AVIT 309 Block 1

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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


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