Can somatosensory evoked potential monitoring predict energy dynamics during controlled hypotension?

Somatosensory evoked potentials and redox (reduction/oxidation ratio) of cytochrome a,a3 were studied simultaneously before, during, and after controlled hypotension used for arteriovenous malformation resection. These studies were also conducted before and after ED-IC (external-internal carotid) bypass procedures for treatment of patients with transient ischaemic attacks. The former served as an acute model and the latter as a chronic model of low blood flow (ischaemia). The use of non-invasive reflection spectrophotometry (for redox studies) in conjunction with somatosensory evoked potentials (SSEP) has demonstrated that metabolic and electrophysiological changes parallel each other during "controlled" hypotension. The authors conclude that an analysis of SSEP changes are valuable in the study of metabolic and functional states of the brain during controlled hypotension.