INTRODUCTION: Hyperbaric oxygen therapy is the standard treatment of decompression sickness and the main opinion is that the condition responds better to early treatment than delayed treatment. There is no randomized controlled evidence supporting this opinion.
PURPOSE: To find and evaluate the evidence for whether decompression sickness is more susceptible to early then delayed hyperbaric oxygen therapy.
MATERIAL AND METHODS: A semi-structured search in the PubMed database, McMaster Plus, Google scholar and reference search lead to 17 articles that have been included and assessed. Guidelines, summaries and textbooks have also been reviewed in order to answer the question. Several case histories with extensive delays to treatment have also been assessed. Additionally, a retrospective analysis of patient data from the hyperbaric unit at Oslo University Hospital, Ullevål has been done to evaluate current practice.
RESULTS: The results differ substantially and the statistical methods used on retrospective uncontrolled data have considerable uncertainty attached to it. Seven studies have concluded that there is a significant relation between time to treatment and outcome, strongest demonstrated for serious DCS, but the equal number of studies made the opposite conclusion. Associations are mainly found with use of univariate analyses, and several studies found that when results were applied on multivariate analyses, adjusted for other factors, these relations became weak or insignificant.
CONCLUSION: Delay to treatment seems to have little or no influence on the outcome of mild cases of decompression sickness, where the majority achieves complete resolution independent of time to treatment. In cases of severe neurological decompression sickness the symptoms presents earlier, they are graver and generally respond less to hyperbaric oxygen treatment. For these patients evidence is stronger, supporting early treatment. Evidence suggests that HBOT given within 6 hours after symptom start may be an optimal time frame.Minimal delay is no guarantee for complete recovery, even if treatment is given within minutes, and even with substantial delay patients with serious DCS may achieve complete recovery.