TECHNOLOGY AREA(S): Biomedical, Human Systems

ACQUISITION PROGRAM: PMA-202 Aircrew Systems

OBJECTIVE: Develop technology that provides real-time, accurate feedback on hydration levels in naval aircrew to aid in preventing dehydration and subsequent cognitive deficits.

DESCRIPTION: The rise of both the incidence and prevalence of physiological signs and symptoms (termed �physiological episodes�) that result in termination of a flight has prompted the naval aviation community to explore new ways of monitoring the health status of aircrew. Dehydration has been an increasingly high-profile concern in naval aviation, especially as mission profiles increase in length. The lack of adequate relief equipment, especially for female aviators [Ref 1], has prompted both intentional (�tactical�) and unintentional dehydration prior to and during flight. Additionally, factors in the flight environment, such as heavy clothing, gear, and radiant heat exposure, contribute significantly to fluid loss during flight. While not necessarily apparent to the aviator, dehydration introduces significant cognitive deficits that can negatively impact in-flight performance and further contribute to physiological episodes [Refs 2, 3, 4] and is contraindicated by the Naval Air Training and Operating Procedures Standardization (NATOPS) manual [Ref 5]. Therefore, it is believed that a system that measures and reports real-time aviator hydration levels would be a valuable benefit to the Navy.

The designed solution must be non-invasive, accurately measure hydration levels, and function in a naval aviation flight environment. While there are a few commercial, or near commercial, products that claim to be able to measure dehydration levels, none appear to be aimed at measuring dehydration in aviators. The highly dynamic flight environment [Ref 5] introduces unique challenges that have to be overcome when developing sensor suites. These challenges include, but are not limited to, high levels of motion (-3 to +7 g-forces), reduced pressure (up to 20,000 feet), a wide humidity range (5% to 95%), and extreme temperature variations (<32 �F to 150 �F) [Ref 5]. The proposed solution must be wearable alongside an existing flight suit (CWU-27/P) and, potentially, heavy flight gear (e.g., vest, G-suit). Limb placement is recommended to mitigate gear interference. The proposed solution must address those issues, while providing real-time, accurate feedback to the operator with minimal to no input or calibration. The proposed hardware solution would also need to have an open communication interface, as it will ultimately integrate with other sensor suites under development. The proposed solution must be independent of the air vehicle (e.g., be self-powered). The proposed solution will be evaluated against current methods of detecting dehydration in aircrew (e.g., fluid loss from weight change and urinalysis), as well as by ex vivo/in silico lab measures intended to simulate dehydration.

Note: NAVAIR will provide Phase I performers with the appropriate guidance required for human research protocols so that they have the information to use while preparing their Phase II Initial Proposal. Institutional Review Board (IRB) determination as well as processing, submission, and review of all paperwork required for human subject use can be a lengthy process. As such, no human research will be allowed until Phase II and work will not be authorized until approval has been obtained, typically as an option to be exercised during Phase II.

PHASE I: Design, develop, and demonstrate the feasibility of a proposed approach to non-invasively and accurately measure hydration levels. Demonstrate how the approach accounts for the challenges inherent to the flight environment, such as motion, humidity, and temperature. The technology should exit this phase at Technology Readiness Level (TRL) 3. Produce a plan to develop a Phase II prototype.

Note: Please refer to the statement included in the Description above regarding human research protocol for Phase II.

PHASE II: Develop and demonstrate a prototype of the measurement device in the relevant environment (i.e., representative of flight conditions). For example, this can include human volunteers wearing pilot life support equipment testing in an environmental chamber that simulates conditions similar to an aircraft in flight (controlling temperature, humidity, radiant heating) [Ref 5]. It may also include stand-alone device testing in an environmental chamber. Test and compare performance of the prototype using methods that simulate various hydration levels.

Note: Please refer to the statement included in the Description above regarding human research protocol for Phase II.

PHASE III DUAL USE APPLICATIONS: Transition the developed sensor into a full operational environment and support integration into the full physiological sensor suite. Provide support for verification and validation in a flight environment. (Note: The prototype should exit this phase at TRL 9.) Advances in hydration detection can have real and valuable benefits to a myriad of industries that involve working in high-risk or high-endurance environments and could benefit from real-time monitoring solutions. These industries include commercial aviation, Police/Fire/EMS communities, mines and steelworks, and athletics.

REFERENCES:

1. Anonymous. �To pee, or not to pee...� Approach: The Naval Safety Center's Aviation Magazine, March 2003, 48(3), p. 29. https://web.archive.org/web/20080630192803/http://www.safetycenter.navy.mil/media/approach/issues/mar03/ToPeeorNot.htm

2. Flight Safety Foundation. �Dehydration presents unique risks for pilots�. Human Factors & Aviation Medicine, July/August 2001, 48(4).� https://www.flightsafety.org/hf/hf_jul-aug01.pdf

3. Lindseth, P. D., Lindseth, G. N., Petros, T. V., Jensen, W. C. and Caspers, J. �Effects of hydration on cognitive function of pilots�. Military Medicine, 2013, 178(7), p. 792. http://dx.doi.org/10.7205/MILMED-D-13-00013

4. Nunneley, S. A. and Stribley, R. F. �Heat and acute dehydration effects on acceleration response in man�. Journal of Applied Physiology, July 1, 1979, 47(1), pp. 197-200.� http://www.physiology.org/doi/pdf/10.1152/jappl.1979.47.1.197

5. Office of the Chief of Naval Operations. OPNAV Instruction 3710.7U, Chapter 8, 2009.� http://www.public.navy.mil/airfor/vaw120/Documents/OPNAVINST_3710.7U%20(IC%2045).pdf

KEYWORDS: Dehydration; Physiological Measurement; Naval Aviation; Hydration; Aircrew Performance; Physiological Episode