Diving Emergencies: Dysbarism and Decompression Sickness John Saucier MD

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  • Diving Emergencies: Dysbarism and Decompression Sickness John Saucier MD
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  • Outline Conditions related to a water environment Conditions related to underwater pressure changes Conditions related to gas mixtures
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  • The water environment Hypothermia Immersion/submersion Boating injuries Entrapment Bites and stings Pre-existing medical problems Seizures, Diabetes, Cardiac Ischemia, Pulmonary disease
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  • Conditions related to pressure changes. Barotrauma/ Dysbarism Decompression Illness
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  • 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
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  • 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%
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  • Diving Emergencies: Its all about the pressure 1 ATA increase: 33 feet seawater 1 ATA decrease: 19,000 feet air 23 mm hg / fsw
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  • The 3 Laws of Diving Boyles Law 1662 Pascals Law 1650 Daltons Law 1801
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  • Boyles Law
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  • 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
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  • Respiratory Physiology Hypoxia: Partial pressure of Oxygen (PO 2 ) is low. Hypoxemia: The oxygen saturation (SO 2 ) of hemoglobin is low. Stimulus to breathe: Hypoxia (small) Hypercarbia (big)
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  • 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.
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  • 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.
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  • 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
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  • Beaked Whale 1899 meters 85 minutes
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  • 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
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  • Pascals Law The pressure exerted on a portion of a confined non-compressible liquid is experienced by the whole liquid.
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  • Problems On Decent Mask squeeze Ruptured tympanic membrane Suit squeeze Sinus squeeze
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  • 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.
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  • Problems on Ascent Dental squeeze Alternobaric trauma GI squeeze
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  • Pulmonary Overpressure Syndrome High Intra- alveolar pressure Pneumomediastinum Pneumothorax Pulmonary Hemorrhage Pulmonary Edema
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  • 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
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  • AGE: Treatment Place Supine not Trendelenberg Increases ICP Higher risk of Coronary emboli 100 % Oxygen IV Fluids Hyperbaric Chamber
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  • What are the options for gas? Air Oxygen alone Helium/ Oxygen Mixtures of the above
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  • Daltons Law The total pressure of a gas is the sum of the partial pressure of its component gasses.
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  • Hold on! Why use Nitrogen at all? Nitrogen Narcosis: Rapture of the Deep CNS toxicity at depths > 100 fsw Martinis Law: 50 fsw = 1 martini But: Oxygen Toxicity = Convulsions Air (21% O 2 ) at 218 fsw: PO2: 1050 mm Nitrox ( 32% O 2 ) at 132 fsw: PO2: 900 mm 100 % O 2 at 20 fsw : PO2: 760 mm
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  • How about Helium?? Heliox mix (10% O 2 /40 % N 2 /50% He) Safer for deeper dives High Pressure Nervous Syndrome > 600 fsw Seizure, coma, tremor, vomiting
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  • 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
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  • 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
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  • Secondary survey Visible mask squeeze Visible suit squeeze Visible TM rupture Left elbow contusion
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  • CXR
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  • 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
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  • Additional history from wife On vacation in Jamaica Flew out this afternoon Was sick last evening after eating Grouper for supperbut GI symptoms rapidly improved Complained of CP, dyspnea, and tingling in arm mid-flight to Newark Improved in Newark worsened on flight to PWM
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  • 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
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  • Ciguatera Rapid onset GI symptoms Delayed onset Neuro symptoms (6-48 hours) Na channel blocker Headache, numbness, pain, nonfocal Symptomatic treatment.
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  • 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
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  • Decompression Sickness (DCS) The Problem is pressurized Nitrogen
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  • DCS Uncommon 30/ 100,000 dives Henrys Law: Dissolved gas load Higher pressure higher load More time more dissolved gas
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  • Decompression Sickness (DCS) Nitrogen Solubility in Tissue Daltons 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
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  • 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 PFOs : ? Risk for AGE Onset may not be immediate Most < 6 hours May progress (Little bubbles make big bubbles)
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  • 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 )
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  • DCS types 1 and 2 DCS Type 1: Lymphatics Skin Musculoskeletal DCS Type 2: Other organs CNS, Pulmonary
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  • 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
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  • 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
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  • 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 2 nd flight Progressive DCS Pulmonary and the bends (improves slightly with BP cuff) ? Arterial Gas Emboli Rx: 100 % O2, fluids, hyperbaric chamber.
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  • Diagnosis Cardiac ultrasound
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  • Treatment ABCs 100 % O2 Check for PTX pre intubation and pre chamber Steroids for Neuro symptoms: u