Acceleration Atelectasis in the F-22

Transcription

1 Acceleration Atelectasis in the F-22 Return of an old friend Lt Col Jay Flottman, USAF F-22 Pilot-Physician

2 Disclosure Information I have no financial relationships to disclose. I will not discuss off-label use and/or investigational use in my presentation This presentation contains the opinion of the author and does not the reflect the view of the U.S. Air Force or Department of Defense.

3 Overview Historical literature review Acceleration Atelectasis definition F-22 OBOGS Review Upper Pressure Garment Review Personal History

4 Historical Literature Review (sample) Ernsting, J. Some Effects of Oxygen Breathing, Proceeding of the Royal Society of Medicine, 1960 Langdon, D.E. and G.E. Reynolds, Post-Flight Respiratory Symptoms Associated with 100% Oxygen and G Forces: Aerospace Medicine, 1961 Green I.D., and B.F. Burgen, An Investigation into the major factors contributing to post-flight chest pain in fighter pilots: Flying Personnel Research Committee, Air Ministry, 1962 Levy, P.M., et al, Aeroatelectasis: A Respiratory Syndrome in Aviators, Aerospace Medicine, 1962 Glaister, D.H., Pulmonary gas exchange during positive acceleration, Flying Personnel Research Committee, Air Ministry, 1963 Ernsting, J., The ideal relationship between inspired oxygen concentration, Aerospace Med. 34, 1963 York, E., et al, Post-Flight Chest Discomfort in Aviators: Aero-Atelectasis: Bureau of Medicine and Surgery, 1965 Glaister, D.H., The Effects of Gravity and Acceleration on the Lung: The Advisory Group for Aerospace Research and Development. NATO, 1970 Tacker, W.A., et al, Induction and Prevention of Acceleration Atelectasis: Aviation, Space Environmental Medicine, 1987 Glaister, D.H., Effect of Acceleration on the Distribution of Ventilation in Man: RAF Institute of Aviation Medicine, 1994 Balldin UI. Pressure Breathing and Acceleration Atelectasis. Raising the operational ceiling. A workshop on the life support and physiological issues of flight at 60,000 and above, June 1995

5 Acceleration Atelectasis Collapse of alveoli in the dependent lung due to increased accelerative forces Symptoms cough, inability to take a deep breath, pain in the chest (Keefe, 1958) May last minutes to several hours (Balldin, 1995)

6 Atelectasis Cont. Glaister reported three conditions required for development of Atelectasis (AGARD, 1970): Acceleration, elevation of the diaphragm (Anti-G Suit), 100% Oxygen Reduction of incidence recommended 40% Nitrogen for air mixtures up to 25,000 ft cabin altitude (Ernsting, 1963)

7 Life Support System Task Force (LSS) further identified specific factors in the F-22 (see flow diagram) that may have been contributing factors Atelectasis Cont.

8 We believe there is a certain amount of atelectasis. If we conduct the study that Dr. Balldin is suggesting relating to assisted PBG, I think the fit and tightness of the Jerkin will be critical, (Ackles, 1995) Atelectasis Cont.

9 F-22 OBOGS Review F-22 OBOGS MAX F-22 OBOGS AUTO Transition to MAX at 11K Cabin Altitude F-15 LOX F-15E MSOGS F-16 OBOGS

10 Upper Pressure Garment Operation 6 Deep Breath #1 Deep Breath #2 4 InWg Mask Pressure UPG Pressure Delta Pressure Altitude: 8K Altitude Chamber Typical of 12 of 12 pilots Seconds F-22 Baseline Configuration (w/ UPG), Mask-UPG Differential Pressure UPG is designed to inflate during Positive Pressure Breathing (PPB) only During non-ppb operation, UPG should not inflate Test results show UPG fills and retains BRAG safety pressure at all times UPG pressure is often above mask pressure Pilots are forced to breathe against UPG restriction Non-PPB Designed UPG Pressure

11 Upper Pressure Garment Breathing Changes 4 Deep Breath #1 Deep Breath # InWg lpm F-22 Baseline w/o UPG Mask Pressure F-22 Baseline (w/upg) Delta Pressure F-22 Baseline w/o UPG Flow F-22 Baseline (w/upg) Flow Altitude: 8K seconds 0 F-22 Baseline (w/ UPG) vs. F-22 Baseline w/o UPG, Pressure Flow Comparison UPG causes pilots to adjust their breathing patterns F-22 Baseline w/o UPG had higher peak flows than F-22 Baseline (w/upg) for similar inhalation cycles UPG restricts pilot peak flow rate by one third UPG restricts thoracic expansion

12 Personal Testimony April 2012 Red-Air F- 22 Sortie, Elmendorf Cold WX gear including undergarments, ATAGS, UPG, C2A1 canister, fingermounted pulse oximeter, survival vest, MAX OBOGS selection with mask up from start to shutdown

13 Personal Testimony April 2012 Red-Air F-22 Sortie, Elmendorf Cold WX gear including undergarments, ATAGS, UPG, C2A1 canister, finger-mounted pulse oximeter, survival vest, MAX OBOGS selection with mask up from start to shutdown Relatively low G; 2-3 x high G turns (+6-7G) lasting only few seconds Less than 1.5hr mission Post flight: inability to breathe deeply without substernal chest pain (pain lasted 3-4 hours), pulse ox drop to 94-95% immediately post-flight that lasted 2-3 minutes, minor cough Classic symptoms per original literature reviews (60 s and 70 s) discussed with Boeing Led Physiology Team during Physiologic Event Investigation

14 Take Away Need to further explore AFE fitting procedures Placement of AFE on the torso (i.e. survival vest) AFE in general was it contributing to the symptoms that had been reported by pilots in the field? Importance of HSI in life support equipment development