Early nitrogen wash-out for inside attendants during hyperbaric oxygen therapy: a novel oxygen distribution regimen

Introduction: Hyperbaric oxygen therapy (HBOT) is widely used as treatment of decompression sickness (DCS). The patient breathes oxygen at an elevated oxygen partial pressure of up to 280 kPa, whereas any inside attendant (IA) normally breathes air. This results in nitrogen uptake and tissue loading in the IA, which must be considered during decompression. The US Navy Treatment Table 6, and its equivalent used by the Swedish Armed Forces, prescribe periods of oxygen breathing prior to and during decompression to reduce the risk of DCS for the IA. However, since these oxygen periods are concentrated toward the latter part of the hyperbaric treatment, they do not account for the possibility of rapid decompression in the event of an earlier emergency. Methods: We suggest rescheduling the distribution of oxygen for the IA to an earlier stage of the HBOT, which would allow early emergency decompression to a greater extent than the traditional IA oxygen regimen. To verify the duration of oxygen periods and their timing, we used the exponential linear Thalmann decompression algorithm with SWEN21B parameters to analyse compartmental gas load and perform a comparison between the original and our newly proposed regimens. Results: We identified an alternative oxygen regimen for the inside attendant (IA) that remains within the permissible limits of the decompression algorithm yet allows for emergency decompression to be performed over an extended section of the period of compression. Conclusions: Based on the decompression model used herein, we can conclude that greater flexibility in emergency decompression is possible if the oxygen regimen for the inside attendant (IA) is administered at an earlier stage of the therapy session.