the medical and avoid deferral.
The FAA currently allows the use of most antihypertensive medicines except the centrally acting agents (reserpine, guanethidine, and methyldopa), which are rarely used. Approved medications include all the common antihypertensive medications. These include diuretics, angiotension-converting enzymes (ACE) inhibitors, alpha- and beta- blockers, calcium channelblockers, direct vasodilators or combinations.
So, remember, blood pressure control is really a health issue. Almost all treatment for hypertension is approved by the FAA and requires a minimum amount of paperwork. It is better to be on medication to control your blood pressure and have a long and healthy life of flying, than to ignore it and put your quality of life at risk and possibly shorten your flying days. Also, remember, the FAA blood pressure requirements are actually higher and more lenient than most doctors would tolerate. A high blood pressure reading should be your signal to investigate further with your medical doctor. Let's keep everyone flying!