Diving Emergencies:
Dysbarism and Decompression Sickness
John Saucier MD
Outline
• Conditions related to a water environment
• Conditions related to underwater pressure
changes
• Conditions related to gas mixtures
The water environment
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Hypothermia
Immersion/submersion
Boating injuries
Entrapment
Bites and stings
Pre-existing medical problems
• Seizures, Diabetes, Cardiac Ischemia, Pulmonary
disease
Conditions related to pressure changes.
• Barotrauma/ Dysbarism
• Decompression Illness
Diving Demographics
• 10 million certified divers worldwide
• 90 diving related deaths in US / year
• 1) Drowning
• 2) Arterial Gas Embolism
• Most common Minor Incidents
• Ear Squeeze
• Sinus Squeeze
• Tooth Squeeze ( rare)
• Long Term Morbidity
• Tinnitus
• Hearing Loss
Diving in Maine
• Commercial Diving
• Sea Urchin
• Sea Cucumber
• Sea Scallops
•Insufficient Gas: 14%
•Rough Seas/Strong Current: 10%
•Entrapment: 9%
•Equipment Problems: 8%
•Could Not be Determined: 20%
•Natural Disease: 9%
Diving Emergencies:
It’s all about the pressure
1 ATA increase:
33 feet seawater
1 ATA decrease:
19,000 feet air
23 mm hg / fsw
The 3 Laws of Diving
• Boyles Law 1662
• Pascal’s Law 1650
• Dalton’s Law 1801
Boyle’s Law
Watch out for the first Step!
• Pressure gradients from sea level
• Each 33 feet adds one atmosphere
• The increase is most dramatic in the first
few feet.
• At 2 feet below sea level ~ 200 PSI pushing on
chest:impossible to breath
• Pulmonary Edema/Hemorrhage
Respiratory Physiology
• Hypoxia: Partial pressure of Oxygen (PO2)
is low.
• Hypoxemia: The oxygen saturation (SO2) of
hemoglobin is low.
• Stimulus to breathe:
• Hypoxia (small)
• Hypercarbia (big)
15 year old near drowning victim
• Patient and friend were competing: who
could hold their breath the longest.
• They both dove to the bottom of a 12 foot
pool
• After 2 minutes they both
headed to the surface.
• Our patient blacks out
on the way to the surface.
Why did our patient blackout?
• Hyperventilation before diving reducing CO2
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drive.
Oxygen presented to tissue was high at 12 feet
O2 high CO2 low: Urge to breath low
Less pressure near surface: less oxygen at tissues
Shallow water black out
• Latent hypoxia.
Breath-hold diving with and without weights
• Static Apnea records
• Men : 11m 25 s
• Women: 8 m 23 s
• Dynamic Apnea with fins
• Men : 273 meters
• Women: 225 meters
•King Penguin: 353 meters
Beaked Whale
• 1899 meters
• 85 minutes
Dysbarism
Direct Volume /Pressure Effects
• On Descent:
• Volume in airspaces decreases
• Negative pressure damages lining of air spaces
• On Ascent:
• Volume in airspaces increases
• Positive pressure can blow out non confined airspaces
Pascal’s Law
• The pressure exerted on a portion of a
confined non-compressible liquid is
experienced by the whole liquid.
Problems On Decent
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Mask squeeze
Ruptured tympanic membrane
Suit squeeze
Sinus squeeze
SCUBA
• Provide gas at ambient pressure
• Fill pressure 6 ATA
• Up to 150 fsw
• You are pressurized to 6 ATA
• You need to give off that pressure gradually as
you surface to 1 ATA.
Problems on Ascent
• Dental squeeze
• Alternobaric trauma
• GI squeeze
Pulmonary Overpressure Syndrome
• High Intra- alveolar pressure
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Pneumomediastinum
Pneumothorax
Pulmonary Hemorrhage
Pulmonary Edema
POPS/Arterial Gas Embolism
• Sudden intraarteriolar pressure(>80 mm)
• Air forced into pulmonary capillaries
• Air bubble enlarges in L atrium/ventricle
• Sudden hypotension (>65 cc air)
• Sudden stroke symptoms
• Cardiac arrest
AGE: Treatment
• Place Supine …not Trendelenberg
• Increases ICP
• Higher risk of Coronary emboli
• 100 % Oxygen
• IV Fluids
• Hyperbaric Chamber
What are the options for gas?
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Air
Oxygen alone
Helium/ Oxygen
Mixtures of the above
Dalton’s Law
• The total pressure of a gas is the sum of the
partial pressure of its component gasses.
Hold on! Why use Nitrogen at all?
• Nitrogen Narcosis:
• Rapture of the Deep
• CNS toxicity at depths > 100 fsw
– Martini’s Law: 50 fsw = 1 martini
• But: Oxygen Toxicity = Convulsions
• Air (21% O2) at 218 fsw: PO2: 1050 mm
• Nitrox ( 32% O2) at 132 fsw: PO2: 900 mm
• 100 % O2 at 20 fsw : PO2: 760 mm
How about Helium??
• Heliox mix (10% O2 /40 % N2/50% He)
• Safer for deeper dives
• High Pressure Nervous Syndrome
• > 600 fsw
• Seizure, coma, tremor, vomiting
CC: Chest Pain/ Dyspnea
• 35 yo WM
• Med-control: Arriving from the jetport
• Chest pain/Dyspnea
• NTG / Oxygen no relief
• Morphine: some relief requests more
Trauma Room
• Athletic appearing, well tanned 34 yo wm
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• looks familiar:
Very dyspneic, c/o chest pain
Appears confused
Pain in left arm with tingling
BP 110/60, P: 110, RR: 24, Temp wnl
O2 sat 92% on 15 l NRB
• “Crunch” heard with heart beat midsternum
Secondary survey
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Visible mask squeeze
Visible suit squeeze
Visible TM rupture
Left elbow contusion
CXR
15 minutes
• VS stable continues hypoxemic (O2 sat
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93%)
Morphine helps a little with the pain.
O2 helps with the dyspnea
Complains of left upper arm pain when BP
cuff deflates
Complains of continued tingling in Left
hand and slight vertigo
Additional history from wife
• On vacation in Jamaica
• Flew out this afternoon
• Was sick last evening after eating Grouper for
supper…but GI symptoms rapidly improved
• Complained of CP, dyspnea, and tingling in
arm mid-flight to Newark
• Improved in Newark worsened on flight to
PWM
Differential
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GERD
ACS
CVA
Thoracic Aneurysm
TTP
Ruptured esophagus
PE
• NEJM: increased risk over 5-7,000 km flight.
• 4.8 cases /million over 10,000 KM
• 0.01 cases /million < 5,000 KM
Ciguatera
• Rapid onset GI symptoms
• Delayed onset Neuro symptoms (6-48
hours)
• Na channel blocker
• Headache, numbness, pain, nonfocal
• Symptomatic treatment.
More history from wife
Wife
• Several dives over last week
• Last dive on the morning before the flight
• Some chest and neck pain on surfacing.
• Dove to ~ 30 feet for 30 minutes
• Was going to be late for shuttle so surfaced
quickly
Decompression Sickness (DCS)
The Problem is
pressurized Nitrogen
DCS …Uncommon
• 30/ 100,000 dives
• Henry’s Law:
• Dissolved gas load
• Higher pressure higher load
• More time more dissolved gas
Decompression Sickness (DCS)
Nitrogen Solubility in Tissue
• Dalton’s Law: pT = pA + pB + pC
• Most Recreational Divers use Air
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79% N ….21% O2
Solute load: Pressure, Time, Solubility
Exceeding No Decompression Limit
Too Rapid ascent:
• Nitrogen bubbles form in
venous system
The Bad things about Nitrogen bubbles
• Nitrogen is inert i.e. not
metabolized
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Stretch and disrupt tissues
Mechanical Blockage
Immune Reaction
1/3 people with PFO’s : ? Risk for AGE
Onset may not be immediate
• Most < 6 hours
• May progress (Little bubbles make big bubbles)
Clinical Manifestations of DCS
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Muscular Skeletal (Bends) 70 %
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Shoulders/ elbows
Niggles: isolated joints
• Neurologic 20 %
• Spinal Cord
• Cauda Equina
• Skin: Urticaria (creeps), local
swelling, itching
• Pulmonary (Chokes)
• Like PE ( venous gas
embolism)
• “Mill Wheel” Murmur
• Vasomotor:
• Decompressive shock (rare)
• Inner Ear (Staggers )
DCS types 1 and 2
• DCS Type 1:
• Lymphatics
• Skin
• Musculoskeletal
• DCS Type 2:
• Other organs
• CNS, Pulmonary
Diagnosis DCS
• History , History , History!!
• Equipment used
• Dive watch, gas mix, rebreather
• Total time, intervals, depth for last 72 hours
• Decompression stops
• In water air recompression
• Site : water temp, altitude
• Activity during dive and afterward
• When did symptoms occur
• Flight within 24 hours of dive
Dive History Algorithm
• Determine when symptoms occurred
• During descent: barotrauma to the middle ear,
inner ear, external ear, face or sinuses
• At depth: nitrogen narcosis, hypothermia,
contaminated gas, oxygen toxicity
• During Ascent:
• Rapid: ABV, POPS, AGE, pneumothorax,
pneumomediastinum, pulmonary hemorrhage,
barodentalgia, GI barotrauma
• Long/deep/near limit: DCS I, DCS II
Our Patient
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Develops POPS at dive site
Small pneumomediastinum
Mask squeeze, ear squeeze
Decompresses in flight to 8000 ft
• Improves on landing then worsens on 2nd flight
• Progressive DCS
• Pulmonary and the bends (improves slightly with BP
cuff)
• ? Arterial Gas Emboli
• Rx: 100 % O2, fluids, hyperbaric chamber.
Diagnosis
• Cardiac ultrasound
Treatment
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ABC’s
100 % O2
Check for PTX pre intubation and pre chamber
Steroids for Neuro symptoms: unproven
Aspirin : no harm
Lidocaine: ? Neuro protective
The sooner in the chamber the better.
• Still effective if delayed
Other Worries
• Carbon Monoxide
• Lipoid Pneumonitis
• Carbon Dioxide Toxicity
• Rebreathers
Prevention
• Don’t Dive with URI
• Asthma: Caution
• Air Trapping, Triggered Attacks
• ? Screen for PFO’s..No !
• Stick to: No Decompression limits
• Avoid Antihistamines
• Sudafed, clophenarimine OK
• No dive until 4 weeks post DCS
• Pregnancy …No!!
• Seizures …..No!!
Summary
• Diving Injuries: It’s the Pressure !!
• The squeezes
• POPS
• DCS: Delayed and progressive
• Treatment: Hyperbaric Chamber
• Don’t forget about environment
• Preexisting diseases
Resources
• www.diversalertnetwork.org
• Network of New England Hyperbaric
Centers