Serum pH may not tell the complete story in describing the body's response to disease processes. To provide information we have developed a technique for measuring tissue pH and have collected data from animals in which their physiology was altered by either hemorrhagic shock, lactic acid and bicarbonate infusion, or altered ventilation. We conclude that the tissue and serum pH vary in the same direction in the situations tested, but the magnitude of change depends upon the insult to the animal. We conclude there is sufficient evidence to show that tissue pH is a sensitive index to changes in tissue perfusion and might, therefore, be used clinically.
Wolpert PW, Noller K, Shaughnessy D, Houchin DN, Baccari ME, Miller FA. Tissue pH: A New Clinical Tool. Arch Surg. 1970;101(2):308–313. doi:10.1001/archsurg.1970.01340260212031