Laser safety in fiber-optic monitoring of spinal cord hemodynamics: A preclinical evaluation

David R. Busch, James Davis, Angela Kogler, Robert M. Galler, Ashwin B. Parthasarathy, Arjun G. Yodh, Thomas F. Floyd

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

The prevention and treatment of spinal cord injury are focused upon the maintenance of spinal cord blood flow, yet no technology exists to monitor spinal cord ischemia. We recently demonstrated continuous monitoring of spinal cord ischemia with diffuse correlation and optical spectroscopies using an optical probe. Prior to clinical translation of this technology, it is critically important to demonstrate the safety profile of spinal cord exposure to the required light. To our knowledge, this is the first report of in situ safety testing of such a monitor. We expose the spinal cord to laser light utilizing a custom fiber-optic epidural probe in a survival surgery model (11 adult Dorset sheep). We compare the tissue illumination from our instrument with the American National Standards Institute maximum permissible exposures. We experimentally evaluate neurological and pathological outcomes of the irradiated sheep associated with prolonged exposure to the laser source and evaluate heating in ex vivo spinal cord samples. Spinal cord tissue was exposed to light levels at 18× the maximum permissible exposure for the eye and ∼1/3 for the skin. Multidisciplinary testing revealed no functional neurological sequelae, histopathologic evidence of laser-related injury to the spinal cord, or significant temperature changes in ex vivo samples. Low tissue irradiance and the lack of neurological, pathological, and temperature changes upon prolonged exposure to the laser source offer evidence that spinal cord tissues can be monitored safely with near-infrared optical probes placed within the epidural space.

Original languageEnglish (US)
Article number065003
JournalJournal of Biomedical Optics
Volume23
Issue number6
DOIs
StatePublished - Jun 1 2018

Fingerprint

Laser safety
spinal cord
hemodynamics
Hemodynamics
Fiber optics
fiber optics
safety
Monitoring
evaluation
lasers
sheep
ischemia
Tissue
Lasers
probes
spinal cord injuries
Safety testing
blood flow
irradiance
surgery

Keywords

  • diffuse optics
  • hemodynamics
  • intraoperative monitoring
  • ischemia
  • optical monitoring
  • Spinal cord

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Biomedical Engineering

Cite this

Laser safety in fiber-optic monitoring of spinal cord hemodynamics : A preclinical evaluation. / Busch, David R.; Davis, James; Kogler, Angela; Galler, Robert M.; Parthasarathy, Ashwin B.; Yodh, Arjun G.; Floyd, Thomas F.

In: Journal of Biomedical Optics, Vol. 23, No. 6, 065003, 01.06.2018.

Research output: Contribution to journalArticle

Busch, David R. ; Davis, James ; Kogler, Angela ; Galler, Robert M. ; Parthasarathy, Ashwin B. ; Yodh, Arjun G. ; Floyd, Thomas F. / Laser safety in fiber-optic monitoring of spinal cord hemodynamics : A preclinical evaluation. In: Journal of Biomedical Optics. 2018 ; Vol. 23, No. 6.
@article{85265afd742c4bf8aff4ef1b3be10042,
title = "Laser safety in fiber-optic monitoring of spinal cord hemodynamics: A preclinical evaluation",
abstract = "The prevention and treatment of spinal cord injury are focused upon the maintenance of spinal cord blood flow, yet no technology exists to monitor spinal cord ischemia. We recently demonstrated continuous monitoring of spinal cord ischemia with diffuse correlation and optical spectroscopies using an optical probe. Prior to clinical translation of this technology, it is critically important to demonstrate the safety profile of spinal cord exposure to the required light. To our knowledge, this is the first report of in situ safety testing of such a monitor. We expose the spinal cord to laser light utilizing a custom fiber-optic epidural probe in a survival surgery model (11 adult Dorset sheep). We compare the tissue illumination from our instrument with the American National Standards Institute maximum permissible exposures. We experimentally evaluate neurological and pathological outcomes of the irradiated sheep associated with prolonged exposure to the laser source and evaluate heating in ex vivo spinal cord samples. Spinal cord tissue was exposed to light levels at 18× the maximum permissible exposure for the eye and ∼1/3 for the skin. Multidisciplinary testing revealed no functional neurological sequelae, histopathologic evidence of laser-related injury to the spinal cord, or significant temperature changes in ex vivo samples. Low tissue irradiance and the lack of neurological, pathological, and temperature changes upon prolonged exposure to the laser source offer evidence that spinal cord tissues can be monitored safely with near-infrared optical probes placed within the epidural space.",
keywords = "diffuse optics, hemodynamics, intraoperative monitoring, ischemia, optical monitoring, Spinal cord",
author = "Busch, {David R.} and James Davis and Angela Kogler and Galler, {Robert M.} and Parthasarathy, {Ashwin B.} and Yodh, {Arjun G.} and Floyd, {Thomas F.}",
year = "2018",
month = "6",
day = "1",
doi = "10.1117/1.JBO.23.6.065003",
language = "English (US)",
volume = "23",
journal = "Journal of Biomedical Optics",
issn = "1083-3668",
publisher = "SPIE",
number = "6",

}

TY - JOUR

T1 - Laser safety in fiber-optic monitoring of spinal cord hemodynamics

T2 - A preclinical evaluation

AU - Busch, David R.

AU - Davis, James

AU - Kogler, Angela

AU - Galler, Robert M.

AU - Parthasarathy, Ashwin B.

AU - Yodh, Arjun G.

AU - Floyd, Thomas F.

PY - 2018/6/1

Y1 - 2018/6/1

N2 - The prevention and treatment of spinal cord injury are focused upon the maintenance of spinal cord blood flow, yet no technology exists to monitor spinal cord ischemia. We recently demonstrated continuous monitoring of spinal cord ischemia with diffuse correlation and optical spectroscopies using an optical probe. Prior to clinical translation of this technology, it is critically important to demonstrate the safety profile of spinal cord exposure to the required light. To our knowledge, this is the first report of in situ safety testing of such a monitor. We expose the spinal cord to laser light utilizing a custom fiber-optic epidural probe in a survival surgery model (11 adult Dorset sheep). We compare the tissue illumination from our instrument with the American National Standards Institute maximum permissible exposures. We experimentally evaluate neurological and pathological outcomes of the irradiated sheep associated with prolonged exposure to the laser source and evaluate heating in ex vivo spinal cord samples. Spinal cord tissue was exposed to light levels at 18× the maximum permissible exposure for the eye and ∼1/3 for the skin. Multidisciplinary testing revealed no functional neurological sequelae, histopathologic evidence of laser-related injury to the spinal cord, or significant temperature changes in ex vivo samples. Low tissue irradiance and the lack of neurological, pathological, and temperature changes upon prolonged exposure to the laser source offer evidence that spinal cord tissues can be monitored safely with near-infrared optical probes placed within the epidural space.

AB - The prevention and treatment of spinal cord injury are focused upon the maintenance of spinal cord blood flow, yet no technology exists to monitor spinal cord ischemia. We recently demonstrated continuous monitoring of spinal cord ischemia with diffuse correlation and optical spectroscopies using an optical probe. Prior to clinical translation of this technology, it is critically important to demonstrate the safety profile of spinal cord exposure to the required light. To our knowledge, this is the first report of in situ safety testing of such a monitor. We expose the spinal cord to laser light utilizing a custom fiber-optic epidural probe in a survival surgery model (11 adult Dorset sheep). We compare the tissue illumination from our instrument with the American National Standards Institute maximum permissible exposures. We experimentally evaluate neurological and pathological outcomes of the irradiated sheep associated with prolonged exposure to the laser source and evaluate heating in ex vivo spinal cord samples. Spinal cord tissue was exposed to light levels at 18× the maximum permissible exposure for the eye and ∼1/3 for the skin. Multidisciplinary testing revealed no functional neurological sequelae, histopathologic evidence of laser-related injury to the spinal cord, or significant temperature changes in ex vivo samples. Low tissue irradiance and the lack of neurological, pathological, and temperature changes upon prolonged exposure to the laser source offer evidence that spinal cord tissues can be monitored safely with near-infrared optical probes placed within the epidural space.

KW - diffuse optics

KW - hemodynamics

KW - intraoperative monitoring

KW - ischemia

KW - optical monitoring

KW - Spinal cord

UR - http://www.scopus.com/inward/record.url?scp=85049216274&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85049216274&partnerID=8YFLogxK

U2 - 10.1117/1.JBO.23.6.065003

DO - 10.1117/1.JBO.23.6.065003

M3 - Article

C2 - 29923371

AN - SCOPUS:85049216274

VL - 23

JO - Journal of Biomedical Optics

JF - Journal of Biomedical Optics

SN - 1083-3668

IS - 6

M1 - 065003

ER -