Having run a chamber or two in my day, the treatment protocols are to get the patient back to depth as rapidly as possible, so crab is correct.
Depending upon the type of DCS (Decompression Sickness, Type I is simple pain such as joint pain, Type II involves neurological damage), tissue is busily dying the longer that gas not in solution (bubbles, essentially) is in the tissues. Recompression forces gas back into solution so that it can come out of solution via the alveoli in the lungs. Open a bottle of beer to see the process in reverse.
A common myth is that there is a requirement to go to a great depth to contract DCS. Not true. The final 3m in the water column to the surface are the most dangerous because of the steeper pressure gradient.