Diving Emergencies: Dysbarism and Decompression Sickness

1. Diving Emergencies:Dysbarism and Decompression Sickness John Saucier MD

2. Outline • Conditions related to a water environment • Conditions related to underwater pressure changes • Conditions related to gas mixtures

3. The water environment • Hypothermia • Immersion/submersion • Boating injuries • Entrapment • Bites and stings • Pre-existing medical problems • Seizures, Diabetes, Cardiac Ischemia, Pulmonary disease

4. Conditions related to pressure changes. • Barotrauma/ Dysbarism • Decompression Illness

5. 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

6. 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%

7. 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

8. The 3 Laws of Diving • Boyles Law 1662 • Pascal’s Law 1650 • Dalton’s Law 1801

9. Boyle’s Law

10. 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

11. 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)

12. 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.

13. 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.

14. 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

15. Beaked Whale • 1899 meters • 85 minutes

16. 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

17. Pascal’s Law • The pressure exerted on a portion of a confined non-compressible liquid is experienced by the whole liquid.

18. Problems On Decent • Mask squeeze • Ruptured tympanic membrane • Suit squeeze • Sinus squeeze

19. 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.

20. Problems on Ascent • Dental squeeze • Alternobaric trauma • GI squeeze

21. Pulmonary Overpressure Syndrome • High Intra- alveolar pressure • Pneumomediastinum • Pneumothorax • Pulmonary Hemorrhage • Pulmonary Edema

22. 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

23. AGE: Treatment • Place Supine …not Trendelenberg • Increases ICP • Higher risk of Coronary emboli • 100 % Oxygen • IV Fluids • Hyperbaric Chamber

24. What are the options for gas? • Air • Oxygen alone • Helium/ Oxygen • Mixtures of the above

25. Dalton’s Law • The total pressure of a gas is the sum of the partial pressure of its component gasses.

26. 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

27. 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

28. 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

29. 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

30. Secondary survey • Visible mask squeeze • Visible suit squeeze • Visible TM rupture • Left elbow contusion

31. CXR

32. 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

33. 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

34. 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

35. Ciguatera • Rapid onset GI symptoms • Delayed onset Neuro symptoms (6-48 hours) • Na channel blocker • Headache, numbness, pain, nonfocal • Symptomatic treatment.

36. 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

37. Decompression Sickness (DCS) The Problem is pressurized Nitrogen

38. DCS …Uncommon • 30/ 100,000 dives • Henry’s Law: • Dissolved gas load • Higher pressure higher load • More time more dissolved gas

39. 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

40. 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)

41. 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 ) Clinical Manifestations of DCS

42. DCS types 1 and 2 • DCS Type 1: • Lymphatics • Skin • Musculoskeletal • DCS Type 2: • Other organs • CNS, Pulmonary

43. 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

44. 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

45. 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.

46. Diagnosis • Cardiac ultrasound

47. 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

48. Other Worries • Carbon Monoxide • Lipoid Pneumonitis • Carbon Dioxide Toxicity • Rebreathers

49. 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!!

50. Summary • Diving Injuries: It’s the Pressure !! • The squeezes • POPS • DCS: Delayed and progressive • Treatment: Hyperbaric Chamber • Don’t forget about environment • Preexisting diseases