@doctormike once again excuse my naivety, does this mean that the chamber is used only to save lives/prevent permanent damage in DCS cases? What I mean is say someone had DCS, that affected their vision for example and joints, if they didn't attend a chamber but abstained from diving, it means that the body would still off gas but the N2 could have caused permanent damage due to being in the affected tissue for soo long?
Profile was not planned for deco but photography gets hold of me and a nice bommie appeared at 23/22m which held my attention for too long. Mistake I know, hopefully one I haven't paid for. But they are the lessons you learn.
Better to ask DCS questions of DDM or one of the decompression experts around here (like Dr. Mitchell). But basically, DCS is the term for the clinical manifestations of tissue injury that result from inert gas (like N2) transitioning from the dissolved state (in a liquid) to the free state (bubbles).
All divers need some sort of pressure gradient to get rid of excess dissolved gas, to get it to be exhaled through the lungs. The pressure gradient happens on ascent, and if you let that gradient get too big the transition happens forming bubbles. Therefore, all decompression strategy involves avoiding injury by ascending fast enough so that most of the gas goes directly from the dissolved state to the lungs and out within a reasonable amount of time, but not so fast that the gradient gets big enough to cause that transition.
The mechanism for tissue injury is poorly understood, but classic DCS may be a local inflammatory reaction to the bubbles. There is also, as you mentioned, DCI which includes DCS but also larger bubbles crossing from the venous circulation to the arterial circulation through one of a variety of pathways, and then ending up blocking blood flow as they "embolize", most critically in the brain. This is an AGE (arterial gas emboli).
A recompression chamber is for people who have not avoided that transition, and have bubbles which cause injury. The chamber reduces that gradient which causes the bubbles to transition back to the liquid phase, and then gives the diver another chance at a more appropriate ascent strategy including periods of time breathing no inert gas at all (pure O2). This both treats the clinical injury caused by the bubbles, and aims to eliminate the excess N2 safely through the lungs. Patients with residual tissue injury may get benefit from more than one treatment.
If a patient has non-fatal DCS and doesn't get recompressed, their symptoms could go away on their own as they naturally offgas, or the bubbles could cause injury that persists even after the excess N2 is gone. There is a bell curve for everything.
In my case, my symptoms resolved breathing O2 at the dive site, but I still had a chamber treatment on the advice of DAN. After a certain length of time, recompression is unlikely to help with DCS since the problem now is the residual tissue injury, not the fact that the excess N2 never left the system.
As far as sinusitis, that's more in my wheelhouse. I'm reluctant to diagnoses anyone over the Internet for that, but you didn't describe any sort of sinus squeeze or other features that would suggest that specifically, and headaches are such a common symptom that sinus barotrauma is only one of many possibilities. For more than that, you would need an exam and possibly some sort of sinus imaging.
Finally, we won't beat you up TOO badly for letting a fish put you at risk for serious injury, but I hope that your DCS scare (even if it isn't likely to be that) will make you understand the issue with unplanned deco. If you don't have the gas to deal with your required decompression, next time it could be a lot worse. Don't let the fact that you may have gotten away with it this time lead you towards
normalization of deviance.
