Airline Medicine over the Years - Royal Aeronautical Society

AIRLINE MEDICINE OVER THE YEARS

Prof Michael Bagshaw

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First airline aeromedical department

➢ Eastern Airlines - General manager Eddie Rickenbacker➢ Miami 1926

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First airline doctor

➢ Dr Ralph N. Greene – Eastern Airlines

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ROLE OF THE FIRST AIRLINE DOCTOR

Principle of constant surveillance of aircraft and engine performance to be applied to pilots

➢Regular medical examinations

➢Be the family physician

➢Fly with them frequently

➢Technical reports on in-flight physiological measurements

➢Campaign for Federal law limiting airline pilots to 85 flying hours per month

➢Control and prevention of tropical ailments

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MEDICAL CONDITION CONSIDERATIONS

Is the condition affected by reduction in ambient pressure, hypoxia or acceleration?

Is the condition static? If so, what is the degree of functional incapacitation?

Is the condition progressive? If so, is the course predictable or unpredictable?

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▪ Can the condition result in sudden incapacitation?

▪ Can the condition result in subtle incapacitation?

▪ In the case of assessing fitness to fly as a passenger, does the condition impede mobility?

FLIGHT CREW MEDICAL

Poor predictive validity

What existing condition does pilot have?

- Not what condition is the pilot going to have?

Screening process

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CREW INCAPACITATIONPartial or total

Causes: gastro-intestinal disorders

fatigue, disruption of circadian rhythms

anxiety, stress

barotrauma

hypoxia

carbon monoxide intoxication

acute pain from medical condition (eg renal stone, angina)

medication side effect

decompression sickness

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INCAPACITATION

Sudden

Insidious

1% rule

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THE 1% RULE

Risk of pilot failure assessed in same way as risk of failure of any component of the aircraft system

[Note Dr Ralph N. Greene – Eastern Airlines, 1926]

Target fatal accident rate (all causes) 0.1 per 1 million flying hours

0.1 in 106 or 1 in 107

Medical incapacitation ≤ 10% 1 in 109

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Medical incapacitation as proportion of all-cause fatal accident rate

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THE 1% RULE

Critical periods of flight Take off & initial climb

Approach & landing

In 2 crew, trained 2nd pilot safely takes over in 99 of 100 incapacitations

Fatal accident result from 1 incapacitation per 100 at critical period 2nd pilot reduces risk by factor of 100

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Critical and non-critical phases of flight with respect to medical incapacitation

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THE 1% RULE ASSUMPTIONS

Critical portions of flight represent 10% of total flight time (average flight duration 1 hour)

Incapacitations occur randomly during flight

2nd pilot safely takes over on all incapacitations outside critical portions of flight

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THE 1% RULE

Incapacitation rate of 1 in 106 hours equivalent to approx 1% per year

1 in 106 hours = 0.01 in 104 hours

= 1/100 in 104

= 1% in 104

= 1% in 1 year

(8760 hrs ~ 10000)

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THE 1% RULE

Despite weaknesses, provides objective standard to assess medical fitness of professional pilots

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Concorde SSTPassenger service 1976 - 2003

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SUPERSONIC TRANSPORT

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60,000 ft

210 minutes

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CONCORDE SST

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OZONE

Biological effects:

Odour

Nose and pharyngeal irritation

Cough

Expectoration

Dyspnoea

Chest pain and respiratory distress

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OZONE

Occupational exposure limit:

0.1 ppmv, 40 hr working week over 5 days

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Ozone

Thermally unstable

Transformed to molecular oxygen at 400 degC for 0.5 sec.

Concorde:

Climb and cruise – engine bleed air 400 degC (100% dissociation)

Descent – engine bleed air 300 degC (90% dissociation)

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Oxygen equipment

Concorde cruising altitude up to 60,000 ft.

Airworthiness requirements –

Cabin alt not> 15,000 ft after reasonably probable failure (1 in 103 – 105 flying hrs)

Cabin alt not> 25,000 ft after remote failure (1 in 105 – 107 flying hrs)

Cabin alt > 25,000 ft only after extremely remote failure (<1 in 107 flying hrs)

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Oxygen equipment

Example worst case scenario :

Loss of rear cabin window at 65,000 ft

& emergency descent within 30 sec –

Max cabin altitude <25,000 ft in 3 mins, declining to 15,000 ft 6.5 min after failure.

[Small cabin volume, engine high mass flow, small diameter windows, aircraft high rate of descent]

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Oxygen equipment

Passengers & cabin crew –

➢‘Rubber jungle’ at 14,000 ft cabin alt

➢Portable equipment, one per cabin crew member, 30 min supply, 120 litre

➢Therapeutic equipment, 2% of pax or 2 persons (whichever greater), 30 min supply, 180 litre.

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Oxygen equipment

Flight crew –

➢On demand dilution system, delivering 150 litres/minute BTPS up to 35,000 ft.

➢Pressure breathing up to 30 mmHg.

➢One-handed quick-donning mask –

Donned within 5 sec

Communicating within 7 sec.

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Cosmic RadiationVariation of Particle type with Altitude

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Muons

EM Showers

Protons

Charged Pions

Neutrons

Pe

rce

nt

of

To

tal

(%)

80

70

60

50

40

20

10

30

0

Altitude (ft)

0 10 000 20 000 30 000 40 000 50 000 60 000


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31


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Radiation Summary

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• Performance with time on task (TOT)

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• Performance with time of day

42Department of Behavioral Biology, Walter Reed Army Institute of Research

Sleep and performance

San Francisco

London

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Circadian Phase - London

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Circadian Phase – San Francisco

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Sleep and alertness

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0

5

10

15

20

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

major sleep episode

MS

LT

sco

re (

min

)

Local time (hr)

SSS scale

1

.

.

4

.

.

7

SSS

A

B

MSLT

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

A:SSS – Subjective measurementB:MSLT – Objective measurement

MANAGING TRAVEL FATIGUE

Review trip schedule

Decide on appropriate strategies sleep sleep scheduling good sleep habits napping

alertness sleep scheduling strategic use of naps strategic use of caffeine

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MANAGING TRAVEL FATIGUE

Other strategies light exposure

diet

special diets have not been shown to be of any scientific benefit

gentle exercise

improves NREM sleep

avoid within 2-3 hours of bedtime

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EPIDEMIOLOGY

British Airways flight crew 1950 – 1992

[Irvine D, Davies DM. The mortality of British Airways pilots 1966-1989: a proportional mortality study. ASEM 1992; 63: 276-9]

➢6209 pilots, 1153 flight engineers

143 500 person years of observation

➢life expectancy at age 55 - 65

4 - 5 years better for long haul crew

2 - 3 years better for short haul crew

➢cases of leukaemia less than expected

➢no excess of cancer apart from melanoma

Comparable with other studies

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EPIDEMIOLOGY

Air New Zealand Pilot Morbidity Study[Sykes AJ et al. A study of Airline Pilot Morbidity. ASEM 2012; 3(10): 1001-1005]

➢595 pilots Nov 2009 – Oct 2010cf New Zealand Health Survey 2006-2007

➢Pilots lower prevalence most medical conditions

➢Exceptions: Kidney disease 3.3% vs 0.6%

Melanoma 19/1000 vs 0.4/1000

➢No excess of cancer apart from melanomaComparable with other studies

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DVT - TRAVELLER’S THROMBOSIS

Increased media interest following a passenger death sensational reporting

‘airlines to blame’

‘airlines not informing passengers of the risks of air travel’

scant attention to scientific facts and level of knowledge

airlines ‘guilty until proven innocent’

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Daily Mail, 18th November 2000

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TRAVELLER’S THROMBOSIS

Virchow, 1856 Venous Thromboembolic Disease (VTE), precipitated by venous stasis

induced by immobility

Virchow’s Triad1. reduction in blood flow

2. change in blood viscosity

3. damage/abnormality in vessel wall

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‘.... As is so often true of venous thrombosis, this group of cases reveals a tendency rather than a proved relation of cause and effect.’

Homans, J. NEJM 1954, 250, 148-149

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CONCLUSION

Current evidence –

Any association between symptomatic deep vein thrombosis and travel by

air is weak.

Incidence less than impression given by media publicity.

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Is the flight environment a factor?

low humidity

relative hypoxia

What is the evidence from crew?

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Johnston et al Review of UK CAA medical records 1990 - 2000

12782 professional fixed wing pilots

incidence of DVT 0.21/1 000/yr

16/27 cases had well documented predisposing factors

of the remainder 2 sustained DVT as passengers

‘....this relatively low incidence would suggest that VTE is indeedmultifactorial and the aircraft cabin per se does not pose anoccupational risk.’

Johnston, RV, et al, Abstracts of the 49th ICASM 2001, Geneva, Switzerland

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Is the flight environment a factor?

seated immobility

appears to act as one of multiple risk factors those with normal venous/haemostatic symptoms will probably not experience

traveller’s thrombosis

multiple journeys may result in a greater risk than single trips

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Daily Mail, 18th November 2000

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WRIGHT PROJECT

WHO Research Into Global Hazards of Travel

WRIGHT project aims to determine if the risk of VTE is increased by air travel

to determine the magnitude of the risk

to determine other factors in the association

to determine the effect of interventions

Study types within the WRIGHT project epidemiological

clinical

physiological

pathophysiological

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WRIGHT PROJECT

Time scale 4 years from January 2002

Cost 12 million Euros

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WRIGHT PROJECT

CONCLUSIONS

• To confirm if the risk of VTE is increased by air travel

Increased risk applies to all forms of travel (air, car, bus, train)

• To determine the magnitude of the risk

Absolute risk I in 6000 in healthy population

Risk doubles after 4 hours inactivity

• To determine the effect of other factors on the association

No association with hypobaric hypoxia

• To study the effect of interventions on risk

No effective intervention for healthy individual65

IN FLIGHT MEDICAL INCIDENTS


Airlines required to provide first aid training for cabin crew

Cabin crew responsible for managing any in-flight medical incidents

Regulatory requirements for carriage of first aid and medical kits Detailed policies at discretion of each nation and its airlines

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Cabin crew trained ~

Recognise common symptoms of distress

First-aid

Basic resuscitation techniques

Use of emergency supplemental oxygen

Use of basic medical kit and OTC drugs

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Crew may contact ground-based medical service provider Airline medical department

3rd party provider (MedAire; SAMU; Mayo)

Crew may request assistance from on-board medical professional Medical kit released if appropriate credentials

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MEDICAL TELEMETRY

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1995 – Professor Angus Wallace

Treated in-flight post-traumatic tension pneumothorax using:

coat hanger - trocarurinary catheter - cannulaused brandy bottle - under-water seal

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AEDS

Cost-benefit analysis Costs of acquisition, maintenance and training

Versus

Probability of need

Expectations of travelling public

European Resuscitation Committee & American Heart Association protocol includes early transfer to intensive care facility

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AEDS

USA – carriage mandated by FAA: Air carriers with max payload >7500 lb with at least one flight attendant

Rest of the world: Optional

Carried by most major airlines

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1986 – Dr Peter Chapman - Defibrillators

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Dr Eric Donaldson - Defibrillators

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Dr David McKenas - Defibrillators

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Dr Paulo Alves - Defibrillators

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2006 - RDT Tempus Remote monitoring kit

AEROMEDICAL ASPECTS OF NEW GENERATION CIVILIAN AIRCRAFT

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A380 vs A318

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First class 14

Club World (Business) 97

World Traveller Plus 55

World Traveller (Economy) 30

Total seats 469

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A380

Does the introduction of very large passenger aircraft pose any unique aeromedical issues to: Passengers?

Crew?

Others?

If so, what needs to be done?

IN-FLIGHT MEDICAL INCIDENTS (IFMIS)

Incidence?

Outcomes?

Diversions? Incidence and Causation?

Medical contributions to outcomes?

Effect of high passenger capacity?

Medical Incidents - Age Profile

0

5

10

15

20

25

30

0 20 40 60 80 100

Pe

rce

nta

ge

Passengers Incidents Diversions

Enplanements and Medical Diversions per annum

0

2,000,000

4,000,000

6,000,000

8,000,000

10,000,000

12,000,000

14,000,000

2001 2002 2003 2004 2005

0

2

4

6

8

10

12

14

16

18

Enplanements

Medical Diversions

(Correlation coefficient 0.93)

Medical Diversion Rates 2000-2005

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

2000 2001 2002 2003 2004 2005

Rate per Billion RPKMs

Rate per Million

enplanements

A380 DIVERSIONS - IMPACT

Safety Unplanned approach / unfamiliar airfield

May be hours from suitable airfield on ULR flights

Benefit to patient vs. risk to others

Logistics Airport compatibility – runway / taxiway / towbar

Challenge to receiving airfield - accommodation / medical

Inconvenience to pax

Costs? Fuel

Missed connections

Accommodation

Crew costs 94

ULR DIVERSIONS

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MEDICAL EQUIPMENT ENHANCEMENT

More Defibrillators?

More EMKs?

Disposables?

Other equipment?

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MEDICAL TELEMETRY

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CONCLUSIONS ON IFMES

IFMEs are uncommon events

The high capacity fleet will have an increased medical incident rate per a/c

Airport compatibility issues and passenger numbers make diversions even less desirable.

Telemedicine devices may be a cost effective way to improve passenger outcomes and diversion decision making

Performance needs close audit

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Where will it end?? Boeing/NASA Blended Wing

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Questions???

Documents

Airline Medicine over the Years - Royal Aeronautical Society