ABSTRACT
This chapter introduces the capacity to monitor the individual's level of fatigue might be useful in the range of operational environments listed. Transcranial Doppler Sonography (TCD) measures the difference in frequency between the outgoing and reflected energy as the outgoing energy strikes moving erythrocytes. At a practical level, cerebral blood flow velocity (CBFV) as measured by the TCD procedure is potentially a useful addition to diagnostic tests for operator fatigue. TCD is a noninvasive neuroimaging technique that employs ultrasound signals to gauge CBFV or hemovelocity in the middle, anterior, and posterior intracranial arteries. The utility of TCD in the transportation context is also supported by data showing bilateral declines in CBFV during a monotonous drive. The utility of TCD-determined CBFV as a diagnostic index of alertness suggests that other hemodynamic measures, especially Functional Near-Infrared Spectroscopy measures of regional cerebral oxygen saturation 2 should be similarly related to vigilance.
