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Joint Service Sub Aqua Diving Centre. DIVING ILLNESS’ & TREATMENT REVIEW. Objectives. Revise Basic Life Support (BLS) skills For diving incidents: understand the conditions recognise signs and symptoms understand how oxygen administration benefits these conditions

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Joint service sub aqua diving centre l.jpg

Joint Service Sub Aqua Diving Centre




Objectives l.jpg

  • Revise Basic Life Support (BLS) skills

  • For diving incidents:

    • understand the conditions

    • recognise signs and symptoms

    • understand how oxygen administration benefits these conditions

  • Understand appropriate equipment and the practicalities of its use

  • Revise oxygen administration skills

    • breathing casualties

    • non-breathing casualties

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  • BLS

  • Medical conditions

    Casualty Assessment

  • Oxygen administration equipment

  • Oxygen administration in practice

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Lesson Outline

  • BLS skills:

    • Essential rescue skills

    • Deteriorate quickly if not frequently exercised

    • Advice/techniques evolve

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Assessing the Need

Indicators of the need for BLS:

  • no response

  • no chest movement

  • no feel of air movement

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  • D r A B C

  • Danger – to casualty and rescuer

  • Response (AVPU)

  • Airway

  • Breathing

  • Circulation

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Airway blocked by tongue

Head tilt/chin lift clears airway

Clear airway

Foreign objects


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  • Danger – to casualty and rescuer

  • Response

    • A–Alert

    • V– Responds to Voice

    • P– Responds to Pain

    • U–Unresponsive

  • Airway – clear of obstructions

  • Breathing– check for normal breathing (10 secs.)

  • Circulation– Cardiac Compressions

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BLS: Decision Process



Leave casualty and get help


Shout for help, open up airway


Leave casualty and get help, return and give 30CCs

Breathing normally?


  • Stop to recheck only if breathing resumes, else continue until:

  • Qualified help arrives

  • Normal breathing

  • You are exhausted

Recovery position

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Basic Life Support (BLS)

  • Monitor effectiveness:

  • Sequence:30 compressions : 2 breaths

  • Rate of 100 compressions/minute

  • 4–5cm compression

  • Stop if normal breathing resumes/medical assistance arrives

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Rescue breaths (RB)

  • Monitor effectiveness:

  • Sight

  • Feel

  • Sound

  • Appearance

Don’t over


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Oxygen Partial Pressure Scale (bar)

Abilities impaired



Long term toxicity risk












Short term toxicity risk




Inspiration default set points

Oxygen Exposure

  • At high concentrations oxygen is toxic

  • PO2<0.16 bar does not support life

  • Need to remain within accepted oxygen exposure limits

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Abilities impaired









  • What is it:

    • Lack of oxygen

    • PO2< 0.16 bar

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Abilities impaired









  • Symptoms:

    • Inability to think clearly, confusion, sense of losing it

    • Loss of co-ordination

    • Unconsciousness, death

    • Primary danger is symptoms may be vague or absent

    • It can occur suddenly and without warning!

Hyperoxia l.jpg

Long term toxicity risk







Short term toxicity risk



  • What is it:

    • Too much oxygen

    • Oxygen becomes toxic at elevated partial pressures

  • There are two different effects of Hyperoxia:

    • Whole Body Oxygen Toxicitywhen PO2>0.5 bar for long periods

    • Central Nervous System (CNS) toxicity when PO2>1.4 bar for even short periods

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Whole Body Toxicity

  • Cause: long exposures to PO2>0.5 bar

  • Monitored to allow for recompression treatment

  • Physiological reactions including:

    • Inflammation in the lungs

    • Reduction in vital capacity

    • Congestion, oedema, bronchitis, swelling of alveolar walls, thickening of pulmonary arteries

    • Visual impairment

  • Symptoms:

    • Dry cough, discomfort in breathing cycle, increased breathing resistance, shortness of breath,

    • Severe pain, sub-sternal pain or burning

    • Temporary short sightedness (Hyperoxic Myopia)

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CNS Toxicity

  • Also known as Acute Oxygen Toxicity

  • Reaction to PO2 generally > 1.4 bar

  • Symptoms:

  • CON- Convulsions

  • V- Vision

  • E- Ears, hearing disturbances

  • N- Nausea

  • T- Twitching

  • I- Irritability

  • D- Dizziness

  • Until convulsions begin, minor symptoms:

    • Can occur in ANYorder or combination

    • Increase in severity

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CNS Toxicity

  • Convulsions

    • Tonic phase – do not assist

      • Muscles become tense

      • Casualty becomes rigid and holds breath

    • Clonic phase – do not assist

      • May occur seconds or minutes after the tonic phase

      • Casualty jerks violently (convulsion)

    • Depressive phase - assist

      • Casualty relaxes and is unconscious

      • Potential loss of mouthpiece

        • Loop flood – loss of buoyancy

        • Need for Basic Life Support?

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CNS Toxicity

  • Convulsions

  • Phases can occur on surface or after PO2 is reduced (‘Off effect’)

  • Progressive damage to nervous system with each successive convulsion

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Long term toxicity risk







Short term toxicity risk



  • Causes:

    • Inaccurate dive planning

    • Failure to analyse gas

    • Incorrect marking or fitting of cylinders

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Long term toxicity risk







Short term toxicity risk



  • Aggravating factors

    • Actual PO2

    • Duration of exposure

    • Level of exertion

    • Cumulative O2 exposure

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Long term toxicity risk







Short term toxicity risk



  • Avoidance:

    • High PCO2 predisposes to oxygen toxicity

    • Accurately track your oxygen exposure

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Monitoring Oxygen Exposure

  • CNS and Whole Body Toxicity need to be monitored separately

    • Data for both provided in BSAC Oxygen Toxicity Table

  • Dive planning software

  • Nitrox & mixed gas decompression computers

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  • What is it:

    • Excess CO2 in the blood

  • Cause:

    • High inspired PCO2

      • Poor ventilation of diver’s lungs at depth due to increased gas density

      • Absorbent material exhausted in rebreathers

      • Channelling in absorbent material rebrerathers

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  • Symptoms

    • 0.03 bar PCO2 doubles breathing rate (dyspnea)

    • 0.06 bar PCO2 distress, confusion, lack of coordination

    • 0.10 bar PCO2 severe mental impairment

    • 0.12 bar PCO2loss of consciousness, death

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  • Further impact

    • Increases oxygen toxicity potential

    • Increases potential for DCI and narcosis

  • Avoidance

    • Meticulous preparation & monitoring of absorbent life - rebreathers

    • Avoiding over exertion

  • Resolution

    • Stop, slow down breathing rate, relax

    • Bail out to open circuit - rebreathers

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Decompression illness (1)

  • Causes

    • inadequate elimination of nitrogen from the body during ascent

    • Physical damage to the alveoli due to overpressure introduces bubbles of air (emboli) into the blood

Bubbles blocking blood flow

Bubbles in tissues compress blood vessels

Patent foramen ovale (PFO) allows bubbles to pass from venous to arterial circulation

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Decompression Illness (2)

Signs and symptoms

  • Denial!

  • Itches, rashes

  • Numbness, tingling, joint pains

  • Vision disturbances

  • Dizziness, nausea, headaches, confusion

  • Weakness, paralysis, loss of bladder/bowel control

  • Shortness of breath

  • Shock, unconsciousness

  • Any abnormality after a dive

  • Signs and symptoms appear from seconds to many hours after surfacing

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    Decompression Illness (3)

    On-site first aid

    • Lie casualty down flat

    • Keep casualty quiet

    • Administer 100% oxygen

      • Increased nitrogen pressure gradient assists in nitrogen elimination from bubbles in blood and tissue

      • The higher the percentage of oxygen the more effective – whenever possible administer 100%

      • Improved oxygen supply to tissues where blood flow is reduced due to bubble blockage

    • Treat for shock

    Evacuate to a recompression facility as soon as possible

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    Burst lung (1)

    • Cause

      • physical damage to lung tissue from over-extension due to over-pressurisation

    • Types

    Bubbles between organs and tissues (emphysema)

    Collapsed lung


    • Both types can occur in isolation but are usually accompanied by air embolism

    Burst lung 2 l.jpg
    Burst lung (2)

    • Signs and symptoms include

      • chest discomfort/pain, bloody froth

      • shortness of breath

      • changes to vocal tone, crepitation

      • shock

      • unconsciousness, death

    • Signs and symptoms of burst lung are frequently accompanied by those for decompression illness

    Burst lung 3 l.jpg
    Burst Lung (3)

    • Lie casualty down

    • Keep casualty quiet

    • Administer 100% oxygen

      • Assists in re-absorption of the nitrogen content of air in pneumothorax or emphysema

      • Offsets reduced effective lung surface area for gas transfer due to collapsed lung

    • Treat for shock

    • Evacuate to a recompression facility as soon as possible

    On-site first aid

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    Near Drowning (1)

    • Cause

      • Respiratory interruption due to fluid inhalation

    • Signs and symptoms

      • Circumstances

      • No breathing

      • Cyanosis – ashen grey / blue appearance

      • Weak or absent pulse

    Near drowning 2 l.jpg
    Near Drowning (2)

    • Rescue Breathing

      • Oxygen-enriched if possible

      • Concentration of oxygen reaching the casualty’s lungs during RBs is increased

    • Chest compressions if required

    • Recovery position

    • Evacuate to medical attention

      • Even if apparently fully recovered

      • Complications of secondary drowning

    On-site first aid

    Shock 1 l.jpg
    Shock (1)

    • Definition

      • inadequate circulation leading to tissue damage due to inadequate oxygenation and waste removal

    • Present to a greater or lesser degree in all injuries

    • Mechanisms

      • reduced blood volume (bleeding, burns, oedema)

      • massive dilation of blood vessels (e.g. fainting)

      • inadequate cardiac output (e.g. heart attack)

      • allergic reaction to drugs, food or stings

      • removal from the water after prolonged immersion

    Shock 2 l.jpg
    Shock (2)

    • Signs and symptoms

      • weakness, dizziness

      • pallor, sweating

      • rapid pulse rate

      • rapid breathing, feeling breathless

      • unconsciousness

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    Shock (3)

    • On-site first aid

      • Treat prime cause

      • Reassure casualty (TLC)

      • Keep casualty quiet

      • Lay casualty down with legs raised (not in the case of DCI or burst lung)

    • Keep warm and comfortable

    • Administer oxygen

      • Increased oxygen dissolved in the blood offsets effects of inadequate circulation

    • Monitor condition

    • Nothing by mouth (except for DCI)

    • Evacuate to medical attention

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    Shock (4)

    Immersion shock

    • Extreme form of blood vessel dilation due to prolonged immersion

    • Muscles relax due to water supporting body weight

    • If removed from water upright, blood can pool in lower limbs – potentially fatal

    • Keep casualty horizontal at all times

    • Discourage any movement or activity by the casualty

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    Carbon monoxide poisoning (1)

    • Cause

      • breathing gas contaminated with carbon monoxide

    • Effect

      • carbon monoxide combines about 200 times more readily with haemoglobin than does oxygen

      • interferes with the blood's ability to transport oxygen

      • may act as a cellular poison

    Carbon monoxide poisoning 2 l.jpg
    Carbon monoxide poisoning (2)

    • Signs and symptoms

      • headache

      • pale or greyish appearance

      • weakness

      • dizziness, nausea

      • tunnel vision

      • vomiting

      • rapid pulse

      • rapid breathing

      • coma

      • convulsions

    Carbon monoxide poisoning 3 l.jpg
    Carbon monoxide poisoning (3)

    • On-site first aid

      • remove casualty from contaminated breathing supply

      • lie casualty down with legs raised

      • administer 100% oxygen, or oxygen enriched Rescue Breaths, as appropriate

    • Benefits of 100% oxygen

      • more oxygen is transported in solution in the plasma

      • some assistance in breaking down carboxyhaemoglobin

      • helps restore normal cellular function

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    Summary of diving illnesses

    • Administration of oxygen is beneficial to the major diving disorders

    • 100% oxygen will provide the maximum benefit

    • Administer oxygen as early as possible

    • Oxygen is a supplement to other first aid procedures to increase their effectiveness

    • Casualty must always be evacuated to appropriate medical aid:

      • As soon as possible

      • Irrespective of any apparent resolution of their condition

    Casualty assessment l.jpg



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    Lesson Outline

    • Configuration of oxygen administration equipment most suitable for sport diver use

    • Oxygen administration equipment comprises

      • Gas cylinder Colour coding – (BS EN 1089-3)

      • Regulator Pillar valve connections (BS EN 850)

      • two pin index, female outlet, no ‘O’ ring

      • Demand valve and mask At least one demand valve (100 to 160 litres / min. flow rate), 10 litres/min. (minimum) constant flow

    Oxygen l.jpg

    • Characteristics

      • A colourless, odourless, tasteless gas

      • Comprises approximately 21% of the atmosphere (by volume)

      • An essential component of metabolism

      • Carried in the blood stream

        • Primary means - combined with the haemoglobin

        • Secondary means - dissolved in the blood plasma

      • Plasma’s capacity to transport additional oxygen utilised in oxygen administration

    • Will not burn but supports the combustion of other materials

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    Precautions in Use

    • Fire risk - absolute cleanliness a necessity

    • Keep equipment regularly maintained

    • Do-it-yourself equipment or modifications are dangerous

    • Do not use non-standard equipment – risk of confusion

    Casualties l.jpg

    • Incident statistics show that the majority of casualties will be

      • Breathing

      • Conscious

      • Suffering from decompression illness

    • Will need the use of a demand valve and oro-nasal mask for maximum oxygen concentration

    Incidence of casualties requiring Rescue Breaths is much lower

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    Administering Oxygen (1)

    • Start at the earliest opportunity

      • Greater nitrogen pressure gradient

      • Earliest reduction in tissue hypoxia

    • Don’t ration oxygen

    • Tender loving care (TLC)

    • For a second casualty

      • Use second demand valve and oro-nasal mask, if available

      • Otherwise use a pocket mask

      • Accept faster consumption of oxygen

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    Administering Oxygen (2)

    • Be prepared for a possible transient worsening of casualty’s condition

      • Initial reaction of brain to increased oxygen

      • Oxygen diffusing into bubbles

    • Oxygen toxicity

      • Not a problem at surface pressure / durations involved

      • Casualties of underwater O2 toxicity? – administer O2 on surface once any signs or symptoms have disappeared

    • No pain killers

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    Administering Fluids

    • Counter dehydration with fluids

      • Still isotonic drinks best, or water/squash

      • Do not administer caffeinated or fizzy drinks

      • Small amounts, at a rate of approx 1 litre/hour

    • Do not allow to interfere with or delay

      • Administration of oxygen

      • Evacuation to a recompression facility

    • Do not administer fluids if

      • Casualty is likely to vomit

      • Casualty is likely to inhale fluid

      • A general anaesthetic may be required

    • If no oxygen, fluids alone are beneficial

    Evacuation l.jpg

    • Don’t delay call to emergency services

    • Coastguard: VHF Channel 16

    • DDMO / BHA DCI Helplines:

      • England, Wales & N. Ireland:07 831 151 523

      • Scotland: 0845 408 6007

    • On Land (other)


      • Telephone: 999 or 112

    • DCI

      • Irrespective of any apparent improvement, casualty must get medical attention

      • Casualty’s buddy?

    • All relevant information must accompany any casualty

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    Oxygen Supply Exhausted?

    • Closed Circuit Rebreather

    • Can be set to deliver 100% oxygen

  • Nitrox

    • Open Circuit or Semi Closed Circuit Rebreather

    • Reduces the amount of inspired nitrogen

    • Not as effective as 100% oxygen but better than breathing air

  • Common considerations

    • Mouthpiece may not be tolerated

    • Oxygen % reduced by air inspired via nose

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    Missed Decompression

    • If a diver misses decompression stops for any reason, or is subject to a rapid ascent such that it is considered that they may suffer decompression illness as a result:

    • Do not wait for signs/symptoms to appear

    • Lay casualty down and keep quiet

    • Administer oxygen/fluids

    • Seek specialist medical advice on further action from the DDMO/ BHA Help lines

    Entonox l.jpg

    • Mixture of oxygen and nitrous oxide

    • Nitrous oxide is very soluble in blood

      • Large quantity of nitrous oxide passes into nitrogen bubbles to re-establish equilibrium

      • Causes size of bubbles to increase

    • Never administer to a casualty suffering from a diving accident

    Do not administer to a casualty of a non-diving accident if this follows diving

    Ensure emergency personnel fully understand

    - Do this tactfully!

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    DDMO Contact

    • If you suspect a diver may have a diving related problem, even if just a headache after a dive:

    • Call Defence Diving Medical Offr (DDMO)

    • 24/7 manned number

    • 07831151523

    • 02392768020

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    Diving illness & treatments

    • Summary:

      • Signs & symptoms can be similar for different conditions

      • Knowledge of pre –incident history helps

      • Oxygen administration & TLC are beneficial to all diving illnesses & incidents