Simulator sickness in U.S. Navy flight simulators

Flight simulators have become a major factor in pilot training. A general finding from Navy research on simulator design is that equipment features that offer faithful representation improve pilot performance and promote pilot acceptance. To the extent that an aircraft produces motion sickness, its simulator should induce the same result. However, reports of simulator sickness appear to be increasing and a shortcoming in simulation is implied when these effects occur in simulators during maneuvers that do not occasion them in the aircraft. This article presents incidence data from surveys of the 10 simulators at 6 different Naval/Marine Corps Air Stations. Approximately 1,200 simulator flights were recorded. Some severe motion sickness symptoms were recorded and some simulators induced unsteadiness afterwards. Individuals experiencing effects may be at risk if they drive themselves home or return to demanding activities at work. The simulators which exhibited the highest incidences of sickness were helicopter simulators with cathode ray tube (CRT) infinity optics and six-degrees-of-freedom moving base systems. Of those studied, fixed-wing, fixed-base, dome displays had relatively low incidence of simulator sickness.     

A new generation of U.S. Army flight helmets.

Head injuries are the most common cause of fatal injury in helicopter crashes. For over 80 years, the U.S. Army has used crash investigation studies to redesign flight helmets. This paper describes the evolution of the new fielded U.S. Army helmet, the Sound Protection Helmet No. 4B (SPH-4B), and compares its protective features to its predecessors, especially the SPH-4. A major contribution to the helmet design process was made by the Aviation Life Support Equipment Retrieval Program (ALSERP), a functional program at the U.S. Army Aeromedical Research Laboratory (USAARL). ALSERP has analyzed more than 500 helmets involved in crash events since 1972. Based on these studies of critical safety factors, the Army has developed and deployed the SPH-4B, a new helmet with improved energy absorption, retention, and stability.     

Laboratory and flight tests of medical equipment for use in U.S. Army Medevac helicopters

When used in an air medical setting, medical equipment designed for use in hospitals can fail from the stresses of in-flight use, or they interfere with critical rotor-wing aircraft systems. From January 1989 to June 1992, 34 medical devices, including monitor/defibrillators, infusion pumps, vital-signs monitors, ventilators and infant transport incubators, were tested under extreme conditions of temperature, humidity, altitude and vibration (MIL-STD 810D). Electromagnetic emissions and susceptibility were measured (MIL-STD 461C and 462), and human factors were evaluated. The devices were flight tested in a UH-60 MEDEVAC helicopter. Thirty-two percent of the medical devices failed at least one environmental test, and 91% of the devices failed to meet electromagnetic interference standards. Failures included excess conducted and radiated emissions and susceptibility to radiated emissions. Five (15%) of the devices were judged unsuitable for use in the UH-60 MEDEVAC helicopter. Testing is critical to discover the ability of a medical device to perform in the harsh rotor-wing MEDEVAC environment. Failure of a device or interference with aircraft systems can result in loss of a patient or aircrew.     

A survey of U.S. Army aeromedical equipment

Medical equipment is necessary to support patients requiring air transportation, but it may not be compatible with the aviation environment. Aircraft systems may cause errors in the functioning of medical equipment, or that equipment may interfere with the aircraft. Medical equipment has been tested, primarily for fixed wing aircraft, to military standards by the U.S. Air Force. This study reports 1986 and 1987 surveys which document the use of such equipment on U.S. Army medical evacuation aircraft and compares items in current use to the U.S. Air Force's test results. Of the 115 different nonissue items reported in use, 32 have been formally evaluated, and 9 of those were judged unacceptable for use on aircraft. Only two items reported in the survey were tested inflight in helicopters. The remaining 83 items have not been tested. Helicopters have unique requirements, and the U.S. Army has begun a program to evaluate medical equipment for helicopter use.     

Coping behaviors of U.S. Army flight nurses in World War II: an oral history

War is a universally stressful event that may tax or exceed one's ability to cope. This study addressed how flight nurses with the U.S. Army Air Forces in World War II coped with war; the purpose was to analyze data obtained from oral histories of 25 flight nurses who served in World War II. Content analysis of the data revealed two levels of coping; a taxonomy of coping efforts was developed for each level. The microscopic level consisted of specific external and internal demands occurring during the war that necessitated coping. The macroscopic level consisted of behavioral and cognitive efforts used to cope with the war in general. Findings suggest that the women perceived their wartime experience as a challenge rather than as a threat and were thus able to make the best of the stressful wartime situation.     

U.S. Army noncombat munitions injuries

OBJECTIVE: The object of this study was to determine the types of noncombat injuries secondary to munitions sustained by U.S. Army soldiers. METHODS: A retrospective review of all noncombat munitions injuries reported to the U.S. Army Safety Center from August 1989 to September 1996 was conducted. RESULTS: There were 742 incidents reported, resulting in 894 injured soldiers. The most common types of injuries were thermal burns, puncture wounds, and lacerations. The extremities were the most common anatomical location injured. The most common activities associated with injuries were combat training exercises, munitions firing, and rendering munitions safe. CONCLUSION: This study demonstrates a distinctive injury pattern for each category of munitions. Military readiness will be improved if we train all personnel to be familiar with the injury patterns and the most common situations associated with injury. By informing unit commanders which activities are associated with increased risk of injury, they may better prepare preventive measures to decrease the number of noncombat injuries.     

Preparing for war: lessons learned from U.S. Army flight nurses of World War II

The combat posture of today's military forces, and more specifically the emphasis on medical readiness for members of the health care professions, shows that the involvement of flight nurses in armed conflict cannot be ruled out. As part of a larger study of how military nurses cope with war, 25 former U.S. Army flight nurses of World War II were interviewed to learn how they coped with wartime situations they perceived as taxing or exceeding their resources. The purpose of this paper is to describe those aspects of wartime nursing that flight nurses interviewed would like to have been different and, subsequently, what advice they would offer today's flight nurses. The responses are examined within the theoretical framework of stress, appraisal, and coping developed by Lazarus and colleagues.     

A brief review of the epidemiology of HIV in the U.S. Army.

The Department of Defense has conducted extensive HIV testing for over 5 years. We summarize the epidemiology of the HIV infection in the total Army. While screening of civilian applicants effectively ensures seronegativity of enlistees, there are approximately 220 new HIV infections each year among active duty soldiers. High-risk demographic groups in the Army include single soldiers, males, those age 25-35, blacks, and Hispanics (including black and Hispanic females). While preventive efforts in the Army should reflect the higher risk experienced by these groups, all soldiers should be made aware of their susceptibility as the epidemic evolves to include more women and heterosexual men.     

Health assessment of U.S. Army Rangers

PURPOSE: Assess the health behaviors of U.S. Army Rangers, including their diet and physical activity patterns, and their use of alcohol, tobacco, and nutritional supplements. METHODS: Army Rangers (N=38) completed selected self-report and food frequency questionnaires, and anthropometric measures (height, weight, circumferences) were taken. RESULTS: Dietary patterns were collected from questionnaires that asked respondents to report the frequency of usual consumption from a list of foods over a period of 1 year. The data collected indicated a diet high in fat (38.0% of energy) and low in carbohydrates (41.9%). Protein intake (17.9% of energy) was consistent with recommendations for endurance and strength training athletes. Hours engaged in physical activity averaged 12 per week. Overall, 76% of the volunteers reported using alcohol on a regular basis, and 52.6% used some form of tobacco: 50% reported using either snuff or chewing tobacco. The use of supplements was high with 13% taking creatine and ephedrine products on a regular basis. CONCLUSION: Although physical activity patterns indicated a high level of activity, dietary and other health behaviors, such as smoking, alcohol use, and patterns of supplement use, suggest that health education programs may be important in this select Army population.     

Hereditary hemochromatosis among U.S. Army aviators

From 1988 to 1995, there were five reported cases of hemochromatosis among U.S. Army aviators. Three of the five are presented and discussed. The cases of hereditary hemochromatosis were discovered during unrelated work-ups or from investigation of a positive family history, and not by routine flying duty medical examinations. Recent studies show a prevalence of 5 per 1000 in the general population. This study shows the incidence among Army aviators is 0.296 per 1,000 aviator-years of observation. It is possible that there are cases presently undiagnosed in the Army aviation community. Without screening measures in place, the Army Aviation Branch has greater difficulty diagnosing and treating hereditary hemochromatosis. Heightened awareness and a high clinical index of suspicion are necessary to identify affected patients. Early detection and treatment is essential to prevent long-term end organ damage from iron deposition.     

The epidemiology of varicella hospitalizations in the U.S. Army

Varicella infections affect the U.S. Army, but the extent has not been quantified recently. We obtained 1990 to 1997 hospitalization data from the U.S. Army Medical Command and calculated rates using data from the Army Medical Surveillance Activity and the U.S. Army Training Command. There was a decline in the number and incidence of varicella hospitalizations for U.S. Army active duty soldiers from 1990 to 1997. Varicella incidence rates for active duty soldiers are significantly higher for females, blacks, those younger than 20 years, and those whose home of record were tropical island regions. Army initial entry training hospitalizations constitute 11.8% of active duty Army hospitalizations and have also declined. Varicella continues to affect the training and health of the U.S. Army; however, the impact has diminished over the years. A feasible approach to limit varicella in the U.S. Army is to target trainees for screening or vaccination. Refinement of this strategy should be determined from a follow-up cost-effectiveness analysis.     

Occupational back disability in U.S. Army personnel.

Musculoskeletal disorders represent a prevalent source of outpatient visits, lost work time, hospitalization, and disability in the military. Recent research has identified patterns among military occupations, gender, and musculoskeletal disability. Although back disorders accounted for a high percentage of all cases, little is known about the relationship between job type and disability in soldiers. The present study analyzed 41,750 disability cases to determine (1) prevalence of work-related back disability diagnoses, (2) specific jobs associated with greater risk of back disability, and (3) association among gender, job type, and disability. The results indicate that (1) lumbosacral strain and intervertebral disc syndrome represent the most prevalent diagnoses for back disability, (2) certain occupations were associated with higher back disability risk, and (3) specific jobs were identified in which females experienced higher rates of back disability than males. The nature of these high-risk jobs, and recent research on work disability factors in U.S. Army soldiers, suggest that a combination of ergonomic and individual/organizational psychosocial factors may play a role in the development, exacerbation, and maintenance of work disability. Future research that identifies specific job factors contributing to increased back disability risk should assist in the development of empirically based work site prevention programs to improve musculoskeletal health and readiness.     

U.S. Army dental emergency rates in Bosnia.

OBJECTIVE: Our objective is to report on overall dental emergency rates and rates by dental classification of a U.S. Army peacekeeping operation longer than 6 months in the year 2000. MATERIALS AND METHODS: This study was a retrospective cohort analysis of dental emergencies experienced by soldiers of the 3rd Armored Cavalry Regiment as a part of Stabilization Force VII. Before the deployment, all soldiers received dental examinations and the necessary dental treatment to make them class 1 or 2. A dental emergency was identified from field treatment records when a soldier presented to the clinic for a "sick call," emergency, or trauma visit. RESULTS: Retrospective review of the records identified 211 dental emergencies. Class 1 soldiers experienced 75 dental emergencies and class 2 soldiers experienced 136 emergencies. 3rd Armored Cavalry Regiment soldiers spent an average of 201.95 days deployed. The overall emergency rate was 156 dental emergencies per 1,000 soldiers per year. Class 1 and 2 rates were 121 and 185 dental emergencies per 1,000 troops per year, respectively. CONCLUSIONS: The results tend to confirm that dental emergencies continue to be a threat to overall readiness in deployed environments. Military planners need to ensure that the dental component of future forces are sufficient to care for the expected emergencies.     

Physiological evaluation of the U.S. Army one-handed tourniquet

OBJECTIVE: To provide a physiological assessment of the U.S. Army one-handed tourniquet (OHT). METHODS: An OHT was self-applied by 26 subjects, to maximal tolerable tightness, to the proximal arm or thigh under different conditions and positions, and the presence of blood flow was assessed using Doppler ultrasonography or occlusion plethysmography. RESULTS: Doppler sound was eliminated at the radial artery for all subjects with OHT application but was not stopped at the popliteal or dorsalis pedis artery for any subjects. The OHT reduced forearm blood flow by 79% but decreased leg blood flow by only approximately 50%, regardless of condition and position of application to the thigh. CONCLUSIONS: The OHT appears to effectively minimize blood flow in the arm but not in the lower extremities, and clinical assessment of blood flow disappearance by Doppler ultrasonography may underestimate the magnitude of actual blood flow to the limb.     

A survey of infants with neonatal sepsis in U.S. Army hospitals

Data on 109,312 singleton births at U.S. Army hospitals over 3 years were examined to determine differences in perinatal risk factors between infants with a diagnosis of sepsis confirmed by blood culture and those whose cultures remained negative. The incidence of confirmed sepsis (1.1/1000 live births) and the importance of perinatal complications and prematurity were consistent with other reported findings. No reliable indicators of bacteremia that could be used in conjunction with other clinical data were found. These findings support continued empiric therapy in infants at risk until infection can be verified by culture.     

Common peroneal nerve palsy in a UH-60 aviator.

A case of common peroneal nerve palsy in a UH-60 Blackhawk U.S. Army helicopter pilot is reported. A review of the literature revealed several reports of common peroneal nerve palsy, although there were no published reports of this injury secondary to performing flight duties in the UH-60 cockpit. A common practice among Blackhawk pilots is to brace the "collective" with their left knee, subjecting the common peroneal nerve to possible injury. This action should be considered as a possible cause of common peroneal nerve palsy in this select group of aviators.