Decompression illness
Meaning of decompression illness: For the purposes of this Statement of Principles, decompression illness: (a) means an injury caused by the formation of bubbles of nitrogen and other inert gases within tissues and blood vessels, as a result of a reduction in the pressure surrounding the person, and; (b) includes: (i) arterial gas embolism not due to pulmonary barotrauma; and (ii) decompression sickness; and (c) excludes: (i) altitude illness; (ii) arterial gas embolism due to pulmonary barotrauma; (iii) barotrauma; (iv) ebullism; (v) osteonecrosis; (vi) high pressure neurological syndrome/inert gas narcosis; and (vii) cerebrovascular accident not due to an arterial gas embolism.
Reasonable Hypothesis (RH) — Statement of Principles No. 23 of 2023
At least one of the following factors must as a minimum exist before it can be said that a reasonable hypothesis has been raised connecting decompression illness or death from decompression illness with the circumstances of a person's relevant service:
- (1)experiencing a substantial episode of decompression whilst: (a) surfacing from an underwater dive that required decompression stops according to relevant diving decompression tables; (b) flying at >5,486 metres (>18,000 feet) altitude in an unpressurised aircraft, high altitude balloon or high altitude parachute; (c) flying, parachuting or ballooning within the no flying time interval after underwater diving, where the relevant diving decompression tables recommended a no flying time interval; (d) ascending to the surface from a submerged submarine or vessel at >90 metres seawater (296 feet seawater) with a normal internal pressure, or ascending to the surface from a submerged submarine or vessel at increased internal pressure; (e) suffering loss of cabin pressure in an aircraft flying at >5,486 metres (>18,000 feet) altitude or in a spacecraft above the von Karman line; (f) returning to surface air pressure after working in a hyperbaric compressed air environment including working in a tunnel, caisson or tunnel boring machine; (g) transferring from a higher pressure to a lower pressure environment whilst in space including donning an extravehicular space suit; (h) being in a hypobaric chamber; (i) returning to surface air pressure after being in a hyperbaric chamber including hyperbaric oxygen therapy chambers; or (j) returning to surface air pressure after being within a pressure vessel during hyperbaric pressure testing including aircraft cabin excessive leak testing, submarine pressure testing, and nuclear power station pressure testing; within 7 days before the clinical onset of decompression illness;
Note: Substantial episodes of decompression involves a rapid substantial reduction in the ambient pressure exerted by the envelope of gas or water surrounding the person where the person had been at higher pressure for a substantial period.
Note: Underwater diving includes breath hold diving, yo-yo or bounce diving, umbilical/hookah/hard hat diving, SCUBA diving, rebreather diving, and saturation diving. This underwater diving does not including diving within normobaric diving bells or armoured suits.
Note: A decompression stop is a procedure where the diver is required to stop at a specified depth for a specified time interval to allow the inert gas to clear from their body.
- (2)inability to obtain appropriate clinical management for decompression illness;
Aggravation-only factors: the factors in subsection 9(2) apply only to material contribution to, or aggravation of, the condition where it was suffered or contracted before or during (but did not arise out of) the person’s relevant service.
Balance of Probabilities (BoP) — Statement of Principles No. 24 of 2023
2 factors
At least one of the following factors must exist before it can be said that, on the balance of probabilities, decompression illness or death from decompression illness is connected with the circumstances of a person's relevant service:
- (1)experiencing a substantial episode of decompression whilst: (a) surfacing from an underwater dive that required decompression stops according to relevant diving decompression tables; (b) flying at >5,486 metres (>18,000 feet) altitude in an unpressurised aircraft, high altitude balloon or high altitude parachute; (c) flying, parachuting or ballooning within the no flying time interval after underwater diving, where the relevant diving decompression tables recommended a no flying time interval; (d) ascending to the surface from a submerged submarine or vessel at >90 metres seawater (296 feet seawater) with a normal internal pressure, or ascending to the surface from a submerged submarine or vessel at increased internal pressure; Decompression Illness (Balance of Probabilities) (No. BP of 2023) (e) suffering loss of cabin pressure in an aircraft flying at >5,486 metres (>18,000 feet) altitude or in a spacecraft above the von Karman line; (f) returning to surface air pressure after working in a hyperbaric compressed air environment including working in a tunnel, caisson or tunnel boring machine; (g) transferring from a higher pressure to a lower pressure environment whilst in space including donning an extravehicular space suit; (h) being in a hypobaric chamber; (i) returning to surface air pressure after being in a hyperbaric chamber including hyperbaric oxygen therapy chambers; or (j) returning to surface air pressure after being within a pressure vessel during hyperbaric pressure testing including aircraft cabin excessive leak testing, submarine pressure testing, and nuclear power station pressure testing; within 7 days before the clinical onset of decompression illness;
Note: Substantial episodes of decompression involves a rapid substantial reduction in the ambient pressure exerted by the envelope of gas or water surrounding the person where the person had been at higher pressure for a substantial period.
Note: Underwater diving includes breath hold diving, yo-yo or bounce diving, umbilical/hookah/hard hat diving, SCUBA diving, rebreather diving, and saturation diving. This underwater diving does not including diving within normobaric diving bells or armoured suits.
Note: A decompression stop is a procedure where the diver is required to stop at a specified depth for a specified time interval to allow the inert gas to clear from their body.
- (2)inability to obtain appropriate clinical management for decompression illness;
Aggravation-only factors: the factors in subsection 9(2) apply only to material contribution to, or aggravation of, the condition where it was suffered or contracted before or during (but did not arise out of) the person’s relevant service.
