Physiology Lecture

Thermal Effects

Hypothermia

Hyperthermia

Barotrauma

Squeezes/Reverse Blocks

Ear

Sinus

Stomach

Tooth

Lung

Mask

Hood

Suit

Vertigo

Pulmonary Barotrauma = Lung Expansion Injuries

Mediastinal Emphysema

Subcutaneous Emphysema

Pneumothorax

Air Embolism

Gas Effects

O2 Toxicity

CO Toxicity

CO2 Excess

Shallow Water Blackout

N2 Narcosis

Bends = Decompression Sickness

Female Physiology

Thermal Effects

Hypothermia

Description

Core body temperature is lowered.

Symptoms

95-98.6: Shivering, Slight Uncoordination
90-95: Shivering Slows, Uncoordination
85-90: Shivering Stops, Can't Walk or follow simple commands

Causes

Exposed to cool air or water without proper insulation.

First Aid

Passive Warming - remove wet clothing, replace with dry clothes and blankets, put in warm environment

Active Surface Rewarming - Use heated blankets, a warm person, or warm water bottles and apply to the skin.

If victim is alert, give liquids to protect from dehydration. No alcohol or caffeine.

Wetsuits can protect from Hypothermia but can lead the diver to get too hot when out of the water.

Hyperthermia

Description

Core body temperature is elevated.

Symptoms

Heat Exhaustion :
Clammy,cool skin
Heavy Perspiration
Feeling of weakness
Rapid Pulse
 
Heat Stoke:
Hot, dry flushed skin
Rapid Breathing and Pulse

Causes

Overheating can be due to wearing a wetsuit in the heat for too long before or after a dive.

First Aid

Cool the body slowly by covering with wet blankets, spraying with water.

Administer fluids for rehydration

Barotrauma

Squeezes/Reverse Blocks

All squeezes occur due to changing pressure, using Boyle's law.

As you descend the increased depth pressurizes air pockets reducing their volume. Every air pocket is affected by this law: lungs, sinuses, ears, stomach, and air within a BC, hood, mask, and drysuit.

The opposite can occur on ascent, a reverse block is when air pockets will expand.

Ear

Can rupture an ear drum. If rupture occurs water entering the middle ear can lead to vertigo.

Eustachian tube works like a one way valve allowing air to escape upon ascent.

That valve will be force shut if one descends a few feet w/o equalizing.

Equalize using the valsalva maneuver, hold your nose and push air through your eustachian tubes to equalize the pressure on the ear drum.

This must be done as descending, if the pressure builds too high the Valsalva maneuver may not work.

Muscles surrounding the eustachian tubes are used in yawning and swallowing.

 

Do not use earplugs, or the space between the ear plug and the ear drum will not be able to be equalized (outer ear squeeze).

Sinus

Typically the sinus passages equalized automatically.

The opening between the nasal cavity and sinus can become blocked due to swelling or mucus, preventing natural equalization.

Without equalizing the mucus membrane is drawn inward away from the bone, causing irritation.

Stomach

A reverse block is possible as gas generated during the dive expands on ascent.

Tooth

An air pocket due to improper cavity filling may cause a reverse block on ascent.

Lung

Air in your lungs can compress significantly during free diving.

Mask

Equalized by exhaling slightly through your nose into the mask. If no equalization occurs blood vessels in the eyes may break creating "red eyes".

Do not use swimming goggles, the air can not be equalized within the goggles.

Hood

Dead Space - air that can not be equalized. The hood may lie tightly around the ear sealing it and preventing the aire in the outer ear to escape.

Tilt head back or pull your hood open to let air out of the hood.

Want a snug fitting wetsuit hood, or exhaled air will be captured in the hood.

Suit

A drysuit uses an air layer instead of a water layer to insulate the diver.

Vertigo

Differences in pressure or temperature in each ear causes disorientation.

Can be caused by rupture ear drum, allowing cool water into middle ear.

The world spins, if you equalize the symptoms may go away. Grab onto something stable, or yourself until symptoms pass.

Diving in cold water increases susceptibility.

Pulmonary Barotrauma = Lung Expansion Injuries

Mediastinal Emphysema/Subcutaneous Emphysema

Description

Rupture of the lung causes air to travel in the space (the mediastinum) between the two lungs and behind the sternum.

That air may then travel to other locations:
rise into the neck (Subcutaneous Emphysema)
or move into spaces around the heart or other organs.

Symptoms

Bloody Froth
Chest pain under the sternum
Difficulty Breathing
 
Subcutaneous Emphysema Symptoms
Swelling at the base of the neck
Voice Changes
Difficulty Breathing and Swallowing

Causes

Failure to exhale during ascent

First Aid

Oxygen
Treat for shock

Pneumothorax

Description

Rupture of the lung can leak into the lining surrounding the lungs (visceral pleura).

This air between the chest wall and the lung compresses the lung and can partially or fully collapse the lung.

Symptoms

Bloody Froth
Chest pain
Difficulty Breathing
Reduced Chest Movement

Causes

Failure to exhale during ascent

First Aid

Oxygen
Treat for shock

Treatment

Chest Tube Placement

Air Embolism = Arterial Gas Embolism (AGE)

Description

Rupture of lung alveoli, allowing bubbles into the bloodstream which may block circulation to the brain or heart.

Symptoms

Onset is very sudden
Bloody Froth
Chest pain
Breathing Stops
Loss of Vision
Difficulty Speaking
Severe Headache
Convulsions

Causes

Failure to exhale during ascent

First Aid

Oxygen
Treat for shock

Treatment

Recompression Chamber

Gas Effects

Gas effects occur due to Dalton's and Henry's laws.

O2 Toxicity

Description

High concentrations (above 2atm partial pressure O2) can attack the nervous system.

Symptoms

Larger concentrations can lead to:
Muscular twitching
Nausea
Abnormal Vision
Uncoordination
Convulsions

Causes

Breathing high partial pressure of Oxygen, which can occur from breathing air at 10 atm ( 297 ft) . Physiological limit of diving is 297 ft.

First Aid

Return to the surface

Fresh Air

CO Toxicity

Description

Hemoglobin combines with CO about 200 times as readily as oxygen = Carboxyhemoglobin.

This doesn't allow oxygen to combine with hemoglobin.

Symptoms

Headache
Dizziness
Loss of Consciousness
Red Nails/Lips

Causes

Carbon monoxide from exhaust fumes of engines may get into the intake air when refilling tanks.

First Aid

Oxygen

 

CO2 Excess

Description

The body's level of CO2 is used to regulate breathing rates. If CO2 levels are elevated the desire to breath more will occur.

Symptoms

Increased rate of respiration
Respiratory Discomfort
Dizziness
Stupor
Unconsciousness

After-effects

Headache
Dizziness
Nausea

Causes

Skip Breathing (Holding between breaths)

Shallow Breathing (Can come from snorkeling)

First Aid

Fresh Air

Breath Normally

Shallow Water Blackout

Description

Can occur at any depth.

The body's level of CO2 is used to regulate breathing rates.

If CO2 has been flush out of the system (due to hyperventilation), the subsequent build up of CO2 may not be enough to trigger the need for breathing even when all the O2 has been used.

Leads to unconsciousness due to lack of oxygen.

Symptoms

Unconsciousness

Causes

Hyperventilating, then holding ones breath under heavy exertion.

First Aid

Breath Normally

N2 Narcosis

Description

"Rapture of the Deep"

Higher partial pressures of nitrogen are absorbed into body tissues which slows nerve impulses producing an intoxication effect.

Symptoms

Rapid Onset and recovery
Impairment of:
thought
judgment
reasoning
memory
mental/motor skills
Euphoria (Warm Water)
Paranoia (Cold Water)

Causes

Symptoms may begin around 80 -130 ft.

Every 50 ft afterwards is like having an additional Martini.

Martini's Law: Every 33 ft equals 1 Martini.

Deep Diving: limit depths to 130 ft.

First Aid

Ascend until effects are relieved.

Bends = Decompression Sickness

Description

Nitrogen released from body tissue during ascent can not be absorbed into the bloodstream and eliminated through respiration causing nitrogen bubbles.

Bubbles can congregate at joints and other locations blocking circulation.

Symptoms

Skin - Itching, Rash
Throbbing pain in joints
Extreme Fatigue
Tingling in extremities
Paralysis
Unconsciousness
 
Symptoms increase with a hot showers.

Causes

Failure to follow dive tables or dive limits and spending too much time at particular depth which leads to absorbing too much Nitrogen which can not be released safely upon ascent.

First Aid

Oxygen
Treat for shock

Treatment

Recompression Chamber

Navy Maximum No Decompression Dive Times

 Depth Maximum Bottom Time
 35 310
40 200
50 100
60 60
70 50
80 40
90 30
100 25
110 20
120 15
130 10

Female Physiology

Menstration does not typically pose a problem with diving. If cramps are bothersome on land, those affects may be heightened during diving.

Scuba diving is dangerous during any stage of pregnancy.

Due to slightly higher body temperature, women are more prone to hypothermia.