[Usefulness of regional cerebral oxygen saturation monitoring in balloon test occlusion]

Recently, temporary balloon test occlusion (BTO) of the internal carotid artery (IC) has become a well accepted procedure for preoperative evaluation of patients with IC large aneurysms. However, it might be dangerous to move patients fitted with a balloon catheter to the room for single-photon emission computed tomography (SPECT). We attempted to clarify the usefulness of regional cerebral oxygen saturation (rSO2) monitoring during BTO, comparing cerebral blood flow (CBF) obtained from SPECT.

Eight patients with an IC large aneurysm underwent BTO with rSO2 monitoring. Regions of interest in the SPECT were defined in the area below the rSO2 sensor of each hemisphere. Correlations among rSO2, CBF, stump pressure and appearance of symptoms were discussed.

The rSO2 significantly reduced during BTO (74.1 +/- 1.2 to 60.4 +/- 2.7%, p < 0.001). The individual decreases in rSO2 correlated with decreases of CBF from SPECT (r = 0.966, P < 0.001). Four patients with deltarSO2 (baseline rSO2 - rSO2 during IC occlusion) less than 12 points had no symptoms, but 4 patients with deltarSO2 more than 14 points had some symptoms. The stump pressure had no correlation with CBF and rSO2.

The rSO2 significantly correlated with CBF from SPECT and related with appearance of symptoms. Our results revealed that rSO2 monitoring was useful in BTO, and SPECT could be skipped in some cases to determine the strategies for treatment of IC large aneurysms.