Section 870.2770 - Impedance plethysmograph(a)Identification. An impedance plethysmograph is a device used to estimate peripheral blood flow by measuring electrical impedance changes in a region of the body such as the arms and legs.(b)Classification. Class II (special controls). The device, when it is a body composition analyzer which is not intended to diagnose or treat any medical condition, is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 870.9 .45 FR 7907, Feb. 5, 1980, as amended at 84 FR 71812 , Dec. 30, 2019