INTRODUCTION: Compression garments tend to be difficult to don/doff, due to their intentional function of squeezing the wearer. This is especially true for compression garments used for space medicine and for extravehicular activity (EVA). We present an innovative solution to this problem by integrating shape changing materials—NiTi shape memory alloy (SMA) coil actuators formed into modular, 3D-printed cartridges—into compression garments to produce garments capable of constricting on command.METHODS: A parameterized, 2-spring analytic counterpressure model based on 12 garment and material inputs was developed to inform garment design. A methodology was developed for producing novel SMA cartridge systems to enable active compression garment construction. Five active compression sleeve prototypes were manufactured and tested: each sleeve was placed on a rigid cylindrical object and counterpressure was measured as a function of spatial location and time before, during, and after the application of a step voltage input.RESULTS: Controllable active counterpressures were measured up to 34.3 kPa, exceeding the requirement for EVA life support (29.6 kPa). Prototypes which incorporated fabrics with linear properties closely matched analytic model predictions (4.1%/−10.5% error in passive/active pressure predictions); prototypes using nonlinear fabrics did not match model predictions (errors >100%). Pressure non-uniformities were observed due to friction and the rigid SMA cartridge structure.DISCUSSION: To our knowledge this is the first demonstration of controllable compression technology incorporating active materials, a novel contribution to the field of compression garment design. This technology could lead to easy-to-don compression garments with widespread space and terrestrial applications.Holschuh BT, Newman DJ. Morphing compression garments for space medicine and extravehicular activity using active materials. Aerosp Med Hum Perform. 2016; 87(2):84–92.

BACKGROUND: Although several exercise systems have been developed to mitigate the physiological deconditioning that occurs in microgravity, few have the capacity to positively impact multiple physiological systems and still meet the volume/mass requirements needed for missions beyond low Earth orbit. The purpose of this study was to test the gravity-independent Multi-Mode Exercise Device (M-MED) for both resistance (RE) and aerobic (AE) training stimuli.METHODS: Eight men and nine women (mean age 22.0 ± 0.4 yr) completed 5 wk of training on the M-MED: RE 4 × 7 squats 2 d/wk, and AE 4 × 4-min rowing bouts at ∼90% Vo_2max 3 d/wk. Pre- and post-training data collection included an aerobic capacity test, MR imaging, strength testing, and vastus lateralis muscle biopsy.RESULTS: Vo_2max increased 8%, 3RM strength 18%, and quadriceps femoris cross-sectional area (CSA) 10%. Knee extensor strength increased at all isokinetic speeds tested. Subjects also demonstrated improved fatigue resistance in knee extension. At the cellular and molecular level, the biopsy revealed increases in mixed myofiber CSA (13%), citrate synthase activity (26%), total RNA concentration (24%), IGF-I mRNA (77%), and Type IIa myosin heavy chain (MHC) mRNA (8%), and a concomitant decrease in Type IIx MHC mRNA (−23%). None of the changes were gender-specific.DISCUSSION: Both the functional outcomes and biomarker changes indicate that a very low volume of M-MED exercise results in robust adaptation in the cardiovascular and musculoskeletal systems. The M-MED has the potential to provide a wide range of countermeasure exercises and should be considered for testing in ground-based spaceflight simulation.Owerkowicz T, Cotter JA, Haddad F, Yu AM, Camilon ML, Hoang TN, Jimenez DJ, Kreitenberg A, Tesch PA, Caiozzo VJ, Adams GR. Exercise responses to gravity-independent flywheel aerobic and resistance training. Aerosp Med Hum Perform. 2016; 87(2):93–101.

INTRODUCTION: Wearable accelerometers have become ubiquitous in the fields of exercise physiology and ambulatory hospital settings. However, these devices have yet to be validated in extreme operational environments. The objective of this study was to correlate the gravitational forces (G forces) detected by wearable accelerometers with the G forces detected by high performance aircraft.METHODS: We compared the in-flight G forces detected by the two commercially available portable accelerometers to the F/A-18 Carrier Aircraft Inertial Navigation System (CAINS-2) during 20 flights performed by the Navy’s Flight Demonstration Squadron (Blue Angels). Postflight questionnaires were also used to assess the perception of distractibility during flight.RESULTS: Of the 20 flights analyzed, 10 complete in-flight comparisons were made, accounting for 25,700 s of correlation between the CAINS-2 and the two tested accelerometers. Both accelerometers had strong correlations with that of the F/A-18 G_z axis, averaging r = 0.92 and r = 0.93, respectively, over 10 flights. Comparison of both portable accelerometer’s average vector magnitude to each other yielded an average correlation of r = 0.93. Both accelerometers were found to be minimally distracting.DISCUSSION: These results suggest the use of wearable accelerometers is a valid means of detecting G forces during high performance aircraft flight. Future studies using this surrogate method of detecting accelerative forces combined with physiological information may yield valuable in-flight normative data that heretofore has been technically difficult to obtain and hence holds the promise of opening the door for a new golden age of aeromedical research.Rice GM, VanBrunt TB, Snider DH, Hoyt RE. Wearable accelerometers in high performance jet aircraft. Aerosp Med Hum Perform. 2016; 87(2):102–107.

INTRODUCTION: Pilots’ vision and flight performance may be impeded by spatial disorientation and high altitude hypoxia. The Coriolis illusion affects both orientation and vision. However, the combined effect of simultaneous Coriolis illusion and hypoxia on saccadic eye movement has not been evaluated.METHOD: A simulated flight was performed by 14 experienced pilots under 3 conditions: once under normal oxygen partial pressure and twice under reduced oxygen partial pressures, reflecting conditions at 5000 m and 6000 m (16,404 and 19,685 ft), respectively. Eye movements were evaluated with a saccadometer.RESULTS: At normal oxygen pressure, Coriolis illusion resulted in 55% and 31% increases in mean saccade amplitude and duration, respectively, but a 32% increase in mean saccade frequency was only noted for saccades smaller than the angular distance between cockpit instruments, suggesting an increase in the number of correction saccades. At lower oxygen pressures a pronounced increase in the standard deviation of all measures was noticed; however, the pattern of changes remained unchanged.DISCUSSION: Simple measures of saccadic movement are not affected by short-term hypoxia, most likely due to compensatory mechanisms.Kowalczuk KP, Gazdzinski SP, Janewicz M, Gąsik M, Lewkowicz R, Wyleżoł M. Hypoxia and Coriolis illusion in pilots during simulated flight. Aerosp Med Hum Perform. 2016; 87(2):108–113.

BACKGROUND: Few studies have examined the spatial characteristics of missing aircraft in actual distress. No previous studies have looked at the distance from the last radar plot to the crash site. The purpose of this study was to characterize this distance and then identify environmental and flight characteristics that might be used to predict the spatial relationship and, therefore, aid search and rescue planners.METHODS: Detailed records were obtained from the U.S. Air Force Rescue Coordination Center for missing aircraft in distress from 2002 to 2008. The data was combined with information from the National Transportation Safety Board (NTSB) Accident Database. The spatial relationship between the last radar plot and crash site was then determined using GIS analysis.RESULTS: A total of 260 missing aircraft incidents involving 509 people were examined, of which 216 (83%) contained radar information. Among the missing aircraft the mortality rate was 89%; most occurred in mountainous terrain (57%); Part 91 flight accounted for 95% of the incidents; and 50% of the aircraft were found within 0.8 nmi from the last radar plot. Flight characteristics, descent rate, icing conditions, and instrument flight rule vs. visual flight rule flight could be used to predict spatial characteristics.CONCLUSIONS: In most circumstances, the last radar position is an excellent predictor of the crash site. However, 5% of aircraft are found further than 45.4 nmi. The flight and environmental conditions were identified and placed into an algorithm to aid search planners in determining how factors should be prioritized.Koester RJ, Greatbatch I. Missing aircraft crash sites and spatial relationships to the last radar fix. Aerosp Med Hum Perform. 2016; 87(2):114–121.

INTRODUCTION: The frequency and distribution of gastrointestinal (GI) disease in the population of active duty Air Force pilots is poorly understood, even though GI illness can temporarily or permanently lead to disqualification from flying duties. Better understanding of GI disease within this population could yield considerable operational risk and human performance insight and provide data to use in assessing the effectiveness of current medical standards related to flight training and flying duties.METHODS: A dataset reflecting inpatient and outpatient healthcare visits from 2001 through 2013 was developed and reviewed. Gastrointestinal illness was grouped into 18 subcategories of disease, and the frequency and distribution of visits for these categories were tallied. The total burden of GI illness over the target dates was compared between pilots, nonpilot aircrew/special operational duty personnel, and nonaircrew/nonspecial duty personnel.RESULTS: Esophageal disease and dyspeptic conditions were the two most frequently encountered diagnoses among all three population groups, comprising almost 50% of the gastrointestinal diagnoses in age and gender-matched samples of all three populations. The overall burden of disease over the total timeframe of the study was not statistically different in the three populations, with a median of four encounters per person for GI disease. Of interest, the total burden of disease increased over the course of the study period in all populations, driven in large measure by increases in esophageal disease and dyspeptic conditions.DISCUSSION: The general distribution and overall burden of GI disease in populations of Air Force pilots, nonpilot aircrew/special operational duty personnel, and nonaircrew/nonspecial duty personnel were similar. The increase in esophageal and dyspeptic conditions over time warrants further attention.Storms PR, Kinchen MJ. Gastrointestinal disease in pilots, 2001–2013. Aerosp Med Hum Perform. 2016; 87(2):122–127.

BACKGROUND: Space motion sickness (SMS) remains a troublesome problem during spaceflight. The subjective vertical (SV) conflict theory postulates that all motion sickness provoking situations are characterized by a condition in which the SV sensed from gravity and visual and idiotropic cues differs from the expected vertical. This theory has been successfully used to predict motion sickness in different vehicles on Earth.METHOD: We have summarized the most outstanding and recent studies on the illusions and characteristics associated with spatial disorientation and SMS during weightlessness, such as cognitive map and mental rotation, the visual reorientation and inversion illusions, and orientation preferences between visual scenes and the internal z-axis of the body.RESULTS: The relationships between the SV and the incidence of and susceptibility to SMS as well as spatial disorientation were addressed.CONCLUSION: A consistent framework was presented to understand and explain SMS characteristics in more detail on the basis of the SV conflict theory, which is expected to be more advantageous in SMS prediction, prevention, and training.Chen W, Chao J-G, Wang J-K, Chen X-W, Tan C. Subjective vertical conflict theory and space motion sickness. Aerosp Med Hum Perform. 2016; 87(2):128–136.

OBJECTIVE: Divers are vulnerable to barodontalgia (atmospheric pressure change related dental pain), which may jeopardize diving safety and mission completion. Our aim was to investigate the experience of barodontalgia among western military divers.METHODS: French Armed Forces diving personnel were asked to answer a structured questionnaire including questions regarding their oral health, diving and career features, and barodontalgia while diving. For analysis, the participants were divided into commando/clearance divers (Group A) and ship divers (Group B).RESULTS: All the requested 1389 divers agreed to participate in the study (100%) and 1317 divers (94.8%) who fully completed the questionnaire were included in the analysis. Of these 1317 individuals, 96 (7.3%) suffered from at least 1 episode of barodontalgia while diving, with a total of 119 episodes of barodontalgia. Barodontalgia was more frequent in the upper (62.2%) than the lower dentition (37.8%) (OR = 2.7; 95% CI, 1.6–4.5) and appeared more common during descent (77.3%) than ascent (22.7%) (OR = 11.6; 95% CI, 6.3–31.3). Barodontalgia experience was higher in divers who have an examination less than once per year (14.5%) in comparison to divers who usually have a dental examination once a year or more (6.3%) (OR = 2.5; 95% CI, 1.5–4.2).DISCUSSION: Barodontalgia mostly appeared in the maxilla and during descent; therefore, a great role for barosinusitis in the etiology of oral pain while diving may be suggested. The infrequent experience of barodontalgia in divers who routinely visit the dentist once a year or more suggests that the risk of barodontalgia might decrease with the maintenance of a good oral status.Gunepin M, Derache F, Blatteau J-E, Nakdimon I, Zadik Y. Incidence and features of barodontalgia among military divers. Aerosp Med Hum Perform. 2016; 87(2):137–140.

BACKGROUND: Presented is a rare case of transient unilateral facial nerve paralysis occurring in a pilot while on initial ascent in an F-16CM. This pathology is sporadically observed in the diving community, but rarely described in military or civil aviation. This case was particularly unusual in its promptness of onset, rapid recovery, and its association with vertigo.CASE REPORT: This case report describes a previously healthy 26-yr-old F-16 pilot who experienced ear block and subsequent unilateral facial paralysis while on initial ascent. This was relieved quickly after clearing the affected ear without any neurological sequelae. A second episode was associated with vertigo in addition to the ear block and facial symptoms. Both episodes were separated by 3 d.DISCUSSION: Barotrauma to the facial nerve via an uncovered or “dehiscent” facial nerve canal was suggested by the clinical course, computed tomography, and confirmed by expert consultation. Making the diagnosis in an aviator, especially the military aviator, is important for safety of flight, to avoid unwarranted diagnostics, and to minimize operational impact. A mechanism for the aviator’s associated vertigo is suggested.Wimmer MS, Ali TY. Transient unilateral facial nerve baroparesis with vertigo on ascent in the F-16CM. Aerosp Med Hum Perform. 2016; 87(2):141–143.

BACKGROUND: Patients with respiratory disease are at risk of excessive hypoxemia in the hypobaric commercial aircraft cabin environment, and the consensus is that this is easily corrected with supplementary oxygen. However, despite the risks of hypercapnia with increasing inspired oxygen in some patients being well established, this issue is not currently addressed in medical guidelines for air travel.CASE REPORT: A 76-yr-old woman with chronic type 2 respiratory failure underwent hypoxic challenge testing (HCT) to assess in-flight oxygen requirements. She is stable on home ventilation, and baseline arterial blood gases showed mild hypoxemia (P_ao₂ 9.12 kPa), normal P_aco₂ (5.64 kPa) and pH (7.36) with 98% S_pO₂. HCT was performed delivering 15% F_Io₂ via a mask, and the patient desaturated to < 85%. HCT blood gases revealed significant hypoxemia (P_ao₂ < 6.6 kPa), indicating in-flight oxygen. Continuous oxygen at 2 L · min⁻¹ via nasal cannula corrected the hypoxia, although P_aco₂ increased to 6.9 kPa with reduction in pH to the threshold of severe respiratory acidosis (pH 7.25). The patient was advised against flying due to hypoxemia during HCT and the precipitous drop in pH on oxygen.DISCUSSION: It is possible to hyperoxygenate patients with type 2 respiratory failure in flight with the minimum level of supplementary oxygen available on many aircraft. In these cases P_aco₂ and pH should be scrutinized during HCT before recommending in-flight oxygen. No current guidelines discuss the risk of hypercapnia from in-flight oxygen; it is therefore recommended that this be addressed in future revisions of medical air travel guidelines, should further research indicate it.Spurling KJ, Moonsie IK, Perks JL. Hypercapnic respiratory acidosis during an in-flight oxygen assessment. Aerosp Med Hum Perform. 2016; 87(2):144–147.

Brown MR. You’re the flight surgeon: vestibular neuritis. Aerosp Med Hum Perform. 2016; 87(2):150–152.

Puchta P. You’re the flight surgeon: erectile dysfunction. Aerosp Med Hum Perform. 2016; 87(2):152–155.