title: Length-normalized pulse photoplethysmography: a noninvasive method to measure blood hemoglobin.
abstract: To determine whether blood hemoglobin concentration ([Hb]) could be measured noninvasively as the ratio of pulsatile changes in attenuation (absorbance plus scatter) of light (D) across a body part to changes in light path length (l), we measured transmission of near-infrared light (905 +/- 10 nm) through a finger, using a modified pulse oximeter, and simultaneously monitored fingertip diameter, using a sonomicrometer. In 25 subjects with [Hb] ranging from 3.1 to 18.2 gm/dl, and with normal oxygenation, average D/l ratio over 30-60 s correlated strongly with [Hb] measured by Coulter counter (r = 0.84, p << 0.001), though with considerable scatter, with absolute value of differences averaging 17% of the mean. Using 12 gm/dl and 0.75 mm(-1) as the lower limits of normal for [Hb] and D/l, respectively, two of nine normals had low (D/l) (78% specificity), and only one of 16 anemic subjects had borderline normal (D/l) (94%-100% sensitivity). The positive predictive value of a low (D/l) was 88% and the negative predictive value was 87.5%. With further development, this technique may reduce the need for phlebotomy, thereby reducing risks and costs and improving the experience of being a patient.
authors.affiliation: Pulmonary Medicine Division, Montefiore Medical Center and Albert Einstein College of Medicine, Bronx, NY10467, USA. taldrich@montefiore.org
authors.forename: Thomas K
authors.initials: TK
authors.lastname: Aldrich
authors.forename: Mark
authors.initials: M
authors.lastname: Moosikasuwan
authors.forename: Samir D
authors.initials: SD
authors.lastname: Shah
authors.forename: Kedar S
authors.initials: KS
authors.lastname: Deshpande
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000740:Anemia / Q000097:blood*; D002675:Child, Preschool; D019544:Equipment Failure Analysis; D005240:Feasibility Studies; D005260:Female; D006452:Hemoglobinometry / Q000379:methods*; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D008297:Male; D010092:Oximetry / Q000295:instrumentation / Q000379:methods*; D017156:Photoplethysmography / Q000295:instrumentation / Q000379:methods*; D011086:Polycythemia / Q000097:blood*; D011786:Quality Control; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D006454:Hemoglobins