Question of the Day

The Aerospace Medical Association is dedicated to the science of Aerospace Medicine.  The following questions and answers offer those interested in Aerospace Medicine activities the opportunity to test and expand your Aerospace Medicine knowledge.

Question: Which of the following is NOT included in an examination of the sensorium?

a. Orientation to time, place, and person
b. Retention of three unrelated memory items for five minutes
c. General knowledge
d. Depressed or elated mood
e. Proverb interpretation: concrete or abstract.
Answer: d. Evaluation of the mood, and the appropriateness of the patient's affect (emotional reaction) to material being discussed during the interview, is an important part of the mental status evaluation (MSE). Evaluation of the sensorium is concerned with orientation, recall, retention, memory (short and long-term), calculations, intelligence, ability to abstract, judgment, and insight. Although neurotic or psychotic processes may affect the sensorium, serious deficits are more likely to be associated with organic pathologic processes affecting the brain. REFERENCES: American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, 2nd ed. Washington DC: American Psychiatric Assoc, 1968:92. Jacobs JW, et al. Screening for Organic Mental Syndromes in the Medically Ill. Ann Int Med 1977;86:40-46.

Question: Limited resources demand the assessment of the prevention effectiveness of health interventions such as screening programs. Cost-effectiveness analysis is one method of assessing prevention effectiveness. Which of the following best describes cost-effectiveness analysis?

a. A type of economic analysis in which all costs and benefits are converted into dollar values and the results are expressed as the net present value of the dollars of benefit per dollars expended.
b. An economic analysis in which all costs are related to a single, common effect. Results are usually stated as additional cost expended per additional health outcome achieved.
c. An explicit, quantitative, systematic approach to decision making under terms of uncertainty.
d. An iterative consensus process used to determine the "best estimate" of professionals in the field.
e. A method of measuring the value an individual places on reducing risk of death or illness by estimating the maximum dollar amount an individual would pay in a given risk-reducing situation.
Answer: b. In cost-effectiveness analysis, no attempt is made to assign a monetary value to health outcomes. Instead of dollars, other measures of outcomes are chosen that is relevant to the question being studied (e.g. number of deaths prevented). Answer (a) is the definition for cost-utility analysis. Answer (c) describes decision analysis while answer (d) defines the Delphi process. Willingness-to-pay is defined by answer (e). REFERENCES: Haddix AE, Teutsch SM, Shaffer PA, Dunet DO. Prevention Effectiveness. New York: Oxford University Press, 1996.

Question: Which of the following is the most important environmental risk factor for the development of chronic obstructive pulmonary disease (COPD)?

a. Alpha-1-antitrypsin deficiency
b. Airway hyperresponsiveness
c. Smoking
d. Occupational exposures
e. Ambient air pollution
Answer: c. Cigarette smoking accounts for the vast majority of COPD in the United States. Severe alpha-1-antitrypsin deficiency is a significant genetic risk for the development of COPD. Ambient air pollution, a number of occupational exposures (cadmium, gold dust, coal dust) and passive exposure to tobacco smoke have been shown to be independent risk factors for the development of COPD, but none approaches the level of risk associated with active cigarette smoking. REFERENCES: Silverman EK, Speizer FE. Risk Factors for the Development of Chronic Obstructive Pulmonary Disease. Med Clin N Am 1996;80(3):501-522.

Question: Which of the following organisms is considered the prime indicator of fecal contamination of water?

a. Escherichia coli
b. Aerobacter aerogenes
c. Clostridium perfringens
d. Chrenothrix
e. Nitrosomonas
Answer: a. The coliform organism is the indicator of fecal contamination in lieu of other pathogens because of the relative numbers involved. While only a few pathogens may be present in the feces of warm blooded animals, there are billions of coliforms. Therefore the presence of this organism gives presumptive evidence of contamination and a high probability of recovery on a sample medium. Further advantages of the coliform group are (1) relative safety during analysis, (2) ease of analysis, and (3) similar survival times as pathogens. REFERENCES: American Waterworks Assn. Water Quality and Treatment. New York: McGraw-Hill, 1971.

Question: Which of the following statements about dust deposition and clearance from the lungs is true?

a. The size of dust particles in the inspired air is immaterial: deposition of particles occurs in random fashion throughout the respiratory system.
b. Dust particles over 20 microns in size are most likely to cause alveolar disease.
c. Dust particles between 0.5 and 5.0 microns are most likely to be harmful to the lung and are consequently most significant in production of pneumoconioses.
d. Dust particles below 0.5 micron in size are most harmful to the lung since they penetrate further into the respiratory passages and are primarily deposited in the alveoli.
Answer: c. Most inhaled particles are deposited on the walls of the respiratory dead space long before the respiratory bronchiole is reached. Nearly all particles of 20 microns and over come into contact with the walls of the bronchi and are deposited there; they are subsequently delivered into the pharynx by the ciliary mechanism. Particles of under 0.5 microns in diameter tend to remain suspended in the air and deposition is minimal. Particles between 0.5 and 5.0 microns are small enough to resist impingement against the walls of the larger air passages, yet are large enough to settle out into the alveoli in as little as 2 to 3 seconds; they are consequently most harmful. REFERENCES: Morgan WK, Seaton A. Occupational Lung Diseases. Philadelphia: Saunders, 1975:22-23.

Question: Evidenced-based medicine involves integrating current best evidence with clinical expertise, pathophysiological knowledge and patient preferences in making decisions about the care of individual patients. Evidence-based disease management may encourage effective practice and discourage ineffective practice, thereby improving the process of care while optimizing health outcomes and controlling costs. Nevertheless, many concerns exist about disease management programs. Concern(s) regarding this process include:

a. inclusion of too many disciplines to reach an agreement on appropriate care-plans.
b. feeling of an assembly line approach to medicine.
c. poor patient compliance and disruption of continuity in caring for patients.
d. deterioration in clinician's decision-making skills
e. c & d
Answer: e. Three major concerns exist about disease management programs: (1) deterioration in clinician's decision-making skills, and (2) suboptimal patient-provider communication and (3) disruption of the continuity of care. However, population based disease management will never obviate the need for individualization, culturally-competent care, elicitation of patient preferences and shared-decision making. Several studies that have examined the use of the multidisciplinary team approach in disease management to optimize care and measure clinical outcomes and resource management have been encouraging, showing cost reduction and higher patient satisfaction. Further studies will be necessary to determine the continued success of these programs. REFERENCES: Ellrodt G, Cook DJ, Lee J, Cho M, Hunt D, Wingarten S. Evidence-Based Disease Management. JAMA 1997 Nov 26;278(20):1687-1692.

Question: HIV is the leading cause of death for Americans between the ages of:

a. 15-30 years old
b. 20-30 years old
c. 25-35 years old
d. 35-45 years old
e. None of the above.
Answer: e. While HIV/AIDS represented a the leading cause of death in the 25-45 year old demographic in the early to mid-1990s, the advent of antiviral therapies has decreased the number of deaths, placing it behind causes such as accidents, suicide, homicide, and heart disease in the demographics listed. REFERENCES: National Vital Statistics Reports, Vol. 53, No. 17, March 7, 2005

Question: The death rate per 100 million person-miles traveled for motorcycles is more than:

a. 10 times that of cars
b. 25 times that of cars
c. 35 times that of cars
d. 50 times that of cars
e. 75 times that of cars
Answer: c. Motorcycles are a hazardous means of transportation, with the death rate per 100 million person-miles of travel more than 35 times that of cars. Most serious or fatal injuries in motorcyclists involve the head. A large body of literature accumulated over the past decade indicates that helmets reduce but by no means eliminate the risk of head injury. In case studies of hospitalized motorcyclists, the risk of a head injury was 2 to 4 times as high for unhelmeted riders as for those who wore helmets. In a comparison of riders on the same motorcycle, one of whom was helmeted and the other of whom was not, a helmet decreased the risk of fatal head injury by 27%. REFERENCES: Rivera FP, Grossman DC, Cummings P. Injury Prevention: First of Two Parts. N Engl J Med 1997 Aug;337(8):543-548.

Question: The cause of birth defects in children usual is usually unknown. However, prenatal counseling and control of various medical conditions results in considerable reduction in birth defects in selected individuals. All EXCEPT which of the following maternal conditions can be treated prenatally to reduce birth defect rates?

a. Phenylketonuria
b. Diabetes Mellitus
c. Hypothyroidism
d. Folic acid deficiency
e. Hypertension
Answer: e. Hypertension is deleterious to pregnancy, yet not a teratogen. Control of diabetes prior to conception reduces the birth defect rate back to background rates. The teratogenic effect of hyperphenylalaninemia can be avoided by control during pregnancy. Folic acid deficiency is a known factor in neural tube defects. Fetal cretinism can be avoided with thyroid replacement therapy. REFERENCES: Platt LD, et. al. Maternal Phenylketonuria Collaborative Study, Obstetric Aspects, and Outcome: The First 6 Years. Am J Obstet Gynecol 1992:166:1150. Kitzmiller JL, et al. Preconception Care of Diabetes. JAMA 1991;265:731 Czeizel AE, Dudas I. Prevention of the First Occurrence of Neural Tube Defects by Periconceptional Vitamin Supplementation. N Engl J Med 1992;327:1832. Milunsky et al. Multivitamin/Folic Acid Supplementation in Early Pregnancy Reduces the Prevalence of Neural Tube Defects. JAMA 1989;262:2847. Cunningham, et al, eds. William's Obstetrics. Stamford: Appleton and Lange, 1997.

Question: In considering the "dose-response" curve, the following assumptions may be made:

a. The magnitude of the biologic response is a function of the concentration of the agent at the biologic site of action.
b. The concentration at the site of action is a function of the dose administered.
c. The response and the dose are causally related.
d. All of the above are true.
Answer: d. The most fundamental concept in toxicology states that a relationship exists between the dose of an agent and the response that is produced in a biologic system. REFERENCES: Proctor NH, Hughes JP. Chemical Hazards of the Workplace. Philadelphia: Lippincott, 1978:5.

Question: The following statements concerning the use of positive pressure breathing (PPB) for G-protection (PBG) are true EXCEPT:

a. PBG can aggravate arm pain in some seat configurations.
b. PBG can approximately double the duration of G-exposure that a pilot can tolerate.
c. PBG is effective in preventing G-LOC when used without anti-G trousers.
d. Chest counterpressure increases pilot comfort and allows for the use of higher levels of PPB.
Answer: c. The use of PBG without anti-G trousers leads to blood pooling in the extremities and loss of consciousness. It does not prevent G-LOC under these circumstances. REFERENCES: Prior ARJ. Positive Pressure Breathing for G Protection. AGARD AMP Lecture Series on Current Concepts on G-Protection Research and Development, AGARD LS-202.

Question: A 23-year-old male in excellent health flew from sea level to a ski resort at 2,700 m for a week of skiing. He began skiing the day after arrival but as he skied he developed progressive malaise, myalgias, and headache. That evening he noted shortness of breath and later that night developed a cough productive of bloody sputum. On examination the next morning (the second day after arrival) he was found to have a temperature of 38.8C and moist rales were heard diffusely in both lung fields. A chest roentgenogram demonstrated fluffy infiltrates in both lung fields, and a white count was 15,300 with over 85% polymorphonuclear leukocytes. Arterial blood gases on room air demonstrated a PO2 of 82 mm Hg, a PCO2 of 29 mm Hg and a pH of 7.46. What is the most probable diagnosis?

a. Pulmonary infarct with pulmonary edema
b. Bacterial pneumonia
c. High altitude pulmonary edema
d. Congestive heart failure precipitated by exposure to the decreased pO2 at 2,700 m.
Answer: c. High altitude pulmonary edema is seldom seen below 2,500 m but it occurs with increasing frequency with progressively higher altitude exposure. It is more likely to occur in the unacclimatized individual and it has an insidious onset. Symptoms usually begin within 12 to 48 hours after arrival and initially consist of the fatigue, headaches, weakness, nausea and light-headedness as seen in patients with more common acute mountain sickness. The symptoms then progress to include shortness of breath and cough, initially dry but which may then become productive of pink frothy sputum as the pulmonary edema develops. The accompanying elevated temperature and white counts have led to confusion with and treatment for pneumonia or other etiologies for pulmonary edema. In high altitude pulmonary edema, the cornerstone of therapy is immediate descent to a lower altitude. Oxygen and possibly furosemide are adjuncts to the treatment program but do not substitute for descent. Numerous theories have been proposed to explain the development of high altitude pulmonary edema. Hypoxia does cause an increase in pulmonary artery pressure. Patients with high altitude pulmonary edema seem to show more increase in pulmonary artery pressure for a given degree of hypoxia than do individuals resistant to the condition. It has been suggested that, in patients who develop high altitude pulmonary edema, there is associated non-uniform arteriolar vasoconstriction in some areas of the lung fields. This produces excessive blood flow into other portions of the lung with subsequent pulmonary capillary hypertension. The resultant exudation of fluid into the interstitial tissues and alveoli produces the clinical picture of pulmonary edema. Other possible etiologies are provided in the references. REFRENCES: Kleiner JP, Nelson WP. High Altitude Pulmonary Edema: A Rare Disease? JAMA 1975;234(5):491-495. Houston CS. High Altitude Illness: Disease with Protean Manifestations. JAMA 1976;236(19):2193-2195.

Question: A common cause of foodborne illness inflight is due to:

a. delays in serving meals.
b. infected food handlers.
c. contaminated gravies.
d. nonpotable water.
e. improperly cleaned utensils.
Answer: b. Infected food handlers and improper holding temperatures are the two most common causes of foodborne illness inflight. This can be prevented by utilizing an approved inflight kitchen, ensuring a food-handler training program, and conducting periodic inspections. Food should be consumed within four hours of preparation. Most airlines serve meals shortly after takeoff. Although gravy could be a source of contamination, other foods such as roast beef, turkey, and custards, have been implicated. The major airlines of the world today carry only potable water from an approved source. Utensils have not been implicated in inflight food poisoning. REFERENCES: Lathrop GD, Wolfe WH. Role of Aircraft in the Transmission of Disease. In: DeHart RL, ed. Fundamentals of aerospace medicine, 1st ed. Philadelphia: Lea & Febiger, 1985.

Question: In investigating an aircraft accident the investigator should consider a blood CO level as "significant" when it reaches what level?

a. Any level of CO in the blood
b. 2 % saturation
c. 6% saturation
d. 10 % saturation
Answer: d. "The carbon monoxide content of the pilot's blood is a more important consideration, as it reflects the cumulative effect of the toxic gas; however, a poorly done determination may lead to dangerous conclusions. Many "quantitative" tests in the average laboratory cannot differentiate between dangerous blood-CO levels and those levels that the usual smoker exhibits, which could be up to 8% saturation." REFERENCES: Randal HW. Aerospace Medicine, 2nd ed. Baltimore: Williams & Wilkins, 1971: 270. McMeekin RR. Aircraft Accident Investigation. In: DeHart RL, ed. Fundamentals of Aerospace Medicine. Baltimore: Williams & Wilkins, 1996:845-896.

Question: What is a sanitary airport?

a. An airport provided with public rest rooms and pure drinking water.
b. An international airport designated as sanitary by the World Health Organization (WHO).
c. An airport to which the local health authorities can direct foreign aircraft, arriving from areas of the world where vector-borne infectious diseases are known to exist, so that appropriate public health measures can be implemented (isolation of passengers, disinsecting of aircraft, etc.).
d. An airport of entry and departure for international traffic, designated as sanitary by the local health administration, where the formalities for public health, animal and plant quarantine and similar procedures are carried out; which is provided with pure drinking water and wholesome food; which is provided with an effective system for disposal of excrement, refuse, waste water, etc., and which has at its disposal an organized medical service, facilities for isolation and care of infected persons, facilities for efficient disinfection and disinsecting, access to a bacteriological laboratory, and facilities for vaccination against yellow fever.
e. An airport free of Aedes aegypti and the mosquito-vectors of malaria and where active anti-mosquito measures are maintained within a distance of at least 400 meters around the perimeter.
Answer: d. A sanitary airport is an airport, designated as sanitary by the local health administration of a State. The health administration shall designate a number of sanitary airports in its territory, provided they meet the provisions of article 14 and the conditions of paragraph 2 of article 18 of the IHR. These provisions and conditions are listed in answer option (d). Answer (a). This option covers only two of the many conditions and provisions required. Answer (b). WHO is a specialized agency within the United Nations' system; dedicated to the promotion of global health, it establishes inter alia international regulations such as the IHR, but each Member State is responsible for the implementation of these regulations. Consequently, it is for the local health administration, not for the WHO, to designate an airport as sanitary. Answer (c). There are two provisions in the IHR allowing a State to specify certain airports for isolation of passengers: (1) for aircraft carrying persons taking part in periodic mass congregations, and (2) in areas where the vector of yellow fever is present, for aircraft coming from an infected area. These two provisions do not form part of the definition of a sanitary airport. Answer (e). All airports shall be kept free from Aedes aegypti and the mosquito-vectors of malaria and other diseases of epidemiological significance in international traffic. For this purpose active anti-mosquito measures shall be maintained within a protective area extending for a distance of at least 400 metres around the perimeter. This requirement is not one of the specific conditions or provisions for sanitary airports. REFERENCES: International Health Regulations, 3rd annotated ed. Geneva: WHO, 1983. ICPS Environmental Health Criteria 96 - d-Phenothrin. Geneva: WHO, 1990. Annex 9 to the Convention on International Civil Aviation, ICAO Doc. AN 9, 9th ed. Montreal: ICAO, 1990.

Question: The ventilation-perfusion ratio (Va/Qc) of the lungs is greatest in the:

a. left lung.
b. right lung.
c. upper lobes.
d. lower lobes.
Answer: c. "....when man stands, the lower lobes get more blood flow and the upper lobes less..... gravity does not directly change the distribution of air, the decreases in the lower lobes and increases in the upper lobes." REFERENCE: Comroe. Physiology of Respiration, 2nd ed, 1974:177-178.

Question: While studies of job attitudes in air traffic controllers indicate that controllers are, on the whole, more satisfied with their work than employees in most other types of work settings, there are several factors mentioned frequently as sources of dissatisfaction by controllers. These include all but one of the following:

a. high level of responsibility
b. management
c. rotating shifts
d. night work
Answer: a. The high level of responsibility is mentioned frequently as a source of satisfaction and gratification by controllers, not dissatisfaction. Each of the other three items is mentioned frequently as a source of dissatisfaction. REFERENCES: Rose RM, Jenkins CD, Hurst MW. Air Traffic Controller Health Change Study: A Prospective Investigation of Physical, Psychological and Work-Related Changes. FAA Office of Aviation Medicine, 1978, Report No. FAA-AM-78-39. Smith RC. Comparison of the Job Attitudes of Personnel in Three Air Traffic Control Specialties. Aerospace Med 1973;44:918-927. Smith RC, Cobb BB, Collins WE. Attitudes and Motivations of Air Traffic Controllers in Terminal Areas. Aerospace Med 1971;43:1-5.

Question: Which of the following findings may commonly be seen with third-degree heart block?

1. Widened QRS
2. Ventricular rate < 45
3. Absent ventricular rate response to exercise
4. Widened pulse pressure and diminished venous pulsations in the neck
5. Complaints of weakness, dyspnea, fatigue and syncope

a. 1, 2, 3, 4
b. 2, 3, 4, 5
c. 1, 2, 3, 5
d. 1, 2, 4, 5
e. 2, 3, 5
Answer: c. Complete heart block (third-degree heart block) is usually due to a lesion distal to the bundle of His, often due to previous myocardial infarction. The QRS is wide. The ventricular rate is slowed to 45 beats per minute or less and does not increase with exercise. The first heart sound is variable in loudness. The pulse pressure is wide and cannon venous pulsations are present in the neck. The patient complains frequently of fatigue, dyspnea, weakness, and often has episodes of syncope. Asystole sometimes causes the syncope (during periods of transition from partial to complete heart block). Prolonged syncope can cause convulsions (Stokes-Adams syndrome) and, if lasting 2-3 minutes, can be fatal. REFERENCES: Krupp MA, Chatton MJ. Current Medical Diagnosis and Treatment. Los Altos: Lange, 1979:229.

Question: A smooth, usually rounded, soft-tissue density demonstrated radiographically in a frontal sinus in which pain was experienced during descent in an aircraft is most likely:

a. mucocele.
b. submucosal hematoma.
c. polyp.
d. pneumatocele.
e. osteoma.
Answer: b. A persisting soft-tissue density in a frontal sinus with which the patient can associate pain during descent in an aircraft is most likely a submucosal hematoma. This was demonstrated by Campbell in dogs in the early 1940's. It is a space-filling phenomenon designed to relieve the relatively negative pressure in the sinus cavity. REFERENCES: Campbell PA. Aerosinusitis. Arch Otolaryngol 1942:35:107. Yarington CT, Hanna HH. Otolaryngology in Aerospace Medicine. In: DeHart RL, ed. Fundamentals of Aerospace Medicine, 2nd ed. Baltimore: Williams & Wilkins, 1996:584.

Question: A 44 year old male pilot presents for his periodic aircrew medical assessment. He says he feels in good health, but he admits to a mild smoker’s cough. He gets little exercise and he is overweight (225 lbs/100 kg; 5'9"/175 cm, BMI 32.6), and has gained 10lbs/4kg since his last medical. His nephew (sister's son) developed insulin-dependent diabetes at age 14, but there is no other family history of diabetes. Apart from his obesity, the only finding of concern on your examination is a borderline elevation in blood pressure at 145/90. His fasting plasma glucose is 135mg/dl (7.0 mmol/L), his fasting cholesterol 270 mg/dl (6.96 mmol/L), HDL-cholesterol 31 mg/dl (0.8 mmol/L), triglycerides 225 mg/dl (5.75 mmol/L). You arrange an oral glucose tolerance test which shows a fasting plasma glucose of 120mg/dl (6.7 mmol/L), and 2 hr 180 mg/dl.(8.3). The most serious aeromedical concern in this pilot is the increased risk for:

a. an hypoglycemic episode.
b. acute pancreatitis.
c. a cerebrovascular accident.
d. a coronary event.
e. renal colic.
Answer: d. With his multiple risk factors, he is at increased risk for a coronary event. His risk for a coronary event based on the Framingham nomogram is 28% over the next decade, or 2.8% per year. He is at increased risk for CVA, as well, but, relative to his coronary risk, this is less of a concern. Severe hypertriglyceridemia may cause acute pancreatitis, but not at this level of triglycerides; the risk of this increases as triglycerides rise above 10 mmol/L/400 mg/dl. REFERENCES: Kruyer WB. Screening for Asymptomatic Coronary Heart Disease. Proceeding of AGARD Conference: Cardiopulmonary Aspects of Aerospace Medicine; 1993; Neuilly-Sur-Seine, France. AGARD-LS-189:2-1 to 2-5.

Question: Testicular cancer is of aeromedical significance because it is common and occurs primarily in the pilot age group; the peak age of occurrence is __________. The decision to give a waiver should be based on the fact that progression occurs first in the central nervous system __________.

a. 20-50/very commonly
b. 20-35/very commonly
c. 20-35/very rarely
d. 35-50/very rarely
e. 35-50/about half the time
Answer: c. Testicular cancer is the fourth most common malignancy in males, and the most common in the 20-35 year age group (1 in 500). It is associated with over 99% long term survival if found while still confined to the testicle (stage A), and over 95% if confined to the testis and retroperitoneal lymph nodes(stage B). The pattern of spread is generally very predictable, going to the retroperitoneal lymph nodes before hematogenous dissemination to other organs. Pilots with history of testis cancer must receive frequent follow-up studies from their urologist/oncologist, but should be eligible for waiver as recurrent disease would be most likely found prior to central nervous system involvement. Additionally, the flight surgeon is the ideal person to educate the at risk population of young, asymptomatic males on the importance of self testicular examination. REFERENCES: Rowland RG, Donahue JP. Scrotum and Testis in Adult and Pediatric Urology, 2nd ed. In: Gillenwater JH, et al, eds. St. Louis: Mosby-Yearbook, 1991:1565-1598. Singer AJ, Tichler T, Orvieto R, et al. Testicular Carcinoma: A Study of Knowledge, Awareness, and Practice of Testicular Self Examination in Male Soldiers and Military Physicians. Mil Med 1993;158(10): 640-643.

Question: The magnitude (slow phase velocity) of the electronystagmographic response to a given caloric stimulus is influenced by all EXCEPT one of the follow:

a. the size and straightness of the external auditory canal.
b. a visible but small light source.
c. the direction (ampullopetal vs ampullofugal) of endolymph displacement in a normal ear.
d. position of the plane of the lateral semicircular canals relative to gravity.
e. in corneoretinal potential during the first 15 minutes of dark adaptation.
Answer: c. Results of the caloric test can be influenced by various limitations of fluid flow or heat transfer including size and straightness of the external auditory canal, growth of hair in the canal, and accumulation of cerumen, etc. Temporal bone surgery by reducing bone mass can increase heat transmission to the semicircular canal. Any light source, even a small visual target, may serve as a fixation point and substantially suppress nystagmus. As a matter of fact, failure to suppress nystagmus when a fixation source is purposely introduced is a clinically significant sign. Therefore, inadvertent introduction of light could generate an apparently abnormal caloric response. In conducting the caloric test, the plane of the lateral canals should be placed in alignment with gravity because the caloric stimulus depends upon cooling (or heating) a small portion of endolymph which falls (or rises) due to its density. Therefore, position of the head relative to gravity is an important factor in the caloric test. In the course of a caloric test frequent eye movement calibrations should be taken because the corneoretinal potential can change during dark adaptation, thereby yielding an apparent but not necessarily real change in the intensity of successive responses. In a normal person an equivalent ampullopetal vs ampullofugal endolymph displacement should yield responses approximately equal in magnitude, but of course reversed in direction; therefore (c) was the correct answer. REFERENCES: Barber HO, Stockwell CW. Manual of Electronystagmography. St. Louis: Mosby, 1976.

Question: A 28 y/o aircraft mechanic was using a hammer on a metal cotter pin when he experienced a mild pain in his right eye. He continued to feel as if there was something in his eye so he reported to your office. You found his vision to be 20/20, but in addition there was a small area of the cornea which stained with fluorescein. The most appropriate action for you to take is:

a. instill ophthalmic antibiotic drops.
b. patch the eye for 24 hrs.
c. refer the patient to an ophthalmologist.
d. check his intraocular pressure.
e. obtain x-rays.
Answer: c. Refer the patient to an ophthalmologist. Striking metal on metal is a common history given by patients who sustain an intraocular foreign body as a small piece of metal may break off, impacting the eye at sufficient velocity to penetrate. Symptoms and signs may be minimal so a high index of suspicion is warranted in all such cases. While all of the answers above are correct in that they may be performed during the course of a proper examination to rule out an intraocular foreign body and to treat a corneal abrasion, the most appropriate action for you is to refer the patient to an ophthalmologist who has the instrumentation and training necessary to completely evaluate the eye. REFERENCES: Scheie HG, Albert DM. Adler's Textbook of Ophthalmology, 9th ed. Philadelphia: Saunders, 1969:563.

Question: Which of the following conditions provides the best impact protection for an aerospace vehicle occupant restrained in a double shoulder strap and lap belt harness?

a. Occupant seated on an easily deformable cushion with restraint tightly adjusted.
b. Occupant seated on an easily deformable cushion with restraint loosely adjusted.
c. Occupant seated on no cushion with restraint tightly adjusted.
d. Occupant seated on no cushion with restraint loosely adjusted.
Answer: c. A major goal of impact protection is to restrict the motion of body segments in order to reduce the relative displacements of body segments and internal organs. This is most effectively accomplished by tightly restraining the occupant to a supporting structure such as a vehicle seat. A soft, easily deformable seat cushion interposed between the occupant and the accelerating force generally amplifies the acceleration to which the occupant is exposed. This occurs because the seat cushion material may store energy during the impact and release it in rebound, thereby imparting a larger velocity change to the occupant than the vehicle. Also, the cushion deformations may delay the acceleration of the occupant and create a large velocity difference between the occupant and the vehicle. Of course, the occupant acceleration must eventually exceed the vehicle acceleration in order to eliminate the velocity difference. Generally, ejection seat cushions today are relatively thin and inelastic. REFERENCES: Brinkley JW, Raddin JH. Biodynamics: Transitory Acceleration. In: DeHart RL, ed. Fundamentals of Aerospace Medicine. Philadelphia: Lea & Febiger, 1985. von Gierke HE, Goldman DE. Effects of Shock and Vibration on Man. Harris DM, Crede CE, eds. Shock and Vibration in Man. New York: McGraw-Hill, 1976.

Question: Ebullism:

a. is a misspelling of embolism.
b. occurs above 63,000 ft the Armstrong Line.
c. results from tissue water vaporization.
d. refers to altitude decompression sickness within tissues.
e. b and c above.
Answer: e. (a) is incorrect because it is spelled correctly. (b) is correct because water vapor pressure at body temperature is 47mmHg which equals ambient pressure, 47mmHg, at 63,000 ft, defined as the Armstrong Line. (c) is correct because vaporizing water produces the symptoms known as ebullism. (d) is incorrect because altitude decompression sickness results from supersaturation of tissues with nitrogen, not water vapor. REFERENCES: DeHart RL, ed. Fundamentals of Aerospace Medicine. Philadelphia: Lea & Febiger, 1985.

Question: Medical planning at large airports to deal with major disasters requires:

a. a command post for the triage/treatment center.
b. a temporary roadside church for use by victims and their survivors.
c. a large helicopter for transporting victims to hospitals.
d. an underground series of tunnels for use if severe weather is present.
e. appointment of one regional undertaker to handle all of the fatalities.
Answer: a. A roadside church, underground tunnels and a regional undertaker are not requirements of a disaster plan. Helicopters may not be the best mode of transportation depending on the disaster, therefore are not a requirement. REFERENCES: Federal Aviation Administration. FAR 67. Washington DC: US Government Printing Office, 1996 Sept 16.

Question: Cyclicity or rhythmicity are prominent characteristics of all forms of life. Which of the following constitutes a sufficient description of the mechanisms leading to rhythmicity in man?

a. It is an internal, endogenous, unconditioned characteristic.
b. It is one of the results of evolution.
c. It is the result of external rhythms in the non-living universe.
d. It is driven and enhanced by the day-night cycle.
e. All of the above.
Answer: e. Rhythmicity is clearly universal in both the living and nonliving world. Therefore, it must be seen as an internal, endogenous, unconditioned characteristic. It is clear that this substrate is augmented, enhanced, and further elaborated by evolution, and that synchronization occurs in response to external, rhythmic factors in the physical environment, such as seasonal changes, the cycle of the moon, variations in the tide, etc. The final driving force in man is the day-night cycle, a powerful social conditioner. The net result is a most complex system of cycles working in delicate balance, the disturbance of which results in major physiologic and behavioral changes. REFERENCES: Strughold H. Circadian Rhythms. In Randel HW, ed. Aerospace Medicine, 2nd ed. Baltimore: Williams & Wilkins, 1971:47-55.

Question: Educational programs for crew members given by the flight surgeon on aeromedical hazards should:
1. be given on a regular and scheduled basis, such as at flying safety meetings.
2. be given as needed.
3. be given on a formal lecture basis.
4. be structured somewhat but include informal discussion.
5. be primarily concerned with typical flight operations.
6. include detailed discussion of the pathophysiology applied to the particular aircraft

a. 1, 3, 5, 6
b. 2, 3, 5
c. 1, 4, 5
d. 3, 5, 6
e. 1, 4, 5, 6
Answer: c. A significant requirement for flight surgeons is educating crew members in the aeromedical hazards of flight operations. Such educational programs may be conducted on a scheduled, relatively formal basis, or at seminars or flying safety meetings. Informal discussions and office visits may also be used to provide information. These educational efforts should be primarily concerned with the medical hazards involved in typical flight operations. Include necessary basic pathophysiology discussions of detailed physiology and allow enough time for discussion, thus preventing loss of audience interest. REFERENCE: Moser R, Bonfili HF. Aeromedical Support of Flying Safety Program. Aviat Space Environ Med 1977 May;43(5):465-467.

Question: For heat-acclimatized men performing moderate physical work in a hot environment, which of the following should be provided at the job site?

a. Access to water
b. Access to colas and other sweetened liquids
c. Ad lib intake of salt tablets
d. Supervised intake of salt tablets
e. a, b, and c.
Answer: a. The primary need of workers on the job is water replacement; by making water conveniently available and encouraging drinking, weight losses can be kept below the 3% level characteristic of "voluntary" dehydration. Sugar solutions inhibit gastric absorption of water and produces a sensation of fullness, which discourages further drinking. Salt tablets are no longer recommended, as they are often irritating to the GI tract and can easily produce a detrimental salt overdose. Under most conditions ample electrolyte replacement is obtained with a normal US diet including free use of table salt. REFERENCES: Leithead CS, Lind AR. Heat Stress and Heat Disorders. Philadelphia: FA Davis, 1964:141-177.

Question: A central and fundamental concept in human factors is the System. To borrow from Sanders and McCormick, "A system is an entity that exists to carry out some purpose". Typically a system is comprised of a number of components, each of which serves a function. In describing systems, which of the following statements would NOT be correct?

a. The reliability of a system can be expressed as the probability of successful performance.
b. If components of a system are arranged in series, the system would be more reliable than if the components are arranged in parallel.
c. The maximum possible reliability of a system where the components are arranged in series would be the reliability of the least reliable component.
d. In a system where components are arranged in parallel, one or more components are in some way performing the same function.
e. Adding components in parallel to a system increases the reliability of that system.
Answer: b. If components are arranged in parallel, more than one component is performing the same function, thus ensuring redundancy within the system. If components are arranged in series, reliability is only as good as the reliability of the least reliable component. REFERENCES: Sanders MS, McCormick EJ. Human Factors in Engineering and Design. New York: 1987

Question: Which of the following statements is correct?

a. Classic teaching states that altitude-induced neurological decompression sickness usually involves the brain rather than the spinal cord.
b. Neurological decompression sickness is more commonly associated with flying rather than diving.
c. Pathological fatigue is not seen with altitude induced neurological decompression sickness.
d. Peripheral nerve involvement is seen more often with diving induced neurological decompression sickness than with altitude induced decompression sickness.
Answer: a. Neurological decompression sickness has nearly the same incidence rate in flying and diving. Pathological fatigue is a common complaint in flying and diving decompression sickness and there is no predilection to peripheral nerve involvement in either environment. REFERENCES: Heimbach RD, Sheffield PJ. Decompression Sickness and Pulmonary Overpressure Accidents. In: DeHart RL, ed. Fundamentals of Aerospace Medicine, 1st ed. Philadelphia: Lea & Febiger, 1985.

Call for Papers

The Aerospace Medical Association’s 2015 Annual Scientific Meeting will be held in Buena Vista, FL. This year’s theme is “Making a Difference in Aerospace Medicine.” We encourage presentations from diverse experts that will enhance the world’s knowledge and understanding of the current challenges in Aerospace Medicine.

To read the full Call for Papers, please click here.
The abstract submission site will open on or around September 1, 2014, and the deadline will be October 31, 2014.