What is the criteria for switching from TT6 to TT6A during a dive?

The criteria for switching from TT6 to TT6A during a dive involves the assessment of the diver's condition, particularly within the first 20 minutes at depth. When there is no improvement or a worsening of the diver's condition during this critical time frame, it indicates that the initial treatment protocol may not be effective. Consequently, switching to TT6A, which often involves a more advanced intervention, can be warranted to provide a better chance at addressing the diver's needs.

In contrast, other options describe different scenarios that do not align with the established criteria for a switch to TT6A. Improvement in condition at any depth suggests that the TT6 protocol is working adequately, negating the need for a change. Significant distress experienced by the diver is important, but it does not specify the necessity to switch protocols based on the timeline; actions may vary based on the immediate circumstances. Lastly, resting for more than 30 minutes at depth might indicate a need for further assessment but does not directly inform the decision to transition from TT6 to TT6A based on the criteria.