Scuba Diving Physiology

 

1. we have 2 system in our body: cardiovascular system and respiratory system

 

Cardiovascular system:

 

• heart has 2 functions:

1. pump rich blood( O2) to the tissues via arteries, and pump poor blood (CO2) from the tissues via veins
2. pump poor blood (CO2) to the lungs via arteries and pump rich blood (O2) to the heart

 

the O2 and CO2 is exchange via Capillaries to and from the tissues

 

• if we have too much CO2 it is called Hypercapnia
• if we have not enough O2 it is called Hypoxia
• if we have too much O2 it is called Hyperoxia or O2 toxicity

 

• the heart beats approx 60 to 80 times per minutes and pump 5lt of blood per minutes

 

the O2 and CO2 is transported to and form the tissues via the red blood cells

 

respiratory system

 

• the lungs is where gas exchange occur.

1^st the air enter the trachea  then the bronchioles and then the alveoli.

The alveoli are cover by capillaries and it is where the gas exchange

 

• lungs capacity: (around 6.8lt of air)

1. total lung capacity – from total collapse to full inflation
2. vital capacity – total amount of air inhaled after maximal expiration
3. residual volume – the amount of air left in the lungs after maximal expiration
4. tidal volume – the volume of air who is exchanged during inhalation and exhalation

 

we breath around 12-20x per minute

 

 

we need to breath to decrese the CO2 level in the blood not because we don’t have enough O2

 

because the air we breath at depth is denser, it is more difficult to breath. To compensate, you need to breath more slowly

 

the response to stress from our body is to breath shallower.

By doing that, we don’t exchange enough new air from the regulator and by breathing the same air again and again, our body tells our brain that the level of CO2 is to high and we need to breath.

The best way to stop this pattern ( feeling that we don’t have enough air), breath deeply until you feel better. Otherwise panic occurs.

 

TEMPERATURE

 

      We loose temperature 25X faster in the water than in the air

The most affected is by conduction

The least affected is by radiation

 

TOO COLD

·       Mild Hpyothemia: (body react) not dangerous if handle correctly- don’t need hospital

1.     when the body core temperature (inside the body) is too low (less than 37)

2.     symptoms : shivering, difficulty to move the extremities

3.     best thing to do : stop the dive and dry off, drink hot fluids

 

1.     Advanced hypothermia: (body stop reacting) dangerous- need hospital

1.     fail to handle mild hypothermia

2.     symptoms : no shivering, feeling hot again, blackout, death

3.     best thing to do: stop the dive, dry off, treat for shock while transporting to hospital

TOO HOT

·       Heat exhaustion: (body react) not dangerous if handle correctly – don’t need hospital

1.     when the core body temperature is to hot

2.     symptoms : heavy perspiration (sweat) , cool skin, normal color, nausea

1.     best thing to do: shower, drink, jump in water, open the wetsuit, go away from the sun

 

·       Heat stroke : (body stop reacting) dangerous – need hospital

1.     fail to handle heat exhaustion

2.     symptoms : skin is hot, red, and the sweat stop, blackout , death

3.     best thing to do : protect from heat, wet towels, treat for shock while transporting to hospital

 

 

 

 

 

 

SQUEEZE (BAROTROMA)

 

A squeeze occur when the pressure outside and air space is more than the pressure inside

 

Don’t attempt to forcefully equalization, you can break the round window in the middle ear

 

If you don’t equalize you ears, you can break the eardrum who produce vertigo because cold water enter in the middle ear

 

It can happen in:

1.     THE EARS -   equalize all the way

2.     THE MASK – add air by blowing with the nose

3.     THE DRYSUIT – add air on the way down

4.     THE LUNGS – never empty your lungs on descent

5.     THE SINUSES – equalize all the way

 

REVERSE BLOCK

 

                        A reverse block can happen when the pressure inside an air space is more than the pressure outside and the air cannot escape

 

                        It can happen in:

1.     THE EARS – never take decongestion pills before diving

2.     THE LUNGS – holding the breath on ascent

3.     THE SINUSES - never take decongestion pills before diving

 

If it happen, go down a little a ascent very slowly and

 

ONLY DIVE IF YOUR SINIUSES ARE HEALTY

 

 

SINUSES:

 

                        We have 4 pairs of sinuses:

1.     frontal sinuses – above the eyes

2.     maxillary sinuses – below the eyes

3.     ethmoidal sinises – base of the nose

4.     spenoidal sinuses – deep inside the skull

 

EARS :            the ears are divided in 3 parts:

1.     the outer ear (the part that we see outside until the eardrum

2.     the middle ear (the part who is the most affected by pressure)

3.     the inner ear (who is in the skull and is not affected by pressure

 

when we equalize, we push air from the sinuses into the Eustachian tube and add air to the middle ear.

DECOMPRESSION ILLNESS (DCI)

 

            Is divide in 2 groups :

1.     Decompression sickness

2.     lungs overexpansion

 

Decompression sickness:

            Nitrogen goes out of solution

 

Causes:            - too fast up (max 9m / minute)

-       stay too long (ndl limite) non decompression limit

-       stay too deep (ndl limite) 

 

predisposing factors: 

-    dehydratation (water is taken from the body to rehydrate the dry air from the cylinder)

-       alcool

-       obesity (slow tissues release N2 slower)

-       injury

-       smoking (CO2 bonds 200x better with red blood cells than O2)

-       lack of sleep

-       illness ( the body focuses on the part to repair and send O2 and N2 in that place 1^st)

-       poor fitting equipment

-       certain drug

-       decompression dive

 

symptoms:       - joint pain

- tingling

- Numbness

- irritation

- swelling

- extreme fatigue

- weakness

- paralysis (when the bubbles are around the spinal cord)

- black out

- convulsion (when the bubbles are in the brain)

- nausea

- vomiting

- shortness of breath

- shock

- death

 

            1^st aid:             - 100% o2 for 30’

- treat for shock

- lay down in recovery position

- transport to hospital

- call DAN (diver alert network)

 

LUNGS OVEREXPANTION

 

            4 DIFFERENT KINDS:

1.     Air embolism

2.     mediastinal emphysema

3.     subcutaneous emphysema

4.     pneumothorax

 

 

 

AIR EMBOLISM: air inside the bloodstream

MEDIASTINAL EMPHYSEMA : air in the middle of the chest

SUBCUTANEOUS EMPHYSEMA :  air under the skin

PNEUMOTHORAX : collapse lungs

 

causes: holding the breath on ascent (most dangerous between 10m and the surface) 1.0m DIFFERENCE CAN CAUSE LUNGS OVEREXPANTION

 

symptoms :  SAME AS THE DCS    

- joint pain

- tingling

- Numbness

- irritation

- swelling

- extreme fatigue

- weakness

- paralysis

- black out

- convulsion

- nausea

- vomiting

- shortness of breath

- shock

- death

 

            1^st aid:             - 100% o2 for 30’

- treat for shock

- lay down in recovery position

- transport to hospital

- call DAN (diver alert network)

 

 

 

 

 

NITROGEN NARCOSIS

 

            Causes : high partial pressure of N2 (nitrogen) the Meyer-Overton theory

                                    It can happen as shallow as 24meters

 

            Symptoms : like to be drunk :           

- euphoria

- confusion

- foolish behaviors

- impaired coordination

- false sense of security

- fixation of idea

- visual hallucinations

- deterioration of reasoning

 

            1^st aid : ascent to shallower depth

 

 

CONTAMINED AIR

 

            Causes : Improper filling intake of the compressor (Carbon monoxide, oil vapors)

 

            Avoid: smell and taste the air before diving, fill in a trusted diveshop

 

            Symptoms:      - headache

- red lips

- red finger nails

           

            1^st aid :            - stop diving

- 100% O2

- Hospital if needed

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

OXYGEN TOXICITY

 

            2 KINDS : CNS (central nervous system or pulmonary)

 

                        CNS: due to high partial pressure of O2 more then 1.4 ppO2

 

                        Symptoms:     

- visual disturbances

- ear ringing

- muscle twitching

- vomiting

- convulsions

 

1^st aid : stop the dive

 

 

PULMONARY O2 TOXICITY : too long exposure to high ppO2

 

Symptoms :

-       burning sensations in the lungs

 

1^st aid : stop diving until it’s gone

 

 

GASES:

 

      O2 :     OXYGEN

O2 is about 20.9% of the air that we breath

O2 is transported by the red blood cells, and is absorb via the lungs (alveoli) to the circulatory system by the capillaries

                  O2 is good for us if the partial pressure don’t pass 1.4ppo2

                  Minimum ppo2 to stay conscious is 0.10 ppo2

                  We use 100% of O2 to any diving related problems. Its provide the tissues                        with more O2 than normal air.

 

      N2 :     NITROGEN

                  N2 is about 78 % of the air that we breath.

N2 is transported by the red blood cells and absorb by the tissues if we dive because of the pressure differential.

Without diving, the N2 is not absorb by our tissue

N2 causes nitrogen narcosis when under high partial pressure

 

            CO :    CARBON MONOXIDE

            CO is produce by burning materials :

                        Cigarette à it takes 12 hours to clean the body from 1 cigarette

Gasoline à when petrol driven compressor is used to fill cylinders, a small or big amount can be find inside the cylinder.

The intoxication produce light head, strong headache, excessive hyperventilation , confusion and black out

It can be very dangerous to have even a small amount if it in the cylinder while the air that we breath is denser than at the surface. Always be sure that the filling station and filters are clean and changed as the manufacturer recommends.

 

            CO2:   CARBON DIOXYDE

CO2 is produce by the muscles who use the O2 to produce power. The waist product is CO2. High level of CO2produces Hypercapnia (too much of CO2) and tells the brain to breath.

 

 

A  :      ARGON

argon is present I air in a very small quantity.

In diving it is used for dry suit inflation since it have about twice the isolation capacity than air.

 

He :     HELIUM

            Helium is present in air in a very small amount

            In diving, it is use to counter the effect of nitrogen narcosis is tech diving

            Heliox is a mix of helium and O2 with no N2

            Trimix is a mix of Helium, O2 and N2

            Both of them are use in tech diving