Atmosphere and respiration Flashcards
boyles law
V inversely proportional to P
associated with barotrauma
guy lussac law
volume const
P proportional to T
combined gas law
PV/T=k
ficks law
diffusion
high concentration to areas of low concentration
inversely proportional to thickness of membrane
daltons law
total pressure is equal to sum of the partial pressures
related to hypoxia
henrys law
more pressure, more gas can dissolve into a liquid directly proportional
related to decompression sickness
external respiration
occurs at lungs
between 12-20 breaths per minute at rest
Nose warms ,moistens & filters air
tidal volume
air inhaled & exhaled in normal breath
500ml
inspiratory reserve volume
extra can inhale above normal
3100ml
expiratory reserve volume
extra can exhale above normal
1200ml
residual volume
not all air breathed out. what’s left in lungs
1200ml
total lung capacity
all volumes added
vital capacity
max can actually breath in or out
everything but residual
functional residual capacity
expiratory reserve + residual
inspiratory capacity
tidal volume + inspiratory reserve
altitude at which oxygen partial pressure of O2 drops to 1/2?
10000ft
drops to 55mmHg
altitude at which total pressure drops to 1/2?
18000ft
380mmHG
altitude at which total pressure drops to 3/4?
8000ft
543mmHg
altitude at which total pressure drops to 1/4?
36000ft
187mmHg
total pressure at MSL?
760mmHg
when oxygen partial pressure drops below 55mmHg…
alveoli no longer cope
above 10000ft
percentage of ox remains same but partial pressure decreases
haemoglobin saturation levels
SL- 97%
10000ft- 87%
20000ft- rapidly falls to 65%
saturation less than 90% can result in hypoxia
2 types of hypoxia
hypoxic- due to decrease in partial pressure of oxygen from increase in alt
anaemic- inability of blood to carry oxygen
what makes hypoxia worse?
smoking high workload at altitude unhealthy,alcohol, diet etc higher alt= worse exposure
hypoxia reaction threshold
GL- 7000ft
vision sensory affected as low as 5000ft
newer task/ memory affected
dark adaption affected
hypoxia disturbance threshold
7000-12000
increased blood pressure -
increased heart rate -
maintaining homeostasis
hypoxia critical threshold
12000-22000ft homeostasis doesn't work euphoria cyanosis fornication dizziness headache impaired judgement muscular impairment hyperventilation mental performance degraded to 12000ft memory impaired 12000ft confusion grey out / tunnel vision incapacitation loss of consciousness DEATH
TUC & EPT
time of useful consciousness
effective performance time- time you can perform flying duties effectively in reduced oxygen
TUC
20k- 30 min, mod activity- 5min
30k- 1-2min
35k- 30-90sec
40k- 15-20sec
halved for smokers
hyperventilation
lung ventilation in excess of bodies needs
too much CO2 removed from the blood
less carbonic acid - go into respiratory alkalosis
can lead to hypoxia - vasoconstricts vessels
causes of hyperventilation
stress anxiety travel sickness - motion sickness high Gs shock high or low acid level
hyperventilation symptoms
seizures tingling light headed hot or cold flushes headache lethargy sickness muscle spasm confusion increased heart rate
hyperventilation treatment
breathe into paper bag
hold one nostril
decompression sickness
formation of nitrogen in bubbles after decompression at altitude 18000-25000ft unlikely below 14000ft symptoms: bends- in joints chokes- in lungs staggers- in brain
made worse by: high alt, age, obesity, worse if been scuba diving
prevent with pre oxygenation - 100% ox flushes out nitrogen
rules about scuba diving and flying
must not fly within 12 hours of swimming with compressed air
if exceeding 30ft(10m) don’t fly within 24hours
not applicable to snorkelling
decompression and hypoxia treatment
don mask- 100%ox declare emergency controlled but rapid descent land ASAP on landing seek medical advice
can get decompression symptoms 24 hours after so wait to fly again- can be treated in decompression chamber
prevent with pre oxygenation
hypoxia or hyperventilation
unsure then always treat for hypoxia as its worse
hyperventilation- recover after unconsciousness
hypoxia - die after unconsciousness
below 10000ft hypoxia unlikely so maybe treat for hyperventilation but be aware
oxygen requirements
MSL-10000ft normal air
10000ft - 33700ft- cab pressure, supplementary air/oxygen mix, keeps body at MSL
33700-40000ft - cabin alt, 100% oxygen, keeps body at 10000ft
above 40000ft- pressurised 100%, keeps body at 10000ft
cabin pressure
kept between 6000-8000ft
