Comparison of frequency-domain and continuous-wave near-infrared spectroscopy devices during the immediate transition

Abstract

Background: Non-invasive monitoring of cerebral tissue oxygen saturation (rcSO 2) during transition is of growing interest. Different near-infrared spectroscopy (NIRS) techniques have been developed to measure rcSO 2. We compared rcSO 2 values during the immediate transition in preterm neonates measured with frequency-domain NIRS (FD-NIRS) with those measured with continuous-wave NIRS (CW-NIRS) devices in prospective observational studies. Methods: We compared rcSO 2 values measured with an FD-NIRS device during the first 15 min after birth in neonates with a gestational age ≥ 30 weeks but < 37 weeks born at the Erasmus MC-Sophia Children's Hospital, Rotterdam, the Netherlands, with similar values measured with a CW-NIRS device in neonates born at the Medical University of Graz, Austria. Mixed models were used to adjust for repeated rcSO 2 measurements, with fixed effects for time (non-linear), device, respiratory support and the interaction of device and respiratory support with time. Additionally, parameters such as total haemoglobin concentration and oxygenated and deoxygenated haemoglobin concentrations measured by FD-NIRS were analysed. Results: Thirty-eight FD-NIRS measurements were compared with 58 CW-NIRS measurements. The FD-NIRS rcSO 2 values were consistently higher than the CW-NIRS rcSO 2 values in the first 12 min, irrespective of respiratory support. After adjustment for respiratory support, the time-dependent trend in rcSO 2 differed significantly between techniques (p < 0.01). Conclusion: As cerebral saturation measured with the FD-NIRS device differed significantly from that measured with the CW-NIRS device, differences in absolute values need to be interpreted with care. Although FD-NIRS devices have technical advantages over CW-NIRS devices, FD-NIRS devices may overestimate true cerebral oxygenation and their benefits might not outweigh the usability of the more clinically viable CW-NIRS devices.

Near-Infrared Spectroscopy (NIRS) in Traumatic Brain Injury (TBI)

“…It also assumes that scattering is constant during the entire measurement (ΔG = 0) and DPF is considered to be between one half and one third of the actual emitter–detector separation distance. In consequence, the modified Beer–Lambert law (MBL) is used to calculate the change in chromophores concentrations [ 35 , 38 , 46 , 47 ]. However, its major challenge is to remove any superficial layer contamination from the brain signal, taking into account that the brain is covered by multiple layers which are perfused by vessels that carry hemoglobin, leading to extracerebral signals that play a contaminating role on CW-NIRS [ 48 ].…”

“…Time-resolved spectroscopy mode (TD-NIRS), uses short light pulses to illuminate the tissue, where the scattered photons take more time to be detected than the unscattered photons ( Figure 6 c). Average photons’ arrival time allows the calculation of the light pathlength, therefore enabling the calculation of the chromophores’ absolute concentrations by solving the diffusion equation [ 36 , 41 , 46 , 47 ]. In phase modulated spectroscopy (PMS), the emitted light is modulated in frequency and intensity, thus, measured attenuations and frequency shift are used to estimate the light pathlength and the absorption and scattering properties of the tissue ( Figure 6 d).…”

“…In phase modulated spectroscopy (PMS), the emitted light is modulated in frequency and intensity, thus, measured attenuations and frequency shift are used to estimate the light pathlength and the absorption and scattering properties of the tissue ( Figure 6 d). Once these are derived, at least from two wavelengths, absolute concentrations of HbO 2 and HHb can be calculated from the modified Beer–Lambert law [ 36 , 41 , 46 , 47 ].…”

Cerebral oxygenation is stable in preterm infants transitioning to heated humidified high‐flow nasal cannula therapy

“…While technically superior to continuous‐wave (CW) NIRS, FD‐NIRS devices are more susceptible to noise artefact and cerebral oxygenation values may differ when compared to CW‐NIRS devices. Additionally, the FD‐NIRS device used in this study is not approved for clinical use, limiting its utility to research settings 30 . However, phantom experiments performed by Kleiser et al (2018) have derived equations which convert SO 2 readings between the OxiplexTS and other NIRS devices.…”

Gas in scattering media absorption spectroscopy as a potential tool in neonatal respiratory care

“…NIRS measurements can be achieved using three different modes: CW, frequency domain (FD) or time domain (TD). 48 , 49 CW-NIRS uses a single emitter delivering steady light and two or more detectors with a specific distance. The photodetector is sensing the light coming back from the tissues after interacting with HbO 2 and HHb.…”