title: A novel method to measure regional muscle blood flow continuously using NIRS kinetics information.
abstract: BACKGROUND
  This article introduces a novel method to continuously monitor regional muscle blood flow by using Near Infrared Spectroscopy (NIRS). We demonstrate the feasibility of the new method in two ways: (1) by applying this new method of determining blood flow to experimental NIRS data during exercise and ischemia; and, (2) by simulating muscle oxygenation and blood flow values using these newly developed equations during recovery from exercise and ischemia.
  
  
  METHODS
  Deoxy (Hb) and oxyhemoglobin (HbO2), located in the blood of the skeletal muscle, carry two internal relationships between blood flow and oxygen consumption. One is a mass transfer principle and the other describes a relationship between oxygen consumption and Hb kinetics in a two-compartment model. To monitor blood flow continuously, we transfer these two relationships into two equations and calculate the blood flow with the differential information of HbO2 and Hb. In addition, these equations are used to simulate the relationship between blood flow and reoxygenation kinetics after cuff ischemia and a light exercise. Nine healthy subjects volunteered for the cuff ischemia, light arm exercise and arm exercise with cuff ischemia for the experimental study.
  
  
  RESULTS
  Analysis of experimental data of both cuff ischemia and light exercise using the new equations show greater blood flow (four to six times more than resting values) during recovery, agreeing with previous findings. Further, the simulation and experimental studies of cuff ischemia and light exercise agree with each other.
  
  
  CONCLUSIONS
  We demonstrate the accuracy of this new method by showing that the blood flow obtained from the method agrees with previous data as well as with simulated data. We conclude that this novel continuous blood flow monitoring method can provide blood flow information non-invasively with NIRS.
authors.affiliation: Department of Biochemistry and Biophysics, Medical School of University of Pennsylvania, Philadelphia, PA 19104, USA. nioka@mail.med.upenn.edu
authors.forename: Shoko
authors.initials: S
authors.lastname: Nioka
authors.forename: Ryotaro
authors.initials: R
authors.lastname: Kime
authors.forename: Ulas
authors.initials: U
authors.lastname: Sunar
authors.forename: Joohee
authors.initials: J
authors.lastname: Im
authors.forename: Meltem
authors.initials: M
authors.lastname: Izzetoglu
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.forename: Burak
authors.initials: B
authors.lastname: Alacam
authors.forename: Britton
authors.initials: B
authors.lastname: Chance