TI: Regional Oxygenation and Radiotherapy: A Study of the Degradation of Infused Hydrogen Peroxide II. Measurement of Decomposition of H2O2 Infused Into Flowing Blood DT: December 7, 1970 AU: James I. MacNaughton SO: Int. J. Radiat. Bilog., 1971, Vol. 19, No. 5, pp 415-426 AB: The degree of decomposition of hydrogen peroxide infused into blood blowing in a model system has been measured under various conditions. The results show: 1. that infused peroxide probably tends to stream, and not mix. There is no evidence of marked turbulence at the infusion point which would assist mixing. 2. decomposition is slower than previously believed. 3. in the clinical situation, hydrodynamic factors make precise determination of the pO2 impossible. 4. the probability that free peroxide perfuses tumour tissue is high. 5. in intra-arterial peroxide infusion, only plasma catalase in involved, in the relevant time, in the decomposition process. 6. a half time for catalase-peroxide reaction of approximately 0-35 sec under the conditions of these experiments. A "peroxide effect", comparable to but more potent than the "oxygen effect", is postulated, and experimental studies or earlier workers are reviewed in the light of this postulate.