Non-invasive estimation of intracranial pressure by diffuse correlation spectroscopy

Author(s):  
Jonas B. Fischer ◽  
Ameer Ghouse ◽  
Susanna Tagliabue ◽  
Federica Maruccia ◽  
Anna Rey-Perez ◽  
...  
Author(s):  
Jonas B. Fischer ◽  
Susanna Tagliabue ◽  
Federica Maruccia ◽  
Amelia Jiménez-Sánchez ◽  
Eashani Sathialingam ◽  
...  

2018 ◽  
Vol 40 (1) ◽  
pp. 187-203 ◽  
Author(s):  
Tiffany S Ko ◽  
Constantine D Mavroudis ◽  
Wesley B Baker ◽  
Vincent C Morano ◽  
Kobina Mensah-Brown ◽  
...  

Management of deep hypothermic (DH) cardiopulmonary bypass (CPB), a critical neuroprotective strategy, currently relies on non-invasive temperature to guide cerebral metabolic suppression during complex cardiac surgery in neonates. Considerable inter-subject variability in temperature response and residual metabolism may contribute to the persisting risk for postoperative neurological injury. To characterize and mitigate this variability, we assess the sufficiency of conventional nasopharyngeal temperature (NPT) guidance, and in the process, validate combined non-invasive frequency-domain diffuse optical spectroscopy (FD-DOS) and diffuse correlation spectroscopy (DCS) for direct measurement of cerebral metabolic rate of oxygen ( CMRO2). During CPB, n = 8 neonatal swine underwent cooling from normothermia to 18℃, sustained DH perfusion for 40 min, and then rewarming to simulate cardiac surgery. Continuous non-invasive and invasive measurements of intracranial temperature (ICT) and CMRO2 were acquired. Significant hysteresis ( p < 0.001) between cooling and rewarming periods in the NPT versus ICT and NPT versus CMRO2 relationships were found. Resolution of this hysteresis in the ICT versus CMRO2 relationship identified a crucial insufficiency of conventional NPT guidance. Non-invasive CMRO2 temperature coefficients with respect to NPT ( Q10 = 2.0) and ICT ( Q10 = 2.5) are consistent with previous reports and provide further validation of FD-DOS/DCS CMRO2 monitoring during DH CPB to optimize management.


2019 ◽  
Vol 9 (15) ◽  
pp. 3047 ◽  
Author(s):  
Karthik Vishwanath ◽  
Sara Zanfardino

Diffuse correlation spectroscopy (DCS) has widely been used as a non-invasive optical technique to measure tissue perfusion in vivo. DCS measurements are quantified to yield information about moving scatterers using photon diffusion theory and are therefore obtained at long source-detector separations (SDS). However, short SDS DCS could be used for measuring perfusion in small animal models or endoscopically in clinical studies. Here, we investigate the errors in analytically retrieved flow coefficients from simulated and experimental data acquired at short SDS. Monte Carlo (MC) simulations of photon correlation transport was programmed to simulate DCS measurements and used to (a) examine the accuracy and validity of theoretical analyses, and (b) model experimental measurements made on phantoms at short SDS. Experiments consisted of measurements from a series of optical phantoms containing an embedded flow channel. Both the fluid flow rate and depth of the flow channel from the liquid surface were varied. Inputs to MC simulations required to model experiments were obtained from corrected theoretical analyses. Results show that the widely used theoretical DCS model is robust for quantifying relative changes in flow. We also show that retrieved flow coefficients at short SDS can be scaled to retrieve absolute values via MC simulations.


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