decompression sickness pathophysiology of diving accidents€¦ · venous dcs bubbles &...

Dr. Wilhelm Welslau

Consultant for Diving and Hyperbaric Medicine

German Diving and Hyperbaric Medical Society

Decompression sickness

- Pathophysiology

of diving accidents

Decompression sickness

- Pathophysiology

of diving accidents

Diving accidents

DCS (Decompression sickness)

after long and deep dives

AGE (Arterial gas embolism)

after rapid ascents to the surface

DCI (Decompression injuries)

© Dr. Wilhelm Welslau – www.taucherarzt.at

DCS

Decompressionsickness


Henry‘s gas law„Gases solve in liquids proportional to pressure“


Henry‘s gas law„Gases solve in liquids proportional to pressure“

pressure elevation

saturation

time at

elevated pressure

saturation

pressure reduction

desaturation

time at

atmospheric pressure

desaturation


Saturationtissues load up

with nitrogen (N2)

air

alveola

CNS

skin

muscles

joints

bones


Desaturationtissues get rid

of nitrogen (N2)

air

alveola

CNS

skin

muscles

joints

bones


SaturationDifferent tissues need different time to load nitrogen (N2)

240min.

120min.

60min.

30min.


DesaturationDifferent tissues need different time get rid of nitrogen (N2)

240min.

120min.

60min.

30min.


Decompression tables & computersCalculation of safe decompression procedures


Bubble formationin venous blood

during & after decompression

blood

blood vessel wall

bubble

nucleus

supersaturated tissue

bubble

air

alveola

CNS

skin

muscles

joints

bones


Bubble growthas long as venous blood is over-saturated with nitrogen (N2)

air

alveola

CNS

skin

muscles

joints

bones


Venous bubbles• may stop local circulation• cause tissue hypoxia

air

alveola

CNS

skin

muscles

joints

bones


Venous bubbles• may stop local circulation• cause tissue hypoxia• cause cellular death

air

alveola

CNS

skin

muscles

joints

bones

Courtesy of UHMS

lung

lungshuntlung

circuit

bodycircuit

brain

spinal cord

kidney

muscle

fatty tissue

PFOshunt

Shuntsallow venous blood• with dissolved nitrogen• with nitrogen bubblesto arterialize


Blood shuntingin the lung

when venous gasbubbles occludelung capillaries

lung artery

lung vein

arterioles

capillariesair

alveola

CNS

skin

muscles

joints

bones


PFOPatent foramen

ovale (~30%)

R-L Shunt possiblewhen right atrium

pressure increases

blood pressure

lung vein

lung arthery

body vein

right

atrium

left

atrium

oval window

(scared over)

body artery

blood pressure

right

chamberleft

chamber

cardial septum


lung

lungshuntlung

circuit

bodycircuit

brain

spinal cord

kidney

muscle

fatty tissue

PFOshunt

Shuntsallow venous blood• with dissolved nitrogen• with nitrogen bubblesto arterialize


Shuntsallow venous blood with nitrogen bubbles to arterialize

From: Z. Dujic in: The future of diving: 100 years of Haldane and beyond (2009)

Bubbles in functional terminal arteries

From: Muth CM & Shank ES. NEJM 2000;342:476-482

• endothelial irritation• inflamation• edema• circulation stop• tissue hypoxia• cellular death

Bubbles inneurological tissues

cause loss of function

according to affected region


Possible symptoms

of nitrogen bubbles

• Discolouration and alteration of the skin• Pain• Tingling• Physical weakness• Numbness

• Paralysis• Breathing difficulties• Vision, hearing or speech disturbance

• Vertigo• Nausea

• Impaired consciousness






AGE

Arterial GasEmbolism


Boyle‘s

gas lawpressure p volume V


Depth

Residual

volume

Total

capacity

Barotrauma

of the

lungs

Risk factors:

• obstructivelung diseases

• bullae• tuberculosis

No risk:• < 2 m depth


Barotrauma of the lungsRisk factor: bullae


Barotrauma

of the

lungs

resulting in:

pneumothorax


alveola

Barotrauma

of the

lungs

resulting in:

mediastinalemphysema


alveola

Barotrauma

of the

lungs

resulting in:

arterial gasembolism


alveola

Arterial gasembolism

• endothelial irritation• inflamation• edema• circulation stop• tissue hypoxia• cellular death


Venous DCS bubbles

& arterialised DCS bubbles

& AGE bubbles

may cause similar problems





• Discolouration and alteration of the skin• Pain• Tingling• Physical weakness• Numbness• Paralysis• Breathing difficulties

• Vision, hearing or speech disturbance• Vertigo• Nausea• Impaired consciousness


Venous DCS bubbles

& arterialised DCS bubbles

& AGE bubbles

may be treated similarly

DCI

AGE Pneumo-thorax

Mediastinalemphysema

Pulmonary barotrauma

Shuntmecha-nisms

Inert gasbubbles

DCS

From: Guideline‚Diving Accident‘www.gtuem.org


DSC + AGE = DCI

DecompressionInjury


Thank youfor your attention

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