Page 14 - Effects of radiotherapy and hyperbaric oxygen therapy on oral microcirculation Renee Helmers

Chapter 1
of the tissue surrounding the necrosis, broad resection and often extensive reconstruction are required in these advanced and clinically complicated cases. The HN region is anatomically complex with many vital structures that are important in performing everyday functions such as speech, mastication, swallowing, innervation of facial muscles and esthetics that contribute to social interaction. Inevitably, impaired function in this region has a severe impact on QoL.6,19
HYPERBARIC OXYGEN THERAPY
Hyperbaric oxygen therapy (HBOT) is extensively under investigation concerning its resuscitating potential in the field of tissue repair and regeneration.16,31,34 HBOT is described as breathing of 100% oxygen at a pressure above 1 atmosphere absolute (ATA). Oxygen tension level in blood plasma is elevated with the purpose of mobilizing oxygen to reach hypoxic tissue and induce neoangiogenesis. HBO treatment sessions for LRTI commonly has a duration of 90-120 minutes at 2-2.4 ATA and is administered on a daily basis. Although previous studies report contradicting results on the efficacy of HBOT, its angiogenic potential has been demonstrated in in vitro and in in vivo studies.16,22,34,36,41 Furthermore, evidence of moderate quality exists in support of HBOT improving outcomes associated with LRTI.3,33 However, treatment protocols and the efficacy of HBOT remain a matter of debate33 and more research to determine timing and patient selection is needed.3
Prophylactic HBOT is given if surgical intervention (e.g., tooth extraction or implant placement) is required in previously irradiated tissue. Currently no specific patient selection is considered for administration of preventive HBOT as it is not clear in which patients LRTI will develop and when. However, some risk factors are identified such as fraction dose and health-related factors.11,28,38 Therapeutic HBOT is administered at the time that tissue breakdown is clinically visible and the underlying pathophysiology has progressed towards critical stage. A method for visualizing in-vivo microvascular status could contribute to the understanding of disease progression and monitor the effects of supportive therapies. The ability to examine and observe tissue function and anatomy and to be able to quantify these observations formed the basis and the starting point of this thesis.
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