BACKGROUND AND PURPOSE: Increasing arterial oxygen partial pressure (pO2) by breathing hyperoxic gases is an effective means of improving tumor oxygenation, although the efficacy of adding CO2 to the inspiratory gas has been discussed controversially. This study aimed at analyzing the impact of different inspiratory CO2 fractions on the time course of oxygenation and perfusion changes in experimental tumors during and after inspiratory hyperoxia. MATERIAL AND METHODS: Perfusion and oxygenation of rat DS-sarcomas were studied during spontaneous breathing of pure oxygen or hyperoxic gas mixtures containing different CO2 fractions (1, 2.5 or 5%). Red blood cell (RBC) flux was assessed as a measure of tumor perfusion using the laser Doppler technique and temporal changes in mean tumor pO2 were measured polarographically. RESULTS: Mean tumor pO2 increased 3.6-fold with pure oxygen, approx. 3.3-fold when 1 or 2.5% CO2 was added and 2.7-fold during carbogen breathing. RBC flux also increased by 25-30% with all gases. With pure oxygen and with 1% CO2 (+99% O2), perfusion changes paralleled those of the mean arterial blood pressure whereas with higher CO2 fractions, a decrease in resistance to flow was observed. The differences found with the various gas mixtures were more pronounced after the end of hyperoxia. With pure oxygen, perfusion immediately returned to pretreatment values whereas with higher CO2 fractions perfusion remained elevated for at least 30 min. CONCLUSIONS: Higher inspiratory CO2 fractions (2.5 or 5%) lead to a prolonged improvement of tumor perfusion after the end of inspiratory hyperoxia when compared with pure oxygen breathing. Since no principal differences in oxygenation and perfusion were seen between the gases containing 2.5 and 5% CO2, the former may be preferable for inspiratory hyperoxia.
BACKGROUND AND PURPOSE: Increasing arterial oxygen partial pressure (pO2) by breathing hyperoxic gases is an effective means of improving tumor oxygenation, although the efficacy of adding CO2 to the inspiratory gas has been discussed controversially. This study aimed at analyzing the impact of different inspiratory CO2 fractions on the time course of oxygenation and perfusion changes in experimental tumors during and after inspiratory hyperoxia. MATERIAL AND METHODS: Perfusion and oxygenation of rat DS-sarcomas were studied during spontaneous breathing of pure oxygen or hyperoxic gas mixtures containing different CO2 fractions (1, 2.5 or 5%). Red blood cell (RBC) flux was assessed as a measure of tumor perfusion using the laser Doppler technique and temporal changes in mean tumorpO2 were measured polarographically. RESULTS: Mean tumorpO2 increased 3.6-fold with pure oxygen, approx. 3.3-fold when 1 or 2.5% CO2 was added and 2.7-fold during carbogen breathing. RBC flux also increased by 25-30% with all gases. With pure oxygen and with 1% CO2 (+99% O2), perfusion changes paralleled those of the mean arterial blood pressure whereas with higher CO2 fractions, a decrease in resistance to flow was observed. The differences found with the various gas mixtures were more pronounced after the end of hyperoxia. With pure oxygen, perfusion immediately returned to pretreatment values whereas with higher CO2 fractions perfusion remained elevated for at least 30 min. CONCLUSIONS: Higher inspiratory CO2 fractions (2.5 or 5%) lead to a prolonged improvement of tumor perfusion after the end of inspiratory hyperoxia when compared with pure oxygen breathing. Since no principal differences in oxygenation and perfusion were seen between the gases containing 2.5 and 5% CO2, the former may be preferable for inspiratory hyperoxia.
Authors: Loreta M Rodrigues; Simon P Robinson; Paul M J McSheehy; Marion Stubbs; John R Griffiths Journal: Neoplasia Date: 2002 Nov-Dec Impact factor: 5.715
Authors: Nadeem Khan; Sriram Mupparaju; Shahryar K Hekmatyar; Huagang Hou; Jean P Lariviere; Eugene Demidenko; David J Gladstone; Risto A Kauppinen; Harold M Swartz Journal: Int J Radiat Oncol Biol Phys Date: 2010-08-31 Impact factor: 7.038
Authors: Huagang Hou; Ruhong Dong; Jean P Lariviere; Sriram P Mupparaju; Harold M Swartz; Nadeem Khan Journal: J Radiat Res Date: 2011-07-29 Impact factor: 2.724
Authors: Michael W Chan; George Nathanael; Antonella Kis; Afsaneh Amirabadi; Anguo Zhong; Tammy Rayner; Ruth Weiss; Garry Detzler; Roland Jong; Harpal Gahunia; Rahim Moineddin; Adrian Crawley; Andrea S Doria Journal: Pediatr Radiol Date: 2013-12-24