AVIT 309 Block 1
Four stages of oxygen processing in the humans
1) Ventilation 2) Respiration 3) Oxygen is transported to body's tissues 4) Oxygen is utilized in the tissues to create energy
What is the critical risk value above which evolved gas issues are prevalent?
1.5
Maximum altitude of acclimatization
10,000 ft
Physiologically, supplemental oxygen should be used above what altitude?
10,000 ft
What is the first step one should take in treating hypoxia of any kind?
100% Oxygen
Treatment for hypoxia
100% oxygen with pressure Return rate and depth of breath to normal Check connections Descent below 10,000 ft if possible
Treatment for DCS
100% oxygen with tight mask, repressurize, notify nearest airport of problem and land, hand treatment of patient over to AME, need hyperbaric chamber
Normal breathing rate
12-20 times per minute
Partial pressure of atmosphere oxygen at SL
159 mmHg
How long does it take to fully physiologically acclimatize to a given altitude?
18 days/mile
For someone equilibrated to sea level, what altitude represents the threshold for evolved gas problems?
18,000'
Temperature Lapse Rate of the Atmosphere
2 degrees C/3.5 degrees F
Synergy of CO and cyandide
20%Co-hb and 2 micrograms/kg HCN in the blood is lethal
Composition of the atmosphere
21% Oxygen 78% Nitrogen 0.04% Carbon Dioxide
Carbon monoxide has a greater affinity for hemoglobin by how much?
250x
How much cyanide does it take to kill?
3.3-5 microgram/kilogram
What percent of LOC accidents were caused by inappropriate response to interaction with equipment?
46.3%
How long do you have to put on O2 equipment after rapid decompression?
5 seconds
Below what oxygen level does collapse normally occur?
60%
Normal volume rate of air
8 liters per minute
How long does it take for something you inhale to reach your brain?
9 seconds
According to the FAA, what is the time frame in which aircraft should be evacuated following an aircraft crash?
90 seconds
Histotoxic Hypoxia
A condition that interferes with normal metabolic activity (Kreb's cycle) of O2 in body (brain) cells caused by alcohol, narcotics, cyaide/phosgene gases (plastic), or pyrolyzed oil/hydraulic fluid
Hypemic hypoxia
A condition that interferes with the ability of the blood cells to transport oxygen caused by carbon monoxide poisoning, anemia, or blood loss/donation
What is diluter demand?
A mixture of 100% oxygen and ambient air, based on altitude (aneroid controlled)
Where does the temperature stabilize in the atmopshere?
Above the troposphere (tropopause)
What is present in smoke that causes mostly skin and respiratory tract issues?
Aerosolized acids
How long do you have to wait to fly after diving?
After single dive, no decompression- 12 hrs Multiple no decompression dives/multiple days of diving- 18 hrs minimum Dives requiring decompression stops: longer than 18 hrs (AIM says 24) For all altitudes above 8000, you need to wait at least 24 hrs after any scuba dive.
What causes a flashover?
As materials heat, combustible gases are released. Temperature increases and eventually these gases can ignite, instantly climbing the temp in the cabin to 1200+ Degrees fahreinheit
Barometric pressure density characteristics
As we increase in altitude, pressure decreases. Most change happens before 10,000 ft.
All four presentations of DCS
Bends, Skin, CNS, pulmonary
Proper oxygenation of what type of cells is important for aviators
Brain cells/neurons
Primary control for respiration in humans is regulated:
Carbon dioxide levels as monitored by the medulla and pons
What is the most common product of an incomplete combustion?
Carbon monoxide
What on the aircraft is designed to filter out ozone in the atmosphere?
Catalytic ozone converter
What is the first human function lost to hypoxia?
Cognition
Stagnant
Condtion that interferes with the normal circulation of the blood arriving at the cells caused by GForces, shock, fainting, heart failure, cold temperatures, and hyperventilation
When do you use each type of flow?
Continuous flow: from FL180-FL250 Diluter demand: up to FL350 (FL400 in emergencies) Pressure-demand: Up to FL450 (FL500 in emergencies)
What is the most dangerous gas aviators could potentially be exposed to?
Cyanide
Lungs and trapped gas
During rapid decompression, air exists through the trachea and this can cause pulmonary barotrauma aka alveolar hyperinflation
What is Dalton's Law and what does it pertain to physiologically?
Each component of a gas contribute to the total pressure; pertains to hypoxia
What two areas of trapped gas are most likely to occur on descent?
Ears, sinuses
What are the common areas of trapped gas in in humans?
Ears, sinuses, teeth, GI tract, lungs
What pathway connects the middle ear with throat?
Eustachin tube
Effective Performance Time
FL180-20-30 minutes FL250-3 to 5 minutes FL350-30-60 seconds FL500 and above- 9 to 12 seconds
T/F: Ear blocks are always accompanied by pain
False
T/F: a pilot may be comfortable knowing maintenance checked their oxygen mask prior to flight
False
What is the best way to clear GI gas?
Fart/Blech
Where do most accidents occur?
Final approach and landing
What is continous flow?
Flows constantly whether inhaling or exhaling
What two areas of trapped gas are most likely to occur on ascent?
GI tract, teeth
What happens during respiration?
Gas is exchanged across the alveolar barrier and binds to hemoglobin.
What is Graham's Law and what does it pertain to physiologically?
Gases will diffuse from a high pressure to low pressure naturally; Has to do with respiration
What do oxygen molecules bind to in the transport process?
Hemoglobin
Color codes for pressure
High pressure - Green Low pressure - yellow
What is the most dangerous aspect of hypoxia?
Insidious onset
What are the three mechanisms that contribute to mechanisms in the aircraft?
Internal, external, aircraft systems
What three steps should be taken during a lithium ion battery thermal runaway event?
Isolate, extinguish, cool
What is pressure breathing and why do we do it?
It is a reversal of the normal breathing process when breathing in excess pressure and it is done to maintain normal oxygen transfer at the lung level
What causes an ear block and what are the symptoms?
It is caused by a blocked, swollen, or congested Eustachin tube. Symptoms are fullness, stuffiness, some hearing impairment, increasing pain, tympanic membrane could potentially perforate
What is pressure demand?
It offers the same functions as diluter demand and provides supplemental pressure as altitude increases above 28,000'
Ear and Sinus Block Treatment
Level off and valsalva, climb 1000-2000 ft, retry valsalva, used reduced rates of descent and land
Most commercial fatalities are caused by
Loss of Control, followed by CFIT
What are all the forms of oxygen storage systems?
Low pressure, high pressure, liquid oxygen, chemical, OBOGS
Objective signs of hypoxia
Mental confusion (eye focus), increase in rate and depth of breathing, cyanosis, belligerence, poor judgement, loss of muscle coordination, euphoria, unconsciousness
How to clear an ear block
Move the jaw and swallow at the same time, chewing gum, yawning, valsalva, vasoconstrictor
Objective signs of hyperventilation
Muscle twitching, cold clammy hands, muscle tetany, paleness
Is it safe to use petroleum based product around 100% oxygen?
No
Should vasoconstrictor sprays be used to clear normal ear blocks?
No-only in emergency
Secondary control for respiration in humans is regulated by:
Oxygen saturation levels in blood and cerebral spinal fluid as monitored by aortic bodies
What four elements need to be maintained in humans for homeostasis?
Oxygen, nutrition, rest, hydration
What are the four factors that determine the partial pressure of oxygen in the lung?
Oxygen, pressure, water vapor given off living tissue, CO2 production
Minimum Partial Pressure
P02 of 104 is considered a life support minimum
Low altitude hypoxia effects
Perceptual motor performance has a significantly lower response time, decrease in performing simple navigational tasks, and controlling the aircraft becomes more difficult
Part 91 Oxygen Use Requirements
Pressurized aircraft- No quick don- if two pilots are at the controls, one must put on oxygen mask at FL350 With quick don- if two pilots are at the controls, then one must out on an oxygen mask at FL410 If one pilot leaves the controls above FL350, the other must don a mask Unpressurized aircraft: Need oxygen if Your cabin is between 12,500' and 14,000' for more than 30 minutes If your cabin exceeds 14,000' You must provide it for passengers if the cabin exceeds 15,000'
Tooth pain
Reasons for problem: improperly filled tooth, abscessed tooth. Treatment is to immediately descend, identify the tooth, and see a dentist
What cell is responsible to transport oxygen in the cardiovascular system?
Red blood cells
What is a critical first step for aviators to take in dealing with toxic fumes events?
Respect the emergency and protect your lungs
Gastrointestional pain causes and treatment
Sources: natural digestive process, gas forming foods, swallowing air. Treatment: pass gas, avoid gas forming foods, stomach massage, loosen restrictive clothing
Oxygen System Checklist
Supply Connections Regulator Emergency Equipment Adjustment of the mask Mask condition
What is Boyle's Law and what physiological issue does it affect?
Temperature held constant, pressure is inversely proportional to volume. This has to do with trapped gas.
What is Henry's Law and what physiological issue does it impact?
The amount of gas dissolved in a solution is proportional to the partial pressure of gas over the solution; It has to do with evolved gas/decompression sickness
Most common presentation of DCS to aviators
The bends
Definition of respiration
The exchange of gases between a living organism and its environment
What is Charles' Law?
The pressure of gas is directly proportional to its temperature (Pressure gauge flucutiation)
What are the lung structures?
Trachea, Bronchi, Bronchioles, Alveoli
T/F: hypoxia may affect higher cognitive function at altitudes as low as 5,000'
True
T/F: Human respiration can be voluntarily controlled
True, but not for long
What are the two types of DCS?
Type I: Muscloskeletal Type II: Neurological/respiratory/circulatory
What is the most effective method of clearing an ear or sinus block?
Valsalva
Sinus block cause and symptoms
When the mucosal lining swells and wont allow equalization; symptom is pain
What are the physiological divisions of the atmosphere and their altitudes?
Zone of normal adaption: surface to 10,000 ft Zone of physiological deficiency: 10,000 ft to 50,000 ft Space equivalent zone: Over 50,000 ft
Hypoxic Hypoxia
a condition that interrupts the flow of oxygen into the lungs caused by altitude, drowning, pneumonia, or chronic lung disease
Subjective symptoms of hypoxia
air hunger, headache, nausea, hot and cold flashes, euphoria, tingling, loss of situational awareness, apprehension, dizziness, fatigue, blurred vision, tunnel vision, numbness, overconfidence
Factors that influence effective performance time
altitude, rate of ascent, individual tolerance, physical activity, environment temperature, duration of exposure, psychological factors, physical fitness, fatigue, medication, nutrition, concussions
Breathing zone
bottom third of the cabin
Hypercapnia is caused by excess what in the blood stream
carbon dioxide from hypoventilation
What are the three types of aircraft oxygen delivery systems?
continuous flow, diluter demand, pressure demand
What is the most typical cause of hyperventilation in pilots?
emotional
T/F: a smokehood should always be used before a pilot dons an oxygen mask
false
Which type of oxygen is typically found on commercial aircraft?
gaseous
What to forms of oxygen storage systems are found on civilian aircraft?
gaseous and chemical
What are the four types of hypoxia?
hypoxic, hypemic, histotoxic, stagnant
Most deadly form of DCS
pulmonary (chokes)
What is ventilation?
the movement of air into the lungs. The air is filtered, warmed, and humidified
Subjective signs of hyperventilation
tingling, nausea, light headedness, muscular cramp, faintness, visual problems
What is the purpose of pressure demand regulators?
to raise oxygen partial pressure at the lung level
T/F Ground crews, flight crews, and passengers may be source of toxic fumes
true
True/False: a lack of nutrition may affect an individual's effective performance time
true
