title: Photoplethysmography for non-invasive in vivo measurement of bone hemodynamics.
abstract: Developments in photoplethysmography (PPG) hardware make this device a promising tool for non-invasive deep-tissue hemodynamic measurements. The aim of this study was to validate the use of PPG as a tool for non-invasive bone hemodynamic measurements. A new PPG device capable of measuring bone hemodynamic responses was designed, tested and validated. Validation experiments included cold exposure, arterial occlusion, skin occlusion and nitroglycerin exposure. Cold exposure resulted in a decrease in skin perfusion (p = 0.011) and bone perfusion (p = 0.005); arterial occlusion also resulted in decreased skin perfusion (p < 0.001) and bone perfusion (p = 0.008), with arterial occlusion resulting in a greater decrease in perfusion than cold exposure. The independence of the skin and bone PPG signals was demonstrated by the ability to independently increase (p = 0.003) and decrease (p = 0.005) the skin signal without significantly affecting the bone signal. Our experiments build upon and expand previous PPG developments and validation studies. Our custom-made PPG hardware represents a state-of-the-art tool for non-invasive monitoring of deep tissues, and our data support the use of PPG as a valid tool for measuring bone hemodynamic responses in vivo.
authors.affiliation: Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, 77 Mass Ave., Cambridge, MA 02139, USA. jmateus@alum.mit.edu
authors.forename: Jaime
authors.initials: J
authors.lastname: Mateus
authors.forename: Alan R
authors.initials: AR
authors.lastname: Hargens
mesh_terms: D001158:Arteries / Q000503:physiopathology; D001842:Bone and Bones / Q000098:blood supply* / Q000502:physiology*; D003080:Cold Temperature; D003251:Constriction, Pathologic; D004566:Electrodes; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008297:Male; D005996:Nitroglycerin; D017156:Photoplethysmography / Q000379:methods*; D012815:Signal Processing, Computer-Assisted; D012867:Skin / Q000098:blood supply
chemical_list: D005996:Nitroglycerin