Page 43 - Effects of radiotherapy and hyperbaric oxygen therapy on oral microcirculation Renee Helmers

Hyperoxia-driven microvascular changes
HB NB
T4 T5 T6 T7 T8 2 (FiO2: 21%) (FiO2: 55%) (FiO2: 100%) (FiO2: 21%) (FiO2: 21%)
33 ± 9* 30 ± 8* 29±8** 32±9* 37±11
86±12*80±13** 32 ± 8* 30 ± 7* 87±12*82±13** 96 ± 5 97 ± 5 4.0 ± 0.6 4.1 ± 0.5 97 ± 9 98 ± 6
78±12**85±11**
29±7** 31±8** 78±11**83±8**
95±6 94±7
4.1 ± 0.5 4.3 ± 0.5
99±7 106±11 102±8
0.10 ± 0.37 0.05 ± 0.23 0.03 ± 0.27 -0.21 ± 0.45 -0.07 ± 0.32 3±03±03±03±03±0
microcirculatory parameters. The results indicate that NB/HB hyperoxia-driven changes elicit reversible physiological control of sublingual mucosa blood perfusion in healthy subjects. The results also suggest a loss of microcirculatory vascular response since Øbv was unaltered during HB conditions, indicating an adaptive and potentially beneficial effect associated with maintaining peak tissue perfusion states in the presence of stable cardiovascular function. Furthermore, the use of a clinical handheld optical spectroscopic-based imaging instrument proved feasible for HBOm and the implementation of a continuous microcirculation monitoring strategy.
97±6 37±11 96±6 95±7 4.2 ± 0.5
Adaptation of tissue perfusion to stimuli is an important compensatory mechanism for matching metabolic demands and maintaining safe tissue physiologic biochemical equilibrium. It is well known that arterial vascular tone is increased in the presence of elevated p O levels.24,37,48 Vasoconstriction is an
a2
adverse event associated with hyperoxia37 as it is considered counterproductive
for ameliorating poor blood perfusion in tissue distressed by hypoxia.21 In the present model NB hyperoxia elicited dose-dependent vasoconstriction with rising paO2 levels as indicated by reduced Øbv. Our observations on decreased vessel calibers and capillary density in the presence of elevated paO2 corroborate findings reported in other animal models.44,48 Paralleled with altered sublingual perfusion, basic hemodynamics revealed a trend towards decreased HR (though not significant) with a transient rise in systolic blood pressure during NB hyperoxia. Transiently elevated systolic pressures have been recorded previously in studies based on other animal models,5 similarly observations
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