Device and method for blood hemoglobin measurement without carboxyhemoglobin interference

Abstract

A method for blood haemoglobin measurement without carboxyhaemoglobin interference comprises converting oxyhemoglobin, deoxyhemoglobin and methemoglobin into a methemoglobin derivative, i.e. Imidazole-methemoglobin. Imidazole-methemoglobin and carboxyhemoglobin are collectively quantified by the reflectance spectroscopy of the matrix at 525 nm, the isobestic point between Imidazole-methemoglobin complex and carboxyhemoglobin molecule.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a divisional of U.S. patent application Ser. No. 14 / 412,459 filed on Jan. 2, 2015, which is a national phase application of the International Application No. PCT / IN2013 / 000406 filed on Jul. 2, 2013, which claims priority to Indian Patent Application No. 2074 / DEL / 2012 filed on Jul. 3, 2012, each of which is incorporated by reference herein.BACKGROUNDField[0002]The present invention generally relates to a medical device and a method for blood hemoglobin measurement. More specifically, the present invention relates to a biosensor for blood hemoglobin measurement without carboxyhemoglobin interference.Description of Related Art[0003]Hemoglobin is a metalloprotein of red blood cells and is one of the major constituent of whole blood which is responsible for transporting oxygen in mammals. Hemoglobin primarily exists in five different forms namely, oxy-hemoglobin, deoxy-hemoglobin, methemoglobin, carboxy-hemoglobin and sulfh...

AI Technical Summary

Benefits of technology

The patent is about a new device and method for measuring blood hemoglobin that is portable, easy to use, and accurate. The device requires a small amount of blood sample, making it easier to collect. The method measures the percentage of carboxyhemoglobin in total hemoglobin, which is not affected by changes in the percentage of carboxyhemoglobin in whole blood. Overall, the device and method provide an accurate measurement of blood hemoglobin.

Problems solved by technology

Measuring total hemoglobin accurately and in a cost effective manner is a challenging task primarily due to three reasons.

First, different forms of hemoglobin have different oxidation states and hence they all cannot be quantified using any single redox reaction.

Second, different forms of hemoglobin have different and overlapping optical absorbance spectra with different molar extinction coefficient.

Third, due to their high stability, carboxyhemoglobin and sulfhemoglobin do not react readily with most of the reactants, including oxidants and substituents, and hence their optical spectral interference with any hemoglobin derivatives is practically unavoidable.

Such analyzer systems are highly expensive as they require complex and expensive optical & computing systems.

This method is highly error prone as it heavily depends on the assumed hematocrit value, which is different in different samples.

Moreover, carboxy-hemoglobin's optical absorbance spectrum interferes with the spectra of most of the hemoglobin derivatives.

With varying concentration of carboxy-hemoglobin, this interference of carboxyhemoglobin leads to inaccuracy in results while quantifying the complex at its peak absorbance wavelength.

Such approach fails to address the carboxyhemoglobin interference problem.

Moreover, since this approach requires measurement of absorbance of blood in reagents coated cuvettes, it requires a large amount of blood sample for testing.

These methods too fail to convert to the carboxyhemoglobin form to common specie due to highly stability of this form and its resistance to reactivity with most of the chemical reactions.

This method stays under a risk of low sensitivity and poor signal to noise ratio due to three reasons.

First, the molar extinction coefficient of different forms of hemoglobin at 523 nm is low (nearly 50% of extinction coefficient of oxy-hemoglobin at its peak absorbance wavelength, 540 nm), resulting in low sensitivity of the device and hence inability to differentiate between different concentrations of hemoglobin.

Second, the method is susceptible to low signal to noise ratio as the spectrum of methemoglobin at 523 nm has no clearly differentiated peak and is almost parallel to the abscissa.

This phenomenon also adds to the inaccuracy of the device.

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