Page 37 - Effects of radiotherapy and hyperbaric oxygen therapy on oral microcirculation Renee Helmers

Hyperoxia-driven microvascular changes
Hyperbaric hyperoxia
HB hyperoxia basic hemodynamic and blood gas parameters are summarized in
the second part of Tables 2 and 3 respectively. A statistically significant increase
in systolic blood pressure was observed at FiO2 55% (T5) when compared to
baseline (p=0.009), no other significant difference in systolic pressure was 2 found for other HB time points. No other statistically significant differences
were observed for the remaining hemodynamics parameters. Arterial pH remained within normal reference ranges across all time points. Interestingly although within normal range, a statistically significant decrease in arterial pH was observed at the end of the experimental protocol after ascending back to 1 atm (1.0 bar) (T8) from 2.5 atm (2.5 bar) (p=0.028), indicating mild acidosis. PaO2 and sO2 revealed statistically significant elevations in both parameters across all HB time points (FiO2 21%, 55%, 100%, and 21%, p=0.018 respectively), these normalized again following return to normoxia at 1 atm (1 bar) (T8). Total hemoglobin (tHb) remained within normal ranges across all time points despite a statistically significant increase at the end of the experimental protocol after returning back to 1 atm (1.0 bar) and normoxia (T8) (p=0.018 vs. T0).
The MicroScan instrument was stable under HB pressure. A summary of all microcirculation parameters coinciding with HB hyperoxic time points is presented in the second part of Table 4. Comparative analysis of TVD and PVD with respect to baseline (T0) revealed a significant mean 18% decrease for all HB time points (FiO2 21% (T4), p=0.017; 55% (T5), p=0.004; 100% (T6), p=0.002; and 21% (T7), p=0.007). A sequence of SDFI frames illustrating changes in the microcirculation during the HB experiments is presented in Figure 3B. Return to NB normoxia at the end of the experimental procedure (T8) [Fig. 3C] fully reversed the effects induced by elevated paO2 by normalizing TVD and PVD back to near baseline values (4%).
HB NB
T4 T5 T6 T7 T8
(FiO2: 21%) (FiO2: 55%) (FiO2: 100%) (FiO2: 21%)
134 ± 36 140 ± 15 149 ± 17 145 ± 10 72 ± 7 76 ± 11** 76 ± 7 75 ± 1 60 ± 8 64 ± 7 62 ± 10 61 ± 2 53 ± 7 58 ± 8 57 ± 7 53 ± 2 94 ± 3 97 ± 1 98 ± 1 98 ± 1
(FiO2: 21%)
161 ± 16 73 ± 9 63 ± 4 58 ± 2 96 ± 2
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