Basic Aeromedical Transport Presented at: ACEM Workshop By: Sutuspun Kay Kajornboon, M.D., Dip. Av. Med. (UK) Director, Civil Aeromedical Center, BMC Date: 2011
Basic Aeromedical
Transport
Presented at: ACEM Workshop
By: Sutuspun Kay Kajornboon,
M.D., Dip. Av. Med. (UK)
Director, Civil Aeromedical Center, BMC
Date: 2011
TROPOSPHERE
From sea level to FL 300-600 Depending
on temperature
Temperature Lapse Rate 1.98 oC / 1,000 ft.
Water Vapor : Seasons & Weather,
Turbulance
Most Flying occurs
Dr. Sutuspun Kajornboon
Physiological Division
PHYSIOLOGICAL ZONE:
MSL to 10,000 ft.
PHYSIOLOGICAL DEFICIENT ZONE
10,000 ft. to 50,000 ft.
SPACE - EQUIVALENT ZONE
> 50,000 ft.
Dr. Sutuspun Kajornboon
Physiological impact of decreased atmospheric
pressure
Decrease of Total Pressure
Evolved Gas Problem
*Decompression
sickness
Decrease of Atmospheric Pressure
Decrease of Partial
Pressure
Trapped Gas Problem
*Ear Barotrauma
*Sinus Barotrauma
*Gastrointestinal gas
expansion
*Barodentalgia
*Etc.: pneumothorax,
peumomediastinum
Hypoxia
Dr. Sutuspun Kajornboon
mm Hg0200 400 600 760
80k
70k
60k
40k
30k
20k
10k
50k
Feet
Change of Pressure with Altitude
1/2
1/4
1/10
Partial Pressure
Air at Sea Level
O2 = 21% pO2 = 160 mm Hg
N2 = 78% pN2 = 593 mm Hg
Other = 1% = 7 mm Hg
Total = 100% = 760 mm Hg
Partial Pressure
Air at 10,000 ft.
O2 = 21% pO2 = 110 mm Hg
N2 = 78% pN2 = 408 mm Hg
Other=1% = 5 mm Hg
Total=100% =523 mm Hg
Partial pressures in mm Hg at sea level
103
570
40
47
Alveolar air
Carbon dioxide
Water vapour
Oxygen
Nitrogen
160
593
Atmospheric air
Oxygen
Nitrogen
0
760
Other 7
Alveolar Gases
10,000 ft
523 mm Hg
55O2
381N2
40
47
CO2
H2O
Sea level
760 mm Hg
103O2
570N2
40
47
CO2
H2O
Relationship between alveolar p02, altitude and Hb saturation
0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50 60 70 80 90 100 110
sea level5k10k15k20kAltitude (ft)
Alveolar pO2 (mm Hg)
% Hb
saturation
Alveolar Gases
10,000 ft
523 mm Hg
55O2
381N2
40
47
CO2
H2O
Sea level
760 mm Hg
103O2
570N2
40
47
CO2
H2O
18,000 ft
380 mm Hg
Air
39O2
264N2
30
47
CO2
H2O
Symptoms and Signs
Performance Effects
personality change
loss of judgement
loss of self-criticism
euphoria
loss of short term memory
mental incoordination
Symptoms and Signs
Physical Effects
muscular incoordination
sensory loss - vision
- touch
hot flushes
cyanosis
hyperventilation
Symptoms and Signs
Late Effects
semi-consciousness
unconsciousness
death
Times of Useful Consciousness
Altitude TUC
FL 180 20 - 30 min
FL 220 10 min
FL 250 3 - 5 min
FL 300 1 - 2 min
FL 350 30 - 60 sec
FL 400 15 - 30 sec
FL 430 9 - 12 sec
Factors Affecting Tolerance to
Hypoxia - I
• altitude
• time
• rate of ascent
• exercise
• cold
• illness
Factors Affecting Tolerance to
Hypoxia - II
• fatigue
• drugs and alcohol
• smoking
• stress and workload
• physical fitness
• hangover
TRAPPED GAS
DISORDERS
80k
34k
18k
0
53k
4 x
1 x
10 x
Gas Expansion at Altitude
The Middle Ear
Eardrum
Eustachian tube
Inner earOuter ear
Gas Expansion in
the Ear - Climb
Pressure in the
middle ear is
greater than the
outside’s pressure.
Gas Contraction in
the Ear - Descent
Pressure in the middle
ear is less than the
outside’s pressure.
Acute Barotitis Media
Eardrum
Eustachian tube
BAROTITIS MEDIA
• An acute/chronic traumatic inflammation
caused by pressure difference between
the air in the middle ear and that of the
surrounding atmosphere.
• Symptoms: pain, deafness, tinnitus and
occasionally, vertigo.
Prevention
• Equalized pressure by:
• Chewing action or moving jaw side to
side
• Yawning or swallowing
• Valsalva
• Do not fly with a cold.
Valsalva Maneuver
• Take a deep breath.
• Hold the nostrils shut tight.
• Tense the cheek & neck muscles.
• Force pressure similar to blowing your
nose. ( Strong short burst )
The Sinuses
Frontal sinus
Maxillary sinus
Ethmoidal sinuses
Sphenoidal sinus
Barosinusitis Media
• Signs: fullness around the eyes area to
sharp stabbing pain
• : trace of blood with nasal discharge
Treatment & Prevention
• Seek treatment for URI/Sinusitis
• Do a valsalva maneuver for relief
• Use antihistamine nasal spray
Intestinal Gas Expansion
• Sea Level = 1.0 Liter
• 10,000 ft. = 1.5 Liter
• 30.000 ft. = 4.0 Liter
• 40,000 ft. = 7.0 Liter
• 50,000 ft. = 17.0 Liter
Gas Expansion in
the Stomach
Gas Expansion in
the Large Bowel
Gas Expansion in
the Small Bowel
?
Prevention
• Avoid gas producing food.
• Chew your food completely.
• Avoid drinking large amount of liquid
before flight.
• Start the day with good bowel habits
• Avoid chewing gum during ascent
RELIEF OF SYMPTOMS
• Belching (upper GI)
• Passing wind (lower GI)
• Maintain level flight (for cockpit crew)
• Descent to lower altitude if pain is severe
(for cockpit crew)
Gas Expansion in the Lungs
- pneumothorax
- air embolism
- pneumomediastinum
Prevention of Trapped Gas
Problems
• Fly only when healthy
• See a doctor if ill
• Equalize pressures frequently on
descent
• Avoid gas producing foods, maintain
a healthy diet
Flight Environment• GLARE
• Strong bright light from the sun above and
reflected from the clouds below
• Health effect from UVa & UVb causing
eyes irritation pterygium & cataract
(long term)
• Effect pilot more than cabin crew
Noise & Vibration
Library
Heavy truck
Jet take-off
Pneumatic road drill
Business office
Quiet woods
140 dB
0
Pa 200,000,000
100
80
60
120
40
20
20,000,000
200,000
2,000,000
20,000
2000
200
20
Acceptable Noise Levels.
• No NIHL with 75 - 80 dB(A)
exposures.
• OH&S limit of 85 dB(A) for 8 hour
working day (Daily Noise Dose).
• Aircrew exposures regularly exceed this.
Flight Environment
Noise
• Communication
• Stress
• Fatigue
• Distraction
• Deafness (hearing loss)
• Vibro-acoustic Syndrome
Vibration
• Pain threshold
• Stress
• Fatigue
• Motion Sickness
• Speech problem
• Hyperventilation
• Soft tissue injury (backpain)
Personal Protective Equipment:
Aircrew helmets.
Aircrew headsets.
Earmuffs.
Insert earplugs.
Active Noise Reduction.
Flight Environment• HUMIDITY
• Human are comfortable with humidity around 60-70%; Cabin humidity could be as low as less than 30%
• Can cause throat & upper airway irritation prone to viral infection & make jet lag worse
• Dryness exacerbate chronic skin problems such as allergy, eczema, dandruff
HUMIDITY
• Drinks more water or fluids
• Avoid alcohol, too much
coffee or tea
Flight Environment• UNUSUAL MOTION
• Unexpected movements in all three axis which is not normally encounter on the ground confusion, stress and motion sickness.
• Long term worsen the effect of jet lag and fatigue easily
• Turbulence are health hazard for aircrew
Med-crew Environment
• CONFINED WORKING AREA
• Psychologically stressful: constantly
avoiding obstacles; worse in claustrophobia
• Physically a safety hazard: can get injured
easily especially during turbulence
Thank you for your attention