BACKGROUND: Lower body negative pressure (LBNP) decreases middle cerebral artery blood velocity (MCAv) and can induce hypotension. Mental stress increases MCAv, but the MCAv response to combined LBNP and mental stress (COMBO) is unknown. We hypothesized that performing a stressful
cognitive challenge (i.e., mental stress) concurrently with LBNP would prevent LBNP-induced reductions of MCAv.METHODS: There were 18 subjects (9 men, 9 women; ages 20.1 ± 0.3 yr) who completed 3 randomized 3-min trials: 1) LBNP (−40 mmHg); 2) mental stress (serial
subtraction); and 3) COMBO (LBNP + mental stress). All reported values are mean ± SE. Mean arterial pressure (MAP), heart rate (HR), forearm blood flow (FBF), and MCAv were measured continuously. Subjects also reported perceived stress following the mental stress and COMBO trials.RESULTS:
LBNP decreased MAP (−1.4 ± 0.5 mmHg), MCAv (−2.6 ± 1.1 cm s−1) and FBF (−0.8 ± 0.1 units), and increased HR (2.7 ± 1.2 bpm). Mental stress increased MAP (10.1 ± 1.3 mmHg), HR (17.4 ± 2.2 bpm), and FBF (2.4 ±
0.4 units), while MCAv (2.8 ± 1.3 cm s−1) tended to increase. COMBO increased MAP (5.3 ± 2.3 mmHg) and HR (21.3 ± 2.6 bpm), and tended to increase FBF (0.5 ± 0.3 units). However, MCAv (-4.6 ± 2.0 cm s−1) decreased during
COMBO. Decreases in MCAv during COMBO were not statistically different from LBNP-induced decreases (−4.6 ± 2.0 vs. −2.6 ± 1.1 cm s−1). Subjective ratings of perceived stress (standard 0 to 4 scale) tended to be higher during COMBO than mental stress
(2.9 ± 0.1 vs. 2.5 ± 0.1 units).CONCLUSION: Our results suggest that mental stress does not effectively preserve MCAv when combined with central hypovolemia (i.e., LBNP).Durocher JJ, Carter JR, Cooke WH, Young AH, Harwood MH. Cerebral blood flow velocity during
combined lower body negative pressure and cognitive stress. Aerosp Med Hum Perform. 2015; 86(8):688692.
BACKGROUND: The effect of hypoxia on the exhaled nitric oxide (NO) of humans is unresolved. Many studies have measured the fraction of exhaled NO (FENO) or the partial pressure of exhaled NO (PENO) in normobaric and hypobaric hypoxia, with differing results.METHODS:
To better understand NO physiology and altitude acclimatization, we employed a random effects meta-analysis to determine the effect of acute normobaric hypoxia on the PENO of humans. A total of 93 subjects from 7 published studies (with 9 groups) were included. The median duration
of exposure was 30 min and the mean hypoxic PIo2 was 95 (SD = 10) mmHg.RESULTS: The weighted standardized mean difference (SMD) in PENO measured at baseline and during an acute exposure to normobaric hypoxia was not significantly different from zero
(SMD = 0.09; 95% CI = −0.17, 0.34; z = 0.65).CONCLUSION: Based on this meta-analysis, acute normobaric hypoxia does not affect the PENO measured from the mouths of humans. This result should be considered for interpretations of high-altitude (and hypobaric) measurements
of exhaled NO. As the PENO is a potential biomarker for altitude-illness susceptibility, recognizing that normobaric hypoxia does not affect the PENO will be important for understanding previous associations between low exhaled NO and poor acclimatization to hypoxia.MacInnis
MJ, Carter EA, Donnelly J, Koehle MS. A meta-analysis of exhaled nitric oxide in acute normobaric hypoxia. Aerosp Med Hum Perform. 2015; 86(8):693–697.
INTRODUCTION: Task complexity is regarded as an essential metric that is related to a pilot’s performance and workload. Normally, pilots follow Standard Operating Procedures (SOPs) during a flight. In this study, we developed a measurement named Task Complexity in Flight
(TCIF) to represent the task complexity in the SOPs.METHODS: The TCIF measurement combined four complexity components into one index: actions logic complexity (ALC), actions size complexity (ASC), information control exchange complexity (ICEC), and control mode complexity (CMC).To
verify the measurement, we calculated 11 tasks during the takeoff and landing phases from the SOPs, and invited 10 pilots to perform the same tasks in a flight simulator. After flight, the TCIF results were compared with two workload measurements: the Bedford scale and heart rate.RESULTS:
The results of TCIF and the 4 components of the 11 tasks were calculated. Further, the TCIF results showed a significant correlation with the Bedford scores (R = 0.851) and were also consistent with the difference in heart rate (R = 0.816). Therefore, with the increased TCIF results, both
the Bedford scale and the difference in heart rate increased.DISCUSSION: TCIF was proposed based on the flight operating conditions. Although additional studies of TCIF are necessary, the results of this study suggest this measurement could effectively indicate task complexity in
flight, and could also be used to guide pilot training and task allocation on the flight deck.Zheng Y, Lu Y, Wang Z, Huang D, Fu S. Developing a measurement for task complexity in flight. Aerosp Med Hum Perform. 2015; 86(8):698–704.
BACKGROUND: The aims of this study were to monitor cabin crew fatigue, sleep, and performance on an ultra-long range (ULR) trip and to evaluate the appropriateness of applying data collection methods developed for flight crew to cabin crew operations under a fatigue risk management
system (FRMS).METHODS: Prior to, throughout, and following the ULR trip (outbound flight ULR; mean layover duration = 52.6 h; inbound flight long range), 55 cabin crew (29 women; mean age 36.5 yr; 25 men; mean age 36.6 yr; one missing data) completed a sleep/duty diary and wore
an actigraph. Across each flight, crewmembers rated their fatigue (Samn-Perelli Crew Status Check) and sleepiness (Karolinska Sleepiness Scale) and completed a 5-min Psychomotor Vigilance Task (PVT) at key times.RESULTS: Of crewmembers approached, 73% (N = 134) agreed to
participate and 41% (N = 55) provided data of suitable quality for analysis. In the 24 h before departure, sleep averaged 7.0 h and 40% took a preflight nap. All crewmembers slept in flight (mean total sleep time = 3.6 h outbound, 2.9 h inbound). Sleepiness and fatigue were lower, and
performance better, on the longer outbound flight than on the inbound flight. Post-trip, crewmembers slept more on day 1 (mean = 7.9 h) compared to baseline days, but there was no difference from day 2 onwards.DISCUSSION: The present study demonstrates that cabin crew fatigue can
be managed effectively on a ULR flight and that FRMS data collection is feasible for cabin crew, but operational differences between cabin crew and flight crew need to be considered.van den Berg MJ, Signal TL, Mulrine HM, Smith AAT, Gander PH, Serfontein W. Monitoring and managing cabin
crew sleep and fatigue during an ultra-long range trip. Aerosp Med Hum Perform. 2015; 86(8):705–713.
BACKGROUND: During approach and departure in rotary wing aircraft, a sudden loss of external visual reference precipitates spatial disorientation.METHODS: There were 10 Royal Canadian Air Force (RCAF) Griffon pilots who participated in an in-flight investigation of
a 3-dimensional conformal Helmet Display Tracking System (HDTS) and the BrownOut Symbology System (BOSS) aboard an Advanced System Research Aircraft. For each symbology system, pilots performed a two-stage departure followed by a single-stage approach. The presentation order of the two symbology
systems was randomized across the pilots. Subjective measurements included situation awareness, mental effort, perceived performance, perceptual cue rating, NASA Task Load Index, and physiological response. Objective performance included aircraft speed, altitude, attitude, and distance from
the landing point, control position, and control activity. Repeated measures analysis of variance and planned comparison tests for the subjective and objective responses were performed.RESULTS: For both maneuvers, the HDTS system afforded better situation awareness, lower workload,
better perceptual cueing in attitude, horizontal and vertical translation, and lower overall workload index. During the two-stage departure, HDTS achieved less lateral drift from initial takeoff and hover, lower root mean square error (RMSE) in altitude during hover, and lower track error
during the acceleration to forward flight. During the single-stage approach, HDTS achieved less error in lateral and longitudinal position offset from the landing point and lower RMSE in heading.DISCUSSION: In both maneuvers, pilots exhibited higher control activity when using HDTS,
which suggested that more pertinent information was available to the pilots. Pilots preferred the HDTS system.Cheung B, Craig G, Steels B, Sceviour R, Cosman V, Jennings S, Holst P. In-flight study of helmet-mounted symbology system concepts in degraded visual environments. Aerosp
Med Hum Perform. 2015; 86(8):714–722.
BACKGROUND: Passenger air transport has considerably increased in the past 50 yr. It is estimated that between 7 and 40% of the population of industrialized countries is currently afraid of flying. Programs treating the fear of flying have been developed to meet this problem.
This study measures the effectiveness of one of these programs by focusing on flight-related anxiety before the program and after the first flight following the intervention.METHODS: There were 157 individuals recruited to participate in a 1-d intervention aiming at treating the
fear of flying, and using both cognitive behavioral techniques and virtual reality. Anxiety was measured with the Flight Anxiety Situations (FAS) and the Flight Anxiety Modality (FAM) questionnaires.RESULTS: Statistical analyses were conducted on 145 subjects (69.7% female; ages
from 14 to 64) after the exclusion of individuals with missing data. The results showed a decrease in flight-related anxiety for each subscale of the two questionnaires: the somatic (d = 2.44) and cognitive anxiety (d = 1.47) subscales of the FAM, and the general flight anxiety (d = 3.20),
the anticipatory flight anxiety (d = 1.74), and the in-flight anxiety (d = 1.04) subscales of the FAS.CONCLUSIONS: The effectiveness of the treatment program using both cognitive behavioral techniques and virtual reality strategies for fear of flying reduced flight-related anxiety
in the subjects in our study. Our results show that subjects demonstrated lower anxiety levels after the first flight following the program than before the intervention.Ferrand M, Ruffault A, Tytelman X, Flahault C, Négovanska V. A cognitive and virtual reality treatment program
for the fear of flying. Aerosp Med Human Perform. 2015; 86(8):723–727.
INTRODUCTION: This paper examines the reliability of the Human Factors Analysis and Classification System (HFACS) as tool for coding human error and contributing factors associated with accidents and incidents.METHODS: A systematic review of articles published across
a 13-yr period between 2001 and 2014 revealed a total of 14 peer-reviewed manuscripts that reported data concerning the reliability of HFACS.RESULTS: Results revealed that the majority of these papers reported acceptable levels of interrater and intrarater reliability.CONCLUSION:
Reliability levels were higher with increased training and sample sizes. Likewise, when deviations from the original framework were minimized, reliability levels increased. Future applications of the framework should consider these factors to ensure the reliability and utility of HFACS as
an accident analysis and classification tool.Cohen TN, Wiegmann DA, Shappell SA. Evaluating the reliability of the Human Factors Analysis and Classification System. Aerosp Med Hum Perform. 2015; 86(8):728–735.
INTRODUCTION: Human-system integration (HSI) is a complex process used to design and develop systems that integrate human capabilities and limitations in an effective and affordable manner. Effective HSI incorporates several domains, including manpower, personnel and training,
human factors, environment, safety, occupational health, habitability, survivability, logistics, intelligence, mobility, and command and control. To achieve effective HSI, the relationships among these domains must be considered. Although this integrated approach is well documented, there
are many instances where it is not followed. Human factors engineers typically focus on system design with little attention to the skills, abilities, and other characteristics needed by human operators. When problems with fielded systems occur, additional training of personnel is developed
and conducted. Personnel selection is seldom considered during the HSI process. Complex systems such as aviation require careful selection of the individuals who will interact with the system. Personnel selection is a two-stage process involving select-in and select-out procedures. Select-in
procedures determine which candidates have the aptitude to profit from training and represent the best investment. Select-out procedures focus on medical qualification and determine who should not enter training for medical reasons. The current paper discusses the role of personnel selection
in the HSI process in the context of remotely piloted aircraft systems.Carretta TR, King RE. Personnel selection influences on remotely piloted aircraft human-system integration. Aerosp Med Hum Perform. 2015; 86(8):736–741.
BACKGROUND: Eosinophilic esophagitis (EoE) is an emerging esophageal disease associated with dysphagia and food impaction. Practice guidelines have only recently been developed. It affects 1/1000 individuals, predominantly young men. As this demographic represents a substantial
portion of the military aviation population, aerospace medicine clinicians should be familiar with this diagnosis when evaluating dysphagia or impactions.CASE REPORT: A 23-yr-old Caucasian man, a U.S. Air Force air traffic controller, presented to Flight Medicine following an episode
of food impaction requiring evaluation in the local emergency department. The patient reported a 5-yr history of recurrent episodes of food lodging in his throat, requiring fluid and body repositioning for resolution. Medical history was significant for eczema. Upper endoscopy revealed an
abnormal esophagus with macroscopic features of EoE and biopsies were also consistent with EoE. After further work-up, the patient was diagnosed with EoE and treated. Significant symptom improvement was noted after 2 mo of therapy.DISCUSSION: This case outlines the evaluation of
food impaction as well as the diagnostic criteria for EoE, which is a disease that affects patients with demographics common to the military aviation community. As the diagnostic and treatment guidelines for EoE are relatively new, it may easily be overlooked by the primary care physician,
causing a delay in subspecialist consultation, thus delaying treatment. EoE is a condition with symptoms that pose high risk to the performance of aircrew duties; therefore, flight surgeons must be familiar with the aeromedical standards that accompany this diagnosis.Cochet AA Jr, Cochet
AE, Francis JM. Eosinophilic esophagitis with dysphagia and food impaction in a young adult. Aerosp Med Hum Perform. 2015; 86(8):742–746.
INTRODUCTION: The Ishihara plates are commonly used as an initial occupational screening test for color vision. While effective at detecting red-green deficiencies, the color deficient subject can learn the test using different techniques. Some medical standards such as the European
Aviation Safety Agency (EASA) require plate randomization and apply a stricter pass/fail requirement than suggested by Ishihara. This has been reported to increase the false positive rate up to ∼50%.METHOD: Two modifications to the Ishihara protocol are investigated. These involved
allowing subjects a second attempt where one or two reading errors were made and the presentation of rotated Ishihara plates.RESULTS: A reduction of false positive rate to 5.9% was found. Correct identification of certain rotated Ishihara plates was not affected.DISCUSSION:
By using a modified Ishihara protocol, fewer color normal subjects would require unnecessary advanced color vision examination. Further, additional safeguards would be in place to ensure that no subject with a color vision deficiency could pass the Ishihara test.Chorley AC. A modified
protocol for color vision screening using Ishihara. Aerosp Med Hum Perform. 2015; 86(8):747–751.
Nelms JM. You’re the flight surgeon: probable Herpes zoster. Aerosp Med Hum Perform. 2015; 86(8):754–756.
Duong A. You’re the flight surgeon: arrythmogenic right ventricular cardiomyopathy. Aerosp Med Hum Perform. 2015; 86(8):756–759.
