For surface interval greater than 7 minutes after omitted stop, if a chamber is available, which treatment tables apply?

• A. Chamber available: Use simple surface decompression
• B. Chamber available: Treatment Table 5 for two or fewer SurDO2 periods; Treatment Table 6 for more than two SurDO2 periods
• C. Chamber available: Treat with Table 9
• D. Chamber available: Abort and ascend

Answer: (B)

When a surface interval is longer than 7 minutes after an omitted stop and a decompression chamber is available, the treatment is guided by the number of SurDO2 periods (surface decompression oxygen exposures) that occurred during the surface decompression attempt. The chamber allows controlled decompression using oxygen-enriched stages, and the number of SurDO2 periods determines which table to follow.

If there are two or fewer SurDO2 periods, you follow the schedule on Table 5. If there are more than two SurDO2 periods, you follow Table 6. These tables are designed to tailor decompression based on how much oxygen exposure occurred during surface decompression, balancing faster off-gassing with the risk of oxygen toxicity and bubble formation.

The other options are not appropriate here: simple surface decompression does not exploit the available chamber and oxygen-exposure approach for missed stops, Table 9 is used in different scenarios, and aborting and ascending would be chosen when a chamber isn’t available or safe recompression isn’t possible.