INTRACAPILLARY HBO2 SATURATION IN MALIGNANT-TUMORS DURING NORMOXIA AND HYPEROXIA

Intravascular HbO2 saturations in tumor capillaries are determined utilizing a cryophotometric micromethod whereby the intracapillary hemoglobin absorption spectra are measured in frozen tissue slices at -100° in a vacuum-isolated microscope cryostat and transferred into intracapillary HbO2 saturation values using a multicomponent analysis. The results of measurements on tissue specimens from malignant tumors reveal that during normoxia 67% of the data obtained lie in the range of 0 to 20% HbO2 saturation. Twenty-four percent of the measured values show zero levels. Only 8% of the values exceed 50% saturation. The measurements demonstrate that very low HbO2 saturations predominate in the tumor tissue. Regional differences can be found only in superficial areas of malignant tumors where a sufficient vascularization still exists. During respiratory hyperoxia only a slight increase in the HbO2 saturation values within tumor capillaries is obvious. However, the data obtained under these conditions are not significantly different from those measured within the tissue during normoxia. From the results presented here, it can be concluded that respiratory hyperoxia does not yield any practical improvement of the oxygen supply to solid tumors in situ. © 1979.