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AVMO > High G physiology and protection > Flashcards

High G physiology and protection Flashcards

1
Q

what is the classification of acceleration. Short, intermediate and long

A

Short: impact eg crash <0.5 sec
Intermediate:ejection, catapult/cable. 0.5 - 2.0 secs
Long: linear - takeoff, radial - ACM/manoeuvring >2.0sec

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2
Q

Newton’s first law

A

Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it

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3
Q

Newton’s second law

A

the relationship between an object’s mass, it acceleration and the applied force. F=ma
Acceleration and force are vectors

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4
Q

Newton’s third law

A

For every action there is an equal and opposite reaction. eg acceleration and inertial force

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5
Q

Describe the G axes

A 
\+Gz= superior to inferior
-Gz= inferior to superior
\+Gx=anterior to posterior
-Gx=posterior to anterior
\+Gy= to left
-Gy=to right
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6
Q

G profiles of ADF aircraft

  • F-35
  • Hawk 127
  • PC-21
  • F/A 18 honet
A

F-35 = -3G to +9G
Hawk 127 = -4G to +8G
PC-21 = -4G to +8G
F/A 18 Hornet = -3.5G to +7.5G

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7
Q

Describe the Gz continuum

A 
Weight increase
Grey out
black out
A-LOC
G-LOC
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8
Q

physical Effects of +Gz

A 
Face sag
increase wt
- unassisted escape impossible at >3G
- Can't lift head up >4G
- Can't lift limbs at >8G
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9
Q

Cardiology effects from +Gz environment

A

blood pooling
reduced cerebral blood flow
Dysrhythmogenic due ot autonomic imbalance due to stretching of conduction system

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10
Q

Describe Grey Out

A

Causes tunnelling of vision
+3 to +4Gz
vision affected first due to pressure in eyes
peripheral effected first as greatest distance from optic artery.

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11
Q

Describe Black out

A

Causes complete loss of vision
+ 4 to +4.5 Gz
still conscious but no vision

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12
Q

How does +Gz worsen hypoxia

A

Changes to lung tissue
- upper alveoli are distended, lots of air
- lower alveoli are compressed, no air
Changes to blood flow
- decreased flow to upper lung
- increased flow to lower lung
exacerbates V/Q mismatching predisposing to hypoxia

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13
Q

Describe Oxy lung

A

occurs when >+3Gz, using G suit, breathing oxygen
V/Q mismatch related hypoxia reduced G performance
presents as dry cough, pain beneath the sternum, inability to take a deep breath

resolves quickly post flight with deep inspirations and/or coughing
ACBC

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14
Q

protective factors for Oxy lung

A

AGSM
pressure breathing
>40% nitrogen
incentive spirometers

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15
Q

MSK effects by +Gz

A

Short term
- acute musculo-ligamentous strains and sprains called burners and stingers
Long term: degenerative disc disease and osteoarthitis

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16
Q

explain G measles and G roids

A

G measles: petechial haemorrhages in skin, dependent areas of body
G roads: Haemorrhoids, may cause bleeding and irritation

17
Q

Describe the recovery from G-LOC

A

absolute incapacitation 15 seconds
relative incapacitation 15 seconds
full recovery 1-5 mins
Subtle cognitive impairment up to 24hrs

18
Q

describe almost loss of consciousness

A

G induced impairment of cerebral function with no LOC, short duration, rapid onset G exposure, typical duration approx 5 sec
Lights on but nobody home

Symptoms: 
- sensory disturbances
- euphoria
- amnesia
- apathy
- loss of short term memory
- word forming difficulty
- reduced auditory acuity
- motor disturbances
similar to the relative incapacitation stage of G-LOC
19
Q

what is symptoms during recovery from G-LOC

A 
Euphoria/dreamlike state
confused and disorientated
muscle spasms/seizures
light-headedness
Amnesia in 50% of cases
psychological suppression/denial
20
Q

Factors that increase risk of G-LOC

A 
Unprepared for G
U/S anti-G suit
Rapid onset of G
lack of experience
layoff
minor illness
missed meal
hangover
unfit
21
Q

Immediate actions after G-LOC event

A 
Declare PAN
fly straight and level to regain capability
Simple approach and landing
review by AVMO to ID Risk factors
ASOR
Return to flying next day
22
Q

Clinical management of G-LOC

A 
Medical history
sortie profile
72hr history of the crew
IX predisposing Risk Factors
Manage as appropriate
TMUFF 24 hours - can fly the next day
23
Q

what physiological factors might effect G tolerance

A 
Illness
medications/supplements
hypoxia/hyperventilation
heat stress
dehydration
alcohol
24
Q

Pilot fitness checklist

A 
IM SAFE
illness
medication
stress
alcohol
fatigue
emotion
25
Q

what personal factors affect G tolerance

A 
Unprepared
lack of experience
previous lay-off
missed meal
fatigue
26
Q

What sortie-related factors affect G tolerance

A 
Sortie-related
Peak G level
G onset rate
push pull effect 
poor AGSM
27
Q

How do Baroreflex response to falling BP

A 
baroreceptors inhibited
decreased impulses to the brain
decreased  PNS active and Increase SNS
Effects
- Heart: increase HR &amp; contractility
- Vessels increase vasoconstriction
- Adrenal gland: release of adrenaline and noradrenaline.

results in increase contractility and vasoconstriction = increase BP
take 6-12 secs to work

28
Q

effects of negative G

A

defined as less then +1Gz manouevre
poorly tolerated
Head level BP increase
LOC from - 4Gz

29
Q

Explain what happens during -Gz

A

baroreflexes in reverse
- hydrostatic effects cause stretch which results in heart slows, blood vessels dilate, BP falls

Symptoms: facial pain/fullness, eye discomfort, nose bleeds, red out, headaches, mental confusion, unconscious -4Gz

30
Q

Explain the push - pull effect

A

when performing <1+Gz manoeuvre which triggers baroreflexes to drop blood pressure. then moving to >1+Gz which drops the BP due shift of hydrostatic pressure prior to the baroreflexes being able to increase BP. Results in GLOC earlier then expected

31
Q

what High G defence training strategy

A 
education about High G physiology
AGSM 
Anti G garments
physical conditioning
centrifuge training
32
Q

Steps to prevent neck pain

A

Before flight

  • fitness and training
  • core upper body strength. neck, generic isometric or physio specific.
  • pre-flight stretch and warm up

Inflight

  • pre -positioning
  • plan head movements
  • use of structures

post-flight
- stretch and cool down

symptoms management

  • stop flying
  • early self tx
  • rest, stretch +/- analgesia
  • if no improvement seek AVMO &/or physio early.
33
Q

What is the most effective method to prevent G-LOC

A

anti-G straining manoeuvre

34
Q

Describe AGSM and how much tolerance does it give

A

Adds +3 to 4 Gz tolerance

2 parts

  • Continuous muscle contraction started prior to onset of G force. Contract legs, buttocks, abdominals.
  • Breathing: increase intrathorac pressure which increases cerebral circulation. breath every 3 secs to allow heart to refil.
35
Q

Common mistake with AGSM

A 
failure to anticipate G
Inadequate strain
poorly coordinated strain
Failure to maintain AGSM during G offset
Breathing cadence
Fatigue due to poor energy conservation
36
Q

How much protection does anti G suit give against G

A

Adds 1-1.5 G tolerance
makes AGSM easier

extended coverage adds 2-2.5 G tolerance

37
Q

how much protection does positive pressure breathing for G and what are the problems

A

PBG at 30mmHg fives +3Gz of protection.

problems

  • doesn’t protect against against rapid G onset
  • communication issues
  • mask seal problems
  • high G forearm pain
  • decrease venous return
38
Q 
The most effective form of G protection is provided by 
A the pneumatic anti-G suit
B the AGSM
C positive pressure breathing
D reclined seating
A

B the AGSM

AVMO (49 decks)

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