Newly developed all solid state catheter oxygen pressure (Po2) and pH electrodes were evaluated in dogs in respiratory acidosis and hemorrhagic shock. The electrodes were inserted into the blood vessels and thigh muscle by a percutaneous puncture technique.
In animals with respiratory acidosis, arterial, venous, and intramuscular pH decreased in parallel as arterial carbon dioxide pressure (Pco2) increased. During severe acidosis, arterial and venous Po2 did not change appreciably, but intramuscular Po2 decreased moderately, indicating decreased tissue perfusion.
In animals with hemorrhagic shock, intramuscular Po2 decreased in proportion to the blood loss, whereas the reduction in intramuscular pH and blood pressure lagged behind blood loss. A similar finding was observed during reinfusion of shed blood in surviving animals. In the animals that died, intramuscular Po2 and pH remained low after the reinfusion of all shed blood, although arterial blood pressure did return to base line levels.
Wakabayashi A, Nakamura Y, Woolley T, Mullin PJ, Watanabe H, Ino T, Connolly JE. Continuous Percutaneous Monitoring of Muscle pH and Oxygen PressureA New Technique for in Vivo Use. Arch Surg. 1975;110(7):802-805. doi:10.1001/archsurg.1975.01360130034007