ABSTRACT
We present four head and neck cancer patients who apparently had rapid progression of clinically occult disease during or soon after undergoing hyperbaric oxygenation. This led us to review existing knowledge about the interaction of HBO with tumors. The literature can be summarized as follows: 1. HBO is a useful tool in several situations commonly encountered by head and neck surgeons-infections, radionecrosis, and wound-healing problems. 2. The use of HBO as a hypoxic cell sensitizer during radiation therapy has been extensively studied, with evidence supporting only marginal advantage to this logistically difficult undertaking. 3. Most reports regarding the interaction of HBO with transplanted tumor cells suggest no effect on tumor growth or metastases. 4. Studies of chemically induced carcinogenesis are less conclusive. Some evidence supports a role for HBO in enhancing growth of preexisting tumors. Better understanding of the interaction of HBO with existing tumors is required to ensure that informed choices-weighing potential risks and benefits of HBO treatment--may be made by head and neck surgeons and their patients. Further research into the interaction between HBO and tumor cells is warranted.
Subject(s)
Carcinoma, Squamous Cell/therapy , Head and Neck Neoplasms/therapy , Hyperbaric Oxygenation , Neoplasm Recurrence, Local , Adult , Aged , Carcinoma, Squamous Cell/radiotherapy , Disease Progression , Fatal Outcome , Female , Head and Neck Neoplasms/radiotherapy , Humans , Male , Middle Aged , Treatment FailureABSTRACT
We have developed a two compartment (tissue and blood) lumped parameter model to interpret oxygen disappearance curves (O2 DCs) measured in vivo with PO2 microelectrodes in tissues which are perfused with blood. To include the properties of the oxyhemoglobin equilibrium curve (HEC), we used an algorithm we have recently developed for both standard and nonstandard conditions. The new blood and tissue model is more useful than a previous analysis using the Hill equation for blood and constant oxygen consumption (VO2). The model can be adapted for constant (zero-order) consumption, Michelis-Menten kinetics, or for double cytochrome systems. Examples for the former include brain, and for the latter, carotid body. The models are discussed in relationship to experimental microelectrode measurements in gerbil brain and in cat carotid body after blood flow occlusion.
