Cortical somatosensory evoked potentials during acute hemorrhagic hypotension

Cortical somatosensory evoked potential (SEP) recording to lower-limb stimulation was performed on a patient to monitor surgery for scoliosis. Intraoperatively, the patient developed acute and irreversible hemorrhagic hypotension. Cortical SEPs were clearly present with systolic blood pressures in the low 50s and upper 40s (mm Hg). The potentials deteriorated significantly with systolic pressures in the low 40s and disappeared with further reduction in systemic blood pressures.