Oxygen, Gases and DCI

Question 1

What is oxygen?

How much is inhaled/exhaled as we breathe?

Answer 1

Colorless, odorless, tasteless gas needed for cellular metabolism
21% inhaled, 16% exhaled, 5% consumed

Question 2

How is oxygen transported to body tissues?

Answer 2

Red blood cells - hemoglobin

Question 3

What is carbon dioxide?

How is it eliminated from the body?

Answer 3

Waste product of metabolism
Respiration (5% CO2)
Excess leads to drowsiness, dizziness, or unconsciousness

Question 4

What is nitrogen?

Carbon monoxide what and why dangerous?

Answer 4

Inert gas (78%) - increased levels associated with DCS
Gas that interferes with oxygen uptake and delivery

Question 5

Most important initial actions in responding to diving accidents?

Answer 5

Early recognition and providing oxygen

Question 6

What is decompression illness (DCI)?

Most prevalent symptoms?

Answer 6

Signs and symptoms arising during or after decompression encompassing both DCS and AGE

Pain in joins or muscles, altered sensation/numbness, fatigue, general malaise, nausea, vertigo/dizziness

Question 7

DCS:
primary cause
primary symptoms
Onset time of symptoms?

Answer 7

Decompression sickness - Inert gas not eliminated so creates bubbles in blood/tissues

Joint pain, motor or sensory dysfunctions, skin rash

After surfacing or well into ascent (extreme exposure)

Question 8

Arterial gas embolism is?
Primary risk factor?
Onset time of symptoms?

Answer 8

Lung-overexpansion - gas enters blood

Breath-holding

Suddenly at or near the surface

Question 9

Four benefits of providing a high concentration of oxygen to an injured diver?

Answer 9

Accelerated inert gas elimination
Reduced bubble size
Enhanced delivery to tissues
Reduced pain and swelling

Question 10

What two actions of a partial pressure gas gradient help the injured diver?

Answer 10

Increased O2 breathing in increases inbound gradient which increases O2 uptake and delivery to injured tissues reducing pain and swelling to limit or revers hypoxic injury

Question 11

What is the primary goal of emergency oxygen for injured divers?

What is the priority for oxygen delivery in remote areas?

Answer 11

T0 deliver the highest percentage on inspired oxygen possible to facilitate inert gas washout and improve oxygen delivery to compromised tissue

Maintaining the highest inspired fractions possible

Question 12

What two critical factors affect the percentage of oxygen delivery when using a demand valve?

Answer 12

Mask fit and flow rate

Question 13

What is the initial flow rate for constant-flow oxygen-delivery systems?

Answer 13

10-15 liters per min

Question 14

Concerns for oxygen toxicity when delivering emergency oxygen first aid?

Answer 14

None but if either pulmonary before central nervous

Pulmonary toxicity - high concentrations for prolonged periods - irritation of lung tissue due to free radical build up

Question 15

Five symptoms of nonfatal drowning?

Three actions a first responder should take in a nonfatal drowning?

Answer 15

Difficulty breathing, bluish lips, abdominal distention, chest pain, confusion, coughing pink frothy spit, irritability, unconsciousness

Monitor vital signs, provide O2, transport to medical facility

Question 16

What is the fire triangle, and how is oxygen involved?

Answer 16

Three elements for fire - heat, fuel, oxygen

Oxygen required for fires, higher concentration = greater risk of fire and acceleration

Question 17

Safety precautions to be implemented when handling oxygen equipment?

Answer 17

Reduce heat and oil exposures
Adequate ventilation when using
Using only proper equipment
Turn on slowly, once pressurized open 1 full turn,
Visual inspections for damage to cylinder/hoses/O rings

Question 18

What grade of oxygen should be used for diving first aid?

When and how should reusable oxygen masks and removable plastic oxygen system parts be cleaned?

Answer 18

Aviator or medical grade

After use. Soak in bleach solution (1:9) for at least 10 mins, rinse thoroughly, allow to air dry

Question 19

What documentation is required to receive an oxygen fill?
When should an oxygen unit’s components and cylinder pressure be checked?
How should an oxygen unit be stored?

Answer 19

Documentation of training in use of emergency O2
Check before every dive outing
Stored with valve closed and depressurized but fully assembled

Question 20

What are the components of an oxygen delivery system?

Answer 20

Cylinder, pressure-reducing regulator, hose, face mask

Question 21

What are the hydrostatic testing requirements for an oxygen cylinder?

How often and by whom should an oxygen regulator be serviced?

Answer 21

Same as all compressed-gas cylinders

1 - 10 year overall, 5 yrs in USA

Question 22

What two factors influence what cylinder size is appropriate?

Why is a demand valve the first choice for delivering oxygen to an injured diver?

Answer 22

Distance to medical care/next level of response, size of cylinder

Can deliver optimal concentration with minimal waste preserving supply as long as possible - closest to 100% O2 administration

Question 23

When should the oxygen provider switch to a full cylinder?

Which oxygen regulator is preferred for diving first aid?

Answer 23

When pressure drops below 200 psi

Multifunction regulator to service 2 divers as once (Demand value)