Percutaneous monitoring of tissue pH with a polymer membrane pH transducer

Publisher Summary This chapter discusses a study to investigate the percutaneous monitoring of tissue pH with a polymer membrane pH transducer. The BI pH transducer required 8–12 min for stabilization after placement in the tissue. During the steady state under general anesthesia in the mechanically ventilated dog, the baseline values were arterial blood pH 7.331 ± 0.042 and pHe in the subcutaneous tissue 7.21 ± 0.076 and pHe at the intramuscular site pHe/im 7.265 ± 0.102. The 14-week-old puppies entered the experiment in a state of metabolic acidosis with pH/art 7.25 ± 0.04, pHe/sc 7. 26 ± 0.04, PaCO 2 39 ± 6 torr, and blood lactate 1. 14 ± 0.17 mmol/1. Mean arterial pressure fell during the third bleed and did not recover till the shed blood was reinfused. PHe/sc had started to decrease during the second bleed. A significant pH gap had developed in the 20 min after the 20% blood volume loss, with pH/art still 7.25 ± 0.03, but pHe/sc 7. 18 ± 0.06. At this point neither MAP nor heart rate showed any deviation from the base line. In the hypoperfusion phase after the BV loss totaled 42%, the pH gap widened progressively till reinfusion of shed blood. Following fluid resuscitation, pHe/sc recovered, but slower than pH/art.