# Frequency domain shortwave infrared spectroscopy (FD-SWIRS) for volume status monitoring during hemodialysis in end stage kidney disease

> **NIH NIH R21** · BOSTON UNIVERSITY (CHARLES RIVER CAMPUS) · 2022 · $223,986

## Abstract

PROJECT SUMMARY
Chronic kidney disease (CKD), or the gradual loss of kidney function, is the ninth leading cause of death in the
US and poses an astronomical healthcare burden. CKD eventually leads to end-stage kidney disease (ESKD),
requiring hemodialysis treatment (HD) or kidney transplant for survival. HD is the process of removing excess
water, solutes, and toxins from the blood in patients, as kidneys can no longer perform these natural functions.
In 2017 there were 746,557 Americans with ESKD, and 70% of these were on HD. Patients with ESKD
accumulate fluid in between HD sessions, whose removal is a quintessential function of HD. Insufficient fluid
removal on HD results in volume overload contributing to hypertension, heart failure and eventual cardiovascular
mortality. Excess fluid removal results in hypotension, muscle cramps and compromises vitality after HD. Thus,
it is critical to maintain dry weight, or weight without excess fluid in CKD patients. Despite the central importance
of maintaining volume homeostasis in patients with ESKD, there are currently no quantitative standards for
monitoring volume status of patients undergoing HD. The volume assessment of patients on HD remains the
most challenging aspect of nephrology practice. This project aims to develop frequency-domain shortwave
infrared spectroscopy (FD-SWIRS) for the unmet clinical need of HD volume status monitoring in patients with
ESKD. The SWIR wavelength band (also called NIR II) is more sensitive to water and lipids compared to the
visible or NIR bands, and can potentially provide deeper tissue measurements. FD-SWIRS will provide
measurements of the absolute absorption and reduced scattering coefficients over a broad wavelength range
(900-1310 nm). FD-SWIRS would represent a new technology, and to the best of our knowledge, no similar
technologies have been used for HD monitoring. FD-SWIRS will provide three unique sources of label-free
contrast for HD monitoring: 1) tissue molar water concentration changes calculated from broadband (900-1310
nm) absorption coefficients (µa), 2) broadband reduced scattering (µs′), and 3) bound water index (BWI), which
utilizes subtle spectral shifts related to the binding of water molecules to proteins in tissue. We hypothesize that
that these sources of contrast will accurately reveal volume status and provide a non-invasive indicator of
extracellular versus intracellular water, which has been shown to be important for volume assessment. We will
first develop an FD-SWIRS system and validate performance through rigorous system testing. A multi-layer
inverse model will be developed to extract deep tissue optical properties. We will then perform pre, post and
intradialytic measurements of FD-SWIRS in 50 dialysis sessions with the hypothesis that there will be alteration
in FD-SWIRS signal between pre and post-HD time points. In addition, we posit that FD-SWIRS signal will
change throughout dialysis session and may coincide or precede the...

## Key facts

- **NIH application ID:** 10432546
- **Project number:** 1R21DK132784-01
- **Recipient organization:** BOSTON UNIVERSITY (CHARLES RIVER CAMPUS)
- **Principal Investigator:** Vipul C Chitalia
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $223,986
- **Award type:** 1
- **Project period:** 2022-03-01 → 2024-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10432546

## Citation

> US National Institutes of Health, RePORTER application 10432546, Frequency domain shortwave infrared spectroscopy (FD-SWIRS) for volume status monitoring during hemodialysis in end stage kidney disease (1R21DK132784-01). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10432546. Licensed CC0.

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