Does arterial stiffness change under hyperbaric conditions? (LB796)

Abstract

One of the effects of hyperbaric environment is considered to be peripheral vasoconstriction due to high oxygen tension. It was proposed that this could yield to changes in vascular properties, and to further investigate the issue we examined stiffness index (SI) and reflection index (RI) as calculated from a finger photoplethysmography under normobaric and hyperbaric environment. Eight subjects participated in the study comprising three different conditions spread over one session ‐ breathing air at 1 ATA, breathing air at 2 ATA and breathing 100% oxygen at 2 ATA. Each condition lasted for at least 10 minutes. Photoplethysmography and EKG were continuously recorded using Biopac MP100 multi‐modular system (BIOPAC Systems Inc., Goleta, CA). The compression was done in a multi‐place hyperbaric chamber (Clucas Diving Ltd). The results showed no overall differences in SI and RI when comparing the three conditions. For each subject however there were significant changes in the studied parameters, although in different directions. These findings suggest that SI and RI do change in hyperbaric environment. They also argue that at short exposure and low pressure the vascular effects most probably were not fully developed in order to overcome the inter‐individual differences. Such notion was also supported by the observed stable heart rate in all three conditions and the concomitant small changes in heart rate variability. Grant Funding Source: Saba Ubniversity School of Medicine