A Novel Approach to Evaluating Crosstalk for Near-Infrared Spectrometers.

Multi-channel and multi-parameter near-infrared spectroscopy (NIRS) has gradually become a new research direction and hot spot due to its ability to provide real-time, continuous, comprehensive indicators of multiple parameters. However, multi-channel and multi-parameter detection may lead to crosstalk between signals. There is still a lack of benchmarks for the evaluation of the reliability, sensitivity, stability and response consistency of the NIRS instruments. In this study, a set of test methods (a human blood model test, ink drop test, multi-channel crosstalk test and multi-parameter crosstalk test) for analyzing crosstalk and verifying the reliability of NIRS was conducted to test experimental verification on a multi-channel (8-channel), multi-parameter (4-parameter) NIRS instrument independently developed by our team. Results show that these tests can be used to analyze the signal crosstalk and verify the reliability, sensitivity, stability and response consistency of the NIRS instrument. This study contributes to the establishment of benchmarks for the NIRS instrument crosstalk and reliability testing. These novel tests have the potential to become the benchmark for NIRS instrument reliability testing.

Online Noninvasive Assessment of Human Brain Death by Near-Infrared Spectroscopy with Protocol of O2 Inspiration.

Brain death is the irreversible loss of all the functions of the brain and brainstem. Compared to traditional diagnostic methods of brain death, near-infrared spectroscopy (NIRS) is a noninvasive, objective, cost-effective, and safe way of assessment of brain death. Eighteen brain dead patients and 20 healthy subjects were studied by NIRS, with a multiple-phase protocol at varied fractions of inspired O2 (FIO2). We found that the changes in the concentration ratios of oxyhemoglobin to deoxyhemoglobin (Δ[HbO2]/Δ[Hb]) in the cerebral cortex of brain dead patients were significantly higher than those of healthy subjects, and its low-to-high FIO2 phase was most sensitive, with a recommended threshold in the range 1.40-1.50. Our study indicated that NIRS is a promising technology for assessing brain death. The success of this application potentially offers a supplementary technique for the assessment of brain death in real time in order to be able to promptly offer quality-assured donor organs.

Noninvasive and sensitive optical assessment of brain death.

Brain death is an irreversible loss of all brain functions, and the assessment is crucial for organ supply for transplantation. The noninvasive, sensitive, universally available and timely ancillary method to assess brain death has not been established. Here, we attempted to explore a noninvasive way in brain death assessment. Eighteen brain-dead patients and 20 healthy subjects were measured by near-infrared spectroscopy (NIRS), with a multiple-phase protocol at varied fraction of inspired O2 (FIO2 ). We found that the concentration changes ratios of oxyhemoglobin to deoxyhemoglobin (Δ[HbO2 ]/Δ[Hb]) in the cerebral cortex of brain-dead patients were significantly higher than those of healthy subjects. And, the Δ[HbO2 ]/Δ[Hb] in low-to-high FIO2 phase was most sensitive to distinguish brain-dead patients from healthy subjects, with a recommended threshold ranged in 1.40~1.50. The innovative incorporation of NIRS and a varied FIO2 protocol was shown to be a noninvasive and reliable way in assessing brain death. This successful attempt of NIRS application is a help for fast and accurate evaluation of brain death, promptly offering quality-assured donor organs and indicate us a protocol-aided way to expand the use of NIRS.

Functional near infrared spectroscopy in the noninvasive assessment of brain death.

Brain death, whose assessment is of great significance, is the irreversible loss of all the functions of the brain and brainstem. The traditional diagnostic methods mainly relies on complex, harmful or unstable test, including apnea test,textbf evoked potential test, etc. Functional near infrared spectroscopy (fNIRS) utilize the good scattering properties of blood corpuscle to NIR, has the ability to monitor cerebral hemodynamics noninvasively. To objectively evaluate the brain death diagnosis with fNIRS, we use our portable fNIRS oximeter to measure the physiological data of fifteen brain death patients and twenty-two patients under natural state. The varied fractional concentration of inspired oxygen (FIO2) were provided in different phase. We found that the ratio ofthe concentration changes in oxy-hemoglobin to deoxy-hemoglobin(Δ[HbO2]/Δ[Hb])in normal patients is significantly lower than brain death patients, and its restore oxygen change process in low-high-low paradigm is more remarkable. This resulting promotion indicates potential of fNIRS-measured hemodynamic index in diagnosing brain death.

A Brief Review of OPT101 Sensor Application in Near-Infrared Spectroscopy Instrumentation for Intensive Care Unit Clinics.

The optoelectronic sensor OPT101 have merits in advanced optoelectronic response characteristics at wavelength range for medical near-infrared spectroscopy and small-size chip design with build-in trans-impedance amplifier. Our lab is devoted to developing a series of portable near-infrared spectroscopy (NIRS) devices embedded with OPT101 for applications in intensive care unit clinics, based on NIRS principle. Here we review the characteristics and advantages of OPT101 relative to clinical NIRS instrumentation, and the most recent achievements, including early-diagnosis and therapeutic effect evaluation of thrombus, noninvasive monitoring of patients' shock severity, and fatigue evaluation. The future prospect on OPT101 improvements in noninvasive clinical applications is also discussed.