Definitely,
This actually came up when I was teaching on the NOAA course in Seattle last week when I referred to rash as part of the 'mild' spectrum of DCI. One of the course participants objected to characterization of cutis marmorata as 'mild'. My point then, as it is now, was that the rash per se is not a serious problem. It will not of itself cause you any harm, and if it is the only manifestation present then it can regarded as mild. However, the significance of cutis is that there is a recognized (but not invariable) association with more serious symptoms. So if we see cutis, we should be alert to the possibility that there may be other manifestations present or on the way. This is the basis of confusion about how it should be viewed as a symptom. It certainly gets my attention when I see it and I would make sure there is nothing else going on, but if it turns out to be the ONLY thing going on (as in the OP's case), then I would still regard that as a mild case. IIRC this is how the remote DCI workshop saw it in 2004 when trying to define mild DCI.
Let me illustrate with 3 hypothetical cases that draw on many of the points made in this thread.
Case 1. A diver is at 40' for 30 minutes then panics and comes rocketing to the surface. He holds his breath and suffers pulmonary barotrauma. At the surface he rapidly becomes weak down his left side, and then unconscious. Shortly after, whilst managing his airway and administering oxygen the rescuers notice he has a cutis marmorata-like rash on his chest.
In this case it is almost certain that large bubbles introduced to the arterial circulation by pulmonary barotrauma have gone to the brain. These bubbles have caused a stroke-like syndrome, and the rash may well have arisen through the same brain-related mechanism as in the Kemper pig experiment. Obviously this is not a mild case, but it is serious because of the serious neurological manifestations, not because of the rash.
Case 2. A diver is a 90' for 25 minutes and makes an appropriate ascent and safety stop. Thirty minutes after the dive they notice an itch over the abdomen. Initially there is a pink rash but over the next 15 minutes it develops a blotchy appearance like cutis marmorata. Around this time they also develop tingling in both feet that slowly ascends up the legs, and there is an increasing sense that it is harder to stand and walk. The dive master is informed and the diver is given 100% oxygen. A doctor on board performs a neurological examination and finds weakness in both legs, with some reduction in sensation to pain up to the lower abdomen. The diver is evacuated on 100% oxygen and the rash slowly fades whereas the weakness remains.
This symptoms (rash and neurological symptoms) could not be caused by large bubbles going to the brain. The neurological symptoms are serious, but are localized to the spinal cord, not the brain. It is likely that tiny bubbles have crossed a PFO or pulmonary shunt, been carried to the skin and spinal cord in the arterial blood, and grown from inward diffusion of dissolved nitrogen from the surrounding tissue. Alternatively the bubbles might have formed in the skin or spinal cord tissue itself. Whatever the pathophysiological mechanism, this is obviously not a mild case, but it is serious because of the spinal manifestations, not because of the rash.
Case 3. A diver is a 90' for 25 minutes and makes an appropriate ascent and safety stop. Thirty minutes after the dive they notice an itch over the abdomen. Initially there is a pink rash but over the next 15 minutes it develops a blotchy appearance like cutis marmorata. They feel a little tired (as usual after diving) but otherwise completely well. In particular, there are no neurological manifestations. The dive master is informed and the diver is given 100% oxygen. Over the next hour the rash gradually fades away and diver continues to feel well. A doctor on board performs a neurological examination and can find no abnormalities.
It is virtually certain that this case could not be caused by large bubbles going to the brain (because if large bubbles had gone to the brain there would be other serious symptoms). It is much more likely that tiny bubbles have crossed a PFO or pulmonary shunt, been carried to the skin in the arterial blood, and grown from inward diffusion of dissolved nitrogen from the surrounding skin tissue. Alternatively the bubbles might have formed in the skin tissue itself. Whatever the pathophysiological mechanism, the rash itself will cause no harm, and in the absence of any other more serious symptoms, the case can be considered "mild".
Hope this makes sense.
Simon
