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

OBJECTIVE: Ischemic spinal cord injury remains the most devastating complication after open and endovascular aortic repair. Collateral network near-infrared spectroscopy has been introduced to noninvasively monitor real-time spinal cord oxygenation. In view of recent advancements in endovascular treatment and minimally invasive staged preconditioning before aortic repair, this study sought to evaluate collateral network near-infrared spectroscopy during and after segmental artery occlusion in a chronic porcine model.

METHODS: Surgery for segmental artery occlusion was performed in 12 juvenile pigs, and bilateral lumbar collateral network near-infrared spectroscopy was recorded. Two intervention groups were designed: Group 1 received subtotal segmental artery occlusion (mimicking reimplantation of crucial segmental arteries with patent T12/T13, N = 5), and group 2 received total occlusion (T4-L5, N = 7). Pigs were monitored over 3 days.

RESULTS: All animals were paraplegic during the first 24 hours. The subtotal occlusion group completely recovered, whereas 57% of the total occlusion group remained paraplegic (N = 4/7). After segmental artery occlusion, collateral network near-infrared spectroscopy decreased from 92.3% ± 8% of baseline to 69.3% ± 18% after 10 minutes in the subtotal group (P = .003-.017) and from 90.1% ± 4% to 58.2% ± 9% in the total group (P < .001-.008). Throughout the postoperative period, collateral network near-infrared spectroscopy in the total occlusion group remained lower compared with the subtotal group (<30% baseline threshold, P < .05). Lumbar collateral network near-infrared spectroscopy and neurologic outcome were significantly correlated (R = 0.7, P < .001).

CONCLUSIONS: Lumbar collateral network near-infrared spectroscopy reacts to occlusion of segmental arteries and correlates with neurologic outcome. The preliminary data suggest that collateral network near-infrared spectroscopy may be a valuable noninvasive tool for detecting imminent spinal cord ischemia during and after aortic procedures involving segmental artery occlusion.