I wonder if anyone has data or seen an analysis of correlating the type of DCS symptom (skin itching, bends, neurological, ...) with the depth and duration of dives.
Of course, the deeper and the longer a dive was before the rapid ascent, the stronger the symptoms. AFAIK many think that the light symptoms (DCS type I: skin, joints) appear first and then may or may not get worse (Type II, neurologic, pulmonary).
But when you think about the assumptions of deco calculation models with different compartments, you come to a different conclusion. The model's compartments do not map 1:1 to a particular tissue, but there's the assumption that there are fast tissues (such as blood and spinal chord) that saturate quickly (short halftime) but also withstand more supersaturation (higher M-Value). And there are slow tissues (such as skin, joints, bones) that saturate slowly but are more sensitive (low M-Value).
From this concept I'd expect, that there are two different scenarios depending on the type of dive before the rapid ascent:
(A) long shallow repetitive dives: the slow tissues saturate and cause trouble due to long duration of the dive. The fast tissues withstand the supersaturation because it's shallow. So you'd expect skin and joint trouble, but no neurologic things (pure Type I). Repetitive diving makes a difference as it saturates the slow tissues more and more.
(B) single short deep dive: slow tissues are very little saturated, but the fast ones are and the depth of the dive make them cause trouble. You expect neurologic problems, but no skin or joint problems (pure Type II). Repetitive diving doesn't make a difference, a single dive is enough.
I didn't find any mention of this idea in Mark Powells "Deco for divers". But if this kind of correlation is true, it has implications for dealing with divers after a rapid ascent. For example, if a diver ascends quickly from a short deep dive, you shouldn't expect Type I symptoms to show up, but perform the neurological exam. Whereas if a diver shows Type I symptoms after too many long repetitive shallow dives, he need not expect it to become worse.
So: are you aware of any data or studies that cluster DCS symptoms into "too deep" or "too long" dives and show this correlation?
Of course, the deeper and the longer a dive was before the rapid ascent, the stronger the symptoms. AFAIK many think that the light symptoms (DCS type I: skin, joints) appear first and then may or may not get worse (Type II, neurologic, pulmonary).
But when you think about the assumptions of deco calculation models with different compartments, you come to a different conclusion. The model's compartments do not map 1:1 to a particular tissue, but there's the assumption that there are fast tissues (such as blood and spinal chord) that saturate quickly (short halftime) but also withstand more supersaturation (higher M-Value). And there are slow tissues (such as skin, joints, bones) that saturate slowly but are more sensitive (low M-Value).
From this concept I'd expect, that there are two different scenarios depending on the type of dive before the rapid ascent:
(A) long shallow repetitive dives: the slow tissues saturate and cause trouble due to long duration of the dive. The fast tissues withstand the supersaturation because it's shallow. So you'd expect skin and joint trouble, but no neurologic things (pure Type I). Repetitive diving makes a difference as it saturates the slow tissues more and more.
(B) single short deep dive: slow tissues are very little saturated, but the fast ones are and the depth of the dive make them cause trouble. You expect neurologic problems, but no skin or joint problems (pure Type II). Repetitive diving doesn't make a difference, a single dive is enough.
I didn't find any mention of this idea in Mark Powells "Deco for divers". But if this kind of correlation is true, it has implications for dealing with divers after a rapid ascent. For example, if a diver ascends quickly from a short deep dive, you shouldn't expect Type I symptoms to show up, but perform the neurological exam. Whereas if a diver shows Type I symptoms after too many long repetitive shallow dives, he need not expect it to become worse.
So: are you aware of any data or studies that cluster DCS symptoms into "too deep" or "too long" dives and show this correlation?
