Tissue hemoglobin monitoring is unable to follow variations of arterial hemoglobin during transitions from pulsatile to constant flow in cardiac surgery.

Objective: To test whether the variations of tissue hemoglobin concentration (∆THb) measured by the FORE-SIGHT(TM) cerebral oximeter can accurately detect changes in arterial hemoglobin concentration (∆AHb) before, during, and after cardiopulmonary bypass.

Design: A prospective clinical study.

Setting: Cardiac surgery operating room.