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
- release of bubbles of inert gas into the blood and tissues with mechanical, embolic and biochemical effects
- hypoxia induced vasoconstriction -> increased pulmonary capillary pressure, alveolar fluid transudation, decreased alveolar fluid clearance
- endothelial activation -> capillary leak
- increased leukocyte adhesion, inflammatory response and reperfusion injury
- vessel obstruction
- tissue distortion causing pain
- 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.
Critical Care
Compendium
Leave a Reply