[Cerebral oximetry in neurosurgical patients with cerebrovascular diseases. I. Analysis of causes of intraoperative changes in rSO2 values and its prognostic significance].

A total of 144 neurosurgical interventions were performed in 138 patients with cerebrovascular diseases (arterial aneurysms in the acute and cold periods after a subarachnoidal hemorrhage, arteriovenous malformations, and carotid-cavernous anastomoses). Intraoperative monitoring of regional saturation of hemoglobin with oxygen in the blood flowing in brain vessels was carried out by a cerebral oximeter INVOS 3100 for early intraoperative diagnosis of cerebral ischemia. This paper analyzes factors affecting changes in rSO2 parameter during surgery and discusses the prognostic significance of the detected shifts. Various factors affected the time course of rSO2: decrease in AP within the framework of controlled arterial hypotone and other causes, insertion of autosupported retractor spatulae, temporary clipping and embolism of cerebral arteries, vasospasm, aneurysm rupture, dissection of arteriovenous malformation, etc. Any intraoperative shift of rSO2 surpassing 5%, no matter of what direction (decrease or increase), deserves special attention of anesthesiologist, as it indicates development of cerebral ischemia with a high degree of probability.