Diving Medicine: An Overview

1. Diving Medicine: An Overview MAJ James Lynch, MD, MS U.S. Army Diving Medical Officer

2. Agenda Barotrauma Decompression Sickness Flying After Diving Rebreathers

3. Barotrauma - Anatomy • Eustachian Tube • Connects middle ear with nasopharynx • Allows equalization of middle ear with ambient pressure • Will “lock” closed with excessive pressure in nasopharnyx • Most divers have to actively equalize on descent • Equalization will occur passively on ascent

4. Barotrauma - Anatomy • Four major sinus groups • Maxillary • Frontal • Sphenoid (pain in occipital region) • Ethmoid air cells • Function • Lighten skull • Provide mucous for nasal cavity

6. Barotrauma Boyle’s Law: At constant Temperature, Volume varies inversely proportional to Pressure

7. Barotrauma If rigid gas filled spaces are properly vented, barotrauma will not occur • Elements needed to produce barotrauma • Membrane (vascular) lined space • Ambient pressure change • Rigid walls • Gas filled space • Enclosed space

8. Barotrauma – External • Predisposing factors • Wax impaction • Tight wet suit hood • Ear plugs • Otitisexterna

9. Barotrauma - External • Signs and Symptoms • Ear pain on descent • Hearing loss until pressure is equalized • Hemorrhage in external canal • Treatment • Stop descent • Relieve obstruction • Treat OE if present

10. Barotrauma - Middle • Most common type of pressure-related injury • More common in inexperienced divers • Ineffective valsalva • Etiology is a blocked Eustachian Tube • Upper respiratory infection • Large adenoid tonsils, nasal septal deviation

11. Barotrauma - Middle • Pathogenesis • Relative vacuum forms in middle ear resulting in capillary leakage. • TM rupture will occur between 100-500 mmHg of differential pressure • Signs and symptoms • Fullness or pain • Mild transient conductive hearing loss • TM perforation in severe cases • May have blood in face mask • Transient vertigo and/or tinnitus

13. Barotrauma - Middle Recurrent perforation is common if diving is resumed too soon after severe ear squeeze • Treatment • Restrict diving until resolved • Mild (0-1) 8 to 72 hours • Moderate (2-3) 1 to 8 days • Severe (4-5) may take up to six weeks (for perforations)

14. Barotrauma - Middle • Treatment (continued) • Decongestants • Intranasal steroid • Systemic Steroids – if mod-severe (1mg/kg x 5 days + taper) • Antibiotics if perforated • Avoid topicals if perforated unless recommended by ENT (use otic suspension not solution)

15. Barotrauma - Middle • Prevention • Avoid diving with Eustachian Tube Dysfunction • Topical and systemic decongestants • Stay ahead of pressure changes

16. Barotrauma - Inner • May result in permanent damage to cochlea or vestibular system • Occurs most commonly on descent • Generally starts as middle ear squeeze • Forceful Valsalva causes injury to inner ear • Can be caused by implosion or explosion

18. Barotrauma - Inner } Results in perilymph fistula • Sites of injury • Oval window • Round window

19. Barotrauma - Inner • Signs and symptoms • Vertigo (persistent) • Tinnitus (often described as “roaring”) • Nystagmus with positional testing • Bubbling sensation in ear • Neurosensory hearing loss • Otoscopic findings of middle ear barotrauma

20. Barotrauma - Inner • Treatment • R/O AGE and DCS (covered later) • Strict bed rest • Avoid straining • Consider sedation • ENT referral, early in course if possible • Surgical exploration is often needed

21. Barotrauma – Inner DDX • Caloric Vertigo • Transient; common on descent (thermocline) • Caused by differing water temperatures in external canals or TM rupture allowing water to enter middle ear • Alternobaric Vertigo • Transient; common on ascent • Caused by rapid pressure change transmitted into inner ear

22. Barotrauma - Sinus • Predisposing factors • Infection or Allergy • Anatomic variations • Signs and Symptoms • Pain in sinus area • Dental pain with maxillary sinus involvement • Blood in face mask • Tenderness on sinus percussion

23. Barotrauma - Sinus • Treatment • No diving • Decongestants • Observe for infection • May require surgical correction • Anatomical defects • Polyps • Mucus retention cysts

24. Barotrauma - Teeth • Barodontalgia • Occurs on ascent or descent • Predisposing factors • Dental disease • Failed dental restorations • Recent dental work

25. Barotrauma - Teeth • Signs and Symptoms • Tooth pain • Maxillary sinus pain • Exploding or imploding tooth • Treatment • Pain relief • Dental referral

27. Barotrauma - Face mask • Predisposing factors • Failure to clear mask on descent • Diving with goggles • Signs and Symptoms • Periorbital pain • Periorbitalpetechiae and swelling • Treatment - observe

30. Pulmonary Barotrauma • Pulmonary Over-inflation Syndrome (POIS) • Expansion of gas trapped in lung during ascent (decreasing ambient pressure) with rupture of lung tissue • Causes: • Breath-holding during ascent • Inhaling while pushing purge button • Rapid uncontrolled ascent (blow-up) • Air trapped in lung

31. Pulmonary Barotrauma Air trapped in lung due to: • Airway obstruction as in asthma • Thick secretions • Lung granulomas (sarcoidosis) • Cysts and blebs • spontaneous pneumothorax

32. Pulmonary Barotrauma Clinical presentation • Initial rupture of lung tissue with release of gas • Gas may remain in lung tissue • migrate to pulmonary circulation • move to the pleural space • dissect along the bronchial tree into the mediastinumand subcutaneous tissues

33. Pulmonary Barotrauma Conditions resulting from POIS • Arterial gas embolism • Pneumothorax • Mediastinal emphysema • Subcutaneous emphysema • Pneumopericardium

34. Surface 3 FSW 96 FSW 99 FSW Pulmonary Barotrauma

35. Pulmonary Barotrauma Arterial Gas Embolism • Alveolar rupture with concomitant venous or capillary rupture • Air traverses pulmonary vein to left heart • Emboli are pumped out to the systemic circulation and distributed to all organs

36. Arterial Gas Embolism (AGE)

38. Pulmonary Barotrauma Arterial Gas Embolism • CNS and Heart most susceptible to injury • CVA sxs commonly caused by emboli to brain • Emboli to coronary arteries may cause myocardial ischemia or infarction • Usually present within the first ten minutes of a surface interval

39. Pulmonary Barotrauma AGE– Presenting Signs and Symptoms • Stupor or confusion • Coma with or without seizures • Unilateral motor deficits • Visual disturbances • Vertigo • Sensory abnormalities

40. Pulmonary Barotrauma AGE – Treatment • A, B, C’s ; check vital signs • Keep patient warm • Neutral position, not Trendelenberg • 100% O2 by facemask or ET tube • IV Fluids • Serial Neurological exams • Immediate recompression upon diagnosis • Cabin pressure below 1000 feet

41. Pulmonary Barotrauma Pneumothorax - Simple Symptoms • Chest pain (lateral or apical) • Cough • Shortness of breath Signs • Decreased breath sounds • Typical CXR findings

42. Simple Pneumothorax

43. Pulmonary Barotrauma Pneumothorax – Simple Treatment • Needle thoracostomy, Chest tube • Observe if pneumo is small Resumption of diving • Spontaneous - unsafe for diving • Traumatic - may return to diving after resolution with proper evaluation

44. Pulmonary Barotrauma Pneumothorax - Tension Symptoms • Chest pain and cough • Increasing SOB and tachypnea Signs • Asymmetric chest wall movement • Tracheal deviation • JVD • Rapid pulse with decreasing pulse pressure • Mediastinal shift on CXR

45. Tension Pneumothorax

46. Pulmonary Barotrauma Pneumothorax - Tension Treatment • Immediate needle decompression • Chest tube

47. Pulmonary Barotrauma Mediastinal Emphysema Symptoms • Substernal chest pain or burning • May be worsened by inspiration • Intensity of pain may vary greatly Signs • Mediastinal air on CXR • May hear crepitus - Hamman’s sign

48. MediastinalEmphysema

49. Pulmonary Barotrauma Subcutaneous Emphysema Symptoms • Substernal chest pain or burning • May be worsened by inspiration • Feeling of “Rice Krispies” under skin • Subjective voice changes Signs • Crepitus in neck and supraclavicular area • Audible voice changes

50. Subcutaneous Emphysema