The practice of Internal Medicine in the operational environment is limited by the availability of specialized testing, imaging studies, medications and personnel.  You will not have a Cardiologist, Gastroenterologist, Endocrinologist etc. at your disposal.  In many areas you may not even have a General Internist, especially while underway.  While these limitations may prevent administering the latest antibiotic or most up to date screening laboratory study, they do not hinder the practice of good preventative medicine and application of good internal medicine principles.

Aerospace medicine is not a subset of Internal Medicine.  Rather, it is an environment in which we must learn to adapt what we know about the physiologic changes associated with aviation and apply that knowledge to the care of our patients. Because certain conditions may manifest in an atypical or unpredictable fashion in the aviation environment when compared to the same condition on the ground we have adopted a separate set of acceptable standards for aviation.  These standards are too broad to cover in this arena, however they may be accessed on the NOMI home page on the World Wide Web at http://www.nomi.navy.mil under the Aeromedical Reference and Waiver Guide icon.  These standards are constantly being updated as new information or experience becomes available.  If more current information is needed or the information you need is not covered in the guide then you can contact NAMI Internal Medicine at code243@nomi.med.navy.mil or DSN 922-2257 ext 1022 for up to date information on Internal Medicine topics.

While it would be unrealistic to attempt to cover all of Internal Medicine in this arena, there are certain common conditions that should be addressed as they pertain to Aerospace Medicine.  This is not a treatment guide for acute medical problems rather it is a list of disorders that may be incompatible with continued aviation duties though not necessarily with continued general duty and deployability. 

For acute treatment issues you may want to keep the number of the local clinic Internist available as part of your deployment information.  That includes getting the numbers for a local medical point of contact at your deployment sites.  For emergency treatment you will want to use pre-established protocols such as ACLS or ATLS to stabilize patients prior to making any long term dispositions. The Virtual Naval Hospital at www.vnh.org is an invaluable source of diagnostic and treatment information that is maintained and updated regularly.  It can be used by both providers and patients and can be accessed 24 hours a day.

There are some very general guidelines that can be applied to the disposition of patients in regards to Aerospace Medicine.  If a patient needs a medication either the medication, the condition for which they are taking it or both are likely to be disqualifying.  Do not let that stop you from treating a patient with a clinically indicated therapeutic intervention.  Treat first; worry about flight status later.  When in doubt, issue a grounding notice (NAVMED 6410/1, a “down chit”).  This can be given by any medical department personnel authorized to see and treat patients.  Contact the closest Flight Surgeon later to issue an aeromedical clearance notice (NAVMED 6410/2, an “up-chit”) when appropriate.  Just because a member is taking a disqualifying medication or has a disqualifying condition doesn’t mean they can not be waived. You do not need a diagnosis to ground a patient, just a set of symptoms that, in your opinion, may have a negative effect on safety of flight.  Once grounded a Flight Surgeon can evaluate later to determine when a clearance notice can be issued.  The Flight Surgeons are there to make that type of decision. If more assistance is needed then either you or the Flight Surgeon can contact NAMI for information.  The NOMI web site above has a list of web addresses to various clinics, including internal medicine, and to the standards section, code 42 (BUMED 236) where questions about a specific patient or condition can be answered.

The following topics are discussed briefly as examples of either common or serious conditions where the treatment and standards may vary from non-aviation personnel.

Hypertension:

HTN is defined as BP >139 systolic and/or 89 diastolic.  The Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure from Nov 1997 (JNC VI) provides guidelines for hypertension diagnosis and treatment. The results of JNC VI are available on line at www.nhlbi.nih.gov under the clinical guideline section.

From an aeromedical standpoint there are several important differences to remember when treating an aviator with HTN.  First, BP out of standards is disqualifying.  A three month trial of diet, exercise and lifestyle modifications are permitted if BP <150/100.  After three months the patient is grounded until BP back within standards.  Second, ACE inhibitors are considered first line medications for aviation secondary to their side effect profile.  HCTZ is also permitted on case by case basis.  Angiotensin receptor blockers are allowable in patients intolerant to ACE inhibitors secondary to cough.  Amlodipine has recently been approved for non-high performance aircraft in patients who fail other approved therapy but may have service group restrictions as well.  Beta-blockers are severely restricted secondary to decreased “G” tolerance and consultation with NAMI is recommended before placing patient on beta-blocker therapy.  Centrally acting anti-hypertensives are never approved for aviation duties. Remember to evaluate for secondary HTN in very young patients and in patients who fail to respond to therapy.  Uncontrolled HTN is permanently grounding though mildly elevated HTN will not limit general duty or deployment status.

Diabetes Mellitus:

Diabetes is a common medical condition and is not infrequently diagnosed by the GMO or IDC who recognizes the traditional triad of polyuria, polydypsia, and polyphagia coupled with possible weight loss and blurred vision.  When a patient presents with all of these the diagnosis is straightforward and easily confirmed with a fasting glucose level.  Diabetes is too complicated to adequately review here.  These are just a few reminders when treating a patient with DM. First, once you have made the diagnosis make sure the patient gets properly educated and learns to check finger stick blood glucose levels, control their diet and recognize symptoms of hypo and hyperglycemia.  Second, make sure patients are referred at the earliest possible time for Internal Medicine or Family Practice evaluation.  Lastly, Diabetes is a serious disease with a myriad of complications, both acute and chronic.  The most important aspect of treating a diabetic is obtaining adequate blood sugar control to help prevent or post pone these complications.

For aviation, only diet and exercise control is permitted for pilots.  Other aviation personnel (NFO’s, aircrew, air traffic controllers, etc.) may use metformin to control blood sugars along with diet and exercise.  All diabetics are disqualified but if good control as demonstrated by Hgb A1C <7.5 and FBS <126 then a waiver may be possible.  Only Type II Diabetes is considered for a waiver.  Type I Diabetes generally requires a medical board as these patients are at higher risk for sudden incapacitation from diabetic ketoacidosis.

Anemia:

Anemia is a sign of some other underlying condition (blood loss, hemolysis, bone marrow malfunction, malabsorption).  The presentation varies from incidental discovery during blood draw for some other evaluation (physical exam) to acute incapacitation from rapid blood loss.  Again, the emphasis here is not to explain how to evaluate all anemias but to stress the difference in standards in the aviation environment.  Anemia will decrease a patient’s ability to endure high altitudes and relative hypoxia.  It may also decrease “G” tolerance.  The standards for acceptable hemoglobin in aviation are therefore slightly higher than most laboratory normals.  The most important aspect of evaluating anemia is to not ignore an incidentally discovered low hemoglobin or hematocrit.  The Virtual Naval Hospital can be used as a guide to further evaluation. For aviation, patients with anemia out of aviation standards will only be waived if they have no symptoms and an adequate evaluation has ruled out any significant underlying pathology.

GERD:

Gastroesophageal reflux disease (GERD) is a common condition affecting as much as 18% of the US adult population on a weekly basis.  Most patients have only mild “heartburn” that resolves either spontaneously or with over the counter antacids.  Patients who fit into this category are not likely to come to the attention of a medical professional.  The patients you will see are either presenting with atypical symptoms or have been unable to control their symptoms on their own. 

From an aviation perspective, patients requiring medication that must be prescribed to control their GERD are disqualified.  Use of H-2 blockers or proton pump inhibitors (PPI) may be compatible with continued flying duties but will require a waiver.  There are several concerns with GERD from an aviation perspective.  Anemia from GI bleed, acute pain and worsening symptoms in high “G” environment or in low ambient pressure are all potential problems.  Weight loss, dysphagia or odynophagia, extra-esophageal symptoms or symptoms that recur or persist on therapy are all cause for GI referral.  Patients should be treated as conservatively as possible progressing through a treatment algorithm that starts with lifestyle modification plus as needed over the counter antacids, then adds H-2 blockers first at standard dose then at double dose and finally uses PPI as a last medical therapy.  Patients requiring PPI use need a GI referral.

Reactive Airway Disease:

Reactive Airway Disease (RAD) is a condition that is extremely common in the general population. There are many ways to classify RAD but the unifying factor is that it is a progressive inflammatory condition that tends to worsen in time if not adequately treated.   Clinical asthma is the manifestation of RAD under various circumstances such as post exercise or post irritant exposure.  People with asthma have reactive airways; not all people with reactive airways have clinical asthma. 

Regardless of whether a patient has clinical asthma or sub-clinical RAD, they are disqualified from aviation duty.  The potential for sudden acute incapacitation is too great, especially in the aviation environment where respiratory irritants are abundant, to permit patients with RAD to fly.  The National Heart Lung and Blood Institute at the NIH publishes a guideline for diagnosing and treating asthma.  It can be accessed at www.nhlbi.niv.gov under the clinical guideline section.  Only those patients diagnosed with mild asthma (mild intermittent or mild persistent) per these guidelines will be considered for a waiver.  Candidates will not be considered and designated personnel need to be under excellent control and on approved medication prior to waiver consideration.  Consult the NOMI homepage or your local Flight Surgeon for acceptable medications. These may change as new therapies become available.   

Cardiovascular Disease:

The number of different cardiovascular diseases that may present a potential problem in aviation is too great to expound upon here.  Some general concepts however do apply both here and in any medical condition.  Symptomatic disease is disqualifying, whether it is CAD, valvular disease or arrhythmias. 

CAD will be unusual in the young active duty population but must not be overlooked, especially in patients with risk factors (males >45, females>55, family history of CAD in first degree male <55 or first degree female <65, HTN, DM, Tobacco use, HDL <35). Since most of the active duty population will not be diagnosed unless symptomatic they would be disqualified from aviation.  These cases are generally handled individually by referral to NOMI through the Flight Surgeon. 

Symptomatic valvular heart disease is also disqualifying.  MVP and AS are particularly worrisome in aviation since high “ G” forces will hasten the progression of these conditions.  Even asymptomatic valvular disease, once discovered, is disqualifying though certain conditions may be waived with restrictions on aircraft type or service group depending on the condition. 

Arrhythmias presenting with any symptoms are disqualifying.  As a GMO or IDC the most important role you play in patients with arrhythmias is detecting an abnormality and administering appropriate interventions.  Do not concern yourself with aviation disposition when treating arrhythmias.  Fix the problem first; let the Flight Surgeon worry about the disposition later.  It is usually a safe decision to ground a patient with a suspected arrhythmia or conduction disturbance until confirmed as any arrhythmia is potentially life threatening in the aviation environment. 

It is not unusual to detect an asymptomatic ECG abnormality during routine physical or when ECG is done for some other purpose such as before an elective surgical procedure.  Again, if any doubt ground the patient until the severity of the condition can be sorted out.  For designated personnel it is likely that they have already had an ECG upon entry into aviation duty.  Compare the findings to their old ECG and see if there is any difference.  If the abnormality is the same look to see if there is evidence of it being evaluated (Internal Medicine or Cardiology consult, Echo reports, Holter monitors, Treadmill testing). If previously evaluated and clear disposition has been made then do not re-evaluate for the same condition unless there have been clinical changes.  If no evidence of previous evaluation refer the patient to your Flight Surgeon.

In summary, the scope of Internal Medicine problems that are affected by the aviation environment is extremely broad.  The topics discussed here are representative of common or serious conditions.  They are in no way intended to be all-inclusive.  Treatment for emergencies should be based on pre-arranged protocols.  Aviation disposition can always be deferred until you can contact a Flight Surgeon or NAMI directly.  When in doubt, ground a patient whose condition, symptoms or therapy poses a potential significant threat to aviation safety. 

WEBSITES:

The web sites and e-mail addresses listed below are all mentioned in the preceding text.  They are just some helpful sites for both diagnosis, treatment and aviation dispositions to help guide you as you care for patients in flight status.

 This section was contributed by LCDR Paul Kane, MC, USN (FS).

Home  ·  Military Medicine  ·  Sick Call  ·  Basic Exams  ·  Medical Procedures  ·  Lab and X-ray  ·  The Pharmacy  ·  The Library  ·  Equipment  ·  Patient Transport  ·  Medical Force Protection  ·  Operational Safety  ·  Operational Settings  ·  Special Operations  ·  Humanitarian Missions  ·  Instructions/Orders  ·  Other Agencies  ·  Video Gallery  ·  Phone Consultation  ·  Forms  ·  Web Links  ·  Acknowledgements  ·  Help  ·  Feedback  · 

This web version is brought to you by The Brookside Associates Medical Education Division   ·  Other Brookside Products  ·  Contact Us