Treatment Protocol for Type II Decompression Sickness
Patients with type II decompression sickness should receive an initial US Navy Treatment Table 6 (TT6) at 2.8 ATA (60 fsw), followed by additional treatments as needed based on symptom resolution—typically 1-3 total sessions within the first 24-48 hours, with further treatments guided by clinical response. 1, 2
Initial Treatment Approach
Start with US Navy Treatment Table 6 (TT6) as the standard first-line recompression protocol for type II DCS, which involves treatment at 60 fsw (2.8 ATA) 1, 3, 2
Administer the first treatment as soon as feasible after diagnosis, though delayed treatment (>48 hours) still achieves complete recovery in 76% of cases 2
Early recognition and treatment initiation lead to significantly better outcomes in type II DCS, which represents 61% of all decompression sickness cases 4
Follow-Up Treatment Strategy
If symptoms incompletely resolve after initial TT6, use US Navy Treatment Table 9 (TT9) for subsequent treatments rather than repeating TT6 or using TT5 1
TT9 offers critical safety advantages: maximum pressure of 2.4 ATA (45 fsw) versus 2.8 ATA (60 fsw), substantially reducing CNS oxygen toxicity risk and seizure potential for both patient and inside attendant 1
For severe residual neurologic injury after initial TT6, some clinicians prefer repeating TT6 rather than transitioning to TT9, though this increases oxygen toxicity risk 1
US Navy Treatment Table 7 (TT7) is reserved for refractory cases that remain resistant to TT6 and its extensions, though it carries higher pulmonary oxygen toxicity risk 3
Expected Treatment Course
Most patients require 1-3 hyperbaric sessions total within the first 24-48 hours for type II DCS 5, 1
Complete recovery occurs in 74-78% of patients after initial treatment, with partial recovery in 15-17% 2, 4
26% of patients have residual symptoms after the first session and require additional treatments 4
Continue treatments until symptoms plateau or resolve completely, as delayed recompression (≥48 hours after onset) still achieves complete recovery in 76% when using TT6 protocol 2
Protocol Selection for Subsequent Treatments
US Navy Table 6 protocol trends toward better clinical outcomes (OR=2.786, though not statistically significant) compared to standard 90-minute HBOT at 2 ATA, regardless of symptom severity 2
TT9 matches standard multiplace chamber oxygen/air cycling protocols (2.4 ATA with identical sequencing), making it operationally straightforward to incorporate into daily clinical practice 1
Avoid routine use of TT5 for follow-up therapy in type II DCS, as it exposes inside attendants to 3 hours at 2.0 ATA when extended, creating iatrogenic DCS risk 1
Critical Safety Considerations
Seizure risk during treatment is minimal (0.10% or 1 in 1,037 patients) when standard protocols are followed, though seizures can occur as early as the first or second oxygen breathing period at 2.8 ATA 6, 1
Inside attendants face real DCS risk from repeated exposures, including career-ending and fatal cases, making pressure reduction with TT9 an important safety measure 1
Monitor for pulmonary oxygen toxicity with lung function testing when multiple treatments or TT7 are required 3
Common Pitfalls to Avoid
Do not withhold treatment beyond 48 hours assuming it will be ineffective—delayed recompression maintains 76% complete recovery rates 2
Do not default to repeating TT6 for all follow-up treatments when TT9 provides equivalent efficacy with superior safety profile 1
Do not use TT5 as routine follow-up therapy for incompletely resolved type II DCS, as it was designed for fully resolved type I (pain-only) DCS 1