Decompression Sickness

OVERVIEW

Decompression sickness, is a form of decompression illness, where a reduction in ambient pressure (‘decompression’) leads to de no intravascular and extravascular bubble formation with pathological consequences

  • decompression sickness = ‘small bubbles’
  • arterial gas embolism (AGE) is the other form of decompression illness, characterised by ‘big bubbles’ that are introduced into the circulation following alveolar rupture during decompression
  • the altitude threshold for DCS is generally 18,000 ft
  • most diving is done @ 2-4 atmospheres

PATHOPHYSIOLOGY

Typically affects

  • divers
  • caisson workers
  • aviators
  • astronauts

Mechanism

  1. release of bubbles of inert gas into the blood and tissues with mechanical, embolic and biochemical effects
  2. hypoxia induced vasoconstriction -> increased pulmonary capillary pressure, alveolar fluid transudation, decreased alveolar fluid clearance
  3. endothelial activation -> capillary leak
  4. increased leukocyte adhesion, inflammatory response and reperfusion injury
  5. vessel obstruction
  6. tissue distortion causing pain
  7. embolisation (25% of people have PFO so can embolise to the brain)

CLINICAL FEATURES

  • cough -> respiratory failure

Type I Decompression Sickness

  • musculoskeletal pain (limbs, shoulders, elbows, hips, knees)
  • anorexia
  • malaise
  • fatigue
  • orange appearance of skin from local lymphatic obstruction
  • pruritis (ears, trunk, wrists, hands -> trunk)
  • cyanosis

Type II Decompression Sickness

  • substernal discomfort
  • pleuritic chest pain
  • tachypnoea
  • non-productive cough
  • right heart strain
  • cardiovascular collapse
  • paraesthesia
  • full paralysis
  • convulsions
  • cerebellar signs

MANAGEMENT

Prevention

  • no flying for 24 hours after a dive

Proven Benefit

  • FiO2 1.0 (enhanced de-nitrogenation)
  • CPR
  • isotonic fluid resuscitation — dehydration due to capillary leak, cold diuresis and immersion diuresis
  • hyperbaric therapy (even very late) — 2-3 atm, repeated until no further benefil
  • intubate and fill cuff with saline

Unproven Benefit

  • Trendelenburg position (not longer than 30min c/o cerebral oedema)
  • avoid glucose IV
  • avoid hypertension and anxiety
  • corticosteroids
  • benzodiazepine for seizures
  • aspirin

Questionable Benefit

  • Ca2+ blockers
  • lignocaine 1mg/kg
  • NSAIDS, heparin, prostaglandin
  • induced hypothermia
  • cerebral venoarterial perfusion

Proven Detrimental

  • recompression while submerged
  • alcohol
  • analgesics
  • delayed transport to hyperbaric center
  • additional hypobaric exposures

Transfer by helicopter at 300m, on land or pressurize to sea-level


References and Links

  • Bennett MH, Lehm JP, Mitchell SJ, Wasiak J. Recompression and adjunctive therapy for decompression illness. Cochrane Database Syst Rev. 2012 May 16;5:CD005277. PMID: 22592704.
  • Lynch JH, Bove AA. Diving medicine: a review of current evidence. J Spec Oper Med. 2009 Fall;9(4):72-9. PMID: 20112651.
  • McMullin AM. Scuba diving: What you and your patients need to know. Cleve Clin J Med. 2006 Aug;73(8):711-2, 714, 716 passim. PMID: 16913196.
  • Sebel PS. 20,000 leagues under the sea. Anesth Analg. 2010 Sep;111(3):589-90. doi: 10.1213/ANE.0b013e3181eb64de. PubMed PMID: 20733161.
  • Tetzlaff K, Shank ES, Muth CM. Evaluation and management of decompression illness–an intensivist’s perspective. Intensive Care Med. 2003 Dec;29(12):2128-36. PMID: 14600806.
  • Vann RD, Butler FK, Mitchell SJ, Moon RE. Decompression illness. Lancet. 2011 Jan 8;377(9760):153-64. doi: 10.1016/S0140-6736(10)61085-9. Review. PubMed PMID: 21215883.

CCC 700 6

Critical Care

Compendium

Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also the Innovation Lead for the Australian Centre for Health Innovation at Alfred Health and Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of two amazing children.

On Twitter, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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