Short duration hyperbaric oxygen treatment effects blood flow in rats: pilot observations

Abstract

SummaryHyperbaric oxygen (HBO) treatment has been found to improve healing in living tissues, especially those poor in oxygen. The effects of HBO have also been tested in rat experiments. However, oxygen partial pressure in rat's arterial blood is normally about twice that in humans. Disregarding this, a human HBO protocol has been applied in previous rat experiments with HBO. Laser Doppler flowmetry (LDF) is a non-invasive means for measuring blood flow. Using LDF, we measured the blood perfusion rate in rats receiving HBO, according to a modified protocol, in a region of healing soft tissue with bone defect. The results indicate that, in rats, shorter HBO treatment with high O 2 pressure can significantly improve the blood flow of healing tissues. In this study, an elevated blood perfusion rate was still evident 2 weeks after the ending of HBO therapy, which indicates improved revascularization in the wound area. A short HBO protocol would save time and effort in future HBO experiments on rats.

Hyperbaric oxygen therapy accelerates vascularization in keratinized oral mucosal surgical flaps

“…Wound vascular regeneration and adequate oxygenation are essential for establishing a stable wound microenvironment to support tissue repair and restoration of anatomic function. Previous studies have confirmed a beneficial effect of HBOT on perfusion or neovascularization in chronic and nonchronic wounds . In an experimental study Hopf et al, graded neovascularization subcutaneously in mice by histological assessment after HBOT and found a greater and dose‐dependent angiogenic response in a hyperbaric group compared to controls.…”

“…In another study using LDF, it was reported that acute HBOT on ischemic rat skin flaps improves perfusion by stimulating the microcirculation . Subsequent HBOT investigations later demonstrated elevated blood perfusion in healing tissue of a mandibular bone defect in rats and acceleration of neovascularization in impaired wound models using intravital microscopy in mice . However, despite positive results using HBOT to improve tissue vascularization and microperfusion, contradicting results associated with HBO still persist.…”

Hyperbaric oxygen therapy. Part 2: application in disease

“…Experimental animal models have demonstrated HBOT creates the necessary oxygen gradients between the blood and injured tissues to promote angiogenesis 81 and increased blood flow (on the order of 20% increase in mean perfusion) 16,82 . Oxygen gradients have been shown to be mandatory in angiogenesis during wound healing through regulation of macrophage‐derived growth factors, specifically vascular endothelial growth factor 16,83,84 .…”

“…Neovascularization is important in helping fight infection as well as in the later phases of wound repair as it facilitates the migration of fibroblasts and epithelial cells that continue the healing process. Improved angiogenesis with HBOT has been associated with improvements in healing in such diverse experimental animal models as burns, 85 cartilage and skin grafts, 17,86 dermal wounds, 82,85,87 and bone healing 88 …”

“…The incidence of oxygen‐induced seizures in humans has been shown to be ≤0.03%, 112,113 and an existing seizure condition unrelated to oxygen therapy is not considered a contraindication to HBOT 114 . There are species differences in susceptibility to oxygen toxicity, based on basal metabolic oxygen consumption 82,115 ; therefore, dogs may be more sensitive to oxygen‐induced seizures than humans 89…”