Extracellular muscle surface pO2 and pH heterogeneity during hypovolemia and after reperfusion

Tissue pO2 (ptO2) and pH (ptH) in skeletal muscle are known to be affected at an early stage of hemorrhage. This study examines the effects of hypovolemia on the extracellular ptO2 and ptH distributions at multiple tissue sites using a recently developed multipoint microelectrode, that provides simultaneous measurements of ptO2 and ptH. The results show that the development of tissue acidosis occurs in spatially different patterns and that the magnitude of the acidosis at some tissue sites is larger and remains longer than previously known. The changes described are believed to be due to the heterogeneous blood flow seen during shock and after reperfusion. The degree of local acidosis was correlated to the relative decrease in oxygen tension at that particular site. These new findings can be of importance for the development of future resuscitative measures as well as in constructing patient monitoring systems.