Fiber-optic Monitoring of Spinal Cord Hemodynamics in Experimental Aortic Occlusion

Abstract Background Spinal cord ischemia occurs frequently during thoracic aneurysm repair. Current methods based on electrophysiology techniques to detect ischemia are indirect, non-specific, and temporally slow. In this article, the authors report the testing of a spinal cord blood flow and oxygenation monitor, based on diffuse correlation and optical spectroscopies, during aortic occlusion in a sheep model. Methods Testing was carried out in 16 Dorset sheep. Sensitivity in detecting spinal cord blood flow and oxygenation changes during aortic occlusion, pharmacologically induced hypotension and hypertension, and physiologically induced hypoxia/hypercarbia was assessed. Accuracy of the diffuse correlation spectroscopy measurements was determined via comparison with microsphere blood flow measurements. Precision was assessed through repeated measurements in response to pharmacologic interventions. Results The fiber-optic probe can be placed percutaneously and is capable of continuously measuring spinal cord blood flow and oxygenation preoperatively, intraoperatively, and postoperatively. The device is sensitive to spinal cord blood flow and oxygenation changes associated with aortic occlusion, immediately detecting a decrease in blood flow (−65 ± 32%; n = 32) and blood oxygenation (−17 ± 13%, n = 11) in 100% of trials. Comparison of spinal cord blood flow measurements by the device with microsphere measurements led to a correlation of R2 = 0.49, P < 0.01, and the within-sheep coefficient of variation was 9.69%. Finally, diffuse correlation spectroscopy is temporally more sensitive to ischemic interventions than motor-evoked potentials. Conclusion The first-generation spinal fiber-optic monitoring device offers a novel and potentially important step forward in the monitoring of spinal cord ischemia.

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Towards rapid intraoperative axial localization of spinal cord ischemia with epidural diffuse correlation monitoring

PLoS ONE ◽

10.1371/journal.pone.0251271 ◽

2021 ◽

Vol 16 (5) ◽

pp. e0251271

Author(s):

David R. Busch ◽

Wei Lin ◽

Chia Chieh Goh ◽

Feng Gao ◽

Nicholas Larson ◽

...

Keyword(s):

Spinal Cord ◽

Blood Flow ◽

Cord Blood ◽

Spinal Cord Ischemia ◽

Correlation Spectroscopy ◽

Spinal Cord Blood Flow ◽

Doppler Flowmetry ◽

Spatially Resolved ◽

Highly Correlated ◽

Sensitivity Specificity

Spinal cord ischemia leads to iatrogenic injury in multiple surgical fields, and the ability to immediately identify onset and anatomic origin of ischemia is critical to its management. Current clinical monitoring, however, does not directly measure spinal cord blood flow, resulting in poor sensitivity/specificity, delayed alerts, and delayed intervention. We have developed an epidural device employing diffuse correlation spectroscopy (DCS) to monitor spinal cord ischemia continuously at multiple positions. We investigate the ability of this device to localize spinal cord ischemia in a porcine model and validate DCS versus Laser Doppler Flowmetry (LDF). Specifically, we demonstrate continuous (>0.1Hz) spatially resolved (3 locations) monitoring of spinal cord blood flow in a purely ischemic model with an epidural DCS probe. Changes in blood flow measured by DCS and LDF were highly correlated (r = 0.83). Spinal cord blood flow measured by DCS caudal to aortic occlusion decreased 62%. This monitor demonstrated a sensitivity of 0.87 and specificity of 0.91 for detection of a 25% decrease in flow. This technology may enable early identification and critically important localization of spinal cord ischemia.

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Mouse lumbar and cervical spinal cord blood flow measurements by arterial spin labeling: Sensitivity optimization and first application

Magnetic Resonance in Medicine ◽

10.1002/mrm.22015 ◽

2009 ◽

Vol 62 (2) ◽

pp. 430-439 ◽

Cited By ~ 16

Author(s):

Guillaume Duhamel ◽

Virginie Callot ◽

Patrick Decherchi ◽

Yann Le Fur ◽

Tanguy Marqueste ◽

...

Keyword(s):

Spinal Cord ◽

Blood Flow ◽

Cord Blood ◽

Arterial Spin Labeling ◽

Cervical Spinal Cord ◽

Spin Labeling ◽

Spinal Cord Blood Flow ◽

Flow Measurements ◽

Blood Flow Measurements

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Spatially resolved optical monitoring of spinal cord blood flow with a minimally invasive, multi-level epidural probe

10.1101/2020.10.06.326900 ◽

2020 ◽

Author(s):

David R. Busch ◽

Wei Lin ◽

Chia Chieh Goh ◽

Feng Gao ◽

Nicholas Larson ◽

...

Keyword(s):

Spinal Cord ◽

Blood Flow ◽

Cord Blood ◽

Spinal Cord Ischemia ◽

Correlation Spectroscopy ◽

Spinal Cord Blood Flow ◽

Doppler Flowmetry ◽

Spatially Resolved ◽

Highly Correlated ◽

Sensitivity Specificity

AbstractSpinal cord ischemia leads to iatrogenic injury in multiple surgical fields, and the ability to immediately identify onset and anatomic origin of ischemia is critical to its management. Current clinical monitoring, however, does not directly measure spinal cord blood flow, resulting in poor sensitivity/specificity, delayed alerts, and delayed intervention. We have developed an epidural device employing diffuse correlation spectroscopy (DCS) to monitor spinal cord ischemia continuously at multiple positions. We investigate the ability of this device to localize spinal cord ischemia in a porcine model and validate DCS versus Laser Doppler Flowmetry (LDF).Specifically, we demonstrate continuous (>0.1Hz) spatially resolved (3 locations) monitoring of spinal cord blood flow in a purely ischemic model with an epidural DCS probe. Changes in blood flow measured by DCS and LDF were highly correlated (r=0.83). Spinal cord blood flow measured by DCS caudal to aortic occlusion decreased 62%, with a sensitivity of 0.87 and specificity of 0.91 for detection of a 25% decrease in flow. This technology may enable early identification and critically important localization of spinal cord ischemia.

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Spinal Cord Blood Flow in Experimental Transient Traumatic Paraplegia

Journal of Neurosurgery ◽

10.3171/jns.1980.52.3.0335 ◽

1980 ◽

Vol 52 (3) ◽

pp. 335-345 ◽

Cited By ~ 21

Author(s):

Dean C. Lohse ◽

Howard J. Senter ◽

John S. Kauer ◽

Richard Wohns

Keyword(s):

Spinal Cord ◽

Blood Flow ◽

White Matter ◽

Cord Blood ◽

Spinal Cord Blood Flow ◽

Flow Measurements ◽

Content Type ◽

The Mean ◽

Blood Flow Measurements ◽

Fine Print

✓ Blood flow in the lateral funiculus of the thoracic spinal cord was measured in 24 anesthetized cats using the hydrogen clearance method. In a control series of eight nontraumatized animals, blood flow measurements were taken from the T-5 and T-6 segments for 6 consecutive hours. The mean spinal cord blood flow (SCBF) in the control group was 12.8 ± 3.51 (SD) ml/min/100 gm on the basis of 107 measurements over 6 hours. In the experimental groups, 16 animals were similarly prepared. The spinal cords of these animals were then traumatized by dropping a 20-gm weight 5 cm (100 gm-cm trauma) or 13 cm (260 gm-cm trauma) onto the T-5 segment. Previous experiments have shown that these trauma levels lead to a transient paraplegia of less than 10 and 30 days' duration, respectively. Two hundred blood flow measurements from T-5 and T-6 were taken over the 6 hours following trauma. In the seven animals of the 100 gm-cm group, mean SCBF after trauma from the T-5 segment was 12.6 ± 3.45 (SD) ml/min/100 gm on the basis of 50 measurements taken over 6 hours; not significantly different from the controls (p > 0.70). In the 260 gm-cm group, mean SCBF from T-5 for 6 hours after trauma was 17.3 ± 6.60 (SD) ml/min/100 gm; significantly higher than controls (p < 0.001). Mean SCBF 3 to 6 hours after trauma was significantly elevated over controls (p < 0.05). The mean hyperemia in the 260 gm-cm group was found to be due to marked hyperemia in only four animals of the series, while five animals maintained blood flows in the normal range. This experiment provides quantitative evidence that white matter ischemia does not occur in spinal cord injuries that can be expected to produce only transient paraplegia. The data support the concept that white matter ischemia in the acute phase of severe spinal cord trauma may be related to secondary injury and subsequent permanent paraplegia.

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Regional spinal cord blood flow measurements (r.S.C.B.F.) in spinal cord acute compression caused by an epidural balloon

Acta Neurochirurgica ◽

10.1007/bf01404150 ◽

1987 ◽

Vol 88 (3-4) ◽

pp. 135-141 ◽

Cited By ~ 5

Author(s):

G. Karoutas ◽

Ph. Tsitsopoulos ◽

N. Taskos ◽

D. Karacostas ◽

Th. Tzotzoras ◽

...

Keyword(s):

Spinal Cord ◽

Blood Flow ◽

Cord Blood ◽

Spinal Cord Blood Flow ◽

Flow Measurements ◽

Blood Flow Measurements

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Spinal Cord Blood Flow after Ischemic Preconditioning in a Rat Model of Spinal Cord Ischemia

The Scientific World JOURNAL ◽

10.1100/tsw.2004.186 ◽

2004 ◽

Vol 4 ◽

pp. 892-898 ◽

Cited By ~ 3

Author(s):

David Zvara ◽

James M. Zboyovski ◽

Dwight D. Deal ◽

Jason C. Vernon ◽

David M. Colonna

Keyword(s):

Spinal Cord ◽

Blood Flow ◽

Cord Blood ◽

Ischemic Preconditioning ◽

Spinal Cord Ischemia ◽

Flow Analysis ◽

Lumbar Spinal Cord ◽

Sprague Dawley ◽

Spinal Cord Blood Flow ◽

Significant Difference

Spinal cord blood flow after ischemic preconditioning is poorly characterized. This study is designed to evaluate spinal cord blood flow patterns in animals after acute ischemic preconditioning. Experiment 1: After a laminectomy and placement of a laser Doppler probe over the lumbar spinal cord to measure spinal cord blood flow, 16 male Sprague-Dawley rats were randomized into two groups: ischemic preconditioning (IPC, n = 8), and control (CTRL, n = 8). Rats in the CTRL and the IPC groups were subjected to 12 min of ischemia directly followed by 60 min of reperfusion. IPC rats received 3 min of IPC and 30 min of reperfusion prior to the 12-min insult period. Experiment 2: After instrumentation, the rats were randomized into three groups: control (CTRL, n = 7), ischemic preconditioning (IPC, n = 7), and time control (TC, n = 4). Rats in the CTRL and the IPC groups were subjected to the same ischemia and reperfusion protocol as above. The TC group was anesthetized for the same time period as the CTRL and the IPC groups, but had no ischemic intervention. Microspheres were injected at baseline and at 15 and 60 min into the final reperfusion. All rats were euthanized and tissue harvested for spinal cord blood flow analysis. In Experiment 1, there was a slight, significant difference in spinal cord blood flow during the ischemic period; however, this difference soon disappeared during reperfusion. In experiment 2, there was no difference in blood flow at any experimental time. The results of these experiments demonstrate that IPC slightly enhances blood flow to the spinal cord during ischemia; however, this effect is not sustained during the reperfusion period.

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Effects of aortic occlusion on regional spinal cord blood flow and somatosensory evoked potentials in sheep

Neurosurgery ◽

10.1097/00006123-198711000-00012 ◽

1987 ◽

Vol 21 (5) ◽

pp. 668???75

Author(s):

B J Kaplan ◽

W A Friedman ◽

N Gravenstein ◽

R Richards ◽

R F Davis

Keyword(s):

Spinal Cord ◽

Blood Flow ◽

Evoked Potentials ◽

Cord Blood ◽

Somatosensory Evoked Potentials ◽

Aortic Occlusion ◽

Spinal Cord Blood Flow

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Validation of laser-Doppler flowmetry in measurement of spinal cord blood flow

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1989.257.2.h674 ◽

1989 ◽

Vol 257 (2) ◽

pp. H674-H680 ◽

Cited By ~ 2

Author(s):

P. J. Lindsberg ◽

J. T. O'Neill ◽

I. A. Paakkari ◽

J. M. Hallenbeck ◽

G. Feuerstein

Keyword(s):

Spinal Cord ◽

Blood Flow ◽

Cord Blood ◽

Laser Doppler Flowmetry ◽

Laser Doppler ◽

Microvascular Blood Flow ◽

Base Line ◽

Spinal Cord Blood Flow ◽

Flow Measurements ◽

Doppler Flowmetry

Laser-Doppler flowmetry (LDF) is a non-invasive method for continuous on-line monitoring of microvascular blood flow. LDF has previously been validated with established methods in various tissues, yet its validity and resolution in the central nervous system (CNS) remain unclear. We compared LDF with the microsphere method (MS) using two independent laser probes placed on the dorsal lumbar spinal cord (L5 laminectomy) of anesthetized rabbits (n = 9). After base-line flow measurements, spinal cord blood flow (SCBF) was increased (up to 50%) with phenylephrine (10-80 micrograms.kg-1.min-1 iv) and decreased (up to 50%) with chlorisondamine (10 mg/kg iv) or other stimuli. The percentage changes of lumbar SCBF and vascular resistance (VR) from the base line obtained by LDF and MS excellently agreed (rBF = 0.86, rVR = 0.94, P less than 0.0001). LDF estimated also the absolute SCBF values parallel to MS (r = 0.77, P less than 0.001). In conclusion, the validity of LDF in estimating the SCBF and dynamic changes of BF and VR is confirmed. Therefore, LDF may prove useful for monitoring CNS microcirculation in normal or pathophysiological states.

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