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Decompression. DEC/1. May 2007. We will cover. What is Decompression? Causes of Decompression Sickness When and how symptoms occur Treatment. DEC/2. What is Decompression?. Reduction in ambient pressure Occurs when a diver ascends from depth Tissue absorption rates
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Decompression DEC/1 May 2007
We will cover • What is Decompression? • Causes of Decompression Sickness • When and how symptoms occur • Treatment DEC/2
What is Decompression? • Reduction in ambient pressure • Occurs when a diver ascends from depth • Tissue absorption rates • Gas may remain in some tissues longer • Bubble formation • Other names DEC/3
1 Bar 0.8 0.2 2 Bar 1.6 0.4 3 Bar 2.4 0.6 4 Bar 3.2 0.8 5 Bar 4.0 1.0 Absolute Pressure Partial Pressures Depth PN2 PO2 0 10M 20M 30M 40M DEC/4
How does the gas enter the tissues? • Alveoli in the lungs • Bloodstream • Body Tissues • Amount depends on pressure and duration at pressure DEC/5
Saturation Depth Nitrogen Level in Tissues 0 M Low High 10 M 20 M 30 M 40 M Time DEC/6
Bubbling Out A S C E N T Supersaturated Saturated Undersaturated Supersaturation Saturation Level of N2 Diver’s Level of N2 Depth 0 M 10 M 20 M 30 M DEC/7
Precautions • Standard rate of ascent • Decompression Dive Tables DEC/8
Factors Affecting D.C.S. • Alcohol • Smoking • Dehydration • Fatty tissues • Fatigue • Drugs • Medication • Cold water • Heavy exercise DEC/9
When do Symptoms Occur? • Rarely occur immediately • 50% begin less than one hour after surfacing • 90% occur within 6 hours • Small percentage over 24 hours DEC/10
Symptoms of Decompression Sickness • Skin • Discolouration • Itching • Joints • Ache • Pain (sometimes severe) DEC/11
Symptoms of Decompression Sickness • Nervous System • Behaviour • Numbness • Weakness • Balance • Paralysis DEC/11a
Symptoms of Decompression Sickness • Heart and Lungs • Low blood pressure • Shock • Cyanosis • Vision • Double vision DEC/11b
Recompression Chamber Treatment • First Aid DEC/12
First Aid • Lie victim down • Give 100% oxygen • Keep warm and reassure • Treat for shock • CPR if necessary DEC/13
Summary • What is Decompression? • Causes of Decompression Sickness • When and how symptoms occur • Treatment DEC/14
Body tissues absorb gas at : (a) The same rate (b) Different rates Question 1
Body tissues absorb gas at : (a) The same rate (b) Different rates Question 1
The gas which causes decompression sickness is: (a) Oxygen (b) Carbon Dioxide (c) Nitrogen Question 2
The gas which causes decompression sickness is: (a) Oxygen (b) Carbon Dioxide (c) Nitrogen Question 2
What percentage of decompression sickness usually occurs within 1 hour of surfacing ? (a) 35% (b) 50% (c) 70% (d) 90% Question 3
What percentage of decompression sickness usually occurs within 1 hour of surfacing ? (a) 35% (b) 50% (c) 70% (d) 90% Question 3
Symptoms of The Bends include : (a) Skin discolouration (b) Numbness or weakness (c) Imbalance or paralysis (d) Shock (e) All of the above Question 4
Symptoms of The Bends include : (a) Skin discolouration (b) Numbness or weakness (c) Imbalance or paralysis (d) Shock (e) All of the above Question 4
Treatment of decompression sickness is : (a) Oxygen (b) Recompression chamber (c) In-water recompression (d) Strong drink i.e. brandy Question 5
Treatment of decompression sickness is : (a) Oxygen (b) Recompression chamber (c) In-water recompression (d) Strong drink i.e. brandy Question 5