A plethysmograph for the measurement of digital blood flow.

Venous occlusion plethysmography using a water-filled plethysmograph is an accurate and reliable method for the measurement of limb flow which has been used for many years. The technique has been adapted to produce a plethysmograph for the measurement of digital blood flow. The device is small, light, cheap, simple to use, and can be calibrated directly with the digit 'in situ'. It is especially suitable for the assessment of digital blood flow, since flow through a large portion of the whole digit is measured and the local temperature of the digit is accurately controlled.