DOI: 10.1016/j.jtcvs.2006.05.047 2006;132:1150-1155 J Thorac Cardiovasc Surg

Joseph S. Coselli Jr, Akif Ündar, Zachary C. Schmittling, Xing Li Wang, Charles D. Fraser, Jr and

Scott A. LeMaire, Lyssa N. Ochoa, Lori D. Conklin, Ron A. Widman, Fred J. Clubb, ischemia during intercostal artery ligation: Preliminary experimental results

Transcutaneous near-infrared spectroscopy for detection of regional spinal

http://jtcs.ctsnetjournals.org/cgi/content/full/132/5/1150located on the World Wide Web at:

The online version of this article, along with updated information and services, is

2006 American Association for Thoracic Surgery Association for Thoracic Surgery and the Western Thoracic Surgical Association. Copyright ©

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ranscutaneous near-infrared spectroscopy for detection ofegional spinal ischemia during intercostal artery ligation:reliminary experimental results

cott A. LeMaire, MDa,d, Lyssa N. Ochoa, MDd, Lori D. Conklin, MDd, Ron A. Widmanf, Fred J. Clubb, Jr, DVM, PhDb,kif Undar, PhDc,e, Zachary C. Schmittling, MDd, Xing Li Wang, MD, PhDd, Charles D. Fraser, Jr, MDa,e, and

oseph S. Coselli, MDa,d

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From the Cardiovascular Surgery Service,a

Department of Cardiovascular Pathology,b

and Cullen Cardiovascular Surgical Re-search Laboratories,c Texas Heart Instituteat St Luke’s Episcopal Hospital, Houston,Tex; the Divisions of Cardiothoracic Sur-geryd and Congenital Heart Surgery,e Mi-chael E. DeBakey Department of Surgery,Baylor College of Medicine, Houston, Tex;and the Somanetics Corporation, Troy,Mich.f

Supported by the Michael E. DeBakey De-partment of Surgery Seed Fund and theSomanetics Corporation, Troy, Mich.R.A.W. is Vice President, Medical Affairs,at Somanetics Corporation, the manufac-turer of the device described in this report.

Received for publication March 8, 2006;revisions received April 27, 2006; acceptedfor publication May 8, 2006.

Address for reprints: Scott A. LeMaire,MD, One Baylor Plaza, BCM 390, Hous-ton, TX 77030 (E-mail: slemaire@bcm.tmc.edu).

J Thorac Cardiovasc Surg 2006;132:1150-5

0022-5223/$32.00

Copyright © 2006 by The American Asso-ciation for Thoracic Surgery

adoi:10.1016/j.jtcvs.2006.05.047

150 The Journal of Thoracic and CardDown

bjective: Real-time information about regional spinal cord ischemia can guidentraoperative management and reduce the risk of paraplegia after thoracic aorticurgery. We hypothesized that near-infrared spectroscopy could provide such in-ormation during intercostal and lumbar artery ligation in pigs.

ethods: Transcutaneous near-infrared spectroscopic sensors were placed in theidline over the upper and lower thoracic vertebrae of 4 progressively larger pigs

weight range 21-70 kg). After the entire aorta was exposed, segmental arteries from6 through L1 were sequentially ligated while regional oxygen saturation wasonitored. Decreases in regional oxygen saturation were calculated as percentage

hanges from baseline. The degrees of ischemia in the upper and lower spinal cordere compared histopathologically.

esults: Baseline regional oxygen saturations were similar in the upper (68.8% �.0%) and lower (68.0% � 11.5%, P � .82) cord. After ligation, however, regionalxygen saturation levels were significantly lower in the lower cord (41.3% �0.1%) than in the upper cord (64.8% � 9.3%, P � .037). The regional oxygenaturation had decreased by 39.0% � 11.5% in the lower cord but only by 6.3% �.6% in the upper cord (P � .026). This difference was confirmed microscopically:pper-cord sections had fewer ischemic neurons (8.8 � 9.4) than did lower-cordections (21.3 � 13.6, P � .002).

onclusion: Intraoperative spinal cord ischemia was detectable with near-infraredpectroscopy in pigs weighing as much as 70 kg. The potential utility of thisechnique in patients undergoing thoracic aortic surgery warrants investigation.

he inability to directly measure spinal cord blood flow and oxygenationintraoperatively is a major obstacle to preventing paraplegia after thoracicaortic surgery. Real-time information about spinal cord ischemia can guide

he adjustment of distal aortic perfusion pressure and the reattachment of intercostalrteries.1

Current spinal cord monitoring techniques rely on somatosensory-evoked poten-ials (SSEPs) or motor-evoked potentials (MEPs). Monitoring SSEPs has severalisadvantages, including slow response time (caused by delays between the onset ofschemia and the disappearance of potentials) and poor overall sensitivity andpecificity.2-4 Although MEP monitoring has been successfully used to detect spinalord ischemia, guide surgical strategy, and prevent postoperative neurologic defi-its, it has limitations that have prevented it from being widely adopted.1,5-7

Transcutaneous near-infrared spectroscopy (NIRS), which exploits the uniqueear-infrared absorption profiles of hemoglobin, oxyhemoglobin, and cytochrome

a3, is currently widely used for cerebral oximetry during cardiovascular sur-

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ery.8-12 This technique assesses the oxyhemoglobin frac-ion within a focal area of underlying tissue by measuringhe differential absorption of two wavelengths of near-nfrared light (730 and 810 nm) that reflect deoxyhemoglo-in and total hemoglobin concentration. The purpose of thisilot study was to assess the feasibility of using NIRS toetect spinal cord ischemia during intercostal artery ligationn the pig.

aterials and Methodshe protocol for this study was approved by the institutionalnimal care and use committees of both Baylor College of Med-cine and the Texas Heart Institute. The animals received humaneare and handling in compliance with the “Principles of Labora-ory Animal Care” formulated by the National Society for Medicalesearch and with the “Guide for the Care and Use of Laboratorynimals” (http://www.nap.edu/catalog/5140.html).

nesthetic Managementour domestic swine (weighing 21, 37, 48, and 70 kg) wereremedicated with intramuscular atropine sulfate (0.5 mg/kg),cepromazine maleate (0.1 mg/kg), and ketamine hydrochloride20 mg/kg). Isoflurane (0.5%-3.0%) was given by mask for induc-ion. Crystalloid fluid was infused throughout the procedure, andoluses of hetastarch were given when needed. Monitors includedpulse oximeter placed on the ear, electrocardiographic leads, andrectal temperature probe. The animals were orally intubated withcuffed endotracheal tube through direct laryngoscopy and con-

ected to a volume ventilator that delivered 100% oxygen at a tidalolume of 10 mL/kg. General anesthesia was maintained withnhaled isoflurane (0.5%-3.0%) and pancuronium bromide (0.1g/kg). A warming blanket was placed underneath the pigs toaintain normothermia. A carotid artery catheter was used for

lood pressure monitoring and arterial blood gas sampling.

perative Procedurehe dorsal area was shaved and cleaned, and 5100SAF SomaSen-ors (Somanetics Corporation, Troy, Mich) were placed in theidline over the upper (T6-T7) and lower (T9-T11) thoracic

ertebrae. These sensors were connected to an INVOS 5100 Ce-ebral Oximeter (Somanetics Corporation). A pediatric spinalrainage catheter was inserted into the subarachnoid space throughither a laminectomy or direct puncture between the third andourth lumbar vertebrae.

A left thoracoabdominal incision was made through the sixthntercostal space. The diaphragm was divided, and the entire

Abbreviations and AcronymsMEP � motor-evoked potentialNIRS � near-infrared spectroscopySrO2 � regional spinal oxygen saturationSSEP � somatosensory-evoked potentialTAAA � thoracoabdominal aortic aneurysm

horacoabdominal aorta was exposed. Regional spinal oxygen sat- d

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ration (SrO2) was monitored continuously by both upper andower sensors. Raw optical data from the sensors were stored in aomputer at 4-second intervals. After baseline SrO2 levels wereecorded, segmental intercostal and lumbar arteries from T6hrough L1 were sequentially occluded at approximately 10-inute intervals. Each artery was initially occluded with a bulldog

lamp; after approximately 10 minutes of clamping, SrO2 wasecorded, and the artery was ligated with metallic clips andivided.

After all segmental arteries were ligated, 1 mL indocyaninereen dye (2.5 mg/mL; Akorn, Inc, Buffalo Grove, Ill) was in-ected into the subarachnoid space through the spinal catheter. Thisye absorbs near-infrared light in a band centered at 805 nm. Theatheter was flushed twice with 1 mL saline solution to distributehe dye evenly within the space surrounding the spinal cord.ptical density (the log of the ratio of measured intensity to

ncident intensity) at 810 nm was recorded with the oximeter toetermine changes in light absorption. After ligation of the L1egmental arteries in each of the 3 largest pigs, the animals wereriefly awakened and examined for hind limb paralysis. After thisxamination, the animals were reanesthetized and humanely killedith intravenous potassium chloride.

istopathologyhe entire spinal column was removed from each of the 3 largestigs and placed in formalin after the upper and lower segmentsonitored by the sensors were marked. Identification of the arteria

adicularis magna (Adamkiewicz artery) was not attempted. Theords were sectioned, and representative portions of both regionsere stained with either hematoxylin and eosin or luxol fast blueye. A pathologist (F.J.C.) who was blind to the origin of eachection (upper or lower cord) examined the sections and quantifiedschemic change by counting the number of normal neurons andhe number of ischemic neurons per section.

tatistical Analysishe statistical analyses were performed with SPSS version 12.0 forindows (SPSS Inc, Chicago, Ill). The following intraoperative

ariables were compared: mean upper- and lower-cord SrO2 valuest baseline and after ligation of the segmental spinal arteries T6hrough L1; absolute percentage SrO2 decline from baseline afterach vessel was ligated; and mean heart rate, temperature, andean arterial pressure. The upper and lower cords were compared

n terms of the number of ischemic neurons and the ratio ofschemic to normal neurons. Continuous variables are reported asean � SD and were analyzed with the Student t test for between-

roup differences. We used analysis of variance for comparisonsmong three or more groups. The Bonferroni correction was usedor multiple comparisons.

esultslinicalean physiologic parameters at baseline included heart rate

f 99.0 � 3.6 beats/min, mean arterial pressure of 55.3 �.3 mm Hg, and rectal temperature of 36.1°C � 1.9°C.hese parameters remained stable throughout the proce-

ures. Baseline SrO2 values were similar in the upper

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68.8% � 9.0%) and lower (68.0% � 11.5%) cord seg-ents (P � .82). Upper-cord SrO2 remained stable through-

ut the procedure, whereas lower-cord SrO2 began to de-rease after the T9 segmental artery was ligated. Thisecline continued after ligation of the T10 and T11 vesselsnd became statistically significant after ligation of T12 and1. Most of the declines in SrO2 began within 1 minute ofrterial ligation. After all segmental arteries were ligated,ean SrO2 levels were 64.8% � 9.3% in the upper cord and

1.3% � 10.1% in the lower cord (P � .037); the percent-ge reduction in SrO2 from baseline was much larger in theower cord (39.0% � 11.5%) than in the upper cord (6.3%

7.6%, P � .026; Figure 1).Subarachnoid injection of indocyanine green dye in-

reased near-infrared light absorption at 810 nm (Figure 2)n all the pigs, indicating that a portion of the NIRS photonsenetrated the tissues to the depth of the spinal cord. Afternjection of the dye, reductions in optical density (relative toaseline) for the 4 pigs were 12.3%, 20.7%, 33.1%, and1.2% (mean 21.8% � 8.6%).

Lower spinal cord ischemia was also confirmed by phys-cal examination. Three pigs were briefly awakened andxamined after the operation, and paralysis of the hind limbsithout involvement of the upper limbs was present in each.

istopathologyhe regional difference in the degree of ischemia wasonfirmed by microscopic examination of the lateral corti-ospinal tracts. Lower-cord sections exhibited more pro-ounced ischemic changes than did upper-cord sections,ncluding increased vacuolization, retraction of neurons,

igure 1. Graph showing percentage decline from baselinemean � SD) in SrO2 (rSO2) at T6-7 and T9-11 vertebral levelsuring sequential ligation of intercostal arteries. Once all vesselsere ligated, decrease in SrO2 detected by lower sensor was

ignificantly greater than that detected by upper sensor (P �026).

nd loss of nucleoli (Figure 3). Lower-cord sections also i

152 The Journal of Thoracic and Cardiovascular Surgery ● Novjtcs.ctsnetjourDownloaded from

ad more ischemic neurons (mean 21.3 � 13.6 per section)han did upper-cord sections (mean 8.8 � 9.4 per section, P

.002). These numbers corresponded to a significantlyower ratio of ischemic to normal neurons in the upper cord0.17) than in the lower cord (0.50, P � .005), indicatinghat the regional differences in spinal ischemia indicated byhe NIRS monitor paralleled the regional histopathologicifferences.

iscussionespite the use of numerous protective adjuncts during

horacoabdominal aortic surgery, spinal cord ischemic in-ury leading to paraplegia or paraparesis continues to be aignificant problem. We recently reviewed contemporaryeports of patients who underwent extensive thoracoab-ominal aortic aneurysm (TAAA) repairs and found thateurologic deficits occurred in as many as 32% of pa-ients.13 These neurologic deficits may contribute to mor-ality; in Svensson and colleagues’ analysis14 of a series ofAAA repairs in 1509 patients, those who had paraplegia oraraparesis had a significantly lower 5-year survival (only4%) than did patients without deficits (62%, P � .0001).he risks of paraplegia and paraplegia-related death afterescending thoracic aortic aneurysm and TAAA repairight be reduced if spinal cord perfusion and oxygenation

ould be monitored directly during surgery.Attempts to monitor spinal cord perfusion indirectly dur-

igure 2. Representative graph showing increase in near-infra-ed light absorption at 810 nm after subarachnoid injection ofndocyanine green dye (ICG).

ng aortic aneurysm surgery began with the monitoring of

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SEPs, measurable electrical patterns that occur within thepinal cord when a peripheral sensory nerve (usually theosterior tibial nerve) is stimulated.15 Although SSEP mon-toring showed promise in canine studies,16 a clinical trialy Crawford and associates2 showed that the measurementf SSEPs during aortic surgery did not reduce the incidencef postoperative neurologic deficits.17 The poor sensitivitynd specificity of SSEP monitoring is partially attributableo the fact that the sensory and motor pathways of the spinalord are anatomically separate and have different bloodupplies. The amplitude of SSEPs only indicates the func-ion of sensory tracts, which are located in the dorsal portionf the spinal cord and are not supplied by the anterior spinalrtery, where blood flow is reduced during aortic clamping.s a result, SSEP monitoring provides only delayed infor-ation about spinal cord ischemia.18

In contrast, MEPs reflect the functional integrity of theotor pathways in the anterior (ventral) cord, especially theore vulnerable motor neurons in the anterior gray matter.ecause the anterior cord is supplied by the anterior spinalrtery, MEP monitoring is an anatomically and physiolog-cally sound means of detecting spinal ischemia duringortic clamping. Jacobs and colleagues1,5-7 have used MEPonitoring as part of their spinal cord protection strategy

nd have achieved excellent results. In a pilot study involv-ng 52 consecutive patients with Crawford extent I or IIAAAs, Jacobs and colleagues1 recorded MEPs in all pa-

ients and reported that spinal cord ischemia was detected asarly as 2 minutes after intercostal artery ligation. During

Figure 3. Representative histologic lateral corticospinspinal cord. Compared with proximal sections, distalincluding increased vacuolization (arrowheads), retraarrows). (Hematoxylin-eosin [A, B] and Luxol fast blue[E, F]).

istal aortic perfusion, 14 patients showed a rapid decrease s

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n MEP amplitude to less than 25% of baseline, indicatingpinal cord ischemia; this was corrected by increasing distalortic pressure. Additionally, in 33 patients, aggressive re-ttachment of intercostal arteries returned MEP amplitudeso baseline levels, and no early or late paraplegia occurred.acobs and Mess5 recently reported preventing neurologiceficits in 98% of patients undergoing TAAA repair bysing MEP monitoring.

MEP monitoring is not, however, without limita-ions.19,20 For example, the neuromuscular blocking agentshat are part of the usual anesthetic regimen interfere with

EP monitoring. For this reason, MEP monitoring requireslterations in standard anesthetic management to preventomplete neuromuscular blockage. Also, MEP monitoringepends on signal averaging across a span of seconds,hich limits its ability to detect vascular compromise beforeeurons have been irreversibly injured. Additional limita-ions of this technique include the need for monitoring by aeurophysiologist during the operation and its inability to besed in conscious postoperative patients. For these reasons,lthough MEP monitoring has been shown to reduce the riskf paraplegia, the technique is not widely used.

Other methods of monitoring spinal cord ischemia cur-ently being studied include intrathecal monitoring of cere-rospinal fluid oxygen tension21,22 and transesophagealIRS monitoring of spinal cord Sro2.23 An ideal spinal cordonitoring method would (1) be noninvasive, (2) be simple

nough to use that no additional personnel are required, (3)e highly sensitive and specific to changes in the anterior

act sections from upper (A, C, E) and lower (B, D, E)tions exhibited more pronounced ischemic changes,n of neurons (arrows), and loss of nucleoli (double] staining; original magnifications �20 [A-D] and �40

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pinal cord, (4) allow standard anesthesia delivery, (5) ex-

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ibit no delay in ischemia detection, and (6) be usable inonscious postoperative patients. Transcutaneous NIRS hashe potential to satisfy these criteria.

Our pilot study was designed to assess the potentialsefulness of transcutaneous NIRS as a noninvasive moni-or that provides continuous, real-time information aboutpinal cord oxygenation. NIRS uses transcutaneous sensorso measure the focal oxyhemoglobin fraction in underlyingissue. Currently, this technique is used to monitor cerebralxygenation during a wide variety of cardiovascular oper-tions.4,9,10,12,24 In addition to being entirely noninvasive,he NIRS monitor is simple to use, requires no additionalechnical personnel, and does not require modifications tonesthetic management. In our experiment, we showed thatranscutaneous NIRS can detect intraoperative spinal cordschemia in a porcine model.

An initial concern was that the sensors would detectxygenation levels in the surrounding tissues, such as mus-le and subcutaneous tissue, but not in the underlying spinalord. Given the anatomy of the blood supply shared be-ween the spinal cord and these surrounding tissues, how-ver, NIRS data on regional oxygenation may adequatelyeflect spinal cord perfusion, albeit indirectly. To addresshis issue specifically, we injected indocyanine green dyento the subarachnoid space and found an immediate changen light absorption (Figure 2), suggesting that at least somef the photons were reaching the spinal cord. Additionally,acnab and coworkers25 found that, in a porcine model of

pinal cord hypoxia-ischemia, NIRS detected ischemichanges in the spinal cord whether the sensors were placedirectly on the spinal cord, the spinal lamina, or the spinousrocesses. Further experiments correlating direct measure-ents of spinal oxygenation with transcutaneous NIRS

eadings would help clarify this issue.Real-time information about spinal cord perfusion during

AAA repair would allow the surgical team to intervenehen ischemia occurs. Intervention strategies used duringrO2 monitoring could be based on those outlined in Jacobsnd colleagues’ report1 regarding MEP monitoring duringAAA surgery. For example, when ischemia is detected, theean arterial pressure could be immediately increased. Dis-

al aortic flow and pressure could also be increased wheneft heart bypass is being used. Additionally, temporarycclusion catheters could be placed in segmental arteriesith significant back-bleeding, thereby reducing steal from

he anterior spinal artery. Finally, decline in SrO2 couldrompt the reattachment of specific segmental arteriesithin the isolated aortic segment, and aortic endarterec-

omy could be performed when segmental arteries are noteadily apparent.

Because of its potential value in guiding these types ofnterventions, NIRS monitoring of spinal cord oxygenation

uring thoracic aortic surgery is worthy of clinical investi-

1

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ation. Expanding the application of NIRS to postoperativepinal cord monitoring as a means of preventing delayed-nset paraplegia also merits study.

We gratefully acknowledge Paul Holman, MD, Jean-Paul Wo-insky, MD, Jamie Junkerman, and Gobind Anand for intraopera-ive assistance; and the staff at the Cullen Cardiovascular Researchaboratory of the Texas Heart Institute—especially KathleencKay, Blake Deady, and Amy Porter—for excellent anestheticanagement. Stephen N. Palmer, PhD, ELS, provided editorial

ssistance, and Scott Weldon, MA, provided assistance with illus-rations.

eferences

1. Jacobs MJ, Meylaerts SA, de Haan P, de Mol BA, Kalkman CJ.Strategies to prevent neurologic deficit based on motor-evoked poten-tials in type I and II thoracoabdominal aortic aneurysm repair. J VascSurg. 1999;29:48-57.

2. Crawford ES, Mizrahi EM, Hess KR, Coselli JS, Safi HJ, Patel VM.The impact of distal aortic perfusion and somatosensory evoked po-tential monitoring on prevention of paraplegia after aortic aneurysmoperation. J Thorac Cardiovasc Surg. 1988;95:357-67.

3. Schepens MA, Boezeman EH, Hamerlijnck RP, ter Beek H, Ver-meulen FE. Somatosensory evoked potentials during exclusion andreperfusion of critical aortic segments in thoracoabdominal aorticaneurysm surgery. J Card Surg. 1994;9:692-702.

4. Reuter DG, Tacker WA Jr, Badylak SF, Voorhees WD 3rd, KonradPE. Correlation of motor-evoked potential response to ischemic spinalcord damage. J Thorac Cardiovasc Surg. 1992;104:262-72.

5. Jacobs MJ, Mess WH. The role of evoked potential monitoring inoperative management of type I and type II thoracoabdominal aorticaneurysms. Semin Thorac Cardiovasc Surg. 2003;15:353-64.

6. Jacobs MJ, Elenbaas TW, Schurink GW, Mess WH, Mochtar B.Assessment of spinal cord integrity during thoracoabdominal aorticaneurysm repair. Ann Thorac Surg. 2002;74:S1864-6.

7. Jacobs MJ, Meylaerts SA, de Haan P, de Mol BA, Kalkman CJ.Assessment of spinal cord ischemia by means of evoked potentialmonitoring during thoracoabdominal aortic surgery. Semin Vasc Surg.2000;13:299-307.

8. Edmonds HL Jr, Rodriguez RA, Audenaert SM, Austin EH 3rd,Pollock SB Jr, Ganzel BL. The role of neuromonitoring in cardiovas-cular surgery. J Cardiothorac Vasc Anesth. 1996;10:15-23.

9. Cho H, Nemoto EM, Yonas H, Balzer J, Sclabassi RJ. Cerebralmonitoring by means of oximetry and somatosensory evoked poten-tials during carotid endarterectomy. J Neurosurg. 1998;89:533-8.

0. Daubeney PE, Smith DC, Pilkington SN, Lamb RK, Monro JL, TsangVT, et al. Cerebral oxygenation during paediatric cardiac surgery:identification of vulnerable periods using near infrared spectroscopy.Eur J Cardiothorac Surg. 1998;13:370-7.

1. Deeb GM, Jenkins E, Bolling SF, Brunsting LA, Williams DM, QuintLE, et al. Retrograde cerebral perfusion during hypothermic circula-tory arrest reduces neurologic morbidity. J Thorac Cardiovasc Surg.1995;109:259-68.

2. Murkin JM. Perioperative detection of brain oxygenation and clinicaloutcomes in cardiac surgery. Semin Cardiothorac Vasc Anesth. 2004;8:13-4.

3. Coselli JS, LeMaire SA, Conklin LD, Köksoy C, Schmittling ZC.Morbidity and mortality after extent II thoracoabdominal aortic aneu-rysm repair. Ann Thorac Surg. 2002;73:1107-15.

4. Svensson LG, Crawford ES, Hess KR, Coselli JS, Safi HJ. Experiencewith 1509 patients undergoing thoracoabdominal aortic operations. JVasc Surg. 1993;17:357-68.

5. de Mol BA, Boezeman EH, Hamerlijnck RP, de Geest R. Experimentaland clinical use of somatosensory evoked potentials in surgery ofaneurysms of the descending thoracic aorta. Thorac Cardiovasc Surg.1990;38:146-50.

6. Grabitz K, Freye E, Sandmann W. Somatosensory evoked potential,a prognostic tool for the recovery of motor function following

ember 2006 on June 4, 2013 nals.org

1

1

1

2

2

2

2

2

2

LeMaire et al Evolving Technology

malperfusion of the spinal cord: studies in dogs. J Clin Monit.1993;9:191-5.

7. Mizrahi EM, Crawford ES. Somatosensory evoked potentials duringreversible spinal cord ischemia in man. Electroencephalogr Clin Neu-rophysiol. 1984;58:120-6.

8. Meylaerts SA, Jacobs MJ, van Iterson V, De Haan P, Kalkman CJ.Comparison of transcranial motor evoked potentials and somatosen-sory evoked potentials during thoracoabdominal aortic aneurysm re-pair. Ann Surg. 1999;230:742-9.

9. van Dongen EP, Schepens MA, Morshuis WJ, ter Beek HT, Aarts LP,de Boer A, et al. Thoracic and thoracoabdominal aortic aneurysmrepair: use of evoked potential monitoring in 118 patients. J Vasc Surg.2001;34:1035-40.

0. Guerit JM, Dion RA. State-of-the-art of neuromonitoring for preven-tion of immediate and delayed paraplegia in thoracic and thoracoab-dominal aorta surgery. Ann Thorac Surg. 2002;74:S1867-9; discussion

The Journal of Thoracicjtcs.ctsnetjoDownloaded from

1. Lips J, de Haan P, Bouma GJ, Holman R, van Dongen E, Kalkman CJ.Continuous monitoring of cerebrospinal fluid oxygen tension in rela-tion to motor evoked potentials during spinal cord ischemia in pigs.Anesthesiology. 2005;102:340-5.

2. Christiansson L, Karacagil S, Thelin S, Hellberg A, Tyden H, WiklundL, et al. Continuous monitoring of intrathecal pO2, pCO2 and pH duringsurgical replacement of type II thoracoabdominal aortic aneurysm. EurJ Vasc Endovasc Surg. 1998;15:78-81.

3. Kunihara T, Shiiya N, Matsui Y, Yasuda K. Preliminary reportof transesophageal monitoring of spinal cord ischemia using near-infrared spectrophotometry. J Cardiovasc Surg (Torino). 2004;45:95-6.

4. Murkin JM. Etiology and incidence of brain dysfunction after cardiacsurgery. J Cardiothorac Vasc Anesth. 1999;13:12-7.

5. Macnab AJ, Gagnon RE, Gagnon FA. Near infrared spectroscopyfor intraoperative monitoring of the spinal cord. Spine. 2002;27:

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and Cardiovascular Surgery ● Volume 132, Number 5 1155 on June 4, 2013 urnals.org

DOI: 10.1016/j.jtcvs.2006.05.047 2006;132:1150-1155 J Thorac Cardiovasc Surg

Joseph S. Coselli Jr, Akif Ündar, Zachary C. Schmittling, Xing Li Wang, Charles D. Fraser, Jr and

Scott A. LeMaire, Lyssa N. Ochoa, Lori D. Conklin, Ron A. Widman, Fred J. Clubb, ischemia during intercostal artery ligation: Preliminary experimental results

Transcutaneous near-infrared spectroscopy for detection of regional spinal

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