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: Because of man's inherent inability to adapt to a water environment, it is essential that the survivor accomplishes which of the following as soon as possible?

a. treat injuries.
b. inflate life preservers.
c. get out of the water.
d. erect environmental cover.
Answer: c. It is recognized by the services that man requires special equipment in order to survive the harsh sea environment. No piece of equipment is more important than the life raft. You must get out of the water as soon as possible because of the environmental hazards. Your life preserver keeps you afloat but does not protect from water temperatures. There are very few injuries that can be treated in the water. The cover will only allow you to alter the environment once you are in the raft. REFERENCES: US Air Force. Air Force Manual 64-3. Survival Training Edition. Washington DC: US Government Printing Office, Department of the Air Force, 1969

Question: After a long crew duty day, a pilot is performing a difficult approach in marginal weather conditions. While in a right standard rate turn, he turns his head to check his wingman's position. He subsequently feels his control stick thrust to the right. He is unable to center the stick after repeated effort. When he releases his grip on the stick, it returns to a centered position. The most likely cause of this pilot's difficulty is:

a. a control malfunction.
b. the somatogravic illusion.
c. the Giant Hand phenomenon.
d. severe turbulence.
Answer: c. REFERENCES: Lyons TJ, Simpson CG. The Giant Hand Phenomenon. Aviat Space Environ Med 1989; 60:64-6.

Question: The National Council on Radiation Protection and Measurements (NCRP) was asked to provide guidelines for crew radiation exposure during spaceflight. They focused on the risk of four late effects. Which was NOT included among these four risks?

a. serious genetic defects
b. fatal cancer
c. cataracts
d. gonadal infertility
e. CNS effects
Answer: e. The NCRP focused on the late effects of a-d. (e) is considered an acute effect. For low-Earth orbit flights, (Space Shuttle and Space Station) the NCRP proposed an acceptable risk level comparable to other less safe occupations (those with lifetime risk of acceptable death of 3%). REFERENCES: Davis JR. Medical Issues for a Mission to Mars. Texas Med 1998 Feb;94(2):47-55.

Question: Several hours post exposure of the eyes to a laser source, a clinician observes corneal transparency loss, surface exfoliation, tearing and conjunctival discharge in a patient who is unaware of the laser parameters of exposure. The clinician concludes that the possible wavelength of exposure must have been from:

a. approximately 180 nm (ultra-violet) to 350 nm (violet).
b. approximately 400 nm (violet light) to 1400 nm (near-infrared).
c. approximately 1450 nm (near-infrared) to 10,600 nm (far infrared).
d. the entire electromagnetic spectrum.
e. a and b.
Answer: e. REFERENCES: American National Standards Institute. American National Standard For Safe Use of Lasers in Health Care Facilities. Orlando: The Laser Institute of America: ANSI Z136.31996. American National Standards Institute. American National Standard For Safe Use of Lasers. Orlando: The Laser Institute of America: ANSI Z136.1-1993

Question: Loudness is a psychoacoustic phenomenon. When a listener judges a sound to be twice (or half) as loud when compared to another sound, the difference in sound pressure level between the two sound is approximately:

a. 3dB
b. 4dB
c. 5dB
d. 6dB
e. 10dB
Answer: e. REFERENCES: Berger, Ward, Morrill, Royster. Noise and Hearing Conservation Manual, 4th ed. Akron: American Industrial Hygiene Association, 1986:188.

Question: Nicotine and caffeine may make one more alert and attentive due to the resultant elevation of noradrenalin. They also are associated with an increase in coronary heart disease rates and can lead to dependence. It takes approximately the following amount of caffeine to develop dependence (approximately 100 mg caffeine per 8 ounce cup of coffee):

a. one cup of coffee per day
b. 2 to 3 cups of coffee per day
c. 5 to 7 cups of coffee per day
d. 8 or more cups of coffee per day
Answer: c. The amount of caffeine in coffee varies, as does the size of the cup. The average 8 ounce cup contains 100 mg and, as a generalization, since 10 mg/kg of caffeine leads to dependence, one should take less than this per day, i.e., less than six such cups, and should not take it "to keep going" in stressful situations. Caffeine also exists in many over-the-counter prescriptions and in soft drinks made with cola. One gets 40 mg in a 8 oz. cola drink and 25 mg in a chocolate candy bar; so if a 30 kg child consumes three colas and one chocolate bar a day, he has reached his limit. REFERENCES: Henry JP. Self-Imposed Stress. Aviat Space Environ Med 1978 Mar;49(3):519-520.

Question: The time required for cabin depressurization is determined by all of the following EXCEPT:

a. volume of the pressurized cabin.
b. size of opening.
c. pressure differential.
d. speed of the aircraft.
e. flight pressure altitude.
Answer: d. Speed of the aircraft does not determine the rate of decompression. Answers (a), (b), (c), and (e) are all factors that define the time of decompression. REFERENCES: Heimbach RD, Sheffield PJ. Protection in the Pressure Environment: Cabin Pressurization & Oxygen Equipment. In: RL DeHart, ed. Fundamentals of Aerospace Medicine. Philadelphia: Lea & Febiger, 1985:114.

Question: Which of the following is an effect of altitude exposure?>br/>
a. vasodilation of extremities
b. decrease in arterial oxygen tension
c. decrease in respiratory frequency and tidal volume
d. bradycardia
e. all of the above
Answer: b. Exposure to altitude causes a reduction in alveolar oxygen tension. This in turn causes a decrease in arterial oxygen tension. The carotid and aortic bodies, when stimulated, actually increase respiratory frequency and tidal volume as well as causing vasoconstriction of extremities. As a result, blood pressure increases causing tachycardia, not bradycardia. REFERENCES: Holmstrom FMG. Hypoxia. In: Randel HL, ed. Aerospace Medicine, 2nd ed. Baltimore: Williams & Wilkins, 1971:63.

Question: The primary factor limiting routine Hyperbaric Oxygen treatment of decompression sickness at 60 feet is:

a. oxygen toxicity.
b. increased expense if treatment is prolonged.
c. nitrogen narcosis.
d. patient tolerance to confinement in a small space.
e. prolonged exposure to high pressure on body tissues.
Answer: a. Pulmonary oxygen toxicity will occur on 100% oxygen if treatment is prolonged. Nitrogen narcosis is not a problem when 100% oxygen is used. Pressure on the tissues is not a problem. Expense and confinement tolerance are considerations, but necessity of treatment overrides their importance and should not be allowed to limit treatment. REFERENCES: US Air Force. Air Force Pamphlet. 151-27. Washington DC: US Government Printing Office, Department of the Air Force:8-10.

Question: A common problem that occurs when a cockpit instrument is not placed directly in front of the pilot because of the distance between a pointer on a display and the surface of the scale is a visual factor known as:

a. an illusion.
b. parallax.
c. autokinesis.
d. poor acuity.
e. Presbyopia.
Answer: b. A common problem that occurs when a cockpit instrument is not placed directly in front of the pilot because of the distance between a pointer on a display and the surface of the scale is a visual factor known as parallax. REFERENCES: Hawkins FH. Human Factors in Flight, 2nd rev ed. Vermont: Ashgate, 1993.

Question: The Wind-chill Index was developed by Siple in the 1940's and is widely used to assess cold weather in both military and civilian settings. Which of the following statements correctly describe the Index?

1. It is based on subjective judgments of cold discomfort.
2. It is based on measured cooling power of the atmosphere.
3. It has been empirically correlated with "time to freezing" for exposed flesh
4. It is most accurate under conditions of extreme cold and high winds

a. 1 and 3
b. 1, 2, and 3
c. 2 and 3
d. 2 and 4
e. 2, 3, and 4
Answer: b. The Index was developed from measurements of the cooling rate of water in a cylinder exposed to ambient conditions in Antarctica. Findings were then correlated with time to frost "nip" of the face and subjective judgments of unpleasantness. The concept of "Equivalent Chill Temperature" was a later development which gives the still-air temperature which has the same cooling power as the give combination of wind and air temperature. The Index is less accurate under extreme conditions due to instrumentation problems and a paucity of data in the original series of experiments. REFERENCES: Siple PA. Measurements of Dry Atmospheric Cooling in Sub-Freezing Temperature. Proc Amer Philos Soc 1945;89:177-199. Burton AC, Edholm OG. Man in Cold Environment. New York: Hafner, 1969:110-112.

Question: Participating in typical flight operations has been recognized by the Aerospace Medical Association as one of the most effective methods to develop knowledge of the mission and equipment. Why is this important for the flight surgeon?

1. To assist him in developing appropriate flying safety material.
2. To get flying time and to learn how to fly in case of an emergency.
3. To help in the evaluation of a crew member who has developed a medical problem as a result of flying.
4. As a fringe benefit--trips to interesting places.

a. 1
b. 1, 2, 3
c. 1, 3
d. 2, 4
e. All of the above
Answer: c. It is appropriate to emphasize that flight activities benefit the flight surgeon not only in his flying safety activities, but also in his clinical work. Whether he is evaluating a crewmember who has developed a medical problem as a result of flight duties or determining if a flyer's condition could jeopardize safe flight, the flight surgeon must be well versed in typical flight operations. REFERENCE: Moser R, Bonfili HF. Aeromedical Support of Flying Safety Program. Aviat Space Environ Medicine 1977 May;43(5):465-467.

Question: Sleep follows biological rhythms. Which of the following is true in "good sleepers" (those not bothered by insomnia)?

a. Minimum body temperature occurs at sleep onset.
b. Minimum body temperature occurs about 2 hours after falling asleep.
c. Minimum body temperature occurs about 4 hours after falling asleep.
d. Minimum body temperature occurs about 6 hours after falling asleep.
e. Minimum body temperature occurs upon awakening.
Answer: c. Sleep comes most easily when body temperature is falling and is hardest to sustain when temperature is rising. In good sleepers, body temperature rhythms are appropriately aligned with desired sleep onset and wake-up times, the daily minimum occurring about 4 hours after sleep begins. REFERENCES: Lamberg L. Sleep Specialists Weigh Hypnotics, Behavioral Therapies for Insomnia. JAMA 26 Nov 97;278(20):1647-1649

Question: In regard to potential disasters, tornadoes are an ever present threat and occur, not infrequently, in the US The predilection of this phenomena for open, flat areas of our country results in an increased potential for a disaster involving airdromes and the associated population. In your preventive medicine program involving disaster medicine, in what location listed below would you point out to be the most dangerous during a tornado?

a. house or public building
b. open area
c. automobile or similar vehicle
d. all of the above are probably equally dangerous.
Answer: c. A review by the Center for Disease Control following the tornado disaster at Wichita Falls, TX in April 1979 revealed of the 44 traumatic deaths, 25 were associated with passenger vehicles, 8 occurred in the open, and 4 each occurred in public buildings and in houses. As was noted in the May 4, 1979 issue of the Morbidity and Mortality Weekly Report the least risk of fatal injury appeared to be to those taking shelter in cellars, closets, hallways, and basements, even when the buildings were completely destroyed. Covering with mattresses or heavy blankets provides considerable protection from flying debris. It is advised that automobile passengers should abandon their vehicle and seek shelter in ditches, culverts, or nearby buildings. REFERENCES: Prevention of Tornado Mortality. Am Family Phys 1979 Nov;20(5):184.

Question: Without pressure suit protection, the most imminent danger following a rapid decompression to altitudes above 50,000 feet is:

a. decompression sickness.
b. lung rupture.
c. oxygen lack.
d. boiling of body fluids.
Answer: c. At these altitudes, even when breathing oxygen, the anoxic onset of unconsciousness is inevitable and overwhelming within a few seconds. The other factors, although critical in themselves, become essentially of secondary importance. The onset of decompression sickness, if it should occur, usually requires a delay time that is much longer than the consciousness time. The boiling of body fluids at pressures less than their vapor tension, which is often dramatic, has been found with experimental animals to be much less catastrophic than originally imagined. Lung rupture can only occur during (not following) a rapid decompression when the pulmonary airways are grossly obstructed or blocked. REFERENCES: Bancroft RW. Pressure Cabins and Rapid Decompression. In: Randel HW, ed. Aerospace Medicine, 2nd ed. Baltimore: Williams & Wilkins, 1971:357. Holmstrom FMG. Hypoxia. In: Randel HW, ed. Aerospace Medicine, 2nd ed. Baltimore: Williams & Wilkins, 1971:72.

Question: Human impact tolerance is related to which of the following factors?

a. Direction, magnitude, and time history of the imposed acceleration
b. Restraint harness materials
c. Restraint harness geometry
d. Condition of restraint harness occupant
e. all of the above
Answer: e. The variability and complexity of impact accelerations encountered in aerospace operations are generally well understood qualitatively, but frequently are not adequately quantified. The immediate pre-impact acceleration-time history of the aerospace vehicle also influences the impact response. The restraint harness materials and geometry determine how the force applied to the human body during the impact is to be distributed. A seat occupant restrained by a lap belt and two shoulder straps can survive greater impacts than would be survivable if a lap belt alone was used. Finally, the population to be protected is a key factor in the variance of impact tolerance. This variance, for example, is greater in the general population than is a subset composed of military aviators. The impact tolerance of a given individual is related to his age, size, body habitus, level of physical conditioning and freedom form anatomic variations predisposing to impact injury. REFERENCES: Brinkley JW, Raddin JH. Biodynamics: Transitory Acceleration. In: DeHart RL, ed. Fundamentals of Aerospace Medicine. Philadelphia: Lea & Febiger, 1984. Raddin JH, Hearon BF. Dynamic Preload as an Impact Protection Concept, SAFE Journal, 1982:12(3)

Question: What is the likely explanation for this situation having manifested itself as anxiety about flying?

a. The pilot's motivation to fly was flawed from the beginning of his flying days. The present life stress precipitated an inevitable breakdown in his self-confidence.
b. The pilot is getting older, and one's confidence in one's ability to deal with emergency situations gets shakier as the years pass. His cousin's mishap was the catalyst for his awareness of his aging and vulnerability.
c. The pilot's personality makeup was such that feelings of emotional upset were threatening and had to be repressed. Thus, the anxiety attached itself to another aspect of his life. There may be some symbolic connection, but one may not necessarily have to uncover it.
d. The pilot was so upset that he had subconscious suicidal impulses. His uneasiness about flying was a protective reaction, allowing him to ask for help in handling them.
e. Flying represented an escape from the family situation. He was so conflicted about staying or leaving that the anxiety attached itself to the vehicle that represented his chance to accomplish this escape.
Answer: c. In some instances of acquired fear of flying, choices (a), (d) or (e) may contain a grain of truth, but there is no evidence for any of them in the information provided in this case history. Choice (b) is highly unlikely at this pilot's age, where flying ability is proven, physical capabilities are healthy, motivation has been well-tested, and experience provides a powerful additional safety factor. REFERENCES: Fine PM, Hartman BO. Psychiatric Strengths and Weaknesses of Typical Air Force Pilots. Brooks AFB: USAF School of Aerospace Medicine, SAM Technical Report 68-121, 1968:131-68. Jones DR. Suicide by Aircraft. Aviat Space Environ Med 1977; 48:454-9. Jones DR. Flying and Danger, Joy and Fear. Aviat Space Environ Med 1986; 57;131-6. Jones DR, et al. Neuropsychiatry in Aerospace Medicine. In: DeHart RL. Fundamentals of Aerospace Medicine, 2nd ed. Baltimore: Williams & Wilkins, 1996:610-1.

Question: An applicant visited his AME and a color perception abnormality was detected. What action should be taken by the AME or the applicant?

a. Disqualify the applicant
b. The AME may issue a medical certificate bearing the limitation "Not valid for night flying or by signal control."
c. An applicant who hold a medical certificate bearing color vision limitations may request a reevaluation and ask for the issuance of a SODA (statement of demonstrated ability). If passed, the FAA will issue a medical certificate without limitation.
d. both b and c
Answer: d. Previous standards required "normal color vision" for first class certification, and the ability to distinguish aviation signal colors for second and third class tickets. However, since September of 1996, the FAA has required all applicants to have the ability to perceive those colors necessary for the safe performance of airman duties. REFERENCES: Federal Aviation Administration. Guide for Aviation Medical Examiners. Washington DC: US Government Printing Office, US Department of Transportation, 1996 Sept.

Question: Long term risk of post traumatic epilepsy is determined by:

a. prolonged period of loss of consciousness (LOC) and/ or post traumatic amnesia (PTA).
b. dural penetration.
c. neurologic deficits.
d. evidence of hematoma (epidural, subdural, intracerebral).
e. all of the above
Answer: e. Post traumatic epilepsy (PTE) may be seen in the early (<1 week) post injury period, or delayed months or years following head injury. Two principle determinants in the development of post traumatic epilepsy appear to be a constitutional tendency towards seizures (genetic factors) and the extent of brain damage. Risks for the development of post traumatic epilepsy include early seizure, penetrating injury, multiple lobe injury, depressed skull fracture, dural penetration, intracranial hemorrhage, amnesia/unconsciousness greater than 24 hours, or focal neurologic signs (hemiplegia, aphasia). These risk factors are additive with an increased incidence of post traumatic epilepsy with increased severity of the head injury. REFERENCES: Annegers JF, Grabow JD, Groover RV, Laws ER, Elveback LR, Kurland LT. Seizures After Head Trauma: A Population Study. Neurology 1980;30:683-689. Feeney DM, Walker AE. The Prediction of Posttraumatic Epilepsy: A Mathematical Approach. Arch Neurol 1979;36:8-12. Weiss GH, Feeney DM, Caveness WF, Dillon D, Kistler JP, Mohr JP, Rish BL. Prognostic Factors for the Occurrence of Posttraumatic Epilepsy. Arch. Neurol 1983;40:7-10.

Question: You are seeing a 41 y/o Black loadmaster for his periodic short physical examination. He tells you that his father (70 y/o) recently died of cancer of the prostate and his older brother is undergoing an evaluation for prostate disease. He denies any voiding difficulties. His rectal exam reveals a small, normal prostate without any nodules. His PSA is returned with a value of 3.8 mg/ml. Your next step is:

a. repeat the same evaluation at his next annual physical examination.
b. disregard the PSA results because the digital rectal exam was normal and he is young.
c. refer him to your local urologist as an urgent consultation for probable prostatic cancer.
d. Repeat PSA at 3 and 6 months. If PSA is increasing, refer to urologist.
Answer: d. REFERENCES: Babaian J, et al. The Distribution of Prostate Specific Antigen in Men Without Clinical or Pathological Evidence of Prostatic Cancer: Relationship to Gland Volume and Age. J Urology 1992 May;147:837-840. Osterling JE, et al. Serum Prostate Specific Antigen in a Community Based Population of Healthy Men: Establishment of Age Specific Reference Ranges. JAMA 1993 Aug 18;270: 860-864. Catalona WJ, et al. Detection of Organ-Confined Prostatic Cancer is Increased Through Prostate-Specific Antigen-Based Screening. JAMA 1993 Aug 25;270: 948-954. Safford HR, et al. The Effect of Bicycle Riding on Serum Prostate Antigen Levels. J Urology 1996 Jul;156:103-105.

Question: One important reason why functional hypoglycemia is of aeromedical significance is:

a. it can cause loss of consciousness.
b. it can cause a decreased G tolerance.
c. it can cause convulsions.
d. it can result from skipped meals.
e. it may indicate early diabetes mellitus.
Answer: b. There is evidence that hypoglycemia and acceleration are additive and will cause loss of consciousness: functional hypoglycemia per se will not. It was reported that the brain is able to auto-regulate its blood flow until the arterial pressure falls as low as 60mmHg, which can occur with +Gz. Beyond that point, the brain can sustain its metabolism only by extracting greater amounts of glucose and oxygen from the blood. Therefore, if either of these substances were reduced, there would be a correspondingly reduced tolerance to +Gz acceleration. Hence, if a pilot developed functional hypoglycemia when flying a mission requiring accelerative maneuvers, his G tolerance could be compromised causing loss of consciousness. Functional hypoglycemia occurs 2-4 hours after a heavy carbohydrate meal and causes signs and symptoms of hyperepinephrinemia. It does not cause loss of consciousness or convulsions. Furthermore, skipping meals does not cause hypoglycemia. Although missing a meal can cause hunger pangs, discomfort, and possibly performance decrement, it does not cause a significant change of blood glucose. Although functional hypoglycemia may signal early onset of diabetes mellitus, this is not its primary aeromedical significance. REFERENCES: Raichle E, King WH. Functional Hypoglycemia: A Potential Cause of Unconsciousness in Flight. Aerospace Med 1969;43:76-68. Meyer JF. Blood Glucose During High-Performance Aircraft Flight. Aerospace Med 1969;40:310-315.

Question: Loudness is a subjective awareness of sound as contrasted to sound intensity. Even if a sound is made 20 dB more intense, it may be no louder if the patient still cannot hear it. An abnormally rapid increase in loudness is termed:

a. amplification.
b. recruitment.
c. shadow curve.
d. diplacusis.
Answer: b. Recruitment is an abnormally rapid increase in loudness. A person with normal hearing interprets any two sounds having the same intensity as being equally loud when listening through earphones. When cochlear disease is unilateral as in Meniere's disease, one ear may exhibit recruitment and the other may not. Sounds of equal intensity, presented at threshold levels, will be heard by the good ear but not by the recruiting ear because it is partially deafened and cannot hear faint sounds at all. The phenomenon of recruitment is apparent when the sound intensity is raised sufficiently for the recruiting ear to hear. Amplification is the increase in the sound intensity. Diplacusis is the term used to denote double hearing. A shadow curve is produced normally when a patient is presented with an intense sound to a unilateral dead ear through earphones. The sound travels across his head to his normal ear and is reported as being heard. REFERENCES: DeWeese DD, Saunders WH. Textbook of Otolaryngology, 5th ed. St. Louis: Mosby, 1977:305.

Question: Cardiac arrhythmias which result in syncope can be catastrophic in the aviation setting. Which of the following can lead to atrial sinus arrest and syncope?

a. Positive pressure breathing
b. The M-1 maneuver
c. An attempt to stop hyperventilation by deep breath holding.
d. all of the above.
Answer: d. Positive pressure breathing of 100% oxygen is used as an emergency means of maintaining adequate arterial oxygen saturation in the event of loss of cabin pressurization at or above 40,000 feet. The M-1 maneuver, a continuous forced exhalation through a partially closed glottis, is used to overcome undesirable effects during exposure to accelerative forces. Breath holding in inspiration is often recommended to stop hyperventilation. Each of these respiration related activities has been associated with vagal stimulation, atrial sinus arrest, and syncope in sensitive individuals. REFERENCES: Sundaram PM. Syncope Among Aircrew Evaluated at the USAF School of Aerospace Medicine. Aerospace Med 1969;40(10):1126-1133. Wilson CL, Lang RH. Cardiac Arrhythmias and Syncope During Positive Pressure Breathing. Aerospace Med 1961 Nov:1026-1030.

Question: In aircrew who suffer a spontaneous pneumothorax:

a. the treatment of choice is pleurectomy.
b. the treatment of choice is chemical pleurodesis.
c. the recurrence rate is 30% after a first pneumothorax.
d. the condition may manifest only when airborne.
e. a, c and d are correct.
Answer: e. The aeromedical importance of a spontaneous pneumothorax is related to the tendency to recur: at a rate of 30% after the first event, and rising to 80% after a third. Definitive treatment is therefore necessary before aircrew with the condition may be allowed resume flying. Unlike pleurectomy, chemical pleurodesis is associated with a significant failure rate and morbidity. In-flight occurrence is rare, but a symptomless pneumothorax at ground level may become symptomatic at altitude as ambient pressure falls and volume increases. REFERENCES: Respiratory Diseases. In: Ernsting J, King P, eds. Aviation Medicine, 2nd ed. London: Butterworths, 1988:597-603.

Question: Which of the following statements is true regarding health measures specified by the International Health Regulations (IHR).

a. Health measures stipulated by the IHR are the minimum any state may apply for protection against diseases of significance in international travel.
b. International diplomats are exempt from the provisions of the IHR.
c. Except in case of extreme emergency constituting a grave danger to public health, free pratique cannot be refused for diseases other than plague, cholera and yellow fever.
d. Bodies in sealed coffins are subject to the IHR.
e. A person under surveillance is restricted to the quarantine area of a sanitary airport.
Answer: c. Health measures stipulated by the IHR are the maximum measures that may be applied to Signatory states to control diseases of significance in international travel. A traveler with plague, yellow fever, or cholera should not be permitted to depart. A traveler under surveillance may depart with notification of the destination health authority. Sealed coffins are not subject to IHR's. An international diplomat is only exempt from IHR provisions if he travels in a sealed coffin. REFERENCES: Ernsting J, King. Aviation Medicine, 2nd ed. London: Butterworths, 1988:519-521.

Question: Many plastics and other organic materials used in aircraft interiors give off a particularly hazardous gas when burned. Select the name of that gas from the following list.

a. Chlorine
b. Hydrogen Sulfide
c. Hydrogen Cyanide
d. Vinyl Chloride
Answer: c. "Cyanide is derived from certain commonly used plastics and other organic materials in cabin fixtures and furnishings. Especially productive of cyanide are polyurethane (seat cushions, carpet pads, hat rack structures), acrylonitrile-butadiene-styrene (passenger service unit window structures), modacrylics (dust panes) and wool (seat upholstery)." REFERENCES: Mohler SR. Air Crash Survival: Injuries and Evacuation Toxic Hazards. Aviat Space Environ Med 1975;46(1):86-88.

Question: The aeromedical evacuation of an anemic patient can present serious hazards in regard to O2 delivery to tissues at altitude. When transporting a patient with an anemia of unknown etiology whose hemoglobin is approximately 7.5 gms, the flight surgeon should:

a. transfuse the patient with whole blood, then evacuate by aircraft.
b. not transport the patient by aircraft but should utilize surface transportation as expeditiously as possible.
c. transport by air if most feasible and administer O2 in flight.
d. none of the above.
Answer: c. While anemia results in the reduction of the O2 capacity of blood, it does not necessarily change the O2 saturation of hemoglobin. Those with a hemoglobin of 7 gms at sea level and at rest can compensate quite readily. At altitude, however, the O2 saturation may be reduced; therefore, the administration of O2 can ensure 100% O2 saturation of the available hemoglobin. It is generally accepted that an anemic patient can be aeromedically evacuated and that O2 should be administered if the hemoglobin is below 8.5 gms. Administration of whole blood or packed cells to a patient with undiagnosed anemia may interfere with future studies and management and should be discouraged. REFERENCES: Johnson A. Treatise on Aeromedical Evacuation: I. Administration and Some Medical Considerations. Aviat Space Environ Med 1977 June;48(6):546-549. Reddick EJ. Aeromedical Evacuation. Am Family Phys 1977 Oct;16(4):154-60.

Question: Which of the following conditions requires the patient to descend immediately in all cases?

a. Nausea, weakness and a headache in a confused patient
b. Moderate shortness of breath that is controlled with nifedipine and oxygen
c. A patient with ataxia and confusion but no other symptoms
d. a and c.
e. all of the above.
Answer: d. Any patient with symptoms consistent with HACE should descend immediately to a lower altitude. However, a patient with moderate HAPE who is responding to treatment can be managed at altitude with oxygen, rest and observation. REFERENCES: Bezruchda S. Altitude Illness: Prevention and Treatment. Seattle: The Mountaineers: 1994:47-48.

Question: Studies of miniature swine exposed acutely to G stress up to levels of +9Gz for 45 seconds have consistently revealed subendocardial hemorrhage and cardiomyopathy. The cardiomyopathies include myofibrillar degeneration, translocation and clumping of mitochondria and necrosis of cardiac myocytes. It is believed that these same cardiomyopathies occur in humans who are exposed to similar G forces.

a. True
b. False
Answer: b. Although the swine studies revealed these pathologies at operational G levels, a follow-on study in humans using all available clinical monitoring techniques did not reveal similar conditions. REFERENCES: Burton RR, Mackenzie W. Joint Committee on Aviation Pathology: II Heart: Pathology Associated with Exposure to High Sustained +Gz. Aviat Space Environ Med 1975;46:1251-1253. Burton RR, Mackenzie W. Cardiac Pathology Associated with High Sustained +Gz Stress. Aviat Space Environ Med 1976;47(7):726-733. Gillingham KK. Absence of High-G Stress Cardiopathy in a Human Centrifuge Rider. 1978 May USAFSAM TR 78-17.

Question: Appropriate treatment for phosgene exposure includes:

a. rest, warmth, and sedation.
b. supplemental oxygen.
c. atropine and expectorants.
d. a and b
e. all of the above
Answer: d. Following exposure, the mild irritation initially presents, subsides and a latent (symptomless) period ensues. With the recurrence of chest tightness and coughing, rest, warmth, and sedation are indicated. With the onset of dyspnea, cyanosis, and uneasiness, the patient may benefit from supplemental oxygen. However, atropine and expectorants are not indicated, nor are analeptics or antihistamines. Fluid overload is a distinct possibility and care should be taken to avoid it. REFERENCES: US Air Force. NATO Handbook on Medical Aspects of NBC Defensive Operations. Bolling AFB: Office of the USAF Surgeon General, USAF Pamphlet 161-3, 1973:4-3, 4-4.

Question: Which of the following is NOT a strategy parents and caregivers can employ to help prevent toy-related injuries?

a. Limit play groups to less than 5 children to avoid anger-related outbursts and injuries.
b. Children should use age appropriate toys.
c. Parents should directly supervise children when playing with balloons.
d. Parents should directly supervise children when using potentially dangerous household objects such as knives.
e. Parents should ensure the child is playing on an age appropriate environment.
Answer: a. Parents and caregivers can prevent toy-related injuries by making informed decisions about the correct type of toy to buy and periodically monitoring children's use of toys to ensure that the toys are being used safely. Limiting of a child's playgroup size does not accomplish this goal. REFERENCES: Toy-related Injuries Among Children and Teenagers-US 1996. MMWR 1997;46:1185-1189.

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