Intraoperative assessment of human spinal cord perfusion using near infrared spectroscopy with indocyanine green tracer technique

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• 作者：Amir Reza Amiri ; Cheong Hung Lee ; Terence S. Leung ; Michael Hetreed ; Michael D. Craggs ; Adrian T.H. Casey
• 关键词：Near infrared spectroscopy ; Spinal cord perfusion ; Intraoperative spinal cord monitoring ; Human ; Carbon dioxide reactivity
• 刊名：The Spine Journal
• 出版年：1 December, 2013
• 年：2013
• 卷：13
• 期：12
• 页码：1818-1825
• 全文大小：537 K

文摘

Background context

Despite the significant interest in the assessment of human cerebral perfusion, investigations into human spinal cord perfusion (SCP) are scarce. Current intraoperative monitoring of spinal cord relies on the assessment of neural conduction as a surrogate for SCP. However, there are various inherent limitations associated with the use of these techniques. Near infrared spectroscopy (NIRS) has been successfully used for monitoring and assessment of human cerebral perfusion and has shown promising results in intraoperative assessment of SCP in animal models.

Purpose

The aim of this study was to investigate whether it is possible to monitor physiological changes in human SCP intraoperatively using NIRS with indocyanine green (ICG) tracer technique. We used this technique to calculate the human spinal cord carbon dioxide (CO₂) reactivity index. In addition, we investigated whether the lamina causes significant attenuation of NIRS signals.

Study design/setting

Intraoperative human experimental study.

Patient sample

Eighteen patients undergoing elective posterior cervical spine surgery.

Outcome measures

Carbon dioxide reactivity of human SCP.

Methods

Nine patients underwent transdural assessment of SCP, with an additional nine patients undergoing translaminar measurements. Patients' SCP was continuously monitored using an NIRO-500 NIRS monitor via a set of purpose built optodes. Their arterial ICG concentration was simultaneously assessed using a pulse dye densitometer. Patients' end-tidal CO₂ was gradually increased by 7.5 mm Hg and then returned back to baseline. Three sets of measurements were taken: baseline, hypercapnic, and return to baseline.

Results

After hypercapnia, SCP increased by a mean of 57.2卤23.3% in the transdural group and 46.6卤36.3% in the translaminar group. Carbon dioxide reactivity index was 7.6卤3.2%螖SCP/mm Hg in the transdural group and 6.4卤5.3 %螖SCP/mm Hg in the translaminar group. There was no significant difference in the increase in SCP (p=.475) or the CO₂ reactivity index (p=.581) observed between the transdural and the translaminar groups.

Conclusions

Intraoperative NIRS with ICG tracer technique can identify an increase in the SCP in response to hypercapnia. It is possible to use this technique for monitoring SCP over the dura and the lamina. This technique could potentially be used to provide insight in to the pathophysiology and autoregulation of commonly acquired spinal cord conditions. Further research assessing the use of NIRS for monitoring of SCP is required.