Page 127 - Effects of radiotherapy and hyperbaric oxygen therapy on oral microcirculation Renee Helmers

Effects of HBOT on late irradiation injury
could suggest an adaptation in flow dynamics and intravascular pressures in which bulging would be limited in the oral microcirculation.
HBOT has shown to induce neoangiogenesis and increase vascularity in
wound healing models and compromised tissues.11,14,27 Marx et al. described an
eight- to ninefold increase in microangiographically determined vascular density
after hyperbaric oxygen (20 sessions, 2.4 ATA) compared to both normobaric
oxygen and air-breathing controls in an irradiated rabbit jaw model.18 Earlier, he
described increased microvascular density when obtained and assessed before
and after receiving HBOT (20 sessions, 2.4 ATA) in tissue biopsies of 50 irradiated
HNCP.17 In another clinical study looking at buccal mucosal biopsies (3-4 mm
depth) of 20 irradiated HNCP, blood vessel density was increased by HBOT
after 6 months.31 Svalestad et al. also reported significant increase in blood
flow after heat provocation at 3 and 6 months after HBOT when compared to
controls. Furthermore, an increased oxygen tension was observed in facial skin
after HBOT using transcutaneous oximetry.32 Transmucosal oximetry in ORN
patients demonstrated an increase in gingival oxygen tension values from a
mean of 50% to a mean of 86% of the oxygen tension of healthy controls
after HBOT (30 sessions, 2.4 ATA).36 In the present study the assessment of
multiple microcirculation parameters (i.e., vascular function (flow), vascular morphology, angioarchitecture and vascular density) were captured using IDFI
and the results revealed an increased mean FCD in irradiated buccal mucosa 6
months after HBOT. 6
Contradicting results were published by an experimental study that did not observe an effect of HBOT on histological vascular density in the irradiated mandibular skin of rats after different HBOT regimes (18 and 30 sessions, 2.5 ATA) over a period of 12 weeks.28 Furthermore, an increased vessel diameter was noted after irradiation that did not change after HBOT. The results of the present study did show a reversible effect of HBOT on vessel diameter in buccal mucosa with a significant decrease towards healthy tissue values that appear consistent with datasets described in our previous study.12 It is possible that a delayed effect of HBOT is not detected in studies with a shorter follow up period. However, another experimental study did show histologically increased vascular density in irradiated salivary gland in a mouse model in a short period of 10 weeks after HBOT (20 sessions, 2.4 ATA).29
There are some points of consideration concerning the present study. HNCP often have known comorbidities such as hypertension, diabetes mellitus and
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