FP-C #4 Flashcards
Hypoxia between 0 and 10,000 ft
Indifferent stage
Define: Hypemic hypoxia
The type of hypoxia characterized by an inability to carry oxygen on the red blood cell despite its abundance of oxygen
Mneumonic: Dalton’s law
“Dalton’s gang” - on the ground, the molecules are ganged up
Define: Dalton’s law
Total pressure of a gas mixture is the sum of the individual pressures
Define: Barometric pressure
Direct result of the weight of the air and related to air density
The three physiological zones of the atmosphere
Physiologic zone, physiologically deficient zone, space equivalent zone
How high above sea level the atmosphere extends
348 miles (the edge of space)
Define: Henry’s law
The amount of gas in solution varies directly with partial pressure of a gas over the solution
Define: Charles’ law
Volume and temperature are proportional at constant pressure - as air heats up, gas expands
Define: Time of useful consciousness (TUC)
Period between a person’s sudden deprivation of oxygen at a given altitude and the onset of physical or mental impairment to the point where deliberate function is lost
Temperature variance in the troposphere
62°F to -68.8°F
This is one of the earliest sign of hypoxia in a flight paramedic or flight nurse
Impaired judgment
Concept: Henry’s law
As the pressure over a gas decreases, or gas escapes from the solution (ex: opening a soda can)
Define: Fick’s law
States the rate of diffusion of a gas is proportional to the difference in partial pressure, proportional to the area of the membrane, inversely proportional to the thickness of the membrane
EPT at TUC depend on these 7 factors
Individual tolerance, method of hypoxia, environment before hypoxia, amount of exertion undertaken, percent of oxygen prior to hypoxia, speed of cabin depressurization, higher altitude acclimatization
An alternative name for Dalton’s law
The law of partial pressures
Trapped gas in the chest will expand approximately this much at 18,000 feet
Twice it’s original size
Define: Stagnant hypoxia
The type of hypoxia that occurs when there is a failure to transport oxygenated blood
Boyle’s law
Inverse proportion of volume and pressure - as volume increases pressure decreases
The percent composition that nitrogen accounts for in the atmosphere
78%
This can happen to a pneumothorax at altitude
Pneumothorax can become tension pneumothorax
Effects: Indifferent stage of hypoxia
Night vision deterioration (5000 feet), ECG changes (5000 feet), tachycardia, slight increase in alveolar ventilation
Altitude will usually not become significant until this altitude
3000 feet
Most people (except those with significant respiratory disorders) tolerate altitudes of ____
5000 feet
The densest portion of the atmosphere
Troposphere
Define: Gay-Lussac’s law
States there is a correlation between pressure and temperature with volume is close
Properties: Physiologic zone
Sea level–> 10,000ft - barometric pressure of 760 mmHg–> 523 mmHg
Define: Graham’s law
The rate at which a gas moves through a pore is inversely related to the square root of the mass of one mole of its molecules
The four stages of hypoxia (related to altitude)
Indifferent stage, compensatory stage, disturbance stage, critical stage
Indifferent stage, compensatory stage, disturbance stage, critical stage
Poor blood flow - as in CHF and in acute MIs
Causes: Hypemic hypoxia
Blood loss, anemia, excessive smoking, carbon monoxide, sickle cell disease
Below ___ feet, unhealthy people can experience significant side effects
below 10,000 feet
Define: Histotoxic hypoxia
A type of hypoxia characterized by a cell’s inability to adequately use oxygen
These devices are considered unreliable and IV pumps should be used instead while at altitude
Dial-a-flow
The first two layers of the atmosphere
Troposphere and tropopause
Application of Dalton’s law to critical care
Supplemental oxygen will be required typically at about 5000 feet in sick patients
Trapped gas in the chest will expand approximately this much when going from sea level to 8000 feet
35%
The altitude that the compensatory stage of hypoxia is experienced while on 100% oxygen
39 to 42,000 feet
Reduction of hemoglobin by half reduces the body’s transport ability by ___
Half
The percent composition that argon accounts for in the atmosphere
0.93%
This is the flight level that FAR Part 135 specifies commercial pilots must begin using supplemental oxygen
Above 10,000 ft
These three gases make up 99% of the atmosphere
Nitrogen, oxygen, argon
Mnemonic for Charles’ Law
C for Charles, C for Celsius (of course, Celsius temperature)
Oxygen saturation range: Compensatory stage of hypoxia
87 to 80%
You should do this with nasogastric or orogastric tubes frequently while at altitude
Frequently vent
Locations in the body where gases can be trapped and expand with altitude
Thorax, middle ear, sinuses, stomach, intestines
The four types of hypoxia
Hypoxic hypoxia, histotoxic hypoxia, stagnant hypoxia, hypemic hypoxia
The altitude range where endotracheal tube cuffs will double in size
5000 to 10,000 feet
At altitude, increases in flow rate of fluids in ___ ___ occurs because of an inability for the bottle to expand or contract
Glass bottles
Mnemonic: Boyle’s law
Boil very prudently
Level where night vision impairment occurs without supplemental oxygen
5000 feet
Causes: Histotoxic hypoxia
Poisoning (carbon monoxide, cyanide)
This is the main medical hazard in flight aviation
Hypoxia
Define: Effective performance time (EPT)
The limited timeframe during which a person can’t function without an adequate level of oxygen
The depth of the troposphere
Sea level to 26,400 feet over the poles, sea level to 52,800 feet over the equator
Causes: Hypoxic hypoxic
Lung disease, airway obstruction, low oxygen delivery, decreased altitude
Properties: Space equivalent zone
Extends beyond 50,000 feet to 120 miles, 100% supplemental oxygen required, requires pressure suits and sealed cabins
Patients with an open skull fracture are at risk for __
Pneumocephalus
Application of Henry’s law in critical care
Ascending for a dive too fast resulting in decompression sickness
Define: Hypoxic hypoxia
A type of hypoxia characterized by lack of oxygen entering the blood - formulation or reduction in PO2
The stage of hypoxia experienced at 10 to 15,000 feet
Compensatory stage
Oxygen saturation range: Indifferent stage
98-87%
Finding: High venous oxygen concentration
Confirms histotoxic hypoxia
Concept: Gay-Lussac’s law
As you go up in altitude, the pressure is lower
Properties: Deficient Zone
1: Barometric pressure decreases to levels that will result in hypoxic hypoxia
