BACKGROUND: Individuals who experience motion sickness (MS) frequently mention the presence of smells in the environment as a factor favoring the occurrence of MS symptoms. The aim of the present work was to compare olfactory function in MS sensitive (MS+) and insensitive (MS-) subjects.METHODS: Olfactory testing included determination of odor detection thresholds, subjective evaluation of the quality (intensity, hedonicity, and familiarity) of three different odorants (limonene, isovaleric acid, and petrol) as well as measures of skin conductance responses to these three odorants.RESULTS: Results showed no difference in olfactory sensitivity between MS+ and MS- subjects. However, findings of both subjective (odor quality self-rating) and objective (psychophysiological responses) measures did reveal that the affective response to petrol odor was significantly different in MS+ and in MS- subjects. Indeed, on a scale from 0 (unpleasant) to 10 (pleasant) MS+ subjects rated petrol odor as more unpleasant (mean = 2.52) than MS- subjects (mean = 4.15) and rise-time of skin conductance responses to petrol odor was significantly longer in MS+ (mean = 5.98 s) compared to MS- subjects (mean = 3.22 s).DISCUSSION: Our study delves further into the knowledge of the relationship between motion sickness and olfaction by demonstrating a modified olfactory perception in motion sickness sensitive subjects at both the psychophysical and psychophysiological levels.Jacquot L, Millot J-L, Paillard AC. Assessment of olfactory perception in individuals with motion sickness. Aerosp Med Hum Perform. 2018; 89(5):428–433.

INTRODUCTION: Precooling with ice slurry ingestion attenuates the increase in rectal temperature (T_re) during subsequent running and cycling. It remains unclear how this cooling method affects physiological strain during work while wearing protective garments. This study investigated the effect of ice slurry ingestion on physiological strain during work in hot conditions while wearing firefighter protective clothing.METHODS: In three counterbalanced trials, eight men (mean ± SD; age = 21 ± 2 yr, height = 179.5 ± 3.5 cm, mass = 79.1 ± 4.1 kg, body fat = 11.4 ± 3.7%) wore firefighter protective clothing and walked (4 km · h⁻¹, 12% incline, ∼7 METs) for 30 min in hot conditions (35°C, 40% RH). Every 2.5 min, subjects ingested 1.25 g · kg⁻¹ (relative total: 15 g · kg⁻¹, absolute total: 1186.7 ± 61.3 g) of a tepid (22.4 ± 1.7°C), cold (7.1 ± 1.5°C), or ice slurry (-1.3 ± 0.2°C) beverage.RESULTS: Heart rates (HR) were lower with ice slurry ingestion compared to both fluid trials starting 5 min into exercise (tepid = 158 ± 14, cold = 157 ± 11, ice slurry = 146 ± 13 bpm) and persisting for the remainder of the bout (min 30: tepid = 196 ± 10, cold = 192 ± 10, ice slurry = 181 ± 13 bpm). T_re was lower with ice slurry ingestion compared to cold and tepid trials (min 5: tepid = 37.17 ± 0.38, cold = 37.17 ± 0.39, ice slurry = 37.05 ± 0.43°C; min 30: tepid = 38.15 ± 0.29, cold = 38.31 ± 0.36, ice slurry = 37.95 ± 0.32°C). The physiological strain index (PSI) was lower with ice slurry ingestion compared to fluid trials starting at min 5 (tepid = 3.8 ± 0.7, cold = 3.8 ± 0.6, ice slurry = 3.0 ± 0.5) and remained lower throughout exercise (min 30: tepid = 8.2 ± 0.6, cold = 8.3 ± 0.9, ice slurry = 6.9 ± 1.2).DISCUSSION: A large quantity of ice slurry ingested under non-compensable heat stress conditions mitigated physiological strain during exercise by blunting the rise in heart rate and rectal temperature.Ng J, Wingo JE, Bishop PA, Casey JC, Aldrich EK. Ice slurry ingestion and physiological strain during exercise in non-compensable heat stress. Aerosp Med Hum Perform. 2018; 89(5):434–441.

INTRODUCTION: Lumbar disc herniation (LDH) is a common injury among active duty service members resulting in missed duty hours and limited duty status. Little is known about the current burden of disease and risk factors for LDH among military rotary wing aviators.METHODS: A query was made using the Defense Medical Epidemiology Database (DMED), including patient encounters for the U.S. Military from 2006–2015 using the ICD-9 code for LDH. Incidence rates were calculated for patients with the occupation of helicopter pilot and stratified by age, gender, and branch of service, then compared to matched controls using a Poisson regression analysis. Then, data from a 17-yr period were examined for long term trends.RESULTS: We identified 1218 cases of LDH among 141,383 person-years among helicopter pilots, yielding a 1.22-fold higher incidence rate compared to controls. Significant risk factors identified after Poisson regression analysis were age greater than 30 yr old and Army service branch affiliation. Male gender was not found to be a significant risk factor. Long term data revealed a 2.6-fold increased incidence of LDH among helicopter pilots since 1997.DISCUSSION: We identified significant increased risk of LDH in rotary wing pilots as compared to their nonpilot peers. Among rotary wing pilots, the incidence of this condition has increased, with both increasing pilot age and Army branch affiliation identified as risk factors. This information will allow targeted prevention strategies and further investigation to potential aircraft-specific causes of increased risk in Army pilots.Knox JB, Deal JB Jr, Knox JA. Lumbar disc herniation in military helicopter pilots vs. matched controls. Aerosp Med Hum Perform. 2018; 89(5):442–445.

BACKGROUND: There is only scant information on the influence of the hypobaric environment on luting agents and their efficacy on dental crown cementation. The objective of this study was to provide data on the retentive characters of two cements commonly used on implant abutment surfaces both under normal and under hypobaric conditions.METHODS: There were 56 implant abutments supplied with CAD/CAM milled zirconia oxide crowns. 1) A zinc phosphate cement (ZP), and 2) a resin-modified glass ionomer cement (RMGI), each mixed either A) manually or B) by means of automix capsules, were used for cementation. The cemented crowns of the 4 × 2 subgroups were either kept on the ground or were transported in an aircraft at altitudes up to 13,730 m (45,045.9 ft; N = 28 each), thus being subjected to the pressure changes (80×) every aircrew member or frequent flyer is exposed to. All cemented crowns were stored in climatized boxes during the experimental phase.RESULTS: Hand-mixing of ZP resulted in a significant reduction of mean (± SD) retention forces (581.6 ± 204.5 N) when compared to the control group on the ground (828.4 ± 147.9 N). Automixed ZP (931.9 ± 134.4 N in flight; 996.0 ± 107.4 N on the ground) and RMGI subgroups (ranging from 581.0 N ± 114.3 N to 662.4 N ± 92.5 N) were not affected by hypobaric conditions.DISCUSSION: When treating patients frequently exposed to hypobaric environments, automixing of ZP would seem favorable, while manual mixing should be avoided. RMGI is considered suitable and is not influenced by hand-mixing or barometric pressure changes.Kielbassa AM, Müller JAG. Hypobaric conditions and retention of dental crowns luted with manually or automixed dental cements. Aerosp Med Hum Perform. 2018; 89(5):446–452.

INTRODUCTION: Allergic rhinitis is a prevalent condition warranting special aeromedical consideration due to its potential for acute and painful manifestations involving the middle ear or paranasal sinuses during rapid barometric pressure changes. Although second generation antihistamines and intranasal steroids are safe and effective treatments for this common condition, aeromedical management varies.METHODS: An aeromedical policy review of 14 public access civil and military data repositories was undertaken. Policy within a convenience sample of nine countries (Australia, Canada, Croatia, France, New Zealand, Norway, Sweden, United Kingdom, and United States) was further ascertained through subject matter expert consultation. A convenience sample of recent primary care review articles and ENT guidelines were reviewed in order to substantiate the evidence basis for aeromedical practices.RESULTS: Policies range from disqualification of flight applicants with any history of allergic rhinitis to the authorization of short-term, select undeclared medication use for the management of mild symptoms, with military authorities applying a more conservative approach. A range of intranasal and oral therapies are approved and requirements for waiver vary across most authorities.DISCUSSION: Variation in practices must be considered when managing flight crews as part of military coalition peacetime and combat operations, as well as for international civil aviation missions conducted in support of natural disaster relief, rescue, and other stability efforts. Standardization of approved therapies for allergic rhinitis could be a useful starting point for the harmonization of aeromedical global policies in the future. Beneficial national specific policy updates may be undertaken on the basis of international experience.Powell-Dunford N, Reese C, Bushby A, Munkeby BH, Coste S, Pezer VL, Rosenkvist L. The aeromedical management of allergic rhinitis. Aerosp Med Hum Perform. 2018; 89(5):453–463.

INTRODUCTION: Fatigue plays a critical role in mission success due to its effect on a number of performance variables. The purpose of this study was to gauge the extent to which U.S. Army aviators experience subjective fatigue on a regular basis presently as well as their perceptions of their own sleep quality, quantity, and daytime sleepiness. This information is valuable for prioritizing future research lines with respect to injury prevention and fatigue management as well as updating policy.METHODS: An anonymous, 125-item questionnaire was completed by 214 U.S. Army aviators. A subset of those items (15 questions related to fatigue) are reported in this study. Subjects were primarily male and the mean age was 33 yr.RESULTS: Results suggest that the majority of subjects sleep less than the recommended 8 h per night and nearly half of them report sleeping less than their own preferred amount of sleep. Approximately 40% of the sample indicated that they believed fatigue to be a widespread problem in the U.S. Army aviation community.DISCUSSION: Overall, the findings identified factors contributing to fatigue and performance degradation currently experienced by those sampled in this study. Specifically, inconsistent shiftwork, less than optimal levels of rest, and poor sleep quality in the field were identified. Compared to past research, the extent to which fatigue is perceived to be a widespread problem is significantly lower than reported 15 yr prior.Kelley AM, Feltman KA, Curry IP. A survey of fatigue in army aviators. Aerosp Med Hum Perform. 2018; 89(5):464–468.

BACKGROUND: Metabolic syndrome is a cluster of metabolic abnormalities that can affect a pilot’s health. The aim of the study was to establish the prevalence of metabolic syndrome in the German Air Force.METHODS: All German military pilots are examined regularly at the German Air Force Center of Aerospace Medicine. The data are stored in a special database designed for that purpose. A database query was performed. The following parameters were analyzed: age, duration of observation, BMI, physical working capacity (PWC 170), blood pressure, erythrocyte sedimentation rate (ESR), cholesterol, HDL-cholesterol, triglycerides, fasting blood glucose.RESULTS: For the time period of 1996 to 2016, the data of 12,014 pilots were analyzed. Overall prevalence of metabolic syndrome was 0.9% (95% CI 0.7–1.1%). Participants with a metabolic syndrome had a significantly higher BMI (28.3 vs. 24.1), lower PWC 170 (2.3 vs. 2.7) and higher ESR (4.7 vs. 3.6, mm first hour) than the healthy participants. On average, BMI gradually increased over the years and PWC 170 decreased over the years in all participants. There was no increase of the prevalence of metabolic syndrome during the observational period.CONCLUSION: Prevalence of metabolic syndrome among German Military pilots is low and is not connected to the duration of service.Weber F. Metabolic syndrome in the German Air Force: prevalence and associations with BMI and physical fitness. Aerosp Med Hum Perform. 2018; 89(5):469–472.

BACKGROUND: Diphyllobothriasis is estimated to afflict 10–20 million people worldwide; however, this is the first case reported in a United States military aviator. Among the largest parasites of humans, the “fish tapeworm” grows from 2–15 m in length, can live >20 yr in the intestines, and is contracted through consumption of uncooked, unfrozen freshwater or anadromous fish species.CASE REPORT: A 32-yr-old male F-22 pilot presented with mild stomach cramping, bloating, nausea, and intermittent loose stools. Symptoms were relieved with bismuth subsalicylate until several days later when the patient, during otherwise normal bowel movements, extracted multiple broken segments of tapeworm. Although physically asymptomatic, he was psychologically disturbed. Based on the large number of ova with characteristic shape, size, color, and operculum, coupled with the flattened body, yellowish coloration, and rectangular proglottids with centrally located “rosette” uteri, he was diagnosed with diphyllobothriasis (likely D. latum or D. nihonkaiense). Successful treatment with a single oral dose of praziquantel (>10 mg · kg⁻¹) was confirmed by negative stool examination over 60 d posttreatment. He likely contracted the parasite from ingesting salmon sushi or sashimi while previously stationed in Japan.DISCUSSION: Despite only mild physical symptoms, the pilot’s psychological distress and distraction from knowing about the meters-long tapeworm was significant. Prompt treatment was paramount to resumption of military operations. Aviators should be educated and encouraged to eat only well-cooked or previously frozen fish, especially when indulging in cultural cuisine.Kasteler SD. Diphyllobothriasis in a U.S. military aviator. Aerosp Med Hum Perform. 2018; 89(5):473–477.

BACKGROUND: The spectrum of altitude decompression sickness (DCS) is evolving as more cases of atypical pressure fluctuations occur. This ongoing change makes it a difficult condition to diagnose and even more difficult to identify. Both Flight Surgeons and Undersea Medical Officers (UMOs) must keep DCS on the differential. These two cases describe altitude DCS after unique pressure patterns, with one at a markedly lower than expected altitude for DCS.CASE REPORT: Both cases occurred in the F/A-18C and resulted in DCS requiring hyperbaric chamber treatment. The aviator in case 1 experienced an over-pressurization to an unknown depth with a subsequent rapid decompression during a carrier approach at 600 ft (182.9 m) above sea level. The aviator in case 2 experienced cabin pressure fluctuations between 9000 ft (2743.2 m) and 18,000 ft (5486.4 m). Both cases demonstrate the progression of DCS after partial treatment on ground-level oxygen therapy, and the case sequence illustrates how evaluations and protocols changed with experience.DISCUSSION: Decompression sickness is difficult to identify since it does not have a diagnostic test. These cases were even more difficult because of subtle exam findings, reliance on subjective symptoms, and atypical pressure profiles. Environmental, physiological, and psychosocial factors specific to the aviation community can delay the diagnosis and treatment. Descending in altitude and using in-flight emergency oxygen or ground-level oxygen partially treats and masks symptoms for both the aviator and the physician. The Flight Surgeons’ integration within the squadron and collaboration with UMOs is important to identify the first signs of DCS and decrease time to treatment.Lee KJ, Sanou AZ. Decompression sickness in the F/A-18C after atypical cabin pressure fluctuations. Aerosp Med Hum Perform. 2018; 89(5):478–482.

BACKGROUND: Review of injuries resulting from aircraft accidents and analysis of their mechanisms have proved helpful in generating and implementing survival-related improvements. Ideally, such information should be correlated with seat belt type and use, as well as any brace position adopted. This information should be recorded and made publicly available to future researchers.METHODS: Members of IBRACE have developed two questionnaires to assist accident / cabin-safety investigators to record this information in an integrated consistent manner.RESULTS: One questionnaire relates to the survivors and one to the deceased.DISCUSSION: IBRACE members hope that these questionnaires will assist the investigation of future aircraft accidents.Davies JM, Wallace WA, Colton CL, Yoo KI, Maurino M. Two aviation accident investigation questionnaires for passenger and crew survival factors and injuries. Aerosp Med Hum Perform. 2018; 89(5):483–486.

Franz A. You’re the flight surgeon: Hodgkin lymphoma. Aerosp Med Hum Perform. 2018; 89(5):487–490.