Download aeromedical principles

FLIGHT PHYSIOLOGY
AND…
APPLICATION TO
PRACTICE
Marian Williams RN BN CEN CFRN CTRN
1
2
OBJECTIVES
 To describe two basic aerodynamic principles.
 To define selected aerodynamic terms.
 To list and describe at least 6 stressors of flight
and their applicability to patient care.
 To list 5 Gas laws and apply each law to at least
two air medical interventions.
 To describe interventions for at least 5 in-flight
patient conditions and transport
considerations.
3
BASIC AERODYNAMICS
 Science of forces acting upon bodies and
shapes in motion through the atmosphere
 Aerodyne - aircraft achieving lift from
its forward motion through the air
4
FORCES OF FLIGHT
 LIFT
 GRAVITY (Weight)
 THRUST
 DRAG
 LIFT - Counteracts
gravity (weight)

-Generated by main
rotor blades
 Is equal to gravity
when in straight and
level flight
5
FORCES OF FLIGHT
 THRUST


Force generated by
engines /rotor which
propels the forward
motion of the aircraft
Also produced by tail
rotor in helicopter
 DRAG



Force generated by air
moving across and around
airframe and equipment
Opposes thrust
Caused by blades, skin
friction, airflow around
blades, non-lifting
components of the
aircraft/rotor
6
FORCES OF FLIGHT
 LIFT, GRAVITY(WEIGHT), THRUST
AND DRAG are EQUAL when the
aircraft is in straight and level flight and
at a constant speed
7
8
CENTER OF GRAVITY
 Is the design reference point of the aircraft
around which all of the aerodynamic forces are
balanced and calculated
 Proper weight and the distribution of weight is
considered for the optimum performance and
safety of the aircraft
9
CENTER OF GRAVITY
 Each aircraft has a maximum gross
weight that cannot be exceeded


Altitude and temperature affect
performance
Distribution of weight alters center of
gravity
10
CENTER OF GRAVITY
 Important to:



Find out patient and
passenger weight and
number of bags
Possibly restrict
amount of baggage
Overseas vs. domestic
flight (raft adds to
weight)
 Communicate to
Pilot weights of
patient and/or
passenger and
number of bags
 (Pre-flight
conference)
 Consider small
personal bags for
overnight flights
11
AXIS OF CONTROL
 Three axes of control
of the aircraft in
flight
 LONGITUDINAL or
Roll

Controlled by aileron
 LATERAL or Pitch

Controlled by
elevator
 VERTICAL or Yaw

Controlled by
rudders
12
AXIS OF CONTROL
13
GRAVITATIONAL FORCES
 Centrifugal forces applied to the various
axes of the aircraft and….its occupants
 6 Basic Classifications



+Gz
-Gz
+Gx
-Gx
+Gy
-Gy
14
GRAVITATIONAL FORCES
15
CABIN PRESSURIZATION
 Creates near-the-earth atmosphere
conditions
 Controls temperature and ventilation
16
CABIN PRESSURIZATION
 Atmospheric Zones


Physiologic - sea level - 10,000 feet
Physiologic Deficient - 10,000 - 50,000 feet
• Oxygen required

Space Equivalent - 50,000-250,000 feet
• requires sealed cabin or full-pressure suit

Space - >250,000 feet (120 miles)
• requires sealed cabin or full-pressure suit
• weightlessness
17
CABIN PRESSURIZATION

18
CABIN PRESSURIZATION
 Physiologically Deficient Zone (10K-50K)
• Compensatory Stage from 10,000-15,000 feet
– Increase in HR, BP, RR and depth
• Disturbance Stage from 15,000-20,000 feet
– Dizziness, sleepiness, tunnel vision, cyanosis
• Critical Stage from 20,000-30,000 feet
– Marked mental confusion and incapacitation followed
by unconsciousness
19
CABIN PRESSURIZATION

20
LOSS OF CABIN
PRESSURIZATION
 DUE TO:


Structural failure (window or door)
Mechanical malfunction of pressurization
equipment
 MAY BE:

Slow and gradual or SUDDEN
21
LOSS OF CABIN
PRESSURIZATION
 Physiological Effects





Hypothermia
Gas Expansion
Hypoxia
Decreased Cardiac &
Respiratory activity
Decompression
sickness
 Treatment




100% Oxygen on
crew first and then
patients
Secure Equipment
Unclamp Chest tubes
and Catheters
Descend below 10,000
feet
22
STRESSORS OF FLIGHT
 a. Decreased partial
pressure of Oxygen
 b. Barometric
Pressure Changes
 c. Thermal Changes
 d. Humidity
 e. Noise
 f. Vibration
 g. Fatigue
 h. Gravitational
Forces
 i. Third Spacing
23
STRESSORS OF FLIGHT
 a. Decreased Partial
Pressure of Oxygen

1. Hypoxic hypoxia
• Decrease in alveolar
oxygen exchange
• Interferes with
ventilation and
perfusion
• If requires O2 at sea
level - then O2 will be a
significant issue at
altitude
 Maximum altitude:


8000 feet
Restrict to 5000 feet

Respiratory disease with VC
<900 ml

Recent MI

Cardio-pulmonary disease

Hgb <9; Hct <25

Diving within 24 hours

Thoracic or abdominal
surgery within one week
24
STRESSORS OF FLIGHT
 a. Decreased Partial Pressure of O2
ALTITUDE
SEA LEVEL
10,000 FEET
22,000 FEET
SATURATION
98%
87%
60%
25
STRESSORS OF FLIGHT
 a. Decreased Partial Pressure of O2

2. Hypemic Hypoxia
• Reduction in oxygen-carrying capacity of blood
• Causes:
–
–
–
–
–
Anemia
Hemorrhage
Hgb. Abnormalities e.g. sickle cell
Drugs - sulfur, nitrites
Chemicals - CO, cyanide, cigarette smoke, exhaust
fumes
26
STRESSORS OF FLIGHT
 a. Decreased Partial Pressure of O2


3. Stagnant Hypoxia - reduction in total cardiac output from
pooling of blood, reduction in flow to tissues or restriction of
blood flow
Causes:
• Respiratory failure, shock, acceleration, PE
• Extremes in temperature, continuous positive pressure
ventilation, postural changes, hyperventilation, tourniquets
(restrictive clothes, seat belts)
• Embolism, CVA, PEEP, arterial spasm, CHF
27
STRESSORS OF FLIGHT
 a. Decreased Partial Pressure of O2

4. Histotoxic Hypoxia (tissue
poisoning)
• Inability of cells to use molecular oxygen
• Causes:
– CO, cyanide, alcohol, medications
28
STRESSORS OF FLIGHT
 a. Decreased Partial Pressure of O2

ii. EPT and TUC
• Effective performance time (EPT)
– Amount of time an individual is able to perform
USEFUL flying duties in an environment of inadequate
oxygen
• Time of useful consciousness (TUC)
– Elapsed time from point of exposure to an oxygen
deficient environment to a point where deliberate
function is lost
29
STRESSORS OF FLIGHT
 a. Decreased Partial Pressure of O2

TUC Influence by:
• Rate of ascent , Physical fitness, Physical activity,
• Temperature, Individual tolerance, Self-imposed
Stresses
30
ALTITUDE and TUC
31
STRESSORS OF FLIGHT
 a. Decreased Partial Pressure of O2

Causes of Hypoxia
•
•
•
•
•
High Altitude
Hypoventilation
Pathological Condition of the Lung
Malfunctioning Oxygen Equipment
Miscalculation of Oxygen Needs
32
GRAPH
33
STRESSORS OF FLIGHT
 a. Decreased Partial Pressure of Oxygen

Treatment of Hypoxia
•
•
•
•
•
100% Oxygen delivered with Positive Pressure
Monitor breathing- control hyperventilation
Monitor equipment - Pre-Flight Checks
Descend
Increase fluids, Prevention
34
STRESSORS OF FLIGHT
 a. Decreased Partial Pressure of Oxygen

iii. Hyperventilation
• Is abnormal increase in rate and depth of
breathing
• Causes:
– Psychological stress
– Environmental stress - Hypoxia, Vibration, Heat
– Drugs - Salicylates, Female hormones
35
STRESSORS OF FLIGHT
 a. Decreased Partial Pressure of Oxygen

iii. Hyperventilation
• Treatment
–
–
–
–
Administer 100% Oxygen
Check Equipment
Distraction techniques
Descend
36
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes
• Boyle’s Law - trapped or partially trapped gases
within certain body cavities
–
–
–
–
–
–
Barotitis Media
Barosinusitis
Barondontalgia
Barobaric Trauma
GI Effects
Miscellaneous Effects
37
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes

Ascent
• Pressure is decreased and gases expand

Descent
• Pressure is increased and gases contract
38
STRESSORS OF FLIGHT
 b. Barometric
Pressure Changes


AKA - Atmospheric
pressure
Pressure exerted
against an object or
person by the
atmosphere
 Sea level - 15 pounds
per square inch AKA
psi (14.7 to be exact)
 As altitude increases,
psi decreases
39
B. BAROMETRIC PRESSURE
 b. Barometric
Pressure

Cabin Pressurization
• Maximum Pressure
Differential:
– LEAR - 9.2 lbs. per
square inch
– GULFSTREAM - 9.6
lbs./square inch
– AIRBUS 319 /320 - 8.6
lbs./square inch
– BOEING 777 – 8.0
lbs./square inch
– Boeing 787 Dreamliner
-9.8 lbs./square inch
 As altitude increases
air is pumped into
cabin to pressurize
and is constantly
being exchanged to
maintain oxygen
levels

i.e. Aluminum
balloon with no
expansion properties
40
Altitude/Volume/Pressure
Relationships
41
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes
• a. Barotitis Media
– Failure of ventilation of middle ear via Eustachian tube
– Severe pain, tinnitus, vertigo, nausea, petechial
hemorrhage in ear
– Ascent: Gas volume in middle ear expands and is
passively expelled through the Eustachian tube
– Descent: Gas volume in middle ear contracts creating a
negative pressure within the middle ear and
Eustachian tube collapsing and preventing
equalization of pressure with atmosphere
42
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes
• a. Barotitis Media
– Incidence
» Increased at lower altitudes and on descent
» Increased with URI
– Management
» Yawn, swallow, Valsalva
» Re-ascend and slow descent
» Topical vasoconstrictors - e.g. Neosynephrine
nasal spray
43
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes
• a. Barotitis Media
– Increased incidence with patients with head, facial or
neck trauma
– Treatment for Patients
» Wake sleeping patients
» Tell patients to yawn or swallow, chew gum, if
able, suck on hard candy
» Give babies a pacifier to suck
– May be delayed reaction if on 100% O2 related to
absorption of oxygen by the middle ear
44
Middle Ear / Eustachian Tube
45
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes
• b. Barosinusitis
– Inflammation of soft tissue within the frontal and
maxillary sinus particularly resulting from positive
and negative internal pressure changes developing in
response to altitude changes
– Signs and Symptoms
» Severe pain, maxillary gum pain, teeth pain, facial
pain, lacrimation, epistaxis
» Increases on ascent
46
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes
• b. Barosinusitis
– Interventions
» Re-ascend and slow Descent
» Direct pressure on sinuses
» Topical vasoconstrictors
47
Facial Sinuses
48
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes
• c. Barodontalgia
– Severe toothache from gas expansion may occur in
teeth with defective fillings, decay or abscesses
– Treatment
» Reascent and slow descent
» Warm compresses, analgesia,
» Restrict flight duty 48-72 hours after deep
reconstruction
49
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes
• d. Barobaric (Barobaro)Trauma
– Occurs in obese people with large amounts of adipose
tissue
– High concentrations of nitrogen occur with pressure
changes
– Fragile cell membranes weaken allowing release of
nitrogen with large concentrations of lipids
predisposing the patient to fat and nitrogen emboli
– Signs and Symptoms: SOB; chest pain, petechiae,
pallor, tachycardia
– Treatment: 100% oxygen 15 minutes prior to
transport to decrease nitrogen level
50
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes
• 5. Gastrointestinal Effects
Gases within alimentary canal expand at a higher
rate than gases in other body tissues due to presence of
volatile digestive fluids within the GI tract ( wet gases
expand to a greater extent than dry)
» 1 liter of gas at sea level equals 1.5 liters at 9000 feet
» Intestinal volume may increase 30% at 7-8000 feet
» Occur more in patients with disruption of bowel
function
» Hiatal hernia & GERD patients increased eructation
and pain during ascent
51
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes
• e. Gastrointestinal effects
– Signs and Symptoms
» Pain, Nausea, Vomiting, Hyperventilation, SOB
» Pressure on diaphragm and decrease expansion especially in pediatric patients
» Syncope - from reflex venous pooling of the blood
caused by overdistention of the abdominal organs
thus decreasing cardiac preload, hypotension and
decreased tissue perfusion
» Possibly shock
52
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes
• e. Gastrointestinal effects
– Staff Interventions
» Avoid carbonated beverages and gas producing
foods
» Avoid chewing gum & avoid eating just prior to
flight
– Patient Interventions
» Stop Gastric feedings at least 4 hrs. prior to flight
to prevent risk of aspiration from turbulence
» Vent Gastric tube several times during flight
» Vent colostomy bags
» Provide airway management if necessary
» Reposition patient; abdominal massage
53
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes
• f. **Respiratory System
– Lung tissue is easily stretched and collapsed in
response to pressure and volume changes of gases
– Ascent
» Can cause a pneumothorax to expand as
barometric pressure drops
» If lung tissue is compressed and no gas expansion
occurs, intrathoracic pressure will begin to rise
» Compression of vascular structures occurs,
decreased cardiac preload, and decreased tissue
perfusion
54
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes
• f. Respiratory System
– Sudden loss of cabin pressurization may cause gases
within the air passages to expand in an explosive
manner leading to pulmonary overpressurization
– Trapped gases can be forced into potential spaces
causing pneumothorax, mediastinal emphysema and
air embolism
– Caution
» Chest trauma patients
» Patients with >20% pneumothorax have a chest
tube placed prior to flight
55
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes
• f. Respiratory System
– Caution
» A 50% Pneumothorax on the ground will become
75% at 10,000 feet
» Chest tubes may clot off from lack of flow
» If chest tube is removed, wait 48-72 hours prior to
fixed wing transport unless sea level altitude can be
maintained
» ETT and Trach tube balloons expand with ascent
and contract with descent - partially deflate on
ascent and reinflate on descent or use sterile water
(Long flights at altitude primarily) Not usually
needed for short rotor flights under 10,000 feet
56
Lung Expansion
57
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes
• g. Cardio-Vascular System
– Decreased Cardiac Output
» Decrease venous return if expanding gas volumes
within thoracic and abdominal cavities create
pressure on vena cava
» Fat/Air Embolism - Barobaric trauma
– Caution
» Hypotensive patients with air trapped in chest or
abdomen
» Obese patients exposed to rapid decompression
58
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes
• h. Extremities
» Soft tissue swelling in injured extremity with
decreased barometric pressure
» May be a particular problem in patients with a
tight fitting splint or cast
» Check distal circulation frequently
» May need to bivalve the cast
» If pneumatic splint applied, will need to release
pressure during ascent
» If MAST suit used, on descent, it will deflate and
patient may experience hypotension (has release
valve when pressure exceeds 90 mm Hg)
59
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes
• i. Decompression Sickness
– Cause:
» Rapid Decompression
» Extended exposure to altitudes over 18,000 feet
» Rapid ascent to altitudes above 25,000 feet
– Symptoms
» Pain in joints of arms or legs; visual disturbances;
» Headaches; dizziness; unilateral paresthesia;
confusion
» Personality changes
60
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes
• i. Decompression Sickness
– ‘Bends’ - limb pain
– ‘Creeps- - skin irritation
– ‘Staggers’ - disturbances of CNS
– ‘Syncope’ - cardiovascular collapse
– ‘Chokes’ - SOB associated with a burning sensation in
mediastinum and a dry cough
61
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes
• i. Decompression Sickness
– Symptoms
» Cardio-pulmonary arrest secondary to massive PE
» Onset of symptoms may be immediate or delayed
up to 6 hours
– Management
» Oxygen preflight
» Rapid descent
» 100% O2
» Splint affected limbs
» Transport to hyperbaric facility
62
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes
• j. Miscellaneous
– A. IV Rates
» Ascent - air volume expands and increases drip
rate
» Descent-air column contracts & decreases drip
rate
» Air volume expansion in glass bottles could break
them
» Remedies
Always use IV pumps
Plastic IV bags
63
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes
• i. Miscellaneous
– B. Pregnancy
» Altitude changes can increase intestinal gas and
increase pressure on uterus and cause or increase
contraction and fetal activity
» 1000-7000 feet - fetal hypoxia unlikely due to fetal
blood has increased capacity to carry oxygen
» If uteroplacental unit is healthy and mother’s
condition is not severely compromised, fetus can
tolerate up to 30 minutes of decreased oxygen
supply
64
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes
• 9. Miscellaneous
– B. Pregnancy
» Caution for conditions that decrease placental
ability to supply oxygen to fetus:
» Placenta abruptio
» Maternal hemorrhage
» Pre-eclampsia (PIH)
» Eclampsia
– Pre-eclamptic patient is at risk for pulmonary edema
due to increased vessel wall permeability
» Altitude & gas expansion increases permeability
65
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes
• 9. Miscellaneous
– B. Pregnancy
» G forces
» Positive acceleration increases ventilation
differences that may already be present
» Increased chance of further dilatation of cervix
and rupture of bulging membranes
» Can increase pressure of fetus against cervix
66
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes
• 9. Miscellaneous
– Pregnancy
– Remedies
» Patient position-safety straps low on pelvic girdle
» For advanced dilatation and amniotic sac
protrusion, place patient head at the back to
decrease pressure on cervix during takeoff
» Patient in left lateral position to decrease uterine
pressure on vena cava
» Oxygen administration
» Patient NPO
» Patient voided
67
STRESSORS OF FLIGHT
 b. Barometric Pressure Changes
• 9. Miscellaneous
– C. Penetrating Eye Injuries
» Caution:
» May rupture eyeball unless flown at sea level
– D. Pressure Monitoring Devices
» Re-zero upon reaching altitude
68
STRESSORS OF FLIGHT
 c. Thermal Changes
– With each 1000 feet altitude increase there is a
corresponding 3 degree F. decrease in temperature
– Hyper- and hypo- thermia increase the body’s oxygen
requirements
– Increased altitude - humidity falls
– Patient Interventions
» Blankets; pad sides of aircraft, warm IV solutions
» Warm fluids, if possible; cover head (especially
pediatric patients)
» Increase aircraft temperature; remove wet
dressings
» Trauma patients more susceptible
69
STRESSORS OF FLIGHT
 d. Humidity



As altitude increases, humidity decreases
90% of atmospheric moisture is
concentrated under 16,000 feet
Long flights - particularly dry
• Signs and Symptoms
– Increased hypoxia due to dry, mucous membranes and
thick secretions
– Dehydration stimulates hypothalmus to increase
body’s BMR and increase Oxygen demand
70
STRESSORS OF FLIGHT
 d. Humidity
• Remedies
–
–
–
–
Humidified oxygen at all times
Increase patient’s fluid intake especially on long flights
Increase IV fluid rate if the patient is NPO
Trauma patients are more susceptible
71
STRESSORS OF FLIGHT
 e. Noise
• Measured in terms of Frequency and Intensity
• Intensity - measured in decibels
–
–
–
–
Heart beat - 10 dB
Jet engine at full power - 170 dB
Intensities >140 dB - also felt as vibration
Generally inside cabin (rotary and fixed wing) - 100120 dB
– 80 dB- one must shout to be heard
– Can tolerate <80 dB for 8 hours/day -no hearing
impairment
• Frequency - pitch
72
STRESSORS OF FLIGHT
 e. Noise
• Effects
–
–
–
–
–
–
–
–
Distraction and mental fatigue
Mild C-V stimulation increases oxygen consumption
Nausea
Visual disturbance
Mild vertigo
Temporary or permanent hearing loss
Fullness and ringing in the ears
Decreased concentration
73
STRESSORS OF FLIGHT
 e. Noise
• Interventions
– Helmets
– Ear plugs (filter 15-20 dB)
– May use Doppler and and NIBP devices to
hear blood pressures
– Develop skills of palpation and inspection
74
75
STRESSORS OF FLIGHT
 f. Vibration
• Is a power source traveling over turbulence in air
• Rotor - worse at a hover
• Fixed wing - storm cloud penetration or high
speed, low level flight
• Low frequency
motion sickness, fatigue, SOB, abdominal and
chest pain
• Increases bubbling and back flow in equipment
for example, oxygen humidifiers
76
STRESSORS OF FLIGHT
 f. Vibration
• Physiological Effects
– Increased metabolic rate, increased RR, HR
– Redistribution of blood flow with peripheral
vasoconstriction
– Disturbance of dynamic visual acuity, speech and fine
muscle coordination
• Interventions
– Avoid direct contract with aircraft frame
– Secure patient; provide adequate padding and skin
care
– Loosen clothing, use oxygen, focus eyes outside aircraft
– Position changes
77
STRESSORS OF FLIGHT
 f. Vibration
• Equipment Effects
– Cause artifact on cardiac monitors
– Pulse oximeters may fail to lock in peripheral pulse
– Pacemakers may malfunction
78
STRESSORS OF FLIGHT
 g. Fatigue


End product of all of the stresses or flight as
they affect the human body
Contributing factors
•
•
•
•
•
•
Poor cardiovascular conditioning
Smoking; alcohol usage
Medication / drug ingestion
Dehydration; unbalanced diet
Inadequate rest / erratic schedule
Noise, vibration, hypoxic environment
79
STRESSORS OF FLIGHT
 g. Fatigue
DEAT H
• D - Drugs
– Antihistamines especially
• E - Exhaustion
– Personal stress
• A - Alcohol
– No ingestion for 12 hours; effects accentuated at
altitude
• T - Tobacco
– CO combines with Hgb and contributes to loss of nite
vision
• H - Hypoglycemia
80
STRESSORS OF FLIGHT
 g. Fatigue

Jet Lag
• Complex bodily functions (reaction, performance
and decision times) are affected by rapid shifts
through several time zones
• It takes one 24 hour period per one hour shift in
time zone to recover
– e.g. cross 4 time zones = 4 x 24 hours to adjust bodily
cycles
• Individual variation
81
STRESSORS OF FLIGHT
 h. Gravitational Forces
• Speed - rate in the direction of travel
• Velocity - rate and direction
• Acceleration - rate of change of velocity
– Linear - acceleration - change of speed and no change
in direction
– Radial - acceleration - change of direction without a
change of speed
• Weight - force exerted by the mass of the
accelerating body
• Mass - inertia of an object
82
STRESSORS OF FLIGHT
 h. Gravitational Forces



1 G is the force exerted upon a body at rest
Axis - longitudinal, lateral and vertical
Patient Considerations
• Patient location and position before takeoff and
landing
» During acceleration there is decreased venous
return and therefore decreased CMO, pooling of
fluid in lower extremities
» CMO decreases with a rapid rate of climb
83
STRESSORS OF FLIGHT
 h. Gravitational Forces

Patient Considerations
• During Ascent
– Patient with head at front of aircraft
» Fluid pools in lower extremities
» Decrease risk of transient increase of ICP
» e.g. Patient with risk of intracranial bleed
»
Patient with head injury
»
Patient with fluid overload
• During Descent
– Opposite of above
84
STRESSORS OF FLIGHT
 h. Gravitational Forces

Patient Considerations
• Cardiac Patients
– Head at back of aircraft for takeoff (head flat)
» Blood will pool in upper part of body which may
assist in myocardial perfusion
85
STRESSORS OF FLIGHT
 h. Gravitational Forces

Patient Considerations
• Head Injury Patient (if head flat)
– Head facing back of plane for takeoff
• Fluid Overload Patient (if head flat)
– Head should be facing back of plane for takeoff
• Intrathoracic Injuries (if head flat)
– Head should be facing back of aircraft for takeoff
• Intraocular Injuries (if head flat)
– Head should be facing back of aircraft for takeoff
86
STRESSORS OF FLIGHT
 h. Gravitational Forces

Positive G forces (acceleration)
•
•
•
•

Blood pooling in lower extremities
Increased intravascular pressures
Stagnant hypoxia
e.g. pushed against seat
Negative G forces
• Stagnant hypoxia (deceleration)
• Blood pooling in upper body
• e.g. fall out of seat; fall through trap door
87
STRESSORS OF FLIGHT
 i. Third Spacing
• Loss of fluid from the intravascular to
extravascular tissue secondary to a decrease in
ambient pressure surrounding the vessel walls
• Associated with long distance or high altitude
flights
• Aggravated by existing fluid leaking, cardiac
disease and nephrotic disease
• Affected by exposure to excessive G forces,
vibration and temperature extremes
88
STRESSORS OF FLIGHT
 i. Third Spacing
• Signs and Symptoms
–
–
–
–
–
–
Edema
Tachycardia
Hypotension
Dehydration
Tachypnea
Shortness of breath
• Remedies
– Rest; adequate fluids; no alcohol within 12 hrs of flight
– No tobacco
– Small frequent meals
89
ELECTROMAGNETIC
INTERFERENCE
 D. Electromagnetic
Interference


May be generated by
all types of electronic
device
Medical equipment
may affect aircraft,
navigational and
communication
systems
 Notify pilots prior to
defibrillation,
cardioversion or
pacing
90
GAS LAWS
 Govern body
responses to changes
in:

Barometric pressure

Temperature

 Critical as the
aircraft

Ascends

Descends
Volume
91
GAS LAWS
 BOYLE’S LAW
 HENRY’S LAW
 DALTON’S LAW
 GRAHAM’S LAW
 CHARLES’ LAW
92
GAS LAWS
 a. Boyle’s Law


Volume of a gas is
inversely
proportional to the
pressure to which
that gas is exposed
i.e. - Gas volume
expands
proportionately to
decreases in
barometric pressure
 Closed containers expand
as altitude increases

e.g.

e.g.
E.T./T.T
balloon
Foley
catheter
balloon,


E.g. IV bags, IV glass
containers
e.g.
Stomach,
lungs,
bladder, bowel, sinuses,
uterus
93
GAS LAWS
94
GAS LAWS
 a. Boyle’s Law

Volume of the air or
gas increases in a
closed body cavity or
equipment space
because the external
pressure is decreasing
 Formula
 P1V1= P2V2
 1 - Initial pressure
 2 - Final pressure
95
GAS LAWS
 a. Boyle’s Law

Lungs expand
• Pneumo-thorax will
increase with altitude
• Rate and depth of
respiration
• Increased intrathoracic
pressure

Bladder
• Increased desire to urinate
 Sinuses, Teeth

Increase pain
 Stomach and Bowels



Increased gas
Increased pain
Increased pressure on
diaphragm
 Uterus
 Brain hemorrhage
96
GAS LAWS
 a. Boyle’s Law

Caution
• Transporting patients with a pneumothorax or
pneumocephaly
• Transporting patients with tube feedings (stop
same prior to transport)
• Empty bladder - Foley / Void
• Women in labor
• Patient with distended and/or bowel obstruction
97
GAS LAWS
 a. Boyle’s Law


 Electronic controlled
ventilators - no effect
Need IVAC Mini-med
to infuse all IV’s
on controls
Equipment needs to
 Flow rate of O2 may
be rechecked and
change, though
recalibrated at
 Oxygen cylinder
altitude and again at
ground level
pressures
98
GAS LAWS
 a. Boyle’s Law



Pilots can control pressure inside cabin to a
certain extent
Pilots perhaps can fly at a lower altitude
Perhaps may decide not to take the patient
99
GAS LAWS
 b. Dalton’s Law of Partial Pressures


The pressure of a gaseous mixture is equal to
the sum of the partial pressures of the gases
in that mixture
As altitude increases and barometric or
atmospheric pressure decreases, gas
expansion causes the AVAILABLE oxygen to
decrease as the gas molecules move farther
apart
100
GAS LAWS
 b. Dalton’s Law of Partial Pressures

Pt = P1 + P2 + P3…..Pn
101
GAS LAWS
102
GAS LAWS
103
GAS LAWS
104
GAS LAWS
105
GAS LAWS
Dalton’s Law
b.


Barometric pressure multiplied by the
concentration of a gas is equal to the partial
pressure of the gas
Therefore, hypoxia occurs with flight to
higher altitudes
• (Oxygen molecules are present but are farther
apart)
106
GAS LAWS
b. Dalton’s Law

Remedies:
• Increase oxygen liter flow
• Increase oxygen percentage by using alternate
methods of O2 administration
• Fly at lower altitude
107
GAS LAWS
 c. Charles’ Law


At a constant pressure, the volume of a given
gas is directly proportional to the absolute
temperature of that gas (if mass and
pressure are held constant)
Increases in temperature cause gas
molecules to move faster thus exerting
greater force and leading to volume
expansion
108
GAS LAWS
 c. Charles’ Law


e.g. As the temperature decreases, the
pressure reading in the oxygen tank
decreases (the converse is true)
e.g. If the patient’s temperature increases,
the PO2 decreases
109
GAS LAWS
 c. Charles’ Law

For example, O2
delivered by a
ventilator may be 72
degrees F, so Tidal
Volume increases as
the oxygen is heated
by the body
110
GAS LAWS
 c. Charles’ Law

Remedies
• Maintain cabin at
constant temperature
(CAMTS – 85 degrees F.)
• Pad aircraft interior
that touches patient
• Maintain patient’s
temperature as near
normal as possible
111
112
GAS LAWS
 d. Henry’s Law

The quantity of gas dissolved in a liquid is
directly proportional to the pressure of that
gas above the liquid.
i.e. The more pressure that is exerted above
a liquid, the amount of that gas dissolved in
the liquid will increase
P1 = P2
A1 A2
113
GAS LAWS
d. Henry’s Law

e.g. Bottle of Perrier water opened

e.g. Only a few cells separate atmospheric gases
from the alveolar- capillary membrane in the lungs.

As pressure is reduced, the amount of gas dissolved
in the solution is reduced, leading to hypoxia and
nitrogen gas bubble formation

Decompression sickness (diver ascends too rapidly)
114
115
GAS LAWS
 e. Graham’s Law of Gaseous Diffusion

Rate of diffusion of a gas through a liquid
medium is directly related to the solubility of
the gas and is inversely proportional to the
square root of its density or gram molecular
weight
• i.e. Gases will go from a higher pressure or
concentration to a region of lower pressure or
concentration
116
GAS LAWS
 e. Graham’s Law


 As altitude increases,
the faster the rate of
CO2 is 19 times more
diffusible than oxygen
diffusion of O2 out of
CO is about 200 times
the tissues and
more diffusible than
therefore a rapid
oxygen
drop in TUC
117
GAS LAWS
 e. Graham’s Law
 Remedies
• Increase oxygen flow and FiO2
• Decrease cabin pressure
• Fly at lower altitude
118
F.
IN-FLIGHT EMERGENCIES
 Cardio-Pulmonary
arrest
 Cardiac Tamponade
 Accidental
Extubation
 Cardiac
Dysrhythmias
 Hypovolemia
 Tension
Pneumothorax
 Hypotension
119
FLIGHT PRACTICE HINTS
 PRE-FLIGHT
CHECKS



As per Pre-Flight
Check List
Check ALL
equipment operations
Know what is in your
packs - check each
flight!
 Have extra IV
supplies in flight suit
 Have ‘stash’ of
emergency drugs
close by
 Know how to use
hands-off
pacer/defibrillator
pads
120
FLIGHT PRACTICE HINTS
 Always call for
patient report prior
to leaving for flight
 Call receiving
hospital to ensure
that they are
expecting the patient
 Place anticipated
articles in one place
 Your pilots are good
sources of
information and
assistance
 Keep overnight bag
with you at all times
 Keep emergency
items with you - e.g.
matches, candle,
water
121
Variable Gas Distribution Relation to
Latitude
 Prevailing environmental temperature
varies from earth’s poles to equator
 The Cooler temperatures at the poles
cause gas volume to shrink (Charles’
Law) resulting in greater gas density
near the earth’s surface-the converse is
true near the equator
 Greater physiological stresses are
experienced in colder environments
122
Variable Gas Distribution
Related to Altitude
 Gases are not uniformly distributed throughout
the different altitudes (curve)
 Air density is greater in lower atmosphere
 Uneven distribution of gases results in greater
barometric change per unit of altitude change
in lower atmospheres
 As amount of Barometric Pressure change
increases, the potential for adverse
physiological effects also increases
123
124
SUMMARY
Aerodynamics of Flight review
Stressors of flight and Gas Law effects alter
you and your patients’ responses.
Know your equipment and be proactive and
prepared for emergencies.
125
THANK YOU!
126