Diffuse optical monitoring of peripheral tissues during uncontrolled internal hemorrhage in a porcine model

Abstract

Reliable, continuous and noninvasive blood flow and hemoglobin monitoring in trauma patients remains a critical, but generally unachieved goal. Two optical sensing methods - diffuse correlation spectroscopy (DCS) and diffuse reflectance spectroscopy (DRS) - are used to monitor and detect internal hemorrhage. Specifically, we investigate if cutaneous perfusion measurements acquired using DCS and DRS in peripheral (thighs and ear-lobe) tissues could detect severe hemorrhagic shock in a porcine model. Four animals underwent high-grade hepato-portal injury in a closed abdomen, to induce uncontrolled hemorrhage and were subsequently allowed to bleed for 10 minutes before fluid resuscitation. DRS and DCS measurements of cutaneous blood flow were acquired using fiber optical probes placed on the thigh and earlobe of the animals and were obtained repeatedly starting from 1 to 5 minutes pre-injury, up to several minutes post shock. Clear changes were observed in measured optical spectra across all animals at both sites. DCS-derived cutaneous blood flow decreased sharply during hemorrhage, while DRS-derived vascular saturation and hemoglobin paralleled cardiac output. All derived optical parameters had the steepest changes during the rapid initial hemorrhage unambiguously. This suggests that a combined DCS and DRS based device might provide an easy-to-use, non-invasive, internal-hemorrhage detection system that can be used across a wide array of clinical settings.

Diffuse Correlation Spectroscopy at Short Source-Detector Separations: Simulations, Experiments and Theoretical Modeling

“…These conclusions are in accordance with previous findings regarding the accuracy absolute flow rates vs. relative flow at longer SDS [13,16,53]. Our results support findings from recent studies, where Equation (2) was successfully used to examine relative changes in DCS flow coefficients from both simulations and in vivo studies in animal models, at short SDS [27,28,30,31]. However, our findings also indicate that quantification of relative perfusion changes reported by these studies would be estimated more accurately, if the relative changes in perfusion at the short SDS channels were computed with MC-derived correction factors with corresponding changes in media optical properties they measured.…”

“…However, there could be clinical opportunities for using endoscopically compatible DCS probes to assess tissue perfusion in vivo, which will need to use short SDS for signal acquisition. Further, recent reports have employed DCS measurements at short SDS (<1 cm) for quantifying tissue perfusion in small animal models [27][28][29][30][31]. Surprisingly, these studies all reported that the classical diffusion-theory based theoretical expression in Equation (2) still provided good parametrization of relative changes in tissue perfusion even at short SDS used.…”

Use of infrared thermography to detect early alterations of peripheral perfusion: evaluation in a porcine model

“…Other technologies have been developed, such as NIRS (Near-infrared spectroscopy) and PPI (Peripheral perfusion index) [6,38]. More recently, spectrometry has been used to demonstrate an alteration of peripheral perfusion in a porcine model of hemorrhagic shock [39]. These methods are still under development, but have brought some evidence of impaired peripheral perfusion in critical patients [6].…”

“…Anesthesia was maintained with sevoflurane (Sevoflo, Zoetis, Malakoff, France) in 30% oxygen, in association with an intravenous constant rate infusion (CRI) of morphine 0.1 mg.kg −1 .h −1 . The respiratory rate and tidal volume were adjusted to obtain an end tidal CO2 of 4.6-6.0 kPa (35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45). Intravenous fluids (Lactated Ringer) were administered throughout the experiment at a basal rate of 5 ml.kg −1 .h −1 .…”

Small separation diffuse correlation spectroscopy for measurement of cerebral blood flow in rodents

“…Thi sufficiently ra al. demonstra highly anisot thicknesses as of DCS has n biological app DCS reflectan [31], mouse a [75,76] e detector rties, this error may not be negligible for studies in which the effect size of interest is small. As mentioned above, constraining g 2 fits to shorter τ may serve to improve accuracy, as these photons have traveled deeper through tissue [59] and become fully randomized before detection.…”