Aerospace
Medicine in
the UK
David P Gradwell
Professor of Aerospace
Medicine, KCL.
Honorary Consultant
Guy’s & St.Thomas’
NHS Trust
Scope
•  A little history
•  Some altitude physiology
•  Relationship to clinical
•  Cases
•  Training
•  Educational opportunities
•  Questions?
The UK Farnborough King’s College London From: ezilon maps RAF Physiological Laboratory AVM Stewart G-loc
in WW II
RAF InsAtute of AviaAon Medicine, Farnborough Novel anA-­‐G research The Boss when I arrived AVM Peter Howard RAF IAM Hunter T7 With thanks to Dr Jon Clark Sea Harrier •
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Engine air test at 40,000 V PB 141 mmHg Spontaneous loss of canopy (1.86 m2) Rapid decompression through 3.5 psi Cabin alAtude 22,000 V, PB 321 mmHg Cabin volume 1275 litres Time of decompression by Flieger’s equaAon 0.004 seconds (Haber & Clamann 0.001s) Al7tude (and pressure rela7ve to sea level) 33,700 feet (1/4) 18,000 feet (1/2) 8,000 feet (3/4) 1 Sea level Gas Volume Changes x4 x2 X1.25 Boyle’s law Volume change is proporAonal to 1/pressure change But change in PAO2 greater 1 Alveolar gases breathing air on ascent SpO2 v PAO2 with alAtude 600 500 400 300 Ambient air mmHg Alveolar gas mmHg 200 100 160 103 39 47 0 Nitrogen Oxygen CO2 Water Total pressure = 760 mmHg (101.3kPa) 1kPa = 7.5 mmHg Sea level parAal pressures 600 500 400 300 Ambient air mmHg Alveolar gas mmHg 200 30 100 22 47 0 Nitrogen Oxygen CO2 Water Approx parAal pressures at 25,000 V, total pressure = 282 mmHg (37.6 kPa) Oxygen
requirements with
altitude
Canberra PR9 Pressure breathing induced syncope during pressure breathing following RD to 60,000 V Eurofighter Typhoon 9Gz > 55,000 V Brakes off to 40,000 V – 90 secs Instrumented subject in high performance hypobaric chamber An extract of a trace of respiratory parameters recorded during a rapid decompression from 22,500 V to 60,000 V in 3 seconds with 70mmHg PPB. Pabs at base alAtude 314 mmHg and 126 mmHg (16.8 kPa) at 60,0000 V. An example trace of alAtude, blood pressure, mask cavity pressure and parAal pressure of carbon dioxide in a rapid decompression from 22,500 V to 60,000 V. High alAtude PPB Changes in Mean BP 60 Change in mean BP (mmHg) 50 40 45,000 V 30 50,000 V 55,000 V 20 60,000 V 60,000 V 10 55,000 V 50,000 V 0 Control 1:1 1:3 Counter-­‐pressure raAos 45,000 V 1:4 45,000 V – 30mmHg PPB 50,000 V – 45mmHg PPB 55,000 V – 60mmHg PPB 60,000 V – 70mmHg PPB Rapid decompression to 60,000 V, PPB 70 mmHg, lower body counter-­‐pressure 1:3 Who flies now? •
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Everyone. Annual passengers flown > 3.1 billion (2013) At any Ame 000’s of people in flight In Europe more 2500 aircraV in the air UK > 231 million per annum (2013) (DoT) Rising to > 320 million by 2030 Atmosphere:
Altitude: 38,000ft
Temp: -56oC
Humidity: Very low
Cabin:
Altitude: 8,000ft
Temp: 21oC
Humidity: Low
Courtesy -­‐ BriAsh Airways Why a concern? •  Air travel has virtual monopoly over most routes •  Passengers becoming unwell on flights usually had the condiAon when boarding the aircraV •  Diversions (1:1000-­‐5000 flights) at best inconvenient, can be expensive and medical services may not match expectaAons. •  Refused flight can = reduced quality of life or employment •  Cardiovascular and respiratory diseases common and thus occur among paAents travelling Flight Cabin Environment •  Cabin alAtudes up to 8,000V –  hypoxia –  gas expansion •  Reduced mobility •  Reduced humidity •  Circadian dysrhythmia •  Access to medicaAons Denied flight •
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InfecAous TB (Req. 3 negaAve sputum smears on Rx) Current closed pneumothorax Major haemoptysis Requirement for O2 at sea-­‐level > 4 l/min IN-­‐FLIGHT MEDICAL EVENT RATES •  44,000 in-­‐flight medical emergencies annually worldwide –  1 every 604 flights –  16 emergencies per million passengers Peterson D, MarAn-­‐Gill C, Guyeoe F, Tobias A, McCarthy C, Harrington S, Delbridge T & Yealy D (2013). Outcomes of Medical Emergencies on Commercial Airline Flights. NEJM 368, 2075-­‐2082 CAUSES OF INFLIGHT MEDICAL EMERGENCIES •
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Syncope & pre-­‐syncope – 37.4% Respiratory – 12.1% Nausea & vomiAng – 9.5% Cardiac symptoms + cardiac arrest – 8% Seizures – 5.8% Peterson D, MarAn-­‐Gill C, Guyeoe F, Tobias A, McCarthy C, Harrington S, Delbridge T & Yealy D (2013). Outcomes of Medical Emergencies on Commercial Airline Flights. NEJM 368, 2075-­‐2082 Areas of aeromedical interest •  Pre-­‐flight medical advice •  In-­‐flight medical care •  Variety of paAent groups: –  Respiratory disease –  Cardiovascular disease –  Haematological –  ENT –  Post surgery –  Diurnal effects – jet lag, medicaAons Respiratory PaAents •  Severe COPD (COLD) •  Asthma •  RestricAve lung disease (involving hypoxaemia +/-­‐ hypercapnia •  Air travel intolerance with respiratory symptoms •  Pre-­‐exisAng requirement for O2, CPAP or venAlatory support •  Co-­‐morbidity especially IHD and heart failure •  Acute respiratory illness inc. recent pneumothorax or acAve TB Thorax 2011 66 Suppl 1 1-­‐33 Alveolar gases on ascent (healthy subjects, aVer 3-­‐5 mins) •  Sea level PAO2 = 103mmHg (13.7kPa) •  8000 V = 64mmHg (8.5kPa) •  Sea level PACO2 = 39mmHg (5.1kPa) •  8000 V = 38.5mmHg (5.1kPa) aVer 3-­‐5 mins Time course of oxygen tension in pulmonary capillary blood at normal and reduced alveolar oxygen tensions. Aeromedical clinic Lane Fox Respiratory Unit, St Thomas’ Hospital, London •  Clinical –  Provision of specialist advice •  Audit –  PaAent access to advice –  Is it used effecAvely? –  What are the barriers? •  Research –  Empirical advice based on consensus guidelines –  A more formal evidence base strengthens the guidelines PaAent assessment Previous air travel Disease pathology & severity Recent history Spirometry & ABGs SpO2 at GL (but SpO2 may drop more than 4% on ascent to 8,000 V) •  Exercise tolerance •  Hypoxia amenable to oxygen therapy? •  Hypoxic challenge: •
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–  Hypobaric chamber 8,000 V –  Reduced oxygen breathing gas of 15.1% O2 –  May not be equivalent (especially over prolonged periods) (Richard & Koehle 2012) Hypoxic challenge test •  15% FiO2 for 15 minutes •
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PaO2 > 6.6 kPa (>50 mmHg) Oxygen not required Or SPO2 =/> 85% PaO2 < 6.7kPa (<50 mmHg) In flight oxygen(2L/min via Or SPO2 < 85% nasal cannulae) M.Sc AvMed PaAent study aim •  To invesAgate the flight outcomes of paAents requiring supplementary oxygen or non-­‐
invasive venAlaAon undertaking air travel –  Rate of in-­‐flight medical events –  CorrelaAon with disease severity –  LogisAcal issues encountered CONCLUSIONS •  In-­‐flight events –  Moderate rate among cohort •  Pre-­‐Flight Assessment –  Stability & severity of disease –  Physician opinion: Primary determinant of management and predictor of in-­‐flight event risk •  Mechanical issues during travel –  Infrequent & unlikely to compromise clinical stability •  LogisAcal barriers include; –  Difficulty obtaining medical insurance –  Airline/airport regulaAons -­‐ equipment carriage & usage Clinical Case 1 •
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65 yr old man Post polio syndrome SpO2 95% on air at sea level FEV <1L Reports desaturaAon in flight to 83% Very quiet on flights SOB when visiAng washroom Case 1 hazards •
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Hypoxia Aggravated by exerAon ? HCT ? Supplemental oxygen ? Means of delivery Case 2 •
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26 yr old female Frequent flier Sickle cell disease Anaemia Hb7.5gm/dl Crises temporally related to flying Not used oxygen on board No test Advice? SCALE OF UK AVIATION ACTIVITY
•  20,000 commercial aircrew
•  33,000 cabin crew
•  8,000 military aircrew
•  3,000 air traffic control officers
•  25,000 light aircraft pilots
•  6,000 glider pilots, sport pilots
•  231 million UK passengers
•  Inbound aeromedically escorted patients
–  950 military patients in 2010
–  5000 escorted civilian patients
–  1700 air ambulance civilian patients
ESTIMATED CURRENT NUMBERS OF
AVIATION AND SPACE MEDICINE
PRACTITIONERS
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300 Civilian Aeromedical Examiners
130 Aeromedical transportation specialists
30 Military Flight Medical Officers
9 Civil Aviation Authority specialists
8 Airline doctors
6 RAF specialists
4 Commercial research specialists
Plus focus for aeromedical nurses,
& Biomedical scientists
WHY THE NEED FOR AVIATION AND SPACE
MEDICINE AS A SPECIALTY?
TRAINING PATHWAY FOR AVIATION AND
SPACE MEDICINE
Selection
CST after 72 months
minimum
Selection
ST3
FY2
General Medical
Training
ST4
ST5
ST6
Aviation and Space Medicine
Specialty Training
Membership exam
DAvMed
Research (MSc, PhD, MD)
>Maintain'
capabilities'and'
develop'
practice'through'
CPD'
✞ Enhance'career'
and'gain'
additional'
expertise'through'
credentialing'in'
special'interest'
areas'
✞Develop'depth'
of'knowledge'
by'learning'
through'
experience'
and'reflecting'on'
their'practice'
>Move'into'
education,'
management'and'
leadership'roles
Workplace-based assessments
Training
Duration
2 years
4-6 years
Rest of
Career
Map of the UK RAF CAM Henlow Farnborough King’s College London CAA Gatwick NATS From: ezilon maps EducaAonal opportuniAes in KCL •  M.Sc in AviaAon Medicine •  Diploma in AviaAon Medicine (RCP Faculty of OccupaAonal Medicine •  European AviaAon Safety Agency –  Basic AviaAon Medicine –  Advanced AviaAon Medicine –  Approved by UK CAA and AAME M.Sc AvMed •
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CVS & RS physiology Library project DAvMed course Research project DAvMed 1 •
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As Post-­‐graduate cerAficate in aeromedical sciences: AlAtude physiology & protecAon AcceleraAon physiology & protecAon AviaAon thermal physiology OrientaAon & disorientaAon Noise & vibraAon AEA IntegraAon MoAon sickness FaAgue Special senses Human performance EjecAon & crash protecAon Space physiology Clinical –  cardiology, pulmonology, nephrology, neurology, psychiatry, ophthalmology, ENT, O&G, haematology, GI, ID, orthopaedics DAvMed 2 -­‐ experiences •
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Hypoxia & pressure breathing European Space Agency Centrifuge Land and sea survival, UHET RAeS AAIB MarAn Baker UK CAA NATS BriAsh Airways (inc. large a/c flight simulator) RAF, Army & RN AvMed Flight AviaAon & Space Medicine high profile increasing clinical requirement crew and pax in aviaAon & space operaAons global educaAonal need UK contribuAon Thank you