Transcutaneous near-infrared spectroscopy for monitoring spinal cord ischemia: an experimental study in swine

Abstract

We aimed to assess the ability of near-infrared spectroscopy (NIRS) to detect spinal cord ischemia, and to evaluate changes in regional oxygen saturation (rSO) following recovery of spinal cord circulation and cerebrospinal fluid drainage. Four 12-month-old female swine weighing 28.7-29.5 kg were acquired for this study. NIRS probes were placed along the midline of the upper (T6/7) and lower (T9/T10) thoracic vertebrae. The thoracic aorta was clamped distal of the left subclavian artery to induce spinal ischemia. Aortic cross-clamping was maintained for 30 min. Fifteen minutes after aortic de-clamping, the cerebrospinal fluid drainage catheter was opened to air, and cerebrospinal fluid drainage was initiated. Following aortic clamping, rSO in both upper and lower regions of the spinal cord decreased by 15 % within 5 min and by 20 % within 10 min (relative change). After aortic de-clamping, rSO values in both regions returned to baseline within 5 min. No changes in rSO in either the upper or lower vertebrae were observed following initiation of cerebrospinal fluid drainage. Histological analysis revealed that ischemic changes had occurred in all spinal levels. NIRS may be used to detect decreases in and recovery of spinal cord circulation following aortic clamping and de-clamping, whereas it may not reflect minor changes in spinal cord circulation due to cerebrospinal fluid drainage. Further clinical studies are required to investigate the potential for NIRS as an index of spinal cord circulation.

Evaluation of collateral network near-infrared spectroscopy during and after segmental artery occlusion in a chronic large animal model

“…Previous experimental and clinical studies on cnNIRS have shown that although in heterogeneous setups and study protocols, it reflects oxygenation changes after aortic crossclamping and distal aortic perfusion in real-time. 7,8,[11][12][13]20 On the basis of these and other studies, cnNIRS emerged as a promising new and economic method, potentially guiding extensive aortic procedures by giving real-time feedback on spinal cord perfusion. 21…”

“…Whether in addition to lumbar cnNIRS optodes, mid and especially lower thoracic cnNIRS measurements also are necessary for a complete and consistent oxygenation mapping of the CN is yet unclear and is the focus of ongoing research. The limitation of optode placement directly above the vertebrae has been acknowledged by their respective authors, who suggested that measuring surrounding tissue may enable indirect cord monitoring via the paraspinal CN, 7,20,23 a concept that represents the rationale for current cnNIRS monitoring practice. 11,12,23 Although sensitivity of cnNIRS after stent deployment during endovascular aortic repair was recently published in 2 reports (total of 3 patients), 21,22 available data from previous case series and ongoing clinical investigations suggest that lumbar cnNIRS does not reliably pick up relevant changes in oxygenation during endovascular procedures in humans (not experiencing procedure-related SCI).…”

Spinal cord autoregulation using near-infrared spectroscopy under normal, hypovolemic, and post-fluid resuscitation conditions in a swine model: a comparison with cerebral autoregulation

“…NIRS estimates mixed tissue hemoglobin oxygen saturation levels of the arterial, venous, and capillary blood within the field of view [10,11], which allows the oxygen supply-and-demand balance to be evaluated under differing conditions. Similar to what has been done with the cerebrum, several studies have measured spinal cord oxygenation using NIRS directly [12][13][14][15] (via surgical procedure or thin fiber-optic probe placed in the intrathecal or epidural space) or indirectly [16][17][18][19] (via paraspinal muscle oxygenation monitoring, based on the paraspinal collateral network concept) to monitor spinal cord perfusion, but few studies to date have assessed spinal cord autoregulation using this method.…”

New Developments in Hemodynamic Monitoring

“…30 After publication of that review, a fourth-generation software was released and tested, concluding that the accuracy of CO values measured with this version has improved greatly compared with previous versions but still did not reach a clinically sufficient level (ie, a percentage error <30%). [31][32][33] Another uncalibrated PCA system for monitoring CO is the ProAQT/PulsioFlex system (Pulsion-Getinge, Feldkirchen, Germany). It essentially uses the PCA-based algorithm of the PiCCO system (Pulsion-Getinge), however, without the possibility of external validation by TPTD.…”