Page 47 - Effects of radiotherapy and hyperbaric oxygen therapy on oral microcirculation Renee Helmers

Hyperoxia-driven microvascular changes
The MicroScan has a long history of application in the oral compartment,
and in particular the sublingual region since non-keratinized epithelium is
thin and facilitates observations of branching microvasculature networks
that regulate nutritive blood perfusion to the mucosa. Serving as a clinical
model for investigating central microhemodynamics and cardiovascular 2
system, the sublingual area is an easily accessible ROI in which normothermic
conditions are isolated from environmental stimuli. Clinical literature on
sublingual microcirculation describes research designs that have solely been
based on intermittent measurements on different sublingual sites resulting
in irreproducible data as measurements of different branched microvascular
networks make it very difficult to draw sound scientific conclusions on
interventional courses. It is difficult to extrapolate the data reported in this
study with other experimental and clinical researches using the MicroScan
due to large variations in research methodology and limited investigations
designed around a continuous monitoring scenario capturing the dynamics
of one and same vascular network. For example, recently Orbegozo Cortés
et al. 33 using SDFI, reported similar microcirculatory observations during ,
NB hyperoxia in a cohort of healthy volunteers, though their intermittent measurements and analytical method differ from our approach, they report approximately 36% reduction in PVD versus our continuous measurement approach with 16% reduction in PVD. Since our investigation consisted of two separate experimental procedures it is interesting to consider the reproducibility achieved in PVD magnitudes. To date only four studies have reported data on continuous-based monitoring in one and the same ROI to intercept both the onset of tissue perfusion changes and the clinical relevance of these observations.4,12,29,49 Continuous monitoring with sequential measurements provide strong evidence of changes in microcirculation parameters from specific tissue microvascular networks that could translate in the near future to identify a host’s state of health and their ability to elicit a physiological response associated with oxygen and/or other interventional strategies. Continuous measurement approaches favor reproducibility in data acquisitions, however careful experimental design and planning is required to obtain viable data for translational interpretations linking patient response with predicting and/or achieving a desired therapeutic outcome. Ultimately the aim of oxygen therapy is to maximize oxygen supplementation to sustain tissue aerobic metabolism. To our knowledge no investigation has as yet advanced knowledge towards sublingual microcirculatory assessments during HBO conditions.
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