Point-of-Care Noninvasive Hemoglobin Determination Using Fiber Optic Reflectance Spectroscopy

Abstract

Rapidly identifying anemia through qualitative observation of the palpebral conjunctiva for pallor is standard medical practice. We report on the ability of using a fiber optic array probe to collect diffusely reflected light from the palpebral conjunctiva and measure hemoglobin concentration noninvasively. Patients (N=102) admitted to the emergency department and receiving a complete blood count (CBC) were enrolled as a convenience set. The tarsal plate was exposed by averting the lower eyelid and illuminated with a white LED while diffusely reflected light was collected using a fiber optic probe and commercial grating spectrometer. Spectra were analyzed using partial least squares regression to extract hemoglobin concentration information and compare to the CBC result. The probe and algorithm demonstrated correlation coefficient of r = 0.82 and standard error of 1.05 g/dL compared to invasive CBC test. Experimental error is due to variability in distance and position of the probe relative to the conjunctiva. This technique has shown the ability to measure total hemoglobin noninvasively and in real-time at the point-of-care using diffuse reflectance spectroscopy of the tarsal plate, leading to potential inclusion of this class of device as a triage centric tool to identify anemia appearing with internal hemorrhage or other acute conditions.

Reflectance spectrometry for real-time hemoglobin determination of placental vessels during endoscopic laser surgery for twin-to-twin transfusion syndrome

“…We have previously demonstrated that, when vascularized tissues are illuminated by a light source with known spectral signature, the relative reflectance intensity in the lower end of the visible spectrum correlates well with the serum Hb concentration. This principle has already been applied to design a portable noninvasive Hb monitor for use in an emergency department or office setting [7,9,14].…”

“…Three different methods of data capture were compared, as the circumstances in laparoscopy differ from the previously validated spectrometry techniques. In contrast with the portable monitor used to analyze the conjunctival tissues [14], the intraoperative setup uses the (strong) light source from the endoscopic tower. Furthermore, small-and medium-sized vessels are interrogated individually, whereas conjunctival analysis captures the reflected light off a capillary bed.…”

Photonics‐based In Vivo total hemoglobin monitoring and clinical relevance

“…This can have the advantage of simplifying the device to a single point spectrometer, but making the calibration and regression analysis less susceptible to variation in tissue optical properties. Our group has disclosed the use of visible reflectance spectroscopy analyzing the palpebral conjunctiva (inner lining of the eyelid) as a method of noninvasively monitoring Hgb [42,43]. Diffuse reflectance spectra were collected from the palpebral conjunctiva and analyzed using a partial least squares regression calibration and leave one out cross validation with the prediction set also used as the calibration set.…”

Progressive evaluation in spectroscopic sensors for non-invasive blood haemoglobin analysis—a review

“…Anaemia is one of the world's most serious health issues and a major contributor to the genesis of disability (Jay et al 2007, McMurdy et al 2008, McMurdy et al 2009, Kassebaum et al 2014, Kim et al 2014. The prevalence of anaemia is 42.6% in children aged from 9 months to 5 years, and it is 38.2% in pregnant women at the global level (World Health Organization (WHO) 2015).…”