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

Abstract

Carbogen (95%O2, 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. Tumour pO2 was measured in 16 patients using the Eppendorf pO2 histograph. After breathing gas containing either 5% or 2% CO2 an increase in median pO2 was measured in every tumour, the frequency of low pO2 values ( < or = 10 mmHg) fell from 47% to 29% in the 5% group and from 55% to 17% in the 2% group. This study confirms that breathing 2% CO2 and 98% O2 is well tolerated and effective in increasing tumour oxygenation.