Fs guide chapter 10

Chapter 10
ISSUES IN INTERNAL MEDICINE
J. Pickard, W. Kruyer, R. Gardner, J. Deering, INTRODUCTION
There are many significant internal medicine problems in aerospace medicine. Althoughdiscussing them all is beyond the scope of this chapter, the following topics have been selectedbecause of their particular importance or frequency in aviation medicine. The emphasis will be onaeromedical significance, evaluation, and disposition rather than general medical diagnosis andtreatment. This emphasis highlights aerospace medicine as preventive medicine--focusing on thepreclinical detection of many problems, such as coronary artery disease, hypertension, anddiabetes mellitus rather than the management of clinical disease. The key aeromedical issue in allof these problems is assessing the potential for sudden incapacitation in flight. The followingissues will be discussed: Initial evaluation of all these problems is performed by the base-level flight surgeon andappropriate consultants. Definitive aeromedical evaluation of most complex or questionablemedical problems is performed at the Aerospace Medicine Consultation Service at Brooks AFB,TX. After extensive evaluation of the aviator, an aeromedical recommendation is made to theappropriate waiver authority.
CARDIOVASCULAR PROBLEMS
Asymptomatic Coronary Artery Disease (CAD)
CAD is a common problem in the US, affecting an estimated five million Americans. Thereare 650,000 CAD deaths and 700,000 MI’s per year. Forty to 50% of people with CAD presentas MI or sudden cardiac death.
Risk factors for CAD are male gender, hyperlipidemia, hypertension, cigarette smoking,diabetes mellitus and family history of premature CAD.
How important is it to diagnose asymptomatic coronary artery disease in aviators? This is anessential aeromedical issue. The diagnosis is important because disease presentation--acutemyocardial infarction, severe angina, dysrhythmias, sudden death--can be suddenly incapacitatingin flight. Also, in high-performance jet aircraft, the increased cardiovascular stress affectscoronary artery blood flow due to rapid onset and sustained high +Gz, rendering minimalasymptomatic disease more significant.
The difficulty is how to diagnose asymptomatic CAD in the USAF aviator population withlow (5%) disease prevalence. Because of this low prevalence, the positive predictive value of thecurrent screening tests for CAD is low: exercise tolerance testing (ETT)--35%, thallium-201scanning--less than 50%, and multiple gated acquisition (MUGA) scanning--less than 25%.
USAF aviators are generally referred for cardiac evaluations at the ACS because ofabnormalities on local non-invasive cardiac testing, with or without symptoms. The following arethe noninvasive tests performed at the Aerospace Medicine Consultation Service: a. Exercise tolerance testing is done with the threshold for a positive test being 1mm or more
depression of the ST segment below baseline at 0.08 sec from the J point. A depression of 0.5-
0.9mm is considered a borderline test.
b. Cardiac fluoroscopy, when positive for coronary artery calcification, increases the
likelihood of a positive catheterization. According to a series at the Aerospace Medicine
Consultation Service, 70% of aviators with positive fluoroscopy will have measurable disease.
c. Myocardial perfusion studies, using the potassium analog thallium-201, when coupled
with exercise are useful in identifying areas of infarction and ischemia.
d. Echocardiography, using the M-mode and two-dimensional techniques, assesses chamber
and valve anatomy and motion. Segmental wall motion abnormalities suggest the possibility of
ischemia or infarction. Furthermore, when coupled with Doppler recording, information can be
obtained about the velocity, direction, amplitude, timing and character (laminar or turbulent) of
blood flow, and valvular regurgitation and stenosis can be identified.
e. Twenty-four hour electrocardiograms are obtained using a Holter monitor to evaluate
cardiac rhythm under normal activity conditions.
Cardiac catheterization remains the gold standard for evaluation of asymptomatic coronary
artery disease. An aviator with a normal catheterization or only intimal roughening qualifies for
Flying Classes II and III. Aviators with minimal CAD may receive a Categorical IIA or IIIA
waiver (Tanker, Transport, Bomber). Minimal CAD is defined as a sum of lesions of 120% or
less, no single lesion with 50% or greater stenosis, and no left main coronary artery disease.
Aviators with waivers for minimal CAD are in an Aerospace Medicine Consultation Service StudyGroup and return annually for noninvasive testing. To assess any disease progression, they haverepeat catheterizations at 3 years, or sooner if annual noninvasive test results become abnormal.
Significant CAD (SCAD) is anything beyond MCAD. Coronary stenoses 50% or greater are
considered medically significant as they may cause myocardial ischemia with exertion. Inaddition, there is a higher cardiac event rate (MI, death) in individuals with SCAD. SCAD isconsidered disqualifying for all flying duties without waiver.
Valvular Heart Disease
With advancing technologies, primarily Doppler echocardiography, the sensitivity of detectingvalvular stenosis and insufficiency has greatly increased over the past two decades. Many currentguidelines for the evaluation of valvular lesions in aviators were derived from what are nowconsidered relatively crude imaging techniques, as well as on the clinician’s exam. Now, forexample, minimal insufficiency of the cardiac valves, identified using current methods of Dopplerimaging, is so common that minimal insufficiency in the absence of any other valvular abnormality(i.e. associated stenosis or structural abnormalities) is not considered pathologic. Therefore, trulyminimal (trace) insufficiency of any structurally normal valve is considered a normal variant anddoes not require further evaluation. The importance of structurally normal valves must bestressed, as a significant proportion of those with trace aortic insufficiency or trace mitralregurgitation also show a bicuspid valve or valvular prolapse, respectively. As well, again due toa greater sensitivity with current imaging systems, the conditions of mild mitral, tricuspid, andpulmonic insufficiency, in the presence of a structurally normal valve, normal chamber sizes,normal ventricular systolic function and hemodynamics, are considered normal variants requiringno further evaluation. (Mild aortic insufficiency, far less common and often associated with abicuspid valve, is considered abnormal.) The principal aeromedical concerns of valvular heart disease are as follows: the risk ofbacterial endocarditis; associated dysrhythmias potentially exposing the aviator to incapacitation,or to a loss of situational awareness; the risk of embolic events; abnormal untoward hemodynamiceffects in the high +Gz environment; myocardial ischemia, and a potentially high rate of pilotattrition due to progression of the valvular disorder and eventual left or right ventricular failure.
Therefore, all aviators found to have moderate or severe regurgitation of any valve, mild to severeregurgitation of the aortic valve, or valvular stenosis of any degree require further evaluation,usually with referral to the Aeromedical Consult Service (ACS). This evaluation routinelyinvolves a thorough history and physical examination by a cardiologist, confirmation of thevalvular heart disease by echocardiography, an assessment of exercise tolerance as well ascoronary artery disease screening by exercise treadmill testing (ETT), and 24-hour Holtermonitoring for associated dysrhythmias. In addition, depending on the valvular disorder involved,its severity, and any associated disorders, further evaluation may be indicated with SPECTthallium-201 imaging, cardiac catheterization, or monitored centrifuge testing. Specific additionalrequirements will be discussed in the following paragraphs.
a. Mitral Regurgitation (MR). The majority of significant MR (greater than mild) that comes
to the attention of the flight surgeon is secondary to mitral valve prolapse (MVP). Usually a soft
pansystolic apical murmur radiating to the axilla is detected on a routine exam in an asymptomatic
aviator. This may be associated with a midsystolic click with varies in relation to S1 with standing
and squatting. This condition is usually waiverable if there are no concomitant associated
symptoms, other valvular heart disease, significant dysrhythmias, chamber dilation thought to be
secondary to the MR, or depressed LV function. Mitral regurgitation due to other causes such as
ruptured chordae tendineae, papillary muscle dysfunction or endocarditis is not generally
waiverable. Reevaluations at the ACS are typically performed at three year intervals, though this
may vary. In the case of MVP, those evaluees who wish to continue flying high performance
aircraft are required to perform monitored centrifuge testing to assess their dysrhythmia potential.
b. Mitral Stenosis (MS). The presence of mitral stenosis in aviators is quite rare. Its etiology
is almost exclusively secondary to rheumatic heart disease. As the diastolic low pitched rumble of
MS is frequently missed on physical exam, this condition can go undiagnosed until the evaluee
presents with symptoms. At this point the appropriate treatment is usually balloon valvuloplasty
or surgical commissurotomy or valve replacement. Due to the associated high risk of recurrence
or thromboembolic complications, mitral stenosis is considered disqualifying without waiver both
before and after treatment.
c. Aortic Insufficiency (AI). The majority of significant AI (greater than trace) that comes to
the attention of the flight surgeon is secondary to a congenitally bicuspid aortic valve. Usually
a soft blowing diastolic murmur, heard best with the bell of the stethoscope at the mid left sternal
border with the evaluee leaning forward, is detected on a routine exam in an asymptomatic
aviator. This may be associated with a systolic ejection click, and can be accentuated with
handgripping or a sudden squat. This condition is considered to be a contraindication to flying
high performance aircraft due to the potentially adverse effects on the valve by elevations in aortic
root pressure which occur due to afterload increases from sustained high-G stress. However, it is
generally considered waiverable for non-high performance aircraft if there are no concomitant
associated symptoms, aortic root disease, chamber dilation thought to be secondary to AI,
significant dysrhythmias, or depressed LV function.
d. Aortic Stenosis (AS). The presence of aortic stenosis in the aviator is also quite rare. The
etiology in this age population is almost exclusively a congenitally bicuspid AV. Though this
congenital anomaly occurs in approximately 1% of the general population, the degree of calcific
degeneration required to cause a gradient across this valve does not typically occur until the 5th
or 6th decade of life. Aortic stenosis is usually easily appreciated on physical exam as a harsh
crescendo-decrescendo systolic murmur heard best at the right upper sternal border, radiating to
the carotids. A systolic ejection click may also be appreciated. Minimal AS, defined by a peak
gradient less than 20 mm Hg in a ventricle with normal systolic function, may be considered for
waiver. The evaluee must be asymptomatic, and have no associated dysrhythmias or left
ventricular hypertrophy. More significant stenosis is not waiverable.
e. Tricuspid Regurgitation (TR). The majority of significant TR (greater than mild) is due to
a pathologic process, usually pulmonary hypertension, right heart dilation, endocarditis or
tricuspid valve prolapse. The murmur is typically holosystolic, located at the lower left sternalborder, and varies in intensity with respiration. If the underlying etiology is pulmonaryhypertension or right heart dilation, it will usually not be waiverable. Pulmonary hypertension inparticular can be aggravated by hypoxic-induced pulmonary vasoconstriction, potentiallyworsening the associated valvular regurgitation. TR due to TV prolapse or as an isolated findingis evaluated on a case by case basis and is potentially waiverable.
f. Tricuspid Stenosis (TS). Tricuspid stenosis is extremely rare in the general population as
well as in aviators. The most common etiologies are rheumatic heart disease and carcinoid
syndrome. It is disqualifying without waiver.
g. Pulmonary Insufficiency (PI). Significant (greater than mild) PI is also an uncommon
finding in aviators. The majority of cases are secondary to pulmonary hypertension and therefore
disqualified without waiver. Isolated cases not associated with this etiology may be considered on
a case by case basis for waiver.
h. Pulmonary Stenosis (PS). In aviators this uncommon valvular lesion is generally
secondary to a congenitally hypoplastic pulmonary valve. On exam, a systolic crescendo-
decrescendo murmur is best heard at the left upper/mid sternum. Unlike AS, this is typically not a
progressive lesion, and can be considered for waiver if there is no associated chamber dilation,
right ventricular hypertrophy, dysrhythmias or conduction abnormalities.
i. Mitral Valve Prolapse (MVP). Mitral valve prolapse, with or without MR, is an
aeromedical concern due to its relatively high prevalence in aviators (2-3%), and its association
with tachydysrhythmias (SVT/VT), endocarditis, and thromboembolic events. The majority of
MVP is detected on routine examination when a midsystolic click is heard. Typically the click
moves closer to S1 when standing from a squatting position. Newer diagnostic capabilities and
more rigid criteria for its diagnosis have led to a decreased estimate of prevalence from what
earlier studies suggested. In part due to the earlier overdiagnosis of cases in the literature, this
disorder had been linked to numerous conditions, with many of these associations yet to be
definitively proven. However, a relatively firm basis exists for the associated complications listed
above. Therefore the ACS established a Study Group to follow aviators with this condition to
assess the natural history as it relates to the aviation environment and to be able to form a rational
basis for waiver decisions. This Study Group is currently being reviewed.
For the present time, aviators with possible MVP are evaluated at the ACS. The diagnosis is confirmed either by agreement of two physicians on auscultation or by echocardiographydemonstrating prolapse on the parasternal long axis or apical long axis views. Evaluation includesan echocardiogram, 24-hour Holter monitoring, and an ETT to detect exercise-induceddysrhythmias, decreased exercise tolerance or concomitant CAD. Further evaluation with SPECTthallium perfusion imaging may be necessary. Monitored centrifuge testing is required to fly highperformance aircraft with this condition. Should there be no disqualifying associateddysrhythmias, reduced exercise tolerance, related chamber dilation, or decreased LV systolicfunction, waiver is usually granted.
Note should be made of the current ACS recommendations for SBE prophylaxis. Werecommend that an evaluee with any valvular lesion associated with significant regurgitation asdefined in the preceding paragraphs, any stenotic valvular lesion or thickened, deformed valve,any regurgitation associated with a murmur on exam, or MVP regardless of the presence orabsence of MR, receive antibiotic prophylaxis for SBE.
Hypertrophic Cardiomyopathy
Although not waiverable, hypertrophic cardiomyopathy deserves comment because it is oftenfound in a younger population, with an average age at presentation of 26 years old. It is usuallydetected in the aviation population by characteristic abnormalities on routine ECG rather than bysymptoms. Even in the clinical literature 22% of patients are asymptomatic and more than 50%have no functional limitation, but hypertrophic cardiomyopathy is permanently grounding becauseof the risk of syncope and sudden death. Echocardiography makes a definitive diagnosis with aratio of septal to posterior wall thickness of 1.3 or greater. The presence of LV outflow tractobstruction due to this hypertrophy is variable. Although the etiology is unknown, the heredity isautosomal dominant. If detected in an aviator, other family members should be screened.
A normal variant that may mimic concentric left ventricular hypertrophy (LVH) is the“athlete’s heart,” a compensatory cardiac response of muscle hypertrophy and mild chamberdilation to prolonged, strenuous exercise. Other evidence supporting this diagnosis besides anexercise history are signs of increased vagal tone such as sinus bradycardia, first degreeatrioventricular (AV) block, Möbitz Type I second degree AV block and a junctional rhythm.
The LVH observed with this entity may be waived if, after a period of minimal or no exercise, theLV returns to normal wall thickness and size as demonstrated on repeated echocardiograms.
Once the diagnosis is confirmed, the aviator may resume the previous exercise program.
Dysrhythmias
The USAF Central ECG Library was established at the Aerospace Consultation Service(ACS) in 1957. Since then, it has been a repository of ECGs on aviators and has allowed serialcomparisons. The Library has helped define the frequency, natural history and aeromedicalsignificance of the various electrocardiographic abnormalities discussed next.
Sinus Bradycardia. Sinus bradycardia is a frequent finding in the young, physically
conditioned USAF aviator with increased vagal tone. For this reason, sinus bradycardia is definedaeromedically as a sinus heart rate less than 50 beats per minute (bpm) rather than the usual 60bpm. The aviator is disqualified if the bradycardia is due to sinus node dysfunction as shown byinadequate response to exercise or by abnormal electrophysiologic studies. A screening test theECG library uses to exclude pathology is the “Hop-a-Gram,” where the subject jumps up anddown until the heart rate reaches 100 beats/min, with a tracing obtained at that rate. Failure toreach a rate of 100 bpm requires a formal exercise tolerance test (ETT).
Sinus Tachycardia. Sinus tachycardia is defined as a sinus heart rate greater than 100 bpm.
It is disqualifying if it is related to an underlying metabolic state or disease process, e.g.
hyperthyroidism. The underlying problem must be managed before aeromedical disposition canbe decided.
First Degree Atrioventricular (AV) Block. First degree AV block is defined aeromedically as
a PR interval greater than 0.22 sec instead of the usual 0.20 sec. This is an important distinctionbecause as noted earlier sinus bradycardia is common in aviators, and the PR interval lengthenswith decreased heart rate. The aeromedical evaluation of an aviator with first degree AV blockinvolves assessment of the PR interval response to increased heart rate with exercise. Once againthe “Hop-a-Gram” is used to exclude pathology; the subject exercises in place until the PR isdemonstrated to shorten to <0.22 sec, documented on ECG. If the PR interval does not shortento normal, an ETT is requested. If the PR interval still is abnormal, the first degree AV block isconsidered disqualifying and a ACS evaluation may be requested.
Second Degree AV Block. Möbitz I (Wenckebach) AV block can also be seen in the healthy,
athletic aviator at rest or sleep due to increased vagal tone. It is considered a normal variant.
Möbitz II AV block is disqualifying for flying duties because it is often indicative of significantconduction system disease and may lead to incapacitating hemodynamic events and third degreeheart block.
Right Bundle Branch Block (RBBB). An ACS Study Group showed that, in an aviator with
an otherwise normal cardiologic evaluation, RBBB is not an indicator of CAD or cardiomyopathyand is unlikely to progress to more serious conduction system disease. Therefore, waiver isusually recommended for flying training as well as Flying Class II duties if a local evaluationincluding internal medicine consultation, ETT, echo, and Holter monitor is normal. The aviator isDNIF during this evaluation. ACS evaluation is pursued prior to waiver recommendation if anyof these studies is abnormal.
Left Bundle Branch Block (LBBB). LBBB is disqualifying for flying training. A trained
aviator with LBBB as a serial change is evaluated at the ACS with cardiac noninvasive studiesand catheterization because of an association with CAD, cardiomyopathy, and progressiveconduction system disease. If all the studies indicate simple LBBB, a waiver may berecommended with ACS follow-up every three years.
Ectopic Beats. The aeromedical concern with ectopy is the possibility that the ectopy
represents a sentinel finding for tachyarrhythmias. However, premature supraventricularcontractions and premature ventricular contractions are common in healthy aviators and arefrequently related to stimulants such as caffeine and alcohol. Premature supraventricularcontractions (PACs, PJCs) and premature ventricular contractions (PVCs) are evaluated withHolter monitoring while the aviator remains on flying status. Rare (<0.1%), and occasional (0.1 -<1%) ectopy are considered normal variants. Frequent (1 - <10%) ectopy and paired ectopy areconsidered abnormal and mandate further testing, which consists of local ETT and echo. If theseare normal then waiver for Flying Class II duties is usually recommended. Very frequent (>10%)ectopy, multiformed ectopy or frequent pairs (>10 in 24 hours) are abnormal and ACS evaluationis recommended.
Supraventricular tachycardia (SVT) is defined as three or more SV ectopics in a row at a
heart rate greater than 100 bpm. It includes atrial tachycardia, junctional tachycardia, atrialfibrillation, and atrial flutter. Multifocal atrial tachycardia may or may not be considered abnormalrequiring further evaluation; this is determined by individual case review. History of a singleepisode of SVT is disqualifying for flying training. Nonrecurrent SVT of 3-10 beats in durationrequires local evaluation while the aviator is DNIF. The local evaluation will at least includeinternal medicine consultation, TFTs, three Holter monitors (one monthly for three months), andETT. If an aviator has a single episode of nonsustained SVT of greater than 10 beats duration, orhas recurrent nonsustained SVT (<10 minutes duration), or a single episode of sustained SVT, hemay be considered for waiver after three additional local Holter monitors and subsequent ACSevaluation, with repeat ACS evaluations at three year intervals. The ACS evaluation consists ofnoninvasive cardiac studies tailored to the age of the aviator. If any of the CAD screening studies(coronary artery fluoroscopy (CAF), ETT, thallium scintigraphy) is abnormal, cardiaccatheterization is required. Any symptomatic/hemodynamically significant SVT, or recurrentsustained SVT of sufficient frequency (<3 years between episodes), is considered permanentlydisqualifying for all classes of flying duties. Current SVT recommendations are based on the 1992Surgeon General SVT Study Group review and analysis.
A generally benign form of SVT is the "holiday heart syndrome." This is usually atrialfibrillation related to fatigue, lack of sleep, hunger, and anxiety along with increased coffee,alcohol, and/or tobacco intake, and is usually self-limited. Future avoidance of the precipitatingsituation usually prevents subsequent recurrence of this arrhythmia.
Ventricular tachycardia (VT) is defined as three or more PVCs in a row at a heart rate of
100 beats/min or greater. It is disqualifying for entry into flight training. Asymptomaticidiopathic VT may be waived for flying in the trained aviator after ACS evaluation, consisting ofcardiac noninvasive studies and occasionally catheterization studies. Flying Class IIA waiver isusually recommended for <5 episodes per evaluation if each is <12 beats duration. Waiver is notrecommended if there is an underlying cardiac diagnosis with possible causal relationship (i.e.
MVP, CAD, cardiomyopathy). A full Flying Class II waiver can only be recommended for asingle episode of VT in the absence of arrhythmogenic substrate (> 1% PVCs, any PVC pairing);the aviator must also undergo monitored centrifuge testing at the initial ACS evaluation. Aviatorsevaluated for VT at the ACS undergo yearly re-evaluation for two years, then re-evaluation atthree year intervals. Current VT recommendations are based on the 1995 Surgeon General VTStudy Group review and analysis.
Short PR Interval Patterns. Wolff-Parkinson-White (WPW) ECG pattern is the most
common example. It is disqualifying for flight training but may be waived for trained aviators as aserial change. Waiver is usually recommended if an ACS evaluation reveals no WPW syndrome(i.e. tachyarrhythmias) or other evidence of organic heart disease. The evaluation may includemonitored centrifuge testing if the aviator flies high performance aircraft. Cardiac catheterizationis generally not included if noninvasive studies are normal. A short PR interval on ECG without aclear delta wave is evaluated locally. The aviator is interviewed for any prior history, eitherdocumented or subjective, suspicious for tachyarrhythmia. If there is no prior history oftachyarrhythmia the pattern is considered waiverable. If there is documentation or suspicion of any tachyarrhythmia then the aviator is referred to the ACS for aeromedical recommendation anddisposition. Waived aviators are re-evaluated at the ACS every three years.
Hypertension
Since hypertension rarely begins before the fourth of fifth decade, and thus would seldom bedetected in the pilot applicant, the prevalence of this disease in the aviator population (10-20%) issignificant, and only slightly lower than the U.S. adult population (17-28%). The difference isprobably due to the increased prevalence of hypertension with increasing age and weight. Theaeromedical concerns are the potential for sudden incapacitation due to stroke or myocardialischemia and the overall increased mortality and morbidity associated with hypertension due toCAD, congestive heart failure and renal failure.
Detecting hypertension in the aviator, as in any other patient, requires blood pressure (BP)measurement in both arms with the proper sized cuff and the patient seated. According to AFI48-123, atch 6, 15 Nov 94, an aviator is hypertensive if a 5-day BP check averages a systolic BPof greater than 140 mm Hg or a diastolic BP greater than 90 mm Hg. As long as the averagesystolic pressure does not exceed 160 mm Hg, and the average diastolic pressure does not exceed100 mg Hg, the aviator may remain on flying status with a 6-month trial of nonpharmacologicmanagement. If the average systolic BP is greater than 160 mm Hg, or diastolic BP is greaterthan 100 mm Hg, the aviator is disqualified from flying duties. This aviator, as well as one whofails nonpharmacologic management, should be started on medication and a waiver requestsubmitted if adequate control is achieved with approved drugs.
Treatment of Hypertension. The six-month trial of nonpharmacologic management in certain
aviators may include the following measures: weight reduction; sodium restriction; moderation ofalcohol intake; regular aerobic exercise; and relaxation therapy and biofeedback. It is estimatedthat 25% of patients with mild hypertension can be managed with nonpharmacologic means. Ifthe aviator fails nonpharmacologic treatment, or has a blood pressure elevation precluding such atrial, he should be grounded and begun on pharmacotherapy. The only antihypertensive agentswhich may be approved for MAJCOM waiver in the USAF are the thiazide diuretics,chlorothiazide or hydrochlorothiazide, although triamterene may be used in combination for itspotassium-sparing effect. The U.S. Army has also approved prazosin and captopril for use byArmy aviators. Most aviators can be controlled by diuretics and nonpharmacologic means, andthe side effect profile is low; dyslipidemia resulting from thiazides appears to be clinicallyinsignificant, and generally disappears within a year anyway. Some however are not wellcontrolled by these means. If an Air Force aviator fails thiazides, he may be considered for ACEinhibitor therapy in consultation with the ACS. In that case, he should be continued (or placedback) on DNIF status, and begun on lisinopril. If he tolerates the drug without significant sideeffects, he should be referred to the ACS for evaluation and possible waiver.
METABOLIC PROBLEMS
Diabetes Mellitus and Glucose Intolerance
The currently recognized criteria for the diagnosis of diabetes mellitus is that established bythe National Diabetes Data Group. The diagnosis of diabetes mellitus is made if the patient has:(a) classic symptoms and unequivocal hyperglycemia; (b) a fasting plasma glucose of 140 mg/dl ormore, on more than one occasion; or (c) a fasting plasma glucose of less than 140 mg/dl but anabnormal response to the oral glucose tolerance test (200 mg/dl or greater at two hours, and atsome other time between 0-2 hours). Patients with either (a) or (b) above do not require an oralglucose tolerance test to make the diagnosis of diabetes mellitus. If the initial diagnosis is madeby an oral glucose tolerance test (OGTT) it should be a standard test with a 75 gram loading doseof glucose and blood sugar measurements every half hour for two hours. It is very important toproperly administer the OGTT. Many other factors other than diabetes can cause an abnormalglucose tolerance such as inadequate physical activity or carbohydrate intake, and eitherinadequate or prolonged fasting prior to the OGTT. Also, illness, trauma and drugs such asthiazide diuretics may cause an abnormal response.
Aeromedically, the concerns of diabetes are hyper- and hypoglycemia, and neurological, renal, cardiovascular and visual complications. There also exists the possibility that the condition maybe exacerbated by uncontrolled diet, chronic fatigue or other conditions encountered duringdeployment.
A Flying Class IIC waiver is possible if the diabetes is controlled by diet alone and there areno sequelae. Otherwise, patients with diabetes mellitus are disqualified. To apply for waiver, aninternal medicine consultation is required. An MEB is not required for diet controlled diabetics.
The initial waiver request should include at least three fasting blood sugar results <140 mg/dl,three measurements <175 mg/dl taken two hours after a meal, one measurement of glycosylatedhemoglobin taken at least three months after control has been established and one measurementfor islet cell antibody. Fasting blood sugar and glycosylated hemoglobin determinations should beobtained at least every six months in follow-up. For waiver renewal this data, as well asophthalmologic and neurologic consultations, should be supplied with the package. Again, diet isthe only treatment compatible with flying; the use of insulin or oral hypoglycemic agents isdisqualifying without waiver. (AFPAM 48-132) Hyperlipidemia
Hyperlipidemia has aeromedical significance because of the increased risk of developingcoronary artery disease (CAD) and because risk modification measures can reduce that risk.
Elevated total cholesterol, elevated LDL cholesterol and reduced HDL cholesterol have all beenshown to be independent risk factors for the development of CAD. The ratio of total cholesterolto HDL cholesterol has also been shown to be a sensitive predictor of CAD risk and is convenientbecause it incorporates two of the above three predictors. In a series of aviators undergoing angiography at the Aeromedical Consultation Service for an abnormal treadmill test, 64% of thosewith a ratio greater than 6.0 had CAD while only 2% of those with a ratio less than 6.0 had CAD.
HDL cholesterol is normally 20-25% of total plasma cholesterol level and is independent ofage in adult life. Increased intake of dietary cholesterol and saturated fats decreases HDLcholesterol, as does smoking. Aerobic exercise and moderate alcohol intake increase HDLcholesterol. Therefore, risk modification measures for an aviator with elevated total serumcholesterol or total cholesterol/HDL cholesterol ratio include smoking cessation, lowered intakeof cholesterol and saturated fats, weight loss to achieve ideal body weight and a graduated aerobicexercise program tailored to the individual. Prescribing moderate alcohol intake to increase HDLcholesterol levels has not been shown to have a CAD risk reduction benefit. Drug therapy may beconsidered if diet and other nonpharmacologic methods are not effective to achieve the targetgoal. Although criticized for being too aggressive, the National Cholesterol Education Program(NCEP) recommendations (JAMA, 16 Jun 93, Vol 269, p 3015-3023) contain very organized andsystematic algorithms to direct nonpharmacologic and pharmacologic therapy. Additionally, theNCEP recommendations incorporate total cholesterol, HDL cholesterol and LDL cholesterol intheir scheme. Currently, cholestyramine and colestipol are approved for use in aviators with aFlying Class II or unrestricted waiver. Lovastatin and gemfibrozil are approved for categorical ornonhigh performance flying waiver (IIA/IIIA). Niacin is not approved for use in rated aviators.
Choice of medication should be guided by the aviator's overall lipid profile and actions of theindividual medication. For instance, cholestyramine tends to elevate triglyceride levels and wouldbe an inappropriate choice in an aviator with already elevated triglyceride levels.
Hypercholesterolemia alone may be disqualifying for entry into flying training. AFI 48-123,15 Nov 94, has much simpler disqualifying criteria for elevated lipids than the previous AFR 160-43. Section A6 states that the following criteria are disqualifying for Flying Class I/IA: totalcholesterol level greater than 300 mg % confirmed by repeat determination or HDL cholesterollevel less than or equal to 15% of the total cholesterol level in the presence of a total cholesterolgreater than 230 mg %, again confirmed by repeat determination. Abnormal lipid profile alone isnot disqualifying for rated aviators, however. According to Section A6, the following criteria arecause to send an ECG and aeromedical summary to MAJCOM/SG and to the AeromedicalConsultation Service for further recommendations: a) total cholesterol greater than 300 mg %,confirmed by repeat determination, or b) total cholesterol between 230-300 mg % andcholesterol/HDL ratio greater than 6 or LDL cholesterol greater than 160 mg % confirmed byrepeat determination or c) abnormal lipid profile with concerning risk factors.
PULMONARY PROBLEMS
Symptomatic pulmonary disease is rare in aviators. Occasionally, pulmonary problems inaviators are detected by abnormal pulmonary function tests (PFT). Aeromedically, abnormalPFTs alone are not disqualifying but the aviator must be thoroughly evaluated.
Chronic obstructive pulmonary disease (COPD)
This includes both chronic bronchitis and emphysema. COPD is disqualifying for initial flighttraining, but may be waived for Flying Class II or III after careful evaluation if the aviator isasymptomatic or has only minimal symptoms, has no evidence of reactivity, and requires nomedication. Smoking cessation is essential. Bullous emphysema is disqualifying because of therisk of rupture and pneumothorax at altitude.
Reactive Airway Disease
Asthma or a prior history of asthma is disqualifying for flying training. It is also disqualifyingas a new condition in rated aviators because it can be adversely affected by many stressors in theaviation environment such as cold dry air, smoke and fumes, pressure breathing, exertion, andpossibly high +Gz. No medications for treatment of asthma are currently authorized for use byUSAF aviators.
Sarcoidosis
This systemic granulomatous disease of unknown etiology usually is detected in a healthy,asymptomatic aviator with the finding of bilateral hilar lymphadenopathy on chest x-ray performedfor other reasons. Occasionally, the aviator presents with cough, wheezing, fever, malaise,mucoid sputum production, and/or weight loss. About 80% of patients presenting in this wayhave complete resolution of the findings within 2-5 years, usually with the chest x-ray clearingwithin 6-24 months. About 5-10% of patients go on to develop severe chronic disease withpulmonary insufficiency and cor pulmonale. The main aeromedical concern is possible cardiacgranulomata which have been associated with bundle branch blocks, AV dissociation, ectopy,paroxysmal tachyarrhythmias, coronary artery compression, and sudden death. An aviatorpresenting with an abnormal chest x-ray or symptoms as above requires a thorough evaluation torule out other disorders, and to rule out significant visceral involvement. The aviator is groundedand referred to an internist, or preferably a pulmonologist if available. The evaluation shouldinclude LFTs, PFTs and Holter monitor, as well as an appropriate biopsy to establish thediagnosis. Acceptable biopsy sites include conjunctiva, tail of the parotid gland, and the lung, inincreasing order of invasiveness but also increasing order of yield. If the local evaluation showsno abnormality (except compatible histopathology on the biopsy) a FC II waiver is recommended,with reevaluation every two years unless symptoms arise sooner. If there is evidence ofinvolvement of the myocardium or nervous system, or evidence of significant disease of any otherviscera (e.g. restrictive lung disease, granulomatous hepatitis) the aviator is disqualified.
GASTROINTESTINAL AND GENITOURINARY PROBLEMS
Gastrointestinal Hemorrhage
Gastrointestinal hemorrhage is disqualifying, but waiverable if a specific treatable andnonpersistent cause is clearly identified. Waiver may be granted for single or recurrentuncomplicated gastric or duodenal ulcers that (a) are subsequently asymptomatic for six monthswith negative monthly hemoccults, (b) heal completely in the expected treatment period, and (c)require no maintenance medication, specialized diets or meal patterns. Diagnosis and response totreatment must be confirmed by radiographic techniques and/or endoscopic studies with additionalprocedures (biopsy, culture or cytology) as indicated. Ulcers which require surgical treatmentmay be waived if the procedure is definitive, and the aviator requires no adjunctive medications oroccupational restrictions as defined by aeromedical standards. Preventive lifestyle changes, suchas avoidance of NSAIDs, alcohol, tobacco, and coffee (both regular and decaffeinated) arestrongly encouraged.
Renal Stones
The aeromedical importance of stones is twofold. The abrupt onset of incapacitating paincould be very hazardous in flight, especially in a single-seat aircraft. Also, prolonged flights andhot environments increase the problem of dehydration associated with stones.
Aviators may present either symptomatically or with stones found incidentally on x-ray. Theaeromedical evaluation includes an excretory urogram to localize the stone and rule out anycongenital or acquired anomaly, renal function studies, and a metabolic workup with 24-hoururine calcium, uric acid, oxalate and cysteine levels. Single or recurrent attacks of renal colic maybe waived if the stone or stones have passed, and if the above evaluation is normal. Aviators withretained stones must be evaluated by a urologist. The aeromedical decision depends on thelocation of the stone, its potential for movement, and on whether the aviator is a candidate for anyprocedure to remove the stone such as endoscopic manipulation, lithotripsy, or surgery. Anaviator is usually qualified for unconditional flying (FC II or III) if the retained stone isparenchymal or is in a calyceal diverticulum and is larger than the diverticulum neck, and if themetabolic and renal evaluations are normal. A categorical (IIA or IIIA) waiver is given if thestone is in the papillary duct or any more distal part of the collecting system, and the renal andmetabolic evaluations are normal.
AEROMEDICAL MANAGEMENT OF FLYING PERSONNEL WITH NEOPLASMS
Therapeutic advances in medical and surgical oncology have cured or returned to their pre-illness levels of function a select group of military aviators. This has provided theopportunity to utilize the investment/experience of these aviators by returning them to flyingstatus when appropriate. The process of returning an aviator with a neoplasm to flying statususually involves multiple specialists, sometimes in multiple hospitals and orchestrated by severalflight medicine services.
Actions to take at the time of diagnosis
Take the individual off flying status.
Discuss with the primary physician managing the aviator’s care, what are the prospects for cure and/or functional recovery. (Wilford Hall pathology staff, specifically the Chairman, Col.
Drehner or Maj. Stokes at DSN 554-7741 are always available to answer any questions.) Prognosis is favorable or uncertain as to return to flying duties. Discuss with the
aviator’s oncologist the need for baseline studies. The list of toxicities associated with varioustherapies is long. Depending on the agents being utilized in the aviator’s therapy, baseline studiesshould be done to document pre-treatment status. Some treatment regimens, in addition tophysical toxicities, have significant risk of residual neuro-psychological problems. For examplethere is a report of a high rate of neuropsychiatric complications, over 50%, in patientsundergoing bone marrow transplantation. This risk became an issue in evaluating a pilot of a highperformance aircraft for return to flying status after allogeneic bone marrow transplant for chronicmyelogenous leukemia (David DG, Patchell RA. Neurologic complications of bone marrowtrans-plantation. Neurologic Clinics 1988; 6:377-387). The absence of baseline studiescomplicated the waiver process for that individual.
Maintain contact with the aviator in the treatment phase. It is important for the aviator and physician. The illness removes the aviator - patient from his profession and his sense of selfworth. Continued interaction with the unit flight surgeon and other squadron members isconcrete evidence of the promise of a good prognosis. For the flight surgeon it is perceived as akey measure of competence by the squadron. In the maelstrom of activities filling your day, it isdifficult to make time for these patients. If their care is being provided outside the immediate areaof your facility maintain contact by phone.
Participate in the tumor board where the aviator’s treatment plan is discussed. Not only do you help the board by providing the aeromedical perspective but you become identified as theperson to whom information about the patient’s care should go. This smoothes the later waiverprocess.
When the aviator is disqualified from flying status continue to be sensitive to his family’s medical needs. Aviators with some malignancies may be disqualified for several years. Whiletheir care should revert to the other clinical services of your MTF, consider how you would wantyour family to be treated. Shifting of patient care responsibility can be perceived negatively bythe squadron. Your credibility as a physician can be lost by mistakes in this area.
Insure the patient’s outpatient record contains relevant summaries of hospitalizations, surgeries and treatments. It’s not your responsibility. However, if you correct deficiencies in thedatabase at this time you’ll recoup your investment when you put the waiver package together.
Prognosis is unfavorable for return to flying status and/or recovery. This is the reason
you are a physician. Sensitivity to the needs of the aviator and his family should be a paramountconcern to you. There is no school solution to this problem. Find out what you can do to helpand do it.
Obtaining a waiver - returning the cured
AFPAM 48-132 is necessary reading before preparing a waiver request. For most common and many uncommon neoplasms it details the USAF experience. It tells you how longaviators characteristically are disqualified from flying duties for the various malignancies covered.
Squadron Leader Michael Gibson, the RAF Exchange officer with the USAF Surgeon General’soffice, recently completed this insightful document. The Surgeon General’s Office has the waiverauthority for malignancies.
Components of a waiver package
1. Current aeromedical summary and physical exam. In the aeromedical summary include the type(s) of aircraft the aviator flew, number of hours, summary of treatment, any residua andhis functional status. A current physical is helpful. Using a physical from before diagnosis of themalignancy is suspect particularly in malignancies requiring treatments with systemic effects. Inthe aeromedical summary address the functional status of the aviator in light of the demands of hislikely subsequent assignments. Can the aviator perform adequately in a deployment or wartimeenvironment? 2. If the therapy entailed treatments with documented increased risks of side effects of aeromedical import studies should be done to document adequate function for aviation duties. Forexample, adriamycin, a chemotherapeutic agent has been associated with cardiac damage. Athallium scan may be indicated to rule out this effect.
3. Secure a tumor board evaluation. A flight surgeon should be a member of the tumor board. Send an aeromedical summary with the tumor board request. The information in theaeromedical summary about the aviators functional status and likely assignments is keyinformation for the members of the tumor board. Before the case is sent to the tumor boardcheck whether the diagnostic pathology specimen(s) was reviewed by the Armed Forces Instituteof Pathology for their concurrence in the diagnosis. This is mandated by Air Force Regulations,except in the case of Basal Cell and non-invasive squamous cell cancers. Carefully review the tumor board recommendations. Sometimes hospital based physicians are unaware that arequirement for follow-up every three months would remove the aviator from mobility position.
4. Discuss the case with both your command surgeon and the waiver section at the Surgeon General’s Office. Your objective is to get their input about any tests or consultationsthey may require for evaluation of the package.
After the waiver
It is a good idea for the aviator to retain copies of certain key components of his medical record. These include: a record of any surgeries done as part of his/her treatment; a copy of thediagnostic surgical pathology report and if possible a copy of the glass slides; copies of key x-raysand other diagnostic studies, and a summary of therapies.
Finally, be vigilant in screening for complications of therapy and relapse.
REFERENCES
1. AFR 160-43. Medical Examination and Medical Standards.
2. DeHart RL. Fundamentals of Aerospace Medicine. Lea and Febiger. Philadelphia: 1985.
3. Hickman JR. Noninvasive methods for the detection of coronary artery disease in aviators - astratified Bayesian approach. AGARD Report No. 758, pp 2-1 to 2-11, 1987.
4. Hickman JR. Aeromedical aspects of mitral valve prolapse. AGARD Report No. 758, pp 4-1to 4-7, 1987.
5. Hickman JR. Coronary risk factors in aerospace medicine. AGARD Report No. 758, pp 10-1to 10-8, 1987.
6. Hull DH. Aeromedical disposition of pulmonary sarcoidosis, chronic obstructive lung disease,reactive airway disease and spontaneous pneumothorax. AGARD Report No. 758, pp 7-1 to 7-5,1987.
7. Kaplan NM. Nonpharmacologic therapy of hypertension. Medical Clinics of North America1987;71(5):921-933.
8. Kruyer WB. Aeromedical evaluation and disposition of electrocardiographic abnormalities.
AGARD Report No. 758, pp 1-1 to 1-8, 1987.
9. Kruyer WB, Schwartz RS. Valvular and congenital heart disease in the aviator. AGARDReport No, 758, pp 3-1 to 3-12, 1987.
10. Kruyer WB. Hypertension in the aviator. AGARD Report No. 758, pp 9-1 to 9- 3, 1987.
11. Moser M. Diuretics in the management of hypertension. Medical Clinics of North America.
1987;71(5):935-945.
12. National Diabetes Data Group. Classification and diagnosis of diabetes mellitus and othercategories of glucose intolerance. Diabetes. 1979;28:1039- 1057.
13. Wyngaarden JB, Smith LH, Jr. (Eds). Cecil's Textbook of Medicine. 17th ed, WB SaundersCo, Philadelphia: 1985.

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