Diffuse optical monitoring of hemodynamic changes in piglet brain with closed head injury

Abstract

We used a nonimpact inertial rotational model of a closed head injury in neonatal piglets to simulate the conditions following traumatic brain injury in infants. Diffuse optical techniques, including diffuse reflectance spectroscopy and diffuse correlation spectroscopy (DCS), were used to measure cerebral blood oxygenation and blood flow continuously and noninvasively before injury and up to 6 h after the injury. The DCS measurements of relative cerebral blood flow were validated against the fluorescent microsphere method. A strong linear correlation was observed between the two techniques (R = 0.89, p < 0.00001). Injury-induced cerebral hemodynamic changes were quantified, and significant changes were found in oxy- and deoxy-hemoglobin concentrations, total hemoglobin concentration, blood oxygen saturation, and cerebral blood flow after the injury. The diffuse optical measurements were robust and also correlated well with recordings of vital physiological parameters over the 6-h monitoring period, such as mean arterial blood pressure, arterial oxygen saturation, and heart rate. Finally, the diffuse optical techniques demonstrated sensitivity to dynamic physiological events, such as apnea, cardiac arrest, and hypertonic saline infusion. In total, the investigation corraborates potential of the optical methods for bedside monitoring of pediatric and adult human patients in the neurointensive care unit.

Regional and Hemispheric Asymmetries of Cerebral Hemodynamic and Oxygen Metabolism in Newborns

“…Thus, DCS measures an autocorrelation function of the intensity fluctuations rather than a power spectrum. Blood flow changes measured with DCS have been extensively validated against other techniques in animal and human studies (Yu et al 2005;Zhou et al 2009;Carp et al 2010;Durduran et al 2010;Kim et al 2010). More recently, our group and others have conducted animal and human (Yu et al 2007;Buckley et al 2009;Roche-Labarbe et al 2010) validation studies to show how DCS provides an absolute number that scales with blood flow.…”

Direct measurement of tissue blood flow and metabolism with diffuse optics

“…it has the wrong units), but the relative change in BFI (i.e. rBFI) has been repeatedly shown (table 1) to be a quantitative measure of relative changes in blood flow (rBF) [1,3,22,27,29,46]. The complete details of a typical DCS experimental set-up can be found elsewhere [2][3][4].…”

“…Such effects will be small and can be accounted for by independent NIRS/DOS measurements. For the mean-square particle displacement, in practice, the Brownian model, Dr 2 (t) = 6D B t, fits the observed correlation decay curves fairly well over a wide range of tissue types and source-detector separations, including rat brain [18][19][20][21][22]; mouse tumours [23][24][25][26]; piglet brain [27]; and human skeletal muscle [28][29][30][31][32], human tumours [33][34][35][36][37][38][39] and human brain [40][41][42][43][44][45][46][47][48] (figure 1c). Here, D B is an effective diffusion coefficient that is a few orders of magnitude larger than the traditional thermal Brownian diffusion coefficient of cells in blood given by the Einstein-Smoluchowski relation [49].…”

Scanning, non-contact, hybrid broadband diffuse optical spectroscopy and diffuse correlation spectroscopy system

“…This provides a blood flow index (BFI), which has been shown to be in good agreement with other flowmetry techniques [1,3]. These techniques have been validated both in human studies [4][5][6][7][8][9] and pre-clinical research on animal models [10,11] for assessing deep tissue (>1 cm) hemodynamic changes.…”