In present-day pulse oximeters, oxygen saturation in arterial blood (SpO2) is computed by utilizing an empirical relationship extracted from a calibration curve. The calibration curve is obtained by curve-fitting data acquired from volunteers. A novel method of computation of SpO2 that does not require the use of a calibration curve is presented in this paper. Based on a model for the attenuation of light through skin, tissue, bone, and blood, suitable processing steps are identified so that the analytical expression derived for the estimation of SpO2 becomes free of not only patient but sensor-dependent parameters as well. The experimental results presented in this paper establish the efficacy of the proposed method. © 2009 IEEE.

Boby George

Department of Electrical Engineering

Varadarajan Jagadeesh Kumar

Analytical expressions

ARTERIAL BLOODS

Biomedical signal processing

Calibration curves

METHOD OF MEASUREMENTS

Novel methods

OXYGEN SATURATION

PHOTOPLETHYSMOGRAPH (PPG)

PROCESSING STEPS

PULSE OXIMETER

blood

Calibration

Curve fitting

ELECTRONIC MEDICAL EQUIPMENT

Oxygen

signal processing

OXIMETERS

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

A Novel Calibration-Free Method of Measurement of Oxygen Saturation in Arterial Blood

IEEE Transactions on Instrumentation and Measurement

A Magnetoplethysmogram (MPG) is obtained by placing a permanent magnet in proximity to a blood vessel such as radial artery and the resulting magnetic flux detected using a flux sensor. It is investigated here and shown that if either the magnet or the sensor is in contact with the skin, the resulting MPG is affected by artifacts. To eliminate such artifacts, a noncontact MPG sensor system is devised and implemented to obtain artifact free MPG. Measurements with MPG sensor in contact and without contact with the skin, obtained from 6 volunteers, establish that the MPG signals obtained using the sensor in contact with the skin is indeed affected by artifacts. © 2018 IEEE.

2018 9th Cairo International Biomedical Engineering Conference, CIBEC 2018 - Proceedings

Motion Artifact-Free Magnetoplethysmogram

A method for determining the concentration of hemoglobin in arterial blood, non invasively, is explored in this paper. A permanent magnet is placed just above the radial artery of a person whose hemoglobin concentration is to be ascertained. The flux produced by the permanent magnet (that links with the blood flow in the radial artery) is sensed to obtain a signal called magnetic plethysmogram (MPG). In this paper, an analytical model for a magnetic plethysmogram is derived. Using the proposed analytical model, a method of estimation of the concentration of hemoglobin in arterial blood is derived. The proposed method is then validated through a limited clinical study. The results of the clinical study establish the viability of measuring hemoglobin concentration, noninvasively, using magnetic plethysmogram. © 2016 IEEE.

2016 IEEE International Symposium on Medical Measurements and Applications, MeMeA 2016 - Proceedings

Non-invasive measurement of hemoglobin concentration using magnetic plethysmo gram

We study the potential of reflectance photoplethysmography (PPG) in monitoring free flaps for arterial and venous thrombosis in post-surgical scenarios. Circulatory disruptions due to thrombosis were simulated using limb ischemia method on 30 volunteers. Arterial and venous occlusions were conducted in this study. The variation in blood flow in the region of interest was captured by a custom built sensor and data acquisition system using dual wavelength reflectance photoplethysmography. The main chromophores in blood, oxygenated and reduced hemoglobin, showed good variation to visible - near infrared wavelengths with concentration and volume changes. Sensitivity of the prototype device in detecting arterial and venous circulation disruptions was evaluated at various different threshold levels of signal parameters. The device showed strong capability to accurately detect circulatory disruptions and has potential in post-surgical monitoring of free flaps. © 2016 IEEE.

A reflectance photoplethysmography based device to detect circulatory disruptions

Photo-plethysmo-graphy (PPG) is a noninvasive method of obtaining a signal proportional to blood volume changes using light. From the initial trials seven decades back, the PPG technique has grown leaps and bounds and today its application has become indispensible not only during surgical procedures but also in patient monitoring in critical care environment. This paper traces the path of advancement of this technique and highlights the research outcomes of an "Indo German" collaborative research between Indian Institute of Technology Madras, Chennai, India and Technical University (RWTH) Aachen, Germany funded by ministry of science (BMBF), Germany, Research projects funded by Department of Science and Technology and Department of Biotechnology, Government of India. © 2013 IEEE.

2013 IEEE International Conference on Smart Instrumentation, Measurement and Applications, ICSIMA 2013

Photoplethsymography for non-invasive diagnostics

Photoplethysmography (PPG) has come to be accepted as a common, non-invasive methodfor measuring the level ofoxygen saturation in arterial blood. This paper describes a variation of the accepted PPG technique, to provide a contact-less and non-invasive method of characterizing dermal perfusion. It employs a 3-CCD, multi-spectral camera, to image the selected area. The acquired images are analysed by making use of the fact that the absorption co-efficient of oxygenated blood is more in the Infra-Red (IR) region of the spectrum, when compared to the red region. This fact is utilised to characterize the extent of dermal perfusion in the selected area of the skin. ©2008 IEEE.

Conference Record - IEEE Instrumentation and Measurement Technology Conference

Contact-less, multi-spectral imaging of dermal perfusion

Existing methods of pulse oximetry rely on a calibration curve for the estimation of oxygen saturation in arterial blood (SpO2). A novel method of computation of SpO2 that does not require the use of a calibration curve is presented in this paper. Based on a model proposed here for the propagation of light through skin, tissue, bone and blood, suitable processing steps are identified so that the analytical expression derived for the estimation of SpO2 becomes free of patient and sensor dependent parameters. Experimental results presented herein establish the efficacy of the proposed method. ©2008 IEEE.

A novel method of measurement of oxygen saturation in arterial blood

System Theory and Practical Applications of Biomedical Signals

IEEE Instrumentation & Measurement Magazine

The measurement of oxygen saturation in arterial and venous blood

IEEE Engineering in Medicine and Biology Magazine

Extinction coefficients of hemoglobin for near-infrared spectroscopy of tissue

IEEE Transactions on Biomedical Engineering

Pulse Oximetry Theory and Calibration for Low Saturations

A novel calibration-free method of measurement of oxygen saturation in arterial blood

Journal	IEEE Transactions on Instrumentation and Measurement
ISSN	00189456
Open Access	No