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

• 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 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

• 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• 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?

• 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• 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

• Visible mask squeeze

• Visible suit squeeze

• Visible TM rupture

• Left elbow contusion

CXR

15 minutes

• VS stable continues hypoxemic (O2 sat 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

• 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

• 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

Wife

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• 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

• 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

• Muscular Skeletal (Bends) 70 %• 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

• 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

• 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