RESPIRATION
AND
OXYGEN
Aerodoc
Crash with B737
14. august 2005
NOTE:
same
Boeing 737,
5B-on
DBY,
Helios'The
Flight
522 departed
Larnaca
a
scheduled
23 minute
flight toon
Athens,
suffered1ahour
lossand
of cabin
pressure
Greece.
After an
stopathere,
was to
December
20,intermidiate
2004 during
flight itfrom
have continued on to Prague, Czech Republic.
Warsaw
Larnaca
passengers
The fight,to
cleared
for .anThree
en route
altitude of
FL340,
reportedly
Cypriotic
needed
medicalnotified
treatment
aftercontrollers
landing
that they had some problems with the air
in Larnacasystem.
. This incident
caused
conditioning
The 737 was
entered
Greekby
air
about
10:30,
by air
traffic
aspace
leaking
door
sealbut
of efforts
the right
hand
rear
controllers
to
contact
the
pilots
were
futile.
door.
Around 11:00 two Greek F-16 fighter planes
were scrambled from the Néa Anghialos air
base. The F-16 pilots reported that they were not
able to observe the captain, while the first officer
seemed to be unconscious. Apparently one or
two other persons seemed to have entered the
cockpit, attempting to control the plane. The F16's continued to track the flight as it flew in a
gradually descending holding pattern. That
person then banked the plane away from
Athens, lowering it first to 2,000 feet and then
climbing back up to 7,000 feet before the plane
apparently ran out of fuel and crashed in
mountainous terrain some 40 km North of
Athens.
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Why?
Why is oxygen important?
Necessary for the production of energy in
cells
20% of all oxygen is used by cells in brain
Brain cells will die if they are deprived
oxygen for over 2 minutes
s. 37
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The Respiratory system
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Airways consist of?
Nose and mouth (warming, moistening,
filtrating)
Throat
Trachea
Bronchi
Bronchioles
Respiratory bronchioles
Alveoli (gas exchange)
s. 37
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s. 39
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Lung Gas Volume (male)
Normal Tidal volume: 500 ml
s. 38
Normal IRV
: 3000 ml
Normal ERV
: 1100 ml
Normal RV
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1200 ml
20-25% less
in female
Gas exchange
s. 38
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Transfer of oxygen and carbon dioxide
When talking of tissue
the diffusion i described
by Fick’s law:
A
Vgas ~ /T D (P1-P2)
s. 41
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Diffusion of oxygen in lung
2 conditions:
1: normal PalvO2 (103 mmHg)
2: low PalvO2 (40 mmHg)
= HYPOXI
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Oxyhaemoglobin dissociations curve
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Effect of Pco2
Tissue
Alv.
Low Pco2 => more oxygen attached to hemoglobin
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Regulation of respiration
CO2↑
RC in Brain
O2↑
CO2↓
Respiratory frequents normal 16 (12-20) breaths/min
s. 37
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The standard atmosphere at MSL
(ICAO)
Pressure 1013,25 mbs(760 mmHg)
Density 1225 g/m3
+ 15o Celsius
Temp. decrease 1,98o C/1.000 ft up to
36000 ft. Thereafter it remains constant at 56,50C to 65000 ft
s. 40
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Pressure in atmosphere
8000 ft
18000 ft
36000 ft
s. 40
: ¾ MSL
: ½ MSL
: ¼ MSL
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Pressure Altitude
Pressure
1 MSL
Sea level
¾ MSL
Cabin
¼ MSL
Outside
Altitude
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How is the composition of the
atmosphere?
(up to 70000 ft)
21 % Oxygen
78 % Nitrogen
0,93 % Argon
0,03 % Carbon dioxide
0,04 % rare gases
s. 40
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Gas Laws
s. 41
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BOYLE´S LAW
GAS EXPANSION
FL 430
As atmospheric pressure
decreases, the air tends
to expand and get thinner
The human body has
several responses to
changes in atmospheric
pressure.
FL 350
FL 250
FL 180
P1 x V1 = P2 x V2
with constant T
s. 41
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Where in the body can Boyle’s
law give rise to problems?
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Aeromedical problems in relation til
Boyle’s law
Barotrauma in middle ear
Barotrauma in sinus
Aerodontalgia
Barotrauma of the Gastro-Intestinal Tract
s. 41
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Ear Block
If you fly with a cold
these passages can
swell up enough to
block the passage of
air, especially when
you are trying to get
air in to equalize
pressure on descent.
Leads to a painful ear
or sinus block!
Do Not Fly with a Cold!
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DALTON´S LAW states that?
The total pressure of the gas mixture is
equal to the sum of its partial pressure.
Pt = P1 + P2 +++++ Pn
s. 41
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What is the Aeromedical problems in
relation to Dalton´s law?
Oxygen in alveoli
Hypoxia and decreased night vision
(pressure in eye)
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HENRY´s LAW
At equilibrium the amount of gas
dissolved in a liquid is proportional
to the gas pressure
s. 41
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What is the Aeromedical problems in
relation til Henry´s law?
Decompression sickness & bends
s. 41
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CHARLE´S LAW
The volume of a fixed mass of gas held
at a constant pressure varies directly
with the absolute temperature
s. 41
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Alveolar gases when breathing
air
(Daltons law in practice)
PalvO2 = PinspO2 – PalvCO2 ( FinspO + (1 - FinspO )/R )
2
2
Correction factor because of nitrogen
in inspired and alveolar gas
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Pressure
Normal
atmospheric
pressure at sea
level is 760 mm
Hg
As you go up in
altitude,
atmospheric
pressure
decreases.
s. 41
100% OXYGEN
UNDER
PRESSURE NEEDED
100% oxygen
SUPL. OXYGEN
NEEDED
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Press
mm Hg
Alt in
Thou. Ft
34
70
54
60
87
50
141
40
226
30
349
20
523
10
760
0
SEA LEVEL
Alveolar air
The partial pressure of oxygen in lung is
less than atmospheric air because of
CO2 + H2O (normal 103 mmHg)
The minimum partial pressure of oxygen in
alveoli for normal operations is 55 mmHg
s. 42
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The gases in the lung
Partial pressure (mmHg)
Constituents
Oxygen
Nitrogen
Water
vapor
Carbon
dioxide
Atmospheric
Air
160 (21%)
600
-
-
Alveolar air
MSL
103 (14%)
570
47
40 (5,3%)
Alveolar air
10000 ft
55
(Limit for
human
activity)
381
47
40
s. 42
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Environmental Requirements
Press
of Oxygen
mm Hg
Ft
As altitude increases,
available oxygen decreases
STRATOSPHERE
TROPOPAUSE
Mt Everest
29,028 ft
100% OXYGEN UNDER
PRESSURE NEEDED
100% OXYGEN
TROPOSPHERE
Andes
Alt in
Thou.
Mt Whitney
OXYGEN
NEEDED
34
34
70 70
5454
60 60
8787
50 50
141
141
40 40
226
30
349
20
523
10
226
349
523
760
30
20
10
0
760LEVEL0
SEA
Highest Human Habitation...18,000 ft
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Thresholds of oxygen requirements
Up to 10000 ft
- air only
(PalvO2 decreases to 55 mmHg)
10.000 – 33.700 ft
- oxygen/air mixture
(PalvO2 = 103 mmHg)
33.700 – 40.000 ft
- 100% oxygen
(PalvO2 decreases to 55 mmHg)
Above 40.000 ft
s. 43
- 100 % oxygen under pressure
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How can people live
permanently at 18000 ft.?
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HYPOXIC HYPOXIA
(Shortage of oxygen in lung)
The most important reason to
hypoxic hypoxia in aviation is
altitude
s. 43
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Saturation of hemoglobin with
altitude
Sea level
s. 43
87
10.000 ft
65
20.000 ft
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What is the symptoms of
HYPOXIA?
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Gaston Tissandier 1843-1899
Balloon flight in 1875 to 8600 m
s. 43
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Environmental Requirements
Oxygen
Lack of oxygen will
affect the brain and
cause fatigue,
sleepiness, headache,
dizziness, blurred
vision and will
eventually cause you
to lose
consciousness.
HYP
XIA
10,000 MSL
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Symptoms
(subjective)
Hypoxia
Air hunger
Apprehension
/ scared
Fatigue
Nausea
Headache
Dizziness
Hot and Cold flashes
Euphoria/Personality Change
Aggressive
Blurred vision
(color/peripheral
Tunnel vision
Formication
Tingling
Signs
(objective)
Hyperventilation
Cyanosis
Mental confusion (Short
memory > 12000 ft)
Impaired judgment
(>12000 ft)
Muscle incoordination
UNCONSCIOUSNESS
DEATH
(within minutes)
s. 43
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Which factors determining the severity of and
the susceptibility to hypoxic hypoxia?
Altitude
Time
Workload
Extremes of temperature (heat/cold)
Illness
Fatigue
Alcohol
Drug
s. 45
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Relative incidence of the causes of 397 cases of
hypoxia in flight in a military air force
Cause of hypoxia
Relative
incidence (%)
Failure of oxygen supply
Failure of oxygen regulator
Regulator off
Inadvertent break of connection in host between
regulator and mask
Hose defect or failure
Inadequate seal of mask to face
Malfunction of mask valves
Decompression of pressure cabin
Toxic fumes giving rise to hypoxia
Others
3
25
1
9
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1
7
3
32
2
17
Treatment
What to do in the air?
OXYGEN
+
Descend to safe level
s. 44
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ANAEMIC HYPOXIA
(Decreased ability of the blood to
carry oxygen)
The most important reason to this
is
CARBON MONOXIDE
POISONING
s. 46
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Smoking
Increases the amount of
carbon monoxide in blood
leading to decreased
OXYGEN CARRIAGE
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20 cigarettes a day will have a
raised CO-haemoglobin by 7%
This equates to a reduction in oxygen
carrying capacity of 4000-5000 ft.
With normal cockpit altitude of 60008000 ft this will give the smoker an
altitude up to 12000 ft with resulting
Anaemic hypoxia
s. 46
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Effect of smoking 20 cigarettes
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Smoking can lead to?
Lung cancer
Breathing problems (COLD)
Circulatory problems
Reduced tolerance of G forces
Increased risk of heart attack
Increased level of adrenaline
Addiction
Degradation of night vision (20%)
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IF YOU SMOKE – STOP
IF YOU DON´T SMOKE
– DON’T START
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What can you do to prevent
Hypoxia?
-
Ensure you now your own symptoms of hypoxia
Ensure supply of oxygen is available (>10000 ft.)
Ensure crew can use it correct (oxygen drill)
Ensure passengers are briefed
Stop smoking
Fly only if fit
Ensure cabin heater is checked and serviceable
s. 44
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Environmental Requirements
Oxygen
A pilot must be
able to recognize
when problems are
due to lack of
oxygen
Altitude chamber
training helps
aircrew to discover
their own hypoxia
symptoms
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Hypoxia in Altitude Chamber
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4 stages/zones of hypoxia 1
The indifferent stage/zone: GL – 10.000 ft
- dark adaption decreases
- performance of new tasks impaired
- slight increase in heart and breathing rates
The compensatory stage/zone: 10.000 ft – 15.000 ft
- increase in heart and breathing rate
- increase in blood pressure
- drowsiness
- decreased judgement and memory (short)
- difficulty in performing tasks requiring mental alertness
- difficulty in performing very small movements
s. 44
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4 stages/zones of hypoxia 2
The Disturbance stage/zone 15.000 – 20.000 ft
- euphoria
- dizziness
- sleepiness
- headache
- fatigue
- intellectual impairment
- memory impairment
- severe impaired motor performance
- loss of judgement
- “grayout” and tunnel vision
s. 42
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4 stages/zones of hypoxia 3
The critical stage/zone 20.000- 23.000 ft
-
Mental performance deteriorates rapidly
Confusion and dizziness occurs within a few minutes
Total incapacitation with loss of consciousness with little or no warning
s. 44
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Mean value of gas tensions after acute
exposure to breathing air at altitude
Partial pressure (mmHg)
160
140
120
100
O2 insp.
O2 alv.
O2 art.
80
60
40
Critical line
20
0
0
8000
15000 18000 20000 22000 25000
Altitude (ft)
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THE CABIN
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Cabin Pressurisation
Pressure
1 MSL
Sea level
¾ MSL
Cabin (6000-8000 ft)
¼ MSL
Outside
Altitude
s. 49
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Cabin Altitude
Ascent 500 ft/min.
s. 49
Descent 300 ft/min
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Cabin decompression
(FL over 25)
Hypoxia
Cold
Decompression sickness
s. 49
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Effect of rapid descent with large
defect in cabin
NOTE –
venturi effect
s. 49
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Effect of rapid descent with small
defect in cabin
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Decompression
Remember the
Venturi effect
(+∆P5000ft)
Too high pressure
in lung
Limit for lung damage
(80-100 mmHg)
Safe limit (< 50 mmHg)
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Alveolar gases during rapid decompression
s. 49
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TUC – Time of useful consciousness
Altitude
(ft)
18.000
20.000
25.000
30.000
35.000
40.000
43.000
s. 47
Progressive decompression
Sitting
Moderate
activity
About 40 min About 30 min
10 min
5 min
5 min
3 min
1,5 min
45 sec.
45 sec.
30 sec.
25 sec.
18 sec.
18 sec.
12 sec.
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Rapid
decompressi
on
20-25 min
3 min
2 min
30 sec.
20 sec.
12 sec.
12 sec.
Time of useful consciousness
induced by rapid decompression in
relation to the high altitude
From 25000 ft
From 8000 ft
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TUC will depend on ?
Individual fitness
Workload
Smoking
Overweight or Obesity
Type of decompression
s. 47
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Remember!
TUC is the time of useful
consciousness but the EPT
(Effective Performance Time)
might be less.
EPT above 40000 ft is
approximately 5-6 seconds
s. 47
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Crew protection
It is very important that crew members
individually take on their oxygen masks and
check flow before helping other members of
the crew or passengers. Remember TUC
and EPT.
The aircraft must descend rapidly to safe
altitude
s. 50
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HYPERVENTILATION
Hyperventilation ⇒ ↓ CO2 ⇒ ↓ H2CO2
⇒ pH ↑ ⇒ ↓ O2 release from hemoglobin
s. 48
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The symptoms of hyperventilation is?
Dizziness/ feeling of unreality
Tingling
Visual disturbances
Hot or cold sensations
Anxiety
Loss of muscular co-ordination and impaired
performance
Increased heart rate
Spasms
Loss of consciousness
s. 48
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Hyperventilation - causes
Hypoxia (must always be ruled out)
Anxiety
Motion sickness
Shock
Vibrations
Heat
High g-forces
Pressure Breathing
s. 48
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Hyperventilation – Hypoxi?
DO NOT ASSUME
HYPERVENTILATION IF IT
COULD BE HYPOXIA
Altitude > 10.000 ft always presume
hypoxia at first
s. 49
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REMEMBER
Hyperventilation → unconsciousness
→ recovery
Hypoxia → unconsciousness → death
s. 49
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DECOMPRESSION
SICKNESS
What is that?
s. 50
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Decompression sickness
(Henry’s law)
– Air bubbles can form in
the body if you go to
high enough altitudes
– These bubbles are
made of nitrogen and
usually dissolve as you
descend.
s. 50
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Decompression Sickness.
What is the symptoms?
– Bubbles that do not dissolve
can get trapped in the joints
and cause pain (Bends)
and in skin causing
(Creeps)
– If they form in the blood
they can go to the lungs
causing (Chokes) and to
the brain causing serious
neurologic symptoms
(Staggers)
s. 50
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What can increase the risk of DCS?
Hypoxia
Cold
Age
Excess body mass / obsesity
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Decompression Sickness
Prevention
s. 50
Prebreathing 100% oxygen for at
least an hour before high altitude
flights can decrease the amount of
nitrogen in the body and decrease
the chance of getting
decompression sickness.
Pressurized cabins or, if
necessary, pressure suits can be
used.
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Decompression Sickness
Treatment
Decompression
sickness can often
be successfully
treated in a
hyperbaric chamber
which dilutes out the
nitrogen with high
pressure
concentrated oxygen
s. 51
Hyperbaric Chamber, Brooks AFB, TX
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Flying and diving
Do not fly within 12 hours of swimming
using compressed air and avoid flying
for 24 hours if a depth of 30 ft has been
exceeded
Why is SCUBA diving a problem?
s. 51
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Crash with B737
14. august 2005
Why?
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