Sonomicrometry data were collected at 250 Hz by the sonomicrometer
Hobo et al., "Cardiac output measurements using sonomicrometer
crystals on the left ventricle at rest and exercise," Equine Veterinary Journal, vol.
have reported on the ability to use NIR transmission through the fingertip at a single pseudoisosbestic wavelength (905 nm) coupled with a sonomicrometer
to monitor pulsatile changes in the optical pathlength through the finger as well as correct for interpatient variation in finger diameter (25).