Improvement in human tumour oxygenation with carbogen of varying carbon dioxide concentrations

Background and purpose: Carbogen (95%O-2, 5%CO2) is being used in clinical trials as a hypoxic radiosensitiser. Tolerance to carbogen can be a problem , this study compares tumour oxygenation during inhalation of hyperoxic gas containing either 2% or 5% CO2. Materials and methods: Tumour pO(2) was measured in 16 patients using the E ppendorf pO(2) histograph. Results: After breathing gas containing either 5% or 2% CO2 an increase in median pO(2) was measured in every tumour, the frequency of low pO(2) value s ( less than or equal to 10 mmHg) fell from 47% to 29% in the 5% group and from 55% to 17% in the 2% group. Conclusions: This study confirms that breathing 2% CO2 and 98% O-2 is well tolerated and effective in increasing tumour oxygenation. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.