INTRODUCTION: There are many potential human-machine interfaces for controlling complex robotics. However, restrictions in hardware, software, or human capability may pose limits on the input device degrees-of-freedom (DOF). This study examined effects on operational performance and strategy when interface DOF were limited, hypothesizing that different limitations on interface DOF would affect operator performance and technique.METHODS: Experiments used a Canadarm2 simulator with a dual-joystick interface adapted to operate under limited DOF conditions. Four interfaces were compared: full multiaxis (FM), limited translation (TL), limited rotation (RL), and without simultaneous translation/rotation or “non-bimanual” (NB). Subjects were tasked with operating the Canadarm2 in a simulated ISS control scenario to approach and grapple a moving cargo vehicle within a 90-s time limit.RESULTS: No significant difference was seen between FM and RL in task time or grapple success, and both were significantly different from TL. NB exhibited significantly increased task time from FM and RL, but no significant difference in grapple success rate. When rotating, subjects decreased time spent using multirotation for NB over FM.DISCUSSION: Similar performance between FM and RL suggests that restricting rotation may be preferred for interfaces with DOF design limits. For the NB condition, there was increased task time combined with decreased multirotation, highlighting potential use for NB in training for rotation efficiency. Two different strategies were observed during TL to overcome inability to visually track, align with, and move toward the target simultaneously. Examination of these techniques provides insight on which strategic elements were most critical for success.Hall SA, Stirling L. Human-machine interface degree of freedom effects on performance in space telerobotics. Aerosp Med Hum Perform. 2018; 89(12):1022–1030.

BACKGROUND: Excess postexercise oxygen consumption (EPOC) is an elevation in oxygen consumption (Vo₂) following exercise. Altitude decreases maximal oxygen uptake; however, studies are equivocal concerning the effect on resting metabolic rate. The EPOC response has not been studied with normobaric hypoxia. The purpose was to observe EPOC following constant-load cycling in normobaric hypoxia.METHODS: Subjects (N = 7 women, 7 men) completed resting metabolic rate testing between 06:00 and 08:30. Constant workload cycle exercise was performed (10 min at 100 W) while breathing air from an altitude simulator under the following conditions: normoxic control (CON), 3353 m (11,001 ft; HI), and 6401 m (21,001 ft; EXT). Subjects completed remaining conditions in a counterbalanced order. Upon completion, participants were reconnected to the metabolic system until a running 5-min average of Vo₂ values returned to baseline (EPOC duration). Magnitude was determined by summing the net oxygen consumption each minute during the EPOC period. Data were analyzed using 2 × 3 repeated measures ANOVA.RESULTS: No sex differences were detected for any variable. EPOC duration increased significantly at each simulated altitude increase (CON = 15.2 ± 1.9 vs. HI = 20.7 ± 1.7 min) (HI vs. EXT = 28.1 ± 2.6 min). Likewise, EPOC magnitude increased significantly at each simulated altitude (CON = 73.5 ± 9.9 vs. HI = 99.1 ± 9.3 ml O₂) (HI vs. EXT = 139.7 ± 14.3 ml O₂).DISCUSSION: The EPOC response to simulated altitude represents elevated caloric expenditure that must be accounted for. Individuals who are active at altitude must consider the increased caloric deficit despite a loss of appetite that is common with altitude exposure.Navalta JW, Tanner EA, Bodell NG. Acute normobaric hypoxia exposure and excess post-exercise oxygen consumption. Aerosp Med Hum Perform. 2018; 89(12):1031–1035.

INTRODUCTION: Sleep restriction may lead to decreased performance and increased accidents and errors. SPHERES, a small satellite testbed, was used to examine the effects of sleep restriction and situation awareness (SA) aids on a simulation of satellite operations.METHODS: Subjects (N = 8) were trained on SPHERES, then, in a randomized order cross-over design, had 3 d of sufficient sleep (SS) or 3 d of sleep restriction (SR) before a testing session. Subjects controlled two SPHERES satellites in a space debris avoidance scenario. Dependent measures included survival time, area covered by the satellites, and satellite motion perception.RESULTS: There were significant interaction effects of sleep protocol Order (SS or SR first) and sleep Condition (SS or SR) on survival time and area covered. Post hoc tests showed longer survival time for the second testing session if the Order was SS first (Mean = 56.1 s, Median = 44.0 s) as compared to SR first (Mean = 42.7 s, Median = 33.5 s). SS-first subjects received benefit from added SA cues of the augmented display in perceiving the satellite motion.DISCUSSION: These data support that learning in a well-rested state may support development of appropriate strategies for better performance. Subjects that were SS during the first session were better able to use added SA cues provided by the augmentation and may have then developed a better mental model of the task and the system. This pilot study suggests that training guidelines for operating multiple robotic assets should permit appropriate rest before and after training to assist in mental model development and task performance.Schneider J, Saenz-Otero A, Klerman E, Stirling L. Strategy development pilot study of sleep-restricted operators using small satellites with displays. Aerosp Med Hum Perform. 2018; 89(12):1036–1044.

INTRODUCTION: Clinical accuracy of pulse oximeters (giving S_po₂) is routinely tested down to an S_ao₂ of 70%, but lower oxygen saturations are often experienced during hypobaric hypoxia. Cerebral (S_co₂) and peripheral tissue (S_to₂) oxygen saturations can be measured using near infra-red spectroscopy. In a project simulating oxygen system failure during high altitude-high opening parachuting (HAHO), S_ao₂, S_po₂, S_co₂, and forearm S_to₂ were measured. The aim of the present analysis was to explore the agreement between S_ao₂ and the three noninvasive measurements of hypoxemia (S_po₂, S_co₂, and S_to₂).METHODS: Healthy volunteers from the Norwegian Special Operations Commando were studied in a hypobaric chamber as supplemental oxygen was removed at 301 hPa ambient pressure (30,000 ft) and recompressed at 25 hPa · min^-1 (1000 ft · min^-1) to ground level simulating a HAHO parachute flight. S_ao₂ was compared with S_po₂, S_co₂, and S_to₂ in scatterplots and Bland-Altman plots, calculating bias and limits of agreement (LOA).RESULTS: The bias ± LOA were: S_ao₂ vs. S_po₂: −5.8% ± 16, S_ao₂ vs. S_co₂: −3.4% ± 11, and S_ao₂ vs. S_to₂: 17% ± 30. The bias for S_ao₂ vs. S_po₂ was dependent on the range of values, and correcting for this with a sloped bias line reduced the LOA to ± 8.2%.DISCUSSION: There were wide limits of agreement between S_ao₂ and S_po₂. S_ao₂ and S_co₂ agreed better, whereas S_ao₂ and forearm S_to₂ had wide LOA. The agreement between S_ao₂ and S_po₂ improved when correcting for the underestimation of S_po₂ at low values. There is a poor agreement between S_po₂ and the gold standard S_ao₂ during extreme hypobaric hypoxemia.Ottestad W, Kåsin JI, Høiseth LØ. Arterial oxygen saturation, pulse oximetery, and cerebral and tissue oximetry in hypobaric hypoxia. Aerospace Med Hum Perform. 2018; 89(12):1045–1049.

BACKGROUND: Previous studies of acute hypoxia have largely examined different altitudes in isolation. Pilots, however, receive two exposures during in-flight hypoxic emergencies (IFHEs): the initial exposure at altitude, followed by a second mild exposure after descending and removing the breathing mask. Conventional wisdom holds that performance recovers with blood oxygen saturation and that exposure to mild hypoxia is safe. This study examined the possibility that the effects of moderate hypoxia may linger to overlap with the effects of mild hypoxia during sequential exposures such as those experienced by pilots during an IFHE.METHODS: Subjects performed a simulated flight task and secondary task while being exposed to normobaric hypoxia via the ROBD-2.RESULTS: Average error on the flight task during exposure to 3048 m (10,000 ft) was marginally worse when preceded by exposure to 7620 m (25,000 ft; 7.40 ± 3.32) than when experienced in isolation (6.42 ± 3.82). Performance on the secondary task was likewise worse when the mild exposure followed the moderate exposure (0.27 ± 0.30 lapses per minute) than when the mild exposure occurred by itself (0.19 ± 0.20 lapses per minute). Minimum S_po₂ showed a similar pattern of results (84.87 ± 4.37 vs. 86.61 ± 2.47).DISCUSSION: We believe our results are most likely due to a failure to recover from the original moderate exposure rather than an additive effect between the exposures. Even so, our findings suggest that pilot impairment following an IFHE may be worse than previously believed.Robinson FE, Horning D, Phillips JB. Preliminary study of the effects of sequential hypoxic exposures in a simulated flight task. Aerosp Med Hum Perform. 2018; 89(12):1050–1059.

INTRODUCTION: Understanding the effects of microgravity on bone is essential, since humans are now considering long-distance spaceflight missions. It is well known that bone mineral density (BMD) decreases during long-duration spaceflight. While the risk of fracture in a microgravity environment is believed to be low, the potential risk for fracture increases upon re-entering a gravity environment. The objective of this study was to determine skeletal regions of high-risk for fracture after long-duration spaceflight and identify management protocols for those fractures.METHODS: A literature search was conducted on current fracture risk predictive models and suggestions for treatment.RESULTS: Exercise with the Advanced Resistance Exercise Device (ARED), T2 treadmill, and cycle ergometer with vibration isolation and stabilization (CEVIS) on the International Space Station (ISS) is part of a fundamental long-duration spaceflight strategy to mitigate BMD loss. Additionally, studies have shown that bisphosphonates have an additive effect for preventing bone loss. However, if a fracture were to occur, treatments that improve bone healing in space (in addition to standard management modalities such as splinting) include the use of low-intensity pulsed ultrasound, electromagnetic field therapy, and intermittent subcutaneous injections of parathyroid hormone. In the event of a complicated fracture, surgical intervention with a universal external fixation device could be a viable option for management.CONCLUSION: In conclusion, the best strategy for mitigating musculoskeletal injuries for deep-space missions will be a combination of BMD loss reduction coupled with improvements in management protocols for potential fractures.Swaffield TP, Neviaser AS, Lehnhardt K. Fracture risk in spaceflight and potential treatment options. Aerosp Med Hum Perform. 2018; 89(12):1060–1067.

INTRODUCTION: Government space agencies and commercial spaceflight companies are seeking to expand human space exploration. Spaceflight can place considerable psychological stressors on humans, yet policies to support behavioral health in human spaceflight are still in their nascent stages. This article reviews international and domestic space policy relevant to behavioral health, as well as existing gaps in policy frameworks regarding the behavioral health of spaceflight crew and passengers. This article highlights behavioral health policy for human spaceflight as an emerging issue and suggests principles to guide the development of such policy moving forward.Morris NP. Behavioral health policy for human spaceflight. Aerosp Med Hum Perform. 2018; 89(12):1068–1075.

INTRODUCTION: In-flight medical emergencies require healthcare providers to operate in confined spaces with limited resources and delayed access to definitive care. These emergencies are common, with an estimated frequency of 1 per 100 to 1000 flights. Despite this, training for medical response in these environments is limited. We hypothesize that integrating such education into a pre-existing medical student elective course would improve knowledge and ability to respond appropriately to in-flight medical emergencies.METHODS: The available literature surrounding in-flight medical emergencies was reviewed. Syncope, respiratory distress, allergic reaction, and cardiac arrest were identified as common and potentially life-threatening complaints. Simulation cases were designed for each of these complaints and a simulation room was modified to mimic an airplane cabin. These simulation cases and accompanying relevant didactic lectures were incorporated into an existing wilderness and extreme environmental medicine course, with multiple-choice tests completed by the students at the beginning and end of the 2-wk course.RESULTS: Participating in this study were 18 students. The pretest average was 76%, which improved to 87% on the posttest. Qualitative feedback regarding this type of training was overwhelmingly positive.DISCUSSION: Simulation-based training for in-flight medical emergencies can significantly improve medical students’ knowledge. This training was very well received by the students. Opportunities for training to manage in-flight medical emergencies remain limited; incorporating such training into existing curricula could provide a means by which to improve provider knowledge. Such a curriculum could be adapted for use by flight crews and other populations.Padaki A, Redha W, Clark T, Nichols T, Jacoby L, Slivka R, Ranniger C, Lehnhardt K. Simulation training for in-flight medical emergencies improves provider knowledge and confidence. Aerosp Med Hum Perform. 2018; 89(12):1076–1079.

BACKGROUND: Perceptions of features of automation, such as its safety and effects on basic flying skills, can shape how someone uses automation and accepts newly developed technology. The purpose of the present study was to evaluate current U.S. Army rotary-wing aviators’ perspectives of cockpit automation in terms of safety features and effects on the retention of basic flying skills. In doing so, future lines of research can utilize this information to develop programs for the transitioning and training of advanced aircraft into the Army.METHODS: An anonymous, 125-item questionnaire was completed by 214 U.S. Army aviators. A subset of five items related to perceptions of automation were examined based on experience level and are reported here. The majority of subjects were male aviators with a mean age of 33 yr.RESULTS: Results suggest a difference in perceptions of some of the safety features, with 8 and 12% more of the experienced pilots reporting safety concerns on two items. A 13% difference in the perceptions of effects of automation on skills retention items were found based on experience level. More experienced aviators’ responses identified possible distrust of several automation features.DISCUSSION: The findings of this survey identified perspectives of automation which differed based on experience level. Specifically, more experienced individuals indicated some distrust of automation features and a possible overconfidence in basic flying skills. This can be used to further develop research aimed at the transition of advanced technology to aviators.Feltman KA, Kelley AM, Curry IP. Army aviators’ perceptions of advanced cockpit aircraft. Aerosp Med Hum Perform. 2018; 89(12):1080–1084.

BACKGROUND: Decompression sickness is a condition that results from an abrupt change from a higher to a lower pressure. It is described most commonly in divers; however, it can occur in aviation incidents, which this case report will discuss.CASE REPORT: Following an acute cabin depressurization incident, 36 patients presented to a small outpatient clinic with multiple symptoms, including fatigue, headache, nausea, vomiting, and dizziness. These patients were evaluated, triaged, and some were able to be successfully treated with supplemental oxygen in clinic. Eight of the patients had symptoms that were either persistent or concerning enough that they were referred to the dive medical clinic, where the dive medical team diagnosed six of the patients with Type II decompression sickness and referred them for hyperbaric oxygen chamber therapy. All patients who received hyperbaric therapy experienced at least some relief of symptoms, with most reporting some residual fatigue after the therapy.DISCUSSION: This case provided both lessons in triage and management of multiple patients in a small outpatient clinic, as well as the challenges in making the diagnosis of decompression sickness.Mancini S, Crotty AM, Cook J. Triage and treatment of mass casualty decompression sickness after depressurization at 6400 m. Aerosp Med Hum Perform. 2018; 89(12):1085–1088.

INTRODUCTION: A number of ophthalmic abnormalities, including optic disc edema, have been reported in several astronauts involved in long-duration spaceflights. An increased understanding of factors contributing to this syndrome, initially designated visual impairment and intracranial pressure syndrome and recently renamed spaceflight-associated neuro-ocular syndrome, has become a high priority for ESA and NASA, especially in view of future long-duration missions, including trips to Mars. The underlying pathophysiological mechanisms of this syndrome are still not well understood. In the present paper, we propose that optic disc edema in astronauts may occur, at least in part, as a result of retention of interstitial fluid in distended paravascular spaces at the prelaminar region of the optic nerve head. Preflight, in-flight, and postflight analysis of the optic nerve head and surrounding structures by optical coherence tomography in long-duration International Space Station crewmembers could provide important structural information in this respect.Wostyn P, De Winne F, Stern C, De Deyn PP. Dilated prelaminar paravascular spaces as a possible mechanism for optic disc edema in astronauts. Aerosp Med Hum Perform. 2018; 89(12):1089–1091.

Heidt SH, Lee AJ, Carnes BG, Pavelites JJ. You’re the flight surgeon: altered consciousness while driving. Aerosp Med Hum Perform. 2018; 89(12):1092–1094.