04 MCAT AND AVMED CARDS (20) Flashcards
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1
Q
1 ATMOSPHERE =
A
- 760 mmHg
- 10m H2O
- 100 kPa/1000 hPa
- 15 psi
- 1 Bar/1000 mBar
2
Q
HEIGHT vs BAROMETRIC PRESSURE (approx)
A
- SEA-LEVEL = 1 atm
- 10,000 ft ~ 2/3 atm
- 20,000 ft ~ 1/2 atm
- 30,000 ft ~ 1/3 atm
3
Q
AIR TEMPERATURE vs ALTITUDE
A
- Air temperature declines linearly at ~ 2 degrees C per 1000 ft until it reaches a minimum of -56C, typically around 36,000 ft, where it stays for tens of thousands of feet before rising again in the upper atmosphere
4
Q
ABOVE WHAT HEIGHT IS OXYGEN REQUIRED IN FLIGHT?
A
- OXYGEN is required above 10,000 ft
5
Q
WHAT HAPPENS ABOVE 63,000ft
A
- above 63,000 ft, the atmospheric pressure falls below 47mmHg, which is the SVP of water at 37C, so the body fluids boil
6
Q
DECOMPRESSION ILLNESS
A
- Body water contains dissolved gases, especially NITROGEN.
- Sudden falls in atmospheric pressure, eg after rapid ascent when diving, or from aircraft decompression, may allow bubbles to form in the tissues and bloodstream.
- This produces 4 clinical manifestations:
- ‘THE BENDS*’ : joint pain
- ‘THE CREEPS’ : skin irritation and rashes
- ‘THE CHOKES’ : dyspnoea & pleuritic pain
- ‘THE STAGGERS’ : CNS deficits eg paralysis and paraesthesia
MANAGEMENT :
- treat even mild symptoms seriously, as they may progress
- recompress if possible, by diving again or descending
- breathe 100% O2 to speed washout of Nitrogen
- avoid flying for 48h after diving (diving supersaturates the blood with Nitrogen)
* named after caisson workers, who walked stooped
7
Q
HYPOXIA WITH ALTITUDE
A
- Normal Sea-level Arterial pO2 is ~100mmHg. This falls with increasing altitude due to the combined effects of
- the falling partial pressure of oxygen in the alveolus as atmospheric pressure declines
- increasing occupation of the alveolus by water vapour, because water has an SVP of 47mmHg at 37C, irrespective of altitude
- below 10,000 ft, effects are minimal, although night vision can be impaired from as low as 4000ft because the peripheral retina is very sensitive to hypoxia
- at 10,000 ft, Art pO2 falls to 55mmHg (87% SpO2) which is the minimum level for reasonable cognitive function, so supplemental Oxygen is required for flight over 10,000 ft
- between 10-15,000 ft, SIGNIFICANT IMPAIRMENT occurs, with headache, fatigue and frequent errors
- betwen 15-20,000 ft, GROSS IMPAIRMENT occurs, with LOC after 30m
- above 20,000 ft, LOC occurs in minutes
- above 40,000 ft, LOC occurs in seconds, with the Time of Useful consciousness (TUC) little more than one lung-brain circulation time
- above 33,000 ft, even breathing 100% O2 cannot maintain a normal sealevel pO2 of 100mmHg, and above 40,000 ft, pressurised breathing systems or cockpits are required
8
Q
DISTINGUISHING BETWEEN HYPOXIA, HYPERVENTILATION AND ‘FUMES IN THE COCKPIT’
A
YOU CAN’T, at least not to reliably exclude HYPOXIA, so actions on suspicion are the same for all:
- go on 100% O2
- go on max positive pressure if a pressurised breathing system
- check all O2 connectors
- descend below 10,000 ft
- declare an emergency and land ASAP
9
Q
WHY DOES EXPLOSIVE DECOMPRESSION CAUSE FOG OR SNOW IN THE CABIN?
A
- because loss of CABIN PRESSURE causes a loss of Cabin TEMPERATURE.
- If the temperature of the air remaining in the cabin falls below its DEW POINT, fog, rain or snow may result
10
Q
RAAF STRETCHER PARTY COMMANDS
A
(Given by LHS rear)
- “Patient protect your face”
- “Prepare to lift”
- “Lift”
- “Forward”
(Given by one of the 2 lead bearers)
- “Halt”
- “Lower”
11
Q
AME PATIENT CLASSES
A
-
CLASS ONE : PSYCH PATIENTS
- 1A = Severe : requires Litter, search, sedation, restraint and supervision
- 1B = Intermediate
- 1C = Moderate : ambulant and co-operative
-
CLASS TWO : LITTER PATIENTS
- 2A = Immobile, helpless in an emergency
- 2B = Limited mobility, may be able help self in emergency
- 2C = Ambulant, but would benefit from litter
-
CLASS THREE : WALKERS
- 3A = Sitter, will need assistance to egress
- 3B = Sitter, will not need assistance
- CLASS FOUR : PASSENGERS (eg Dental patient going for OPD)
12
Q
OXYGEN CYLINDER CAPACITIES - APPROX
A
- C SIZE = 400L
- D SIZE = 1600L
- E SIZE = 4000L
13
Q
C130 MEDICAL OXYGEN CAPACITY?
A
- NIL! all medical oxygen must come from the 2 x 4000L E cylinders in the DARTS CAGE, or from cylinders lashed vertically to the litter staunchions
14
Q
C17 MEDICAL OXYGEN CAPACITY?
A
- The C17 has a DEDICATED medical oxygen system consisting of 2 x 75L LOX tanks, each L of which vaporises to produce 804 L of gaseous Oxygen, giving a total medical oxygen capacity of 120,000 L, but with outlets only on the RHS of the cabin
15
Q
MAXIMUM DUTY HOURS FOR AME PERSONNEL
A
- AME Personnel are regarded as aircrew, so for planning purposes, their maximum duty hours should not exceed 14 (although obviously cant down tools mid mission if ongoing)
