Correlation Of Transconjunctival Po2 With Cerebral Oxygen Delivery During Cardiopulmonary Resuscitation In Dogs

The relationship between transconjunctival PO2 (PcjO2) and cerebral oxygen delivery (DO2) was examined in dogs during sinus rhythm and CPR with an inflatable vest. Microsphere-determined cerebral blood flow (CBF), DO2, and PcjO2 readings were normal during sinus rhythm. During CPR, with carotid pressure of 82 +/- 11/25 +/- 5 (SEM) mm Hg, cerebral perfusion and DO2 fell by 53% and 57%, respectively, while PcjO2 fell by 87%. After epinephrine administration, carotid pressure increased to 128 +/- 13/48 +/- 9 mm Hg, and CBF and DO2 rose to 130% and 115% of pre-arrest levels, respectively, but PcjO2 readings remained at 11% of control values. Thus, PcjO2 failed to reflect accurately either CBF or DO2 during CPR. In the presence of epinephrine, PcjO2 does not seem to provide an accurate index of the effectiveness of CPR.