Harry Oxer

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• Harry Oxer
• Foundation Director
• Hyperbaric Medicine Unit
• Emeritus Consultant in Diving and Hyperbaric
  Medicine
• Fremantle Hospital

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The wise, for cure,on exercise depend
Dryden 1631-1700, on Health
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rôle of GP re divers

• assess fitness to dive
• undertake risk assessment
• recognise diving associated problems
• manage, refer or consult as appropriate

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diving - related problems

• decompression illness
• pulmonary barotrauma
• near drowning
• salt water aspiration syndrome
• breathing media toxicities
• carbon monoxide,
• oxygen, nitrogen

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diving - related problems

• hypothermia
• trauma
• envenomation

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immersion - physiology

• causes pressure
• transmitted throughout fluid
• compresses gases
• dissolves breathed gas in tissues

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pressure

• 1 ATA, 14 psi, 1 bar etc
• increases by 1 bar/ 10 metres sea water
• i.e. doubles pressure by 10 msw
• Boyles Law - halves volume of gas from surface
  to 10 msw
• NO effect on liquid or solid of body

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pressure increase effects

• ear barotrauma
• must clear about every metre near surface
• if exceed pressure, cant clear
• over-violent Valsalva can rupture round window
• instant vertigo, somehearing loss

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ear picture
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pressure increase effect

• sinus squeeze
• volume of gas decreases
• mucosa swells, seeps
• tries to fill space
• bleeds

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pressure increase effect

• lung squeeze
• free diving
• gas supply failure

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pressure increase effect

• dissolves more gas in blood, tissues
• differing rates of uptake and solution
• blood supply, solubility
• time and pressure (depth)

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pressure effect at depth

• increase in gas dissolved with time and depth
• approaches equilibrium with ambient pressure
• tissues saturate - fastest first
• membrane effects
• nitrogen narcosis
• helium - ? HPNS

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pressure decrease effect

• volumes increase
• ears ventilate freely
• sinuses can be very painful
• lung gas expands if not vented
• fastest nearer surface
• buoyancy devices faster near surface

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pressure decrease effect

• volume change 40m-30m 20
• volume change from 10m to surface 100!
• worst problem nearest surface
• 1.2 msw rise can tear lung near surface!
• no place for shallow only
• medical clearance!

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pressure decrease effect

• trapped air - breath-hold
• panic, vomit, emergency
• reactive airways
• choking, inhaled liquid

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pressure decrease effect

• can rupture lung
• air can go
• to chest - pneumothorax
• to parenchyma - surgical emphysema
• into torn blood vessels - gas embolism
• lung capillaries, left atrium, ventricle, brain

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pressure decrease effect

• gas must come out of tissues
• slowly - diffuses to blood to lung
• fast - must come out of solution
• forms bubbles - in tissues, blood

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decompression illness - sequence

• gas dissolves as pressure increases
  pressure down - gas out of
  solution
• bubbles in tissues, blood
• vena cava to lungs

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Rapid ascents with a gas load, especially
uncontrolled
Sudden release of pressure you FIZZ!
Sudden release of pressure - you FIZZ!
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bubble effects

• tissue distortion, pain, damage
• endothelial damage
• capillary leakage, perivascular oedema
• white cell adhesion
• rheological effects, lipids, complement
• cause hypoperfusion

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near drowning

• suffocation
• salt or fresh irrelevant
• surfactant
• role of oxygen
• secondary drowning?

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salt water aspiration syndrome

• 2 - 3 hours onset after dive
• feels like flu with rigors
• goes off by next day

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breathing media toxicities

• oxygen - may exceed 3ATA, if too deep technical
  diving
• gt60m on enriched air 40 O2
• EAN longer, safer, NOT deeper!
• CO - very small amounts, ppm
• CO2 - rarely a problem
• Nitrogen - narcosis

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hypothermia

• body temperature is 37oC
• water temperature is much less even in tropics -
  28 - 300 C
• if not exerting, get hypothermic
• wind chill,long decompressions in water, e.g. O2
• Helium breathing

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trauma

• damaged tissues have impaired blood / O2
• need extra oxygen
• altered consciousness - more needed for brain

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envenomation

• snakes
• blue-ringed octopus / cone shells
• stone fish etc.

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first aid

• all major problems need oxygen
• 100 is best - nitrogen-free
• continuously
• can stop for drinks etcetera

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management - ears

• symptomatic
• decongestants, analgesics
• no diving until better
• dont dive with a cold
• jeopardises others

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gas embolism

• early onset - often as surface
• neurological, dramatic
• altered consciousness
• 100 OXYGEN N2 - free breathing
• URGENT recompression
• call the system

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decompression sickness

• anything unusual after a dive
• onset up to 12 hrs, usually first hour or two
• predisposing factors
• rapid or repeated ascent
• repetitive diving
• deeper dives last
• usual risk factors

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Decompression illness

• circulation effects
• emboli - ? persist, ? envelope
• then pass through - Gorman
• endothelial damage - leaky, sticky
• white cell adhesion, 2o blockage
• perivascular cuffing - James
• effects of treatment

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Decompression illness

• causes
• onset
• progression
• effects of Oxygen
• effects of pressure

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Decompression illnesspresentation

• timing
• speed of onset
• development
• time to treatment

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Decompression illnesssigns and symptoms

• pain - type, location
• paraesthesia, anaesthesia, rash
• weakness, paralysis, balance
• spinal - bladder
• fatigue, lethargy, slowed mentation
• chokes, collapse

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management - decompression sickness

• 100 OXYGEN - N2 - free breathing
• call the system
• arrange recompression
• more than one treatment

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recompression

• Fremantle Hospital Hyperbaric Medicine Unit
• State Referral Centre for Diving and Hyperbaric
  Medicine
• RAN Stirling? Others e.g. Broome, organised
  through us
• DES Diving Emergency Service?

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Fremantle Unit

• 16000 treatments in 8 years
• mostly e.g. problem wounds
• 240 divers - about 35 / year
• few gas emboli, few serious
• 8 - 20 have some residual problem
• usually slight, but not innocuous!

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decompression illness

• whether caused by embolism or gas bubbling
• 100 Oxygen
• transfer for recompression
• call FREMANTLE HOSPITAL
• [phone] Mon-Sat 0830-1630
• [phone] out of hours state Diving
  Problem

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chamber costs

• nil for Medicare patients
• nil for RFDS
• ambulance - nil only if you are in Fund!
• insured or w /comp - all re-imbursed - no gap

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Diving safely and unsafely(from a treatment
unit!)

• safety of recreational diving
• how to dive safely
• how to dive unsafely
• Are they bent? What shall we do?
• how to get to us
• what we do to you!
• Harry
  Oxer

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Ascent Rates

• should be exponential
• slower as near the surface
• stops are compromise
• BSAC fast, then slower
• Pearl - ascend to 8m stop
• Then 3m/ min. - 1m per 20 seconds to surface

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safety of recreational diving

• possibly 40,000 certificated divers in WA
• 35 treated each year
• mostly minor
• one or two die!
• 15-20 minor residuae

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how to dive safely

• be meticulous
• plan dives
• leave a margin
• dont get older on same dives!
• deepest dives first

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how to dive safely

• watch repetitive dives
• avoid repeated ascents late in dive
• watch surface intervals
• take 5 _at_ 5
• SLOW ASCENTS make SAFER DIVING
• break every fourth day

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how to dive unsafely

• macho I can do it! Done it often
• They got away with it - so can I!
• Just going back down for the anchor
• Just one more dive!
• The computer says its OK
• Im only just out of tables!

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Are they bent?

• pain, numbness, tingling
• weakness,
• excessive inappropriate tiredness
• unsteady, dizzy
• mentally cloudy
• anything unusual after a dive

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What shall I do?

• high index of suspicion
• OXYGEN 100
• fluids till passing urine
• communicate

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What shall I do?Communicate!

• Fremantle Hospital Hyperbaric Unit
• [phone] working hrs Mon-Friday
• [phone] out of hours
• state Diving Problem
• will speak to a diving doctor, or they will
  telephone you back very soon

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What shall I do?

• you can ring DES
• they will give first aid advice
• put you in touch with Fremantle Hospital
• they can arrange RFDS, ambulance

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what we do to you!

• we dont criticise!
• we analyse dives
• ask history of events and examine
• change you into cotton theatre gear

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what we do to you!

• Usually get George to treat you
• George is a recompression chamber
• 7 ATA - 60m capability
• two bunks for comfort
• full head room

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what we do to you!

• compress you to 2.8 ATA - 18msw
• it gets warm, you clear your ears often
• at pressure, you put on your gear
• individual transparent oxygen tent
• pure fresh 100 oxygen

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what we do to you!

• 5 mins air breathing break every 20 mins
• 1 hour 15 at 18m
• 1 hour SLOW ascent to 9m
• another 3 hours at 9m!
• total minimum 5 hours 20 minutes.

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what we do to you!

• how do I spend a penny?
• we have a private room
• entry lock
• adequate facilities!

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what else do we do to you!

• do it again next day, always!
• only 2 hours 15 this time
• other options - more treatments
• rarely needed extras include
• deeper and longer
• helium / oxygen 50 / 50

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results - divers

• November 1989 - June 30th 1995
• 197 compressed - 26 not DCI
• 170 decompression sickness
• 7 arterial gas embolism
• 25 last year - 22 OK

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results

• presented 3 hours - 6 months!
• average 3 days!
• long term results at 6/12 - 12 residuae
• minor mainly - tinglings etc
• risk factors for incomplete resolution
• delayed treatment
• rapid ascent, multiple ascents
• severity

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lessons

• diving can be safe - almost always
• not all divers dive safely!
• tables are a guide only, not a permit!
• dive computers are tables
• both only as sensible as the user
• dont dive to the edge - you may fall off!

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lessons

• deepest first, 2 hour surface intervals
• dont be macho!
• avoid repeated ascents, especially at end of dive
• take 5 at 5
• use tables, computers intelligently!
• rest day every fourth, on holiday

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dive safely, then you wont meet George!(or
Mildred!)

• Harry Oxer - 1995

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oxygen

• the breath of life
• Use of Oxygen in Diving
• Harry Oxer

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first aid

• all injured
• all unconscious
• all near drowned
• all salt water aspiration
• all decompression illness

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injuries

• all swell
• swelling impairs oxygen access
• oxygen reduces swelling
• oxygen promotes healing
• give oxygen 100

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unconscious/ near drowning

• brain has been without oxygen
• swells - response to injury
• lack of oxygen to brain cells
• give OXYGEN - 100

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decompression sickness

• nitrogen bubbles
• too much nitrogen in the tissues
• give a nitrogen-free gas to breath
• maximises nitrogen off-gassing
• give OXYGEN - 100

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arterial gas embolism

• bubbles in brain, spinal cord
• block blood vessels to brain cells
• insufficient oxygen to work
• give 100 oxygen - oxygenate brain
• nitrogen-free blood reduces
• nitrogen bubbles fastest

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oxygen - when?

• as soon as possible
• continuously until medical aid

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oxygen - how?

• any means of giving oxygen
• continuous
• 100

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oxygen equipment

• plastic therapy masks?
• NO
• better than nothing, but not much
• not 100
• with reservoir bag - better

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self-filling bags

• only with reservoir bag and oxygen
• second best for diving
• good for resuscitation

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demand valve resuscitators

• Oxy-Viva
• Dräger
• extravagant of Oxygen
• good for resuscitation

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DAN oxygen?

• Dräger -type demand valve
• therapy setting
• still needs a lot of Oxygen
• marketed aggressively

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closed circuit system

• Oxy-Resuscitator DIVE-Ox
• Komesaroff - Oz design, made
• 100 OXYGEN, CO2 absorbed
• 6-8 hours from one cylinder!
• VERY economical of oxygen
• easily refilled - Handicant
• resuscitation

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oxygen for diving?

• military
• NOT for sports diving
• fits can begin at 2.2 ATA - 12m
• less if sensitive!
• raised-oxygen mixtures are dangerous
• unless very thoroughly understood

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oxygen for decompression?

• yes in a chamber
• treatment
• surface O2 for commercial divers
• not in-water oxygen decompression
• except by professionals
• under supervision

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oxygen as surface treatment?

• yes - it helps
• sometimes cures symptoms
• MUST be recompressed too!

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oxygen for resuscitation?

• ventilation is the vital component
• some oxygen is essential
• E.A.R. 16
• highest available is good
• but resuscitation is rare
• OXYGEN first aid much more needed

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when YOU dive

• wheres your nearest OXYGEN?
• do YOU know how to give it?
• how long will it last?
• are there Club emergency procedures?
• known by all?
• is there a simple check-list?
• how is help contacted?

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First Aid

• DRABC
• Oxygen

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Injury

• DRABC
• oxygen
• first aid
• unconscious on side
• control bleeding

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Near drowning

• DRABC
• oxygen
• to medical aid
• call ambulance

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Salt water aspiration

• oxygen helps
• often nothing else needed
• seek medical confirmation
• could be chokes - serious!

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Arterial Gas Embolism

• DRABC
• oxygen
• lie diver flat when appropriate
• communicate, transport
• hospital - recompression

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Decompression illness - other

• DRABC
• lie down if very ill
• Oxygen 100
• clear fluids till passing urine
• communicate, transport
• recompression

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Diving injuries

• near drowning
• other injuries
• hypothermia
• decompression illness
• arterial gas embolism
• salt water aspiration syndrome

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Diving injuries

• communicate - telephone or radio patch
• consult for advice
• mainland - call ambulance
• arrange meeting point
• they will arrange transfer

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Diving Injuries - first aid

• DRABC
• lie, or position of comfort
• 100 oxygen - continuous
• fluids by mouth if well enough
• transfer

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Diving injuries - symptoms

• ANYTHING unusual after a dive
• nausea, dizziness, vomiting, balance
• numbness, tingling, weakness
• paralysis, heaviness, clumsiness
• totally inappropriate fatigue
• inappropriate speech or behaviour
• altered consciousness

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Diving injuries - symptoms

• AGE - come on at once to 15 min
• DCI soon after surface - up to 3-4 hours
• can be up to 12 hours.
• very rare to be more
• can get better, especially AGE
• improve with oxygen
• still need compression!

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Diving Injuries - help

• call Fremantle Hospital
• 0800-1630 Monday - Friday
• [phone] Hyperbaric Unit
• outside these hours
• [phone] Switchboard
• ask for duty Hyperbaric Specialist
• patch, or phone-back

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Diving Injuries - help

• you can ring DES
• (Diving Emergency Service)
• you get St John Ambulance Adelaide
• they put you through to mobile phone
• diving doctor gives advice
• puts you in touch with us!

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Diving Injuries - urgency

• unconscious - very urgent
• arterial gas embolism - asap
• others - dont delay, but dont bust anything
• 100 Oxygen
• talk with us
• we will advise, and usually arrange retrieval

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Diving Injuries - what next?

• seen by diving doctor
• treated in chamber, George or Mildred
• 5.5 hours oxygen 100
• 5 minutes off every half hour
• 18m - 9m
• treat daily until better or plateau 1

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Diving Injuries - cost?

• currently nil from Hyperbaric Unit
• nil if Medicare.
• ambulance - nil if insured, else lots!
• private insurance - nil extra to pay
• eventually will need insurance
• DAN Australia

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Diving Injuries - summary

• recognise diving injuries
• have a high index of suspicion
• know first aid - 100 oxygen
• have enough oxygen!
• have communication gear
• know the numbers to call

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Diving Injuries - summary

• communicate
• talk to us
• well advise and help
• it relieves your tension!

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- and to finish, I like to find a suitable and
erudite quote from classical literature.I sought
one on Exercise -
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Exercise is bunk! If youre healthy, you dont
need it.If youre not, you shouldnt do it!
Henry Ford.