Flight Physiology

Question 1

Boyle’s Law

Answer 1

• Boyle’s = Balloon = Barotrauma
• The pressure of a gas is inversely proportional to the volume of a gas at a constant temperature.
• P1V1 = P2V2
• Affects ETT cuffs, MAST, air splints, increases drip rate
• If pneumocephalus - ICP increase

Question 2

Dalton’s Law

Answer 2

• “Dalton’s Gang”
• Law of partial pressures
• The total pressure of a gas mixture is the sum of the partial pressures of all the gases of the mixture.
• P_T = P₁ + P₂ + P₃ ….
• Responsible for soft tissue swelling at altitude - uptake of inert gases into tissue

Question 3

Charles’ Law

Answer 3

• “Charging Charles”
• At a constant pressure, the volume of gas is directly proportional to the absolute temperature of the gas
• V1/T1 = V2/T2
• Law has very little effect on the human body

Question 4

Gay-Lussac’s Law

Answer 4

• Directly proportional relationship between temperature and pressure
• P1/T1 = P2/T2
• Ex. - Oxygen tank left in the cold will have a lower pressure

Question 5

Graham’s Law

Answer 5

• “Graham’s = Grey Matter”
• Law of Gaseous Diffusion - gas exchange at the cellular level
• The rate of diffusion of a gas through a liquid medium is directly related to the solubility of the gas and inversely proportional to the square root of its density
• Limits ability to move through liquid

Question 6

Henry’s Law

Answer 6

• “Henry = Heineken”
• Solubility of gas in liquid
• The quantity of gas dissolved in 1mL of a liquid is proportional to the partial pressure of the gas in contact with the liquid
• Affects divers, can lead to decompression sickness

Question 7

Decompression Sickness

Answer 7

• “The Bends”
• Related to Henry’s Law
• Type 1 - Nitrogen related, painful joints, motled skin, pruritic
• Type 2 - neurologic S/Sx, hypvolemic shock

Question 8

Cutis Marmorata

Answer 8

Mottled skin, can often look like a sunburn, associated with Type 1 decomrpession sickness

Question 9

Arterial Gas Embolism

Answer 9

• Related to Boyle’s Law
• Caused breath holding during ascent on a dive, air pushes through alveoli and enters skin in neck/chest - causes PTX
• Air is forced into blood vessels - blocks them - ischemia
• Stroke-Like symptoms, cough, epistaxis
• Requires immediate hyperbaric treatment

Question 10

Pulmonary Overpressurization

Answer 10

• Related to Boyle’s Law
• Occurs when “breath holding” compressed air during ascent
• Causes lung overexpansion - alveolar damage, PTX, mediastinal emphysema

Question 11

Atmosphere Calculation

Answer 11

• Every 33 feet below water = 1atm
• Sea Level = 1atm

Question 12

Divers Alert Network

Answer 12

24 hour hotline for diving related injuries and questions.

Question 13

Physiologic Zone

Answer 13

• Sea level to 10,000 feet MSL
• Night vision decreased beginning at 5,000 feet MSL

Question 14

Physiologically Deficient Zone

Answer 14

• 10k to 50k feet MSL
• Oxygen or pressurization required
• If sudden decompression occurs, time of useful consciousness (TUC) is cut in half
  
  • Signs of Decompression - cool temp in cabin, window fogging

Question 15

Sqace Equivalent Zone

Answer 15

> 50,000 feet MSL

Question 16

Oxygen Adjustment Calculation

Answer 16

(FiO₂P₁)/P₂ = FiO₂ required for ascent

P1 = pressure you are at

P2 - pressure you are flying to (cruising altitude)

Question 17

Hypemic Hypoxia

Answer 17

• “Anemic”
• Reduction in the oxygen carrying capcity of blood
• Anemia or hemorrhage

Question 18

Histotoxic Hypoxia

Answer 18

• “Poisoning”
• Limits use of availble oxygen due to poisoning of the cytochrome oxidase system
• Cyanide, alcohol, CO, NTG, Nipride

Question 19

Hypoxic Hypoxia

Answer 19

• “Not enough oxygen in the air”
• Decreased pressure of oxygen at altitude
• Deficiency in alveolar oxygen exchange
• Cardiovascular/PTX patients are more susceptible

Question 20

Stagnant Hypoxia

Answer 20

• “Blood isn’t moving”
• Reduced CO or pulling of blood
• High G forces, cardiogenic shock

Question 21

Hypoxia Stages “ICDC”

Answer 21

• Indifferent - full reasoning ability, loss of night vision
• Compensatory - Increased HR, ventilations, slowed judgment
• Disturbance - slurred speech, “drunk”
• Critical - no longer able to physiologically function

Question 22

DEATH Mnemonic

Answer 22

• Dehydration
• Exhaustion
• Alcohol
• Tobacco
• Hypoglycemia

Question 23

Inherent Stressors of Flight

Answer 23

Thermal Changes
Decreased Humidity
Gravitational Forces
Fatigude
Decreased PO2
Barometric Pressure Change
Noise
Vibration

Question 24

G-Forces

Answer 24

Gx - anterior/posterior, best tolerated

Gz - vertical

Gy - Lateral, least tolerated

Cause BP to drop

Question 25

Altitude Temperature Effects

Answer 25

• Every 1,000ft increase in elevation causes temp. drop 2 degrees C
• Temp. inversely proportional to altitude

Question 26

Barondontalgia

Answer 26

• Teeth
• Occurs on ascent
• Air trapped in fillings expands due to Boyles law
• Also referred to as “aerodontalgia”

Question 27

Barotitis

Answer 27

• Ears
• Occurs on descent
• Air trapped in the middle ear can’t vent through the bloded Eustachian Tube
• “Ear Block”

Question 28

Barosinusitis

Answer 28

• Sinuses
• Can occur on both ascent and descent
• Can also cause pain in the maillary teeth
• Sinus block