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[Oxygen pressure distribution in lymph node metastases and the changes during acute respiratory hypoxia]
V Strnad1, L Keilholz, M Kirschner
1Klinik und Poliklinik für Strahlentherapie, Universität Erlangen-Nürnberg.
Purpose:
The radiosensitivity of tissues is essentially influenced by hypoxia. Based on the oxygen effect a new therapeutic modality has been developed to protect healthy tissues while hypoxic breathing during irradiation.
Patients And Method:
The effect of hypoxic breathing (8.1% O2) on the pO2 in metastatic lymph nodes was studied in 14 patients. Tissue oxygenation was assessed using a polarographic electrode system.
Results:
The median pO2 was 19.6 mm Hg prior to hypoxic breathing with a great intra- and intertumoral variability. The relative frequency of pO2-values < 5 mm Hg was between 0 and 88%. During hypoxic breathing we registered no significant changes in the mean, the median or the pO2 values < 5 mm Hg.
Conclusions:
In metastatic lymph nodes can be found chronic hypoxia with great inter- and intratumoral pO2 variability. The hypoxic breathing (8.1% O2) shows no significant modifications of the tumor oxygenation with increased pO2 variability. This fact explains the experimental and clinical experience, that the hypoxic breathing (8 to 10% O2) protects the healthy tissue without changes in the radiosensitivity of chronic hypoxic tumor tissue.