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Team Aerospace Begins Here!

“He Forgot How to Fly” Lt Col Lisa Snyder 12 APR 2008. Team Aerospace Begins Here!. Overview. U-2 Aircraft Operational Parameters U-2 Physiology Initial DCS Event RTFS Decision Flight Performance Second Physiologic Event ACS Evaluation and Disposition Food for Thought

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Team Aerospace Begins Here!

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  1. “He Forgot How to Fly” Lt Col Lisa Snyder 12 APR 2008 Team Aerospace Begins Here!

  2. Overview • U-2 Aircraft Operational Parameters • U-2 Physiology • Initial DCS Event • RTFS Decision • Flight Performance • Second Physiologic Event • ACS Evaluation and Disposition • Food for Thought • Questions and Discussion

  3. Crew: Cruise Speed: Range: Max Altitude: Mission Length: One 420 knots Greater than 7,000 miles Above 60,000 feet Up to 14 hours U-2 Operational Environment

  4. U-2 Aviator Cockpit Environment • Full Pressure Suit-not continually inflated • 100% Oxygen through helmet • Aircraft cabin altitude 29,000 ft • Ozone toxicity-reduces lung diffusing capacity • Emergency descent requires 35 minutes

  5. U-2 Standard Physiologic Protocols • Pre-breathe • Exercise enhanced pre-breathe • Pharm Fatigue Management Program • No-Go pills • Dextroamphetamine Gel • Caffeine pudding

  6. A photo to wet your appetite…….

  7. Preparation for Flight • MP had arrived to the deployed location 20 days prior • 1800 - MP took no-go and slept • Showed at 0350 • Pre-breathe begun at 0400 • Pilot: pre-breathe potentially delayed and shortened by initial regulator difficulty • Physiologists: pre-breathe time adequate without break • Takeoff approx 0500

  8. Mission Timeline • TO and climb to FL 680(CA FL 295) - uneventful • TO + 3.5- Vertigo and sense of aircraft rolling • TO + 5.0-8.5 - Bilateral knee pain- inflated suit - Frontal Headache- caffeine pudding - Fatigue - Confusion- notified mission cell - Began RTB with vectors -Turn right, Turn left, Stop turn - Attempted emergency O2 activation

  9. Mission Timeline (Cont) • TO + 8.5 - Vomited inside helmet (FL680) - Opened helmet - Attempted to close visor- successful? - Color vision and peripheral vision loss - MFDs unreadable

  10. Mirages scrambling to assist ……

  11. Mission Timeline (Cont.) • TO + 1015- Mirages find MP slumped in cockpit -MA is in graveyard spiral and stall -MP told to play follow the leader • TO + 1030- Traffic pattern entered - MP continues to follow Mirages without awareness of his proximity to the ground

  12. 1 hour below 10,000 ft No memory of descent to airfield (~5 ft AGL) MP’s awareness returns only after experiencing “ground rush”

  13. T + 11 - Gear handle lowered by feel - Landed successfully - FS found pilot slumped Lethargic and pale - Cockpit sprayed with vomitus - O2, IV and monitor - Helicopter to Host Nation hyperbaric chamber - Neurologic DCS diagnosed Incident Timeline (Cont)

  14. Host Nation Hospital Treatment • Navy Table VI with 2 extensions • Multiple episodes of vomiting • Symptoms began to respond after third oxygen period • Unable to ambulate until after second dive • Total of 4 dives • Persistent symptoms during admission: • Headache • Mild confusion and difficulty with ADL’s

  15. Host Nation Hospital Studies • MRI • Multiple punctate high signal intensities mainly involving bi-frontal areas, most likely due to ischemia • CXR, EKG and TEE • Normal, no Patent Foramen Ovale • EEG • Normal

  16. Timeline • MD Mishap Day • MD + 7 Released from HN hospital • MD + 11 Symptoms resolved • MD + 15 Returned to CONUS by commercial air

  17. Should He Return to Fly??

  18. Incident Pilot • Demographics • 47 year old male • Over 4000 Total Flying Hours • Over 30 in the last six months • Past DCS History- First reported at ACS • Five “joint only” DCS incidents – unreported • 1991 – hospitalized for 3 days “dehydration”. Does not recall landing. Retrospectively MP believed episode was possibly neuro- DCS

  19. DCS Risk Factors • General-- Fatigue, age, and dehydration • Altitude attained and duration at altitude • MP risk factors • Possible inadequate pre-breathe for age • Coexistent hypoxia from vomiting episode could potentiate neurological symptoms

  20. AFI 48-123 22 May 2001 • Recurrent decompression sickness (DCS) • Single episode of DCS - no waiver • 72 hours DNIF • Consultation with USAFSAM Hyperbarics and MAJCOM is required • DCS with neurological manifestations - normal examination by a neurologist is required

  21. Policy Letter22 Feb 2002 • Released the requirement for a waiver for recurrent DCS episodes so that a waiver will not be “forced” on an individualwith a normal response to an abnormal environment. This change was in response to a flying community that was not reporting DCS episodes and this change was to reduce the fear of grounding. • Added that DCS cases having persistent residual symptoms should be submitted for a waiver at MAJCOM level if not operationally significant; AFMOA if there is potential operational impact.

  22. MP RTFS • Neurology • Normal neurological exam • MRI revealed multi-focal frontal lobe gliosis • Further correlation and repeat exam requested • DNIF > 72 hours • MAJCOM informed • MD + 100 • As Per AFI - RTFS Retrospective history obtained at ACS- Pilot expressed he wanted to fly, but silently concerned about returning to high altitude flying

  23. Interim Flying Experience • Line returns aviator to flying status • Multiple T-38 flights without incident • Two U-2 flights in dual seat aircraft at FL 680 • Solo low altitude U-2 flight – uneventful And now...the STORY continues...

  24. Home Station Incident • Preflight, Take Off and climb to FL680 uneventful • TO + 2.5 – “Sudden wave of anxiety and confusion” - Sensation he was falling - Believed this was DCS and inflated suit - Declared emergency and RTB • TO + 3.5 - Landed uneventfully feeling well

  25. Post Flight Care • FS examined pilot and called “LEO FAST” • History provided to Davis Hyperbarics: Currently asymptomatic pilot who had “anxiety like symptoms” that lasted several seconds on his first solo flight back in the U2 after a DCS episode 6 months earlier. Symptoms resolved almost immediately and he was normal upon landing. FS stated pilot’s symptoms were similar to the previous “anxiety type episodes” on other flights. He had been on O2 for 5.5 hours by helmet or mask. • Recommendation: No hyperbaric treatment

  26. Post Flight • 36 hours later • Severe, frontal and lasted 10 hours • Drove to elevation of 2,200 feet (+ 400ft gradient) • Bilateral pain in hands • Over next 3 weeks • Multiple episodes of “feeling in the fog” and forgetfulness • FS documented an inability to spell “World” backwards • Symptoms resolved after one month These symptoms were not acutely reported to USAFSAM Hyperbarics

  27. AFI 48 -123 V3 5 Jun 2006 • Any episode of DCS which produces residual symptoms after completion of all indicated treatment, or persists > 2 weeks • DCS episodes require 72 hours DNIF after completion of treatment • Consult base SGP and USAFSAM Hyperbaric Medicine on all cases of acute DCS

  28. AFI 48 -123 V3 • Bends-only DCS that resolve completely within two weeks may be RTFS by local flight surgeon after consultation with base SGP and USAFSAM Hyperbarics and MAJCOM. • DCS with neurological involvement may be RTFS only after complete resolution is confirmed by neurologist ORUSAFSAM hyperbaricist exam, and after consultation with USAFSAM Hyperbarics and MAJCOM.

  29. AFI 48 -123 V3 • DCS cases with persistent residual symptoms require complete evaluation and MAJCOM waiver. NOTE: Previous episodes of DCS do not modify or change requirements noted.

  30. Timeline • MD Incident #1 (Mishap Day 0) • MD + 7 Released from HN hospital • MD + 11 Symptoms resolved • MD + 15 Returned to CONUS • MD + 100 Returned to Flying Status • MD + 165 First flight after RTFS • MD + 185 Incident #2 • MD + 300 ACS evaluation

  31. ACS Evaluation The Aeromedical Consultation Service (ACS) was consulted for evaluation of neuropsychological symptoms of unclear etiology following a high altitude flight in a patient with a history of recurrent decompression sickness (DCS) episodes including a type II neurologic DCS

  32. ACS Neurology • Clinically normal gross neurologic exam • Stable MRI lesions consistent with gliosis (stroke) • review of two studies, six months apart • No PFO or pulmonary shunt • Further challenge to areas of gliosis could lead to transient defects becoming permanent • Risk of recurrent incapacitation and seizure > 1% per year

  33. ACS Neuropsychology Branch • No anxiety or lack of motivation to fly • No psychiatric diagnosis • Cognitive disorder with variable performance decrements • Clinically mild but aeromedically significant, especially in time pressured situations • Findings correlate with areas of brain injury found on MRI

  34. ACS Ophthalmology • Acquired asymmetric Tritan (blue cone) color vision defect • While prior detailed color vision analysis was not available, congenital Tritan defects are present in only .008% of population • Blue cones are most susceptible to hypoxic events

  35. Hyperbaric Medicine • Second episode of DCS • The 36 hour symptom free period can occur, though unusual • FS account and pilot’s story during evaluation have some differences • Of great concern is the prolonged duration of intermittent memory loss following incident #2 • No studies demonstrate an increased risk for subsequent neurologic DCS episodes, HOWEVER… • 2nd event after 4 re-exposures!

  36. ACS Summary • Recurrent neurologic DCS 2. Persistent multifocal areas of gliosis, most likely from hypoxia or inflammation 3. Neurocognitive impairment, aeromedically significant 4. Acquired mild, subclinical Tritan color vision defect

  37. ACS Recommendations • Disqualify – FCII duties 2. No waiver recommended for any flying related duties 3. May require MEB based on clinical progression of neurocognitive deficits 4. ACS re-evaluation in 2008 offered to patient • No waiver reconsideration

  38. Food for Thought- DCS Policy • Does the current AFI guidance on DCS need to be readdressed? • How many DCS episodes is too many? • Should neurocognitive testing be required? • What is the role of MRI in Neurologic DCS evaluation? • Should neuro DCS with altered level of consciousness be considered under A4.24.1.3.4: “All other loss or disturbance of consciousness. For rated personnel, waivers are considered by AFMOA/SGPA, only after evaluation at ACS”

  39. Food for Thought-Safety • Should SIB investigations be conducted for near fatal class C’s/E’s? • Would this type of investigation lead to prevention of future mishaps? • Neuro DCS Study Group? • ACS sponsored • All neuro DCS to ACS before waiver

  40. Food For Thought- Human Systems Integration • High risk population for color and peripheral vision loss due to DCS and Hypoxia so: “Use the round Dial” –BUT….there is not one

  41. PREVIOUS NEW

  42. U-2 BELONGS HERE.... NOT HERE!

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