Decompression v1.0 Decompression DEC/1 May 2007. Decompression v1.0 We will cover What is Decompression?What is Decompression? Causes of Decompression.

Decompression v1.0

DecompressionDecompression

DEC/1May 2007

Decompression v1.0

We will coverWe 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

Decompression v1.0

What is Decompression?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

Decompression v1.0

DepthAbsolute Pressure

Partial Pressures

0

10M

20M

30M

40M

1 Bar 0.8 0.2

2 Bar 1.6 0.4

3 Bar 2.4 0.6

4 Bar 3.2 0.8

PN2 PO2

5 Bar 4.0 1.0

DEC/4

Decompression v1.0

How does the gas enter How does the gas enter the tissues?the tissues?

• Alveoli in the lungsAlveoli in the lungs

• BloodstreamBloodstream

• Body TissuesBody Tissues

• Amount depends on pressure and duration Amount depends on pressure and duration at pressureat pressure

DEC/5

Decompression v1.0

SaturationSaturation

DEC/6

Depth

0 M

10 M

20 M

30 M

40 M

Time

Nitrogen Level in Tissues

Low High

Decompression v1.0

SupersaturationSupersaturation

DEC/7

DepthSaturation Level of N2

0 M

10 M

20 M

30 M

Diver’s Level of N2

Supersaturated

Saturated

Undersaturated

ASCENT

Bubbling Out

Decompression v1.0

PrecautionsPrecautions

• Standard rate of ascentStandard rate of ascent

• Decompression Dive TablesDecompression Dive Tables

DEC/8

Decompression v1.0

Factors Affecting D.C.S.Factors Affecting D.C.S.

DEC/9

• AlcoholAlcohol

• SmokingSmoking

• DehydrationDehydration

• Fatty tissuesFatty tissues

• FatigueFatigue

• DrugsDrugs

• MedicationMedication

• Cold waterCold water

• Heavy exerciseHeavy exercise

Decompression v1.0

When do Symptoms Occur?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

Decompression v1.0

Symptoms of Symptoms of Decompression SicknessDecompression Sickness

DEC/11

• SkinSkin

– DiscolourationDiscolouration

– ItchingItching

• JointsJoints

– AcheAche

– Pain (sometimes severe)Pain (sometimes severe)

Decompression v1.0

Symptoms of Symptoms of Decompression SicknessDecompression Sickness

DEC/11a

• Nervous System Nervous System

– BehaviourBehaviour

– NumbnessNumbness

– WeaknessWeakness

– BalanceBalance

– ParalysisParalysis

Decompression v1.0

Symptoms of Symptoms of Decompression SicknessDecompression Sickness

DEC/11b

• Heart and LungsHeart and Lungs

– Low blood pressureLow blood pressure

– ShockShock

– CyanosisCyanosis

• VisionVision

– Double visionDouble vision

Decompression v1.0

TreatmentTreatment

• First AidFirst Aid

DEC/12

• Recompression ChamberRecompression Chamber

Decompression v1.0

First AidFirst 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

Decompression v1.0

SummarySummary

• 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

Decompression v1.0

QuestionsQuestions

Decompression v1.0

Body tissues absorb gas at :Body tissues absorb gas at :

(a) (a) The same rateThe same rate

(b) (b) Different ratesDifferent rates

Question 1

Decompression v1.0

Body tissues absorb gas at :Body tissues absorb gas at :

(a) (a) The same rateThe same rate

(b) (b) Different ratesDifferent rates

Question 1

Decompression v1.0

The gas which causes The gas which causes

decompression sickness is:decompression sickness is:

(a) (a) OxygenOxygen

(b) (b) Carbon DioxideCarbon Dioxide

(c) (c) NitrogenNitrogen

Question 2

Decompression v1.0

The gas which causes The gas which causes

decompression sickness is:decompression sickness is:

(a) (a) OxygenOxygen

(b) (b) Carbon DioxideCarbon Dioxide

(c) (c) NitrogenNitrogen

Question 2

Decompression v1.0

What percentage of decompression sickness What percentage of decompression sickness

usually occurs within 1 hour of surfacing ?usually occurs within 1 hour of surfacing ?

(a) (a) 35%35%

(b) (b) 50%50%

(c) (c) 70%70%

(d)(d) 90%90%

Question 3

Decompression v1.0

What percentage of decompression sickness What percentage of decompression sickness

usually occurs within 1 hour of surfacing ?usually occurs within 1 hour of surfacing ?

(a) (a) 35%35%

(b) (b) 50%50%

(c) (c) 70%70%

(d)(d) 90%90%

Question 3

Decompression v1.0

Symptoms of The Bends include :Symptoms of The Bends include :

(a) (a) Skin discolourationSkin discolouration

(b) (b) Numbness or weaknessNumbness or weakness

(c) (c) Imbalance or paralysisImbalance or paralysis

(d) (d) ShockShock

(e) (e) All of the aboveAll of the above

Question 4

Decompression v1.0

Symptoms of The Bends include :Symptoms of The Bends include :

Question 4

(a) (a) Skin discolourationSkin discolouration

(b) (b) Numbness or weaknessNumbness or weakness

(c) (c) Imbalance or paralysisImbalance or paralysis

(d) (d) ShockShock

(e) (e) All of the aboveAll of the above

Decompression v1.0

Treatment of decompression Treatment of decompression

sickness is :sickness is :

Question 5

(a) (a) OxygenOxygen

(b) (b) Recompression chamberRecompression chamber

(c) (c) In-water recompressionIn-water recompression

(d)(d) Strong drink i.e. brandyStrong drink i.e. brandy

Decompression v1.0

Treatment of decompression Treatment of decompression

sickness is :sickness is :

Question 5

(a) (a) OxygenOxygen

(b) (b) Recompression chamberRecompression chamber

(c) (c) In-water recompressionIn-water recompression

(d)(d) Strong drink i.e. brandyStrong drink i.e. brandy