Regional variations in brain oxygenation during temporary clipping in aneurysm surgery

Brain tissue oxygen concentration (PbtO(2)) monitoring has been used in aneurysm surgery to detect decreased brain oxygenation during temporary clipping. The effects of circulatory interruption according to different aneurysm locations have not been established. In this work, variations in PbtO(2) during temporary clipping were studied in anterior communicating (AcomA), posterior communicating (PcomA) origin, and middle cerebral artery (MCA) aneurysm surgery.

PbtO(2) was monitored during surgery of 41 patients; aneurysms were located in the AcomA (10 cases), origin of PcomA (8 cases), and MCA bifurcation (23 cases). Temporary clips were used in all cases. Variations in PbtO(2) values obtained during application of temporary clips were evaluated and studied according to the duration and type of circulatory interruption for each aneurysm location.

In AcomA aneurysm surgery, a significant decrease in PbtO(2) values was found in 31% of the periods of temporary clipping, whereas in PcomA and MCA aneurysm surgery, significant decreases were found in all temporary clip applications (100%). In MCA aneurysms, the amplitude of decrease in PbtO(2) was higher when the circulatory interruption lasted for 2 or more minutes, compared with shorter periods of temporary clipping.

During temporary clipping, different variations in PbtO(2) values were obtained when comparing frontal and temporal regions of monitoring: in MCA and PcomA origin aneurysms, significant variations were registered in all periods of temporary regional circulatory interruption, but the same results were not found in frontal monitoring for AcomA aneurysm surgery.