1. Decompression v1.0 Decompression DEC/1 May 2007

2. Decompression v1.0 We will cover What is Decompression?What is Decompression? Causes of Decompression SicknessCauses of Decompression Sickness When and how symptoms occurWhen and how symptoms occur TreatmentTreatment DEC/2

3. Decompression v1.0 What is Decompression? Reduction in ambient pressureReduction in ambient pressure Occurs when a diver ascends from depthOccurs when a diver ascends from depth Tissue absorption ratesTissue absorption rates Gas may remain in some tissues longerGas may remain in some tissues longer Bubble formationBubble formation Other namesOther names DEC/3

4. Decompression v1.0 Depth Absolute Pressure Partial Pressures 0 10M 20M 30M 40M 1 Bar0.80.2 2 Bar1.60.4 3 Bar2.40.6 4 Bar3.20.8 PN 2 PO 2 5 Bar4.01.0 DEC/4

5. Decompression v1.0 How does the gas enter the tissues? Alveoli in the lungsAlveoli in the lungs BloodstreamBloodstream Body TissuesBody Tissues Amount depends on pressure and duration at pressureAmount depends on pressure and duration at pressure DEC/5

6. Decompression v1.0 Saturation DEC/6 Depth 0 M 10 M 20 M 30 M 40 M Time Nitrogen Level in Tissues LowHigh

7. Decompression v1.0 Supersaturation DEC/7 Depth Saturation Level of N 2 0 M 10 M 20 M 30 M Divers Level of N 2 SupersaturatedSaturated Undersaturated ASCENTASCENT Bubbling Out

8. Decompression v1.0 Precautions Standard rate of ascentStandard rate of ascent Decompression Dive TablesDecompression Dive Tables DEC/8

9. Decompression v1.0 Factors Affecting D.C.S. DEC/9 AlcoholAlcohol SmokingSmoking DehydrationDehydration Fatty tissuesFatty tissues FatigueFatigue DrugsDrugs MedicationMedication Cold waterCold water Heavy exerciseHeavy exercise

10. Decompression v1.0 When do Symptoms Occur? DEC/10 Rarely occur immediatelyRarely occur immediately 50% begin less than one hour after surfacing50% begin less than one hour after surfacing 90% occur within 6 hours90% occur within 6 hours Small percentage over 24 hoursSmall percentage over 24 hours

11. Decompression v1.0 Symptoms of Decompression Sickness DEC/11 SkinSkin –Discolouration –Itching JointsJoints –Ache –Pain (sometimes severe)

12. Decompression v1.0 Symptoms of Decompression Sickness DEC/11a Nervous SystemNervous System –Behaviour –Numbness –Weakness –Balance –Paralysis

13. Decompression v1.0 Symptoms of Decompression Sickness DEC/11b Heart and LungsHeart and Lungs –Low blood pressure –Shock –Cyanosis VisionVision –Double vision

14. Decompression v1.0 Treatment First AidFirst Aid DEC/12 Recompression ChamberRecompression Chamber

15. Decompression v1.0 First Aid Lie victim downLie victim down Give 100% oxygenGive 100% oxygen Keep warm and reassureKeep warm and reassure Treat for shockTreat for shock CPR if necessaryCPR if necessary DEC/13

16. Decompression v1.0 Summary What is Decompression?What is Decompression? Causes of Decompression SicknessCauses of Decompression Sickness When and how symptoms occurWhen and how symptoms occur TreatmentTreatment DEC/14

17. Decompression v1.0 Questions

18. Body tissues absorb gas at : (a) The same rate (b) Different rates Question 1

19. Decompression v1.0 Body tissues absorb gas at : (a) The same rate (b) Different rates Question 1

20. Decompression v1.0 The gas which causes decompression sickness is: (a) Oxygen (b) Carbon Dioxide (c) Nitrogen Question 2

21. Decompression v1.0 The gas which causes decompression sickness is: (a) Oxygen (b) Carbon Dioxide (c) Nitrogen Question 2

22. Decompression v1.0 What percentage of decompression sickness usually occurs within 1 hour of surfacing ? (a) 35% (b) 50% (c) 70% (d)90% Question 3

23. Decompression v1.0 What percentage of decompression sickness usually occurs within 1 hour of surfacing ? (a) 35% (b) 50% (c) 70% (d)90% Question 3

24. Decompression v1.0 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

25. Decompression v1.0 Symptoms of The Bends include : Question 4 (a) Skin discolouration (b) Numbness or weakness (c) Imbalance or paralysis (d) Shock (e) All of the above

26. Decompression v1.0 Treatment of decompression sickness is : Question 5 (a) Oxygen (b) Recompression chamber (c) In-water recompression (d)Strong drink i.e. brandy

27. Decompression v1.0 Treatment of decompression sickness is : Question 5 (a) Oxygen (b) Recompression chamber (c) In-water recompression (d)Strong drink i.e. brandy