Flight Physiology Flashcards
Contraindications to air medical transport
- Severe anemia
- AMI within 10 days
- Uncontrolled dysrhythmia
- Pregnancy >24 weeks
- Non-acute hypovolemia
- Recent ocular surgery
Gas composition of atmosphere
21% oxygen
78% nitrogen
- 9% argon
- 1% other gasses (0.04% carbon dioxide)
Layers of the atmosphere (from earth to space)
- Troposphere
- Stratosphere
- Mesosphere
- Thermosphere
- Exosphere
Physiologic zones of the atmosphere (from earth to space)
Physiologic zone - 0-10000 ft, 760-523mmHg
Physiologically deficient zone - 10k-50k ft, 523-87mmHg
Space Equivalent zone - 50k ft-120 miles
Boyle’s Law is the ___ relationship between ___ and ___
- Inverse
- Volume and Pressure
V = 1/P
To what medical scenarios does Boyle’s Law apply?
Tension pneumothorax, pneumocephalus, sinus/ear pain, ET tube cuffs, NG/OG tubes, ostomy bags
What is the medically practical example of Boyle’s Law?
As altitude increases, atmospheric pressure decreases
What is Dalton’s Law?
The pressure of a gas is equal to the sum of partial pressure of the individual gasses
PT = P1 + P2 + P3…
What is Fick’s Law?
The rate of diffusion of a gas is proportional to the difference in concentration of the gas
Fick’s Law is affected by what physical properties?
Gas pressure, membrane surface area, membrane thickness
What is the medically practical application of Fick’s Law?
Diffusion of gas across the alveolar membrane
What is Henry’s Law?
The pressure of a gas disolved in liquid is proportional to the pressure of the gas over the liquid
What is the medically practical example of Henry’s Law?
Decompression Illnesses
What are the four primary forces that act on an aircraft?
Lift, Thrust, Drag, Gravity
What are the risks of aircraft depressurization?
Rapid - hypoxia, decompression illness, hypothermia
Slow - hypoxia, may be unrecognized and cause death
List some primary stressors of flight
Low pO2
Barometric pressure changes
Thermal changes
Aricraft vibration
Decreased humidity
Noise
Fatigue
Gravitational forces
Spatial Disorientation
Flicker Vertigo
Poor Weather
Human factors (aka self imposed factors) that affect tolerance to stressors of flight
DEATH
Drugs, exhaustion, alcohol, tobacco, hypoglycemia
(or)
IM SAFE
Illness, Medications, Stress, Alcohol, Fatigue, Emotion
What is the primary physiological risk factor in aviation?
Hypoxia
What is the most common first sign of hypoxia?
Impaired judgement
In healthy individuals, hypoxia generally becomes a risk starting at what altitude? Supplemental oxygen is usually required starting at what altitude?
5000’
10000’
What factors influence a person’s risk of developing hypoxia?
Physical exertion
Rate of exposure/ascent
Duration of exposure
Physical health
Temperature
What is hypoxic hypoxia?
Low pO2
What is stagnant hypoxia?
Impared ability to move blood around the body (cardiogenic shock)
What is hypemic hypoxia?
Impared ability of blood to carry oxygen
(hypemic anemic)
What is histotoxic hypoxia?
Impared ability of cells to utilize oxygen
What is the indifferent stage of hypoxia?
Minor, if any, physiologic effects
Occurs from 0-10000 ft
What is the compensatory stage of hypoxia?
Body compensates for reduced oxygen by increasing vitals (heart and respiratory rate)
Loss of fine motor control, poor decision making
Occurs from 10000-15000’
What is the disturbance stage of hypoxia?
Body unable to compensate
Loss of cognitive ability, loss of gross motor control
Occurs from 15000-20000 ft
What is the critical stage of hypoxia?
Occurs quickly, <5 min
Loss of gross motor control, rapid incapacitation, seizures/coma -> death
Occurs >20000’
SpO2 < 65%
What rules govern use of supplemental oxygen?
FAR Part 135 - rules for pilots
FAR Part 91 - rules for passengers
What are some physiologic disorders related to changing altitude?
Barotitis media - middle ear pain
Barosinusitis - sinus pain
Barodontalga - tooth pain
Dysbarism - pain in other closed cavities (abdomen)
Define sterile cockpit
Limiting non-essential communicaiton during critical phases (take off, landing, etc) of flight
Includes any and all communication - including with dispatch, hospital, or patient
What is flight following?
Constant monitoring of aircraft by air traffic control
Four primary factors that contribute to air medical crashes
Human error (68%)
Weather (30%)
Mechanical Issue (25%)
Spatial Disorientation (20%)
Priorities of work post crash
Shelter
Fire
Water
Food
What is the rule of 3’s relating to post-crash survival?
Can survive 3 minutes without oxygen, 3 hours without shelter/heat, 3 days without water, 3 weeks without food.
