The U.S. Army Aeromedical Research Laboratory Virtual Reality Vection System.

Introduction: Vection is a stationary individual's illusory experience of self-motion. This illusory self-motion is operationally important for aviation, particularly military aviation, since vection is a dramatic example of spatial disorientation (SD), which is an individual's failure to correctly sense the aircraft's position, motion, and/or attitude with respect to the fixed coordinate system of the Earth's surface and its gravitational vertical. Notably, SD is a major cause of fatal aviation mishaps, and the visual system is particularly prone to provoking vection.

Examining the Influence of Cognitive Load and Environmental Conditions on Autonomic Nervous System Response in Military Aircrew: A Hypoxia-Normoxia Study.

Executing flight operations demand that military personnel continuously perform tasks that utilize low- and high-order cognitive functions. The autonomic nervous system (ANS) is crucial for regulating the supply of oxygen (O2) to the brain, but it is unclear how sustained cognitive loads of different complexities may affect this regulation. Therefore, in the current study, ANS responses to low and high cognitive loads in hypoxic and normoxic conditions were evaluated.

Continuous Physiological Monitoring of the Combined Exposure to Hypoxia and High Cognitive Load in Military Personnel.

Military aviators endure high cognitive loads and hypoxic environments during flight operations, impacting the autonomic nervous system (ANS). The synergistic effects of these exposures on the ANS, however, are less clear. This study investigated the simultaneous effects of mild hypoxia and high cognitive load on the ANS in military personnel.

Feasibility of using normobaric hypoxic stress in mTBI research.

Studies of mild traumatic brain injury (mTBI) recovery generally assess patients in unstressed conditions that permit compensation for impairments through increased effort expenditure. This possibility may explain why a subgroup of individuals report persistent mTBI symptoms yet perform normally on objective assessment. Accordingly, the development and utilization of stress paradigms may be effective for enhancing the sensitivity of mTBI assessment.

A Novel, Inexpensive Method to Monitor, Record, and Analyze Breathing Behavior During Normobaric Hypoxia Generated by the Reduced Oxygen Breathing Device.

Objectives: Since hypoxia remains one of the most important physiological hazards the aviation environment poses, military aviators are trained to recognize symptoms of hypoxia in order to implement appropriate safety procedures and countermeasures when hypoxia occurs. A widely used commercial instrument for hypoxia training, demonstration, and research is the Reduced Oxygen Breathing Device (ROBD). Here we describe a novel, inexpensive method to use the ROBD's breathing loop pressure (BLP) to measure respiration rate, a critically important response parameter for hypoxia.

A History of Mild Traumatic Brain Injury Affects Peripheral Pulse Oximetry during Normobaric Hypoxia.

Introduction: Physiological and emotional stressors increase symptoms of concussion in recently injured individuals and both forms of stress-induced symptoms in people recovering from mild traumatic brain injury (mTBI), but who are asymptomatic when not stressed or are at rest.

Methods: Healthy asymptomatic adults (25.0 ± 5.

A Performance Comparison of Color Vision Tests for Military Screening.

Background: Current color vision (CV) tests used for aviation screening in the U.S. Army only provide pass-fail results, and previous studies have shown variable sensitivity and specificity.

Visual Dysfunctions at Different Stages after Blast and Non-blast Mild Traumatic Brain Injury.

Purpose: To assess the prevalence of visual dysfunctions and associated symptoms in war fighters at different stages after non-blast- or blast-induced mild traumatic brain injury (mTBI).

Methods: A comprehensive retrospective review of the electronic health records of 500 U.S.

Effects of repetitive low-level blast exposure on visual system and ocular structures.

Unlabelled: The purpose of this study was to determine whether repetitive exposure to low-level blasts during military breacher training produces acute and cumulative damage to the ocular tissues or visual system. The effects of low-level blast exposure on high-contrast visual acuity, contrast sensitivity, oculomotor function, color vision, visual field (VF), pupillary light reflex, corneal endothelial cell density (ECD), macular thickness, retinal nerve fiber layer thickness, and cup-to-disc ratio were assessed using a battery of standard clinical ophthalmic tests administered 10 times over a 2-year period. Data from nine breacher instructors (Cadre) were compared with data from four breacher engineers (CONTROL).

Visual field dysfunctions in warfighters during different stages following blast and nonblast mTBI.

Objectives: Traumatic brain injury (TBI) is the leading injury coming out of the past decades' two major military conflicts, with mild TBI (mTBI) being the most commonly diagnosed form. The aim of this study was to assess the frequency and types of visual field (VF) defects seen at different testing stages following nonblast and blast-induced mTBI.

Methods: A comprehensive retrospective review was performed on 500 electronic health records for military personnel sustaining an mTBI during deployment, of which 166 patients were tested with both confrontation VF and 30-2 Humphrey Matrix Frequency Doubling Technology (FDT) perimetry.

Uncovering latent deficits due to mild traumatic brain injury by using normobaric hypoxia stress.

Memory deficits and other cognitive symptoms frequently associated with mTBI are commonly thought to resolve within 7-10 days. This generalization is based principally on observations made in individuals who are in the unstressed environmental conditions typical of a clinic and so does not consider the impact of physiologic, environmental, or psychological stress. Normobaric hypoxic stress can be generated with normal mean sea level (MSL) air, which is about 21% oxygen (O2) and 78% nitrogen (N), by reducing the percentage of O2 and increasing the percentage of N so that the resultant mixed-gas has a partial pressure of O2 approximating that of specified altitudes.

Effectiveness of computerized oculomotor vision screening in a military population: pilot study.

The prevalence of oculomotor dysfunctions associated with blast-induced mild traumatic brain injury (mTBI) in warfighters has increased as a consequence of recent conflicts. This study evaluated the effectiveness of computerized oculomotor vision screening (COVS) in a military population. Oculomotor functions were assessed with COVS and by conventional methods in 20 U.

An independent, objective calibration check for the reduced oxygen breathing device.

Introduction: Normobaric hypoxia, which does not entail an altitude chamber, but reduces the fraction of inspired oxygen (02) by diluting air with nitrogen, is finding increased use. The reduced oxygen breathing device (ROBD-2) is one of several commercial devices for generating such normobaric hypoxia. Reported here are results of a procedure to check the calibration of the ROBD-2 using methods that may be readily available in physiology and psychophysiology facilities.

Visual dysfunctions and symptoms during the subacute stage of blast-induced mild traumatic brain injury.

The purpose of the present study was to assess the occurrence of visual dysfunctions and associated symptoms in active duty warfighters during the subacute stage of blast-induced mild traumatic brain injury (mTBI). A comprehensive visual and oculomotor function evaluation was performed on 40 U.S.

Hypoxia and flight performance of military instructor pilots in a flight simulator.

Introduction: Military aircrew and other operational personnel frequently perform their duties at altitudes posing a significant hypoxia risk, often with limited access to supplemental oxygen. Despite the significant risk hypoxia poses, there are few studies relating it to primary flight performance, which is the purpose of the present study.

Methods: Objective, quantitative measures of aircraft control were collected from 14 experienced, active duty instructor pilot volunteers as they breathed an air/nitrogen mix that provided an oxygen partial pressure equivalent to the atmosphere at 18,000 ft (5486.

Head position of helicopter pilots during slalom maneuvers.

Introduction: Pilots typically tilt their heads when executing coordinated banking turns, a phenomenon commonly attributed to the putative opto-kinetic cervical reflex (OKCR). The OKCR is usually described as a reflex, primarily driven by stimuli in the visual periphery, and is important to a pilot's spatial orientation by providing a relatively stabilized horizontal frame of reference. The present paper presents an alternative hypothesis for the observed head tilting seen in pilots.

Ethics in human experimentation: the two military physicians who helped develop the Nuremberg Code.

The Nuremberg Code is generally considered the beginning of modern ethics in human experimentation. The Code is a list of 10 principles that Judge Walter Beals included in the judgment he delivered at the close of the Nuremberg Medical Trial on 19 August 1947. Recently, scholars have studied the origin of the Code, who wrote it, and why.

The economic context for the development of "blind flight".

On 24 September 1929, at Mitchel Field, Long Island, NY, Jimmy Doolittle performed the first so-called "blind flight." He executed a flight plan and landed using only cockpit instruments, a feat that culminated a research program supported by the Daniel Guggenheim Fund for the Promotion of Aeronautics. Contemporary aviation medicine, with its understanding of the challenges of spatial (dis)orientation, has a special understanding and appreciation of the complex human performance, medical and technical problems that had to be overcome to make instrument flight possible.

Civilian use of night vision goggles.

Civil aviation operators have expressed an increased interest in conducting night operations with night vision imaging systems. The development of special operational concepts, hardware requirements, training requirements, and regulatory change and oversight is necessary to control for the known performance constraints associated with these devices. In 2001, the Aerospace Medical Association initiated an internal request to review the human factors issues concerning the use of night vision goggles (NVGs) in civilian flight operations.