Possibly a twenty hour window? Quite interesting. Suggests that evacuation to a treatment facility for mild DCI should not be unduly hasty if it entails significant additional risks.
“Undersea Hyperb Med. 2010 Mar-Apr;37(2):133-9.
Triage and emergency evacuation of recreational divers: a case series analysis.
Zeindler PR, Freiberger JJ.
Center for Hyperbaric Medicine and Environmental Physiology, Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina, USA.
INTRODUCTION: It is unknown if the benefits of rapid treatment always outweigh the risks of emergency evacuation for recreational divers. To investigate current triage practice, we reviewed a three-year consecutive series of evacuations and analyzed the relationship of evacuation completion time (EvCT) to outcome in the decompression illness (DCI) cases.
METHODS: Checkbox-keyword searches of calls to Divers Alert Network (DAN) between 4/06 and 2/09 identified cases for review.
RESULTS: Of 24,275 calls, 107 were evacuations. Median EvCT, (defined as time from injury to arrival at treatment facility) was 20 hours (mean +/- SD, 27.3 +/- 27.2). Indications were: DCI 56% (60), medical illness 28% (30) or trauma 16% (17). Twenty-five percent of medically indicated evacuations were for pre-existing conditions. One-third of all DCI air evacuations (17 of 51) were for mild cases (pain or tingling only). EvCT and presentation severity were not significant predictors of DCI outcome; however, early data (< 6 hours) was sparse.
CONCLUSION: More data are needed assess the benefits of faster evacuations. However, in real-world scenarios with EvCTs in the 20-hour range, time did not influence outcome. Risk-benefit analysis of emergency transport is advised, especially for mild cases of DCI with a low probability of symptom progression.”