ot6.1 08/02 bsac ocean diver training what happens if …..?
TRANSCRIPT
OT6.108/02
BSAC Ocean Diver Training
What happens if …..?What happens if …..?What happens if …..?What happens if …..?
OT6 208/02
What happens if…..?
What happens if…..? What happens if ….?
Aims
Potential problems Decompression Illness (DCI)
Gas bubbles Lung damage
Nitrogen narcosis Oxygen toxicity Breathing gas
Contamination Loss
Effecting a rescue
OT6 308/02
What happens if…..?
What happens if…..? DCI - Nitrogen
Nitrogen release An ascent will not release all nitrogen absorbed on dive Ascent has to be controlled Nitrogen continues to be released for many hours Another dive within this time period adds to nitrogen level Manage nitrogen to minimize risk of DCI
Tables and computers Dive practice Use a breathing gas with O2 > 21%
OT6 408/02
What happens if…..?
What happens if…..? DCI - Gas Bubbles
Distort and disrupt tissue Compress, damage blood vessels Reduces oxygen delivery to
‘downstream tissues
Cause Inadequate elimination of nitrogen
during ascent - bubbles Gas embolism during ascent
Bubbles can form in/enter blood
Effects Bubbles can form in tissues
Block blood flow Reduces oxygen delivery to
‘downstream’ tissues
OT6 508/02
What happens if…..?
What happens if…..? DCI - Lung Damage
Cause Ascent too fast Breath hold ascent
Effects Over expansion - physical
damage to lung tissue Collapsed lung (Pneumothorax)
Bubbles between organs and tissues (Emphysema)
Pleural Membrane
OT6 608/02
What happens if…..?
What happens if…..? DCI - Signs and Symptoms
Signs and symptoms appear from seconds to many hours after surfacing
DENIAL
OT6 708/02
What happens if…..?
What happens if…..? DCI - Signs and Symptoms
Numbness, tingling Visual disturbances, dizziness Nausea, headaches, confusion Weakness, paralysis Unconsciousness
Chest discomfort, pain Voice change, crepitation Shortness of breath Itches and/or rashes Aches in joints
OT6 808/02
What happens if…..?
What happens if…..? DCI - Treatment
Reduces bubble size and may restore circulation to affected area
Specialist supervision from a diving medic
Increased oxygen level improves delivery to damaged tissues
Assists in nitrogen elimination
Divers’ first aid tool - Oxygen
ONLY ONE ! Recompression Chamber
OT6 908/02
What happens if…..?
What happens if…..? Nitrogen Narcosis
Resolution Re-ascending to shallow depths
immediately resolves narcosis
Cause Thought that nitrogen under
pressure affects nerve impulse transmission - noticed below 30 metres
Signs Generally similar to the effects of
alcohol
OT6 1008/02
What happens if…..?
What happens if…..? Oxygen Toxicity
Oxygen can be toxic depending upon: Depth Time Mix
Signs Visual or auditory disturbances Muscular twitching Convulsions
OO22
OT6 1108/02
What happens if…..?
What happens if…..?
Resolution Abort the dive, return to surface
Prevention Each mix has a “Maximum Operating Depth”
(MOD) 32% - 35 metres for NO-STOP dives 36% - 30 metres for NO-STOP dives
Analyse Nitrox mix before use Do NOT exceed the MOD for your gas mix
Oxygen Toxicity
OT6 1208/02
What happens if…..?
What happens if…..? Contaminated Breathing Gas
Cause Problems with compressor
Detection Oily taste or smell
Reduces lungs’ efficiency Possible carbon monoxide level too high
Reduces oxygen delivery by blood cells to tissues
New cylinder or abort dive immediately
OT6 1308/02
What happens if…..?
What happens if…..? Contaminated Breathing Gas
Effects on diver Nausea Dizziness or disorientation
Headache following a dive
Abort the dive Buddy to assist if necessary Advisable not to dive again on same day Consider seeking medical attention Report to Dive Manager Report to filling station
Resolution
OT6 1408/02
What happens if…..?
What happens if…..? The Incident Pit
Fatal Death
Serious Panic
Emergency Fear
Minorincidents
Normalactivity
Resolving an underwater problem early prevents more serious consequences
OT6 1508/02
What happens if…..?
What happens if…..? Preventing Problems
Diving has a very good safety record
Safety does not happen by accident and problems are prevented by: Dive planning and anticipation Training, practice and experience Equipment, buddy checks Monitoring during a dive Common sense Support of other divers in group
Oxygen administration Rescue management Seeking diving medical expertise
OT6 1608/02
What happens if…..?
What happens if…..? Prevention and Resolution
Practice, practice, practice
Prevention is better than cure
Act early - Regain control
Resolve problem or assist/rescue
Buddy monitoring
OT6 1708/02
What happens if…..?
What happens if…..?
Rescues - Alternative Supply (AS)
AS is a “back up” system Dive should be aborted Rescuer to fully inflate own BC
on surface Inflate casualty’s BC by mouth
AS ascent
Cause Failure to monitor gas supply Equipment failure - rare
Resolution
OT6 1808/02
What happens if…..?
What happens if…..?
Rescues - Controlled Buoyant Lift (CBL)
CBL ascent
Priority to get casualty to surface May involve slightly faster than normal
ascent Ensure casualty buoyant on surface Give emergency signal Alternative means of positive
buoyancy?
If convulsing (O2 toxicity) wait until convulsions stop before lifting
Cause An incapacitated buddy An unconscious buddy - rare
Resolution
OT6 1908/02
What happens if…..?
What happens if…..? Rescues - Free Ascent
Purpose A last resort
Free ascent
May just require finning upwards May require release of weight
system Will result in positive buoyancy
on ascent Exhale continuously
Resolution
OT6 2008/02
What happens if…..?
What happens if…..? Rescues - Surface Support
Experienced divers/surface cover organise assistance on the surface Monitor both rescuer and
casualty Administer oxygen first aid if
required Seek specialist advice of a
Diving medic Arrange urgent recompression
treatment if required
OT6 2108/02
What happens if…..?
What happens if…..? Summary
Resolving potential problems Decompression Illness (DCI) Nitrogen Narcosis Oxygen Toxicity Problems with air
Effecting rescues
Surface support
OT6 2208/02
What happens if…..?
What happens if…..?