Spinal Evoked Potentials are Predictive of Neurologic Function in a Porcine Model of Aortic Occlusion

Abstract

The limitations of somatosensory evoked potentials during aortic occlusion stimulated us to evaluate the sensitivity and specificity of spinal (T10 and L4) evoked potentials (SpEPs) in predicting neurologic function after aortic occlusion. Thirty-six swine were assigned randomly to three equal groups (Group 1, control; Group 2, cerebrospinal fluid (CSF) drainage; Group 3, CSF drainage with 20-mg intrathecal papaverine). After induction of anesthesia and initiation of physiologic monitoring, a left-sided thoracotomy was performed to provide access to the descending aorta. SpEPs were generated by stimulating the thoracic spinal cord and recording the conducted response at the T10 and L4 level. After baseline measurements were recorded, the descending aorta was occluded 1 cm distal to the left subclavian artery. SpEPs were recorded every 2.5 min and physiologic variables every 5 min. The aorta was unclamped 10, 15, or 20 min after loss of the L4 SpEP. If the L4 SpEP was not lost, the aortic occlusion interval was terminated at 90 min. Attenuation of the SpEPs occurred earlier at the L4 level. Group 1 experienced the earliest loss of the L4 SpEP (18.3 +/- 7.8 min, P < 0.005). Loss of the L4 SpEP in Group 2 (49.3 +/- 27.8 min) was earlier than in Group 3 (73.7 +/- 26.1 min, P < 0.05). Early postoperative motor function (modified Tarlov scale) correlated with time from loss of the L4 SpEP until reperfusion of the distal aorta (r = 0.93). The sensitivity, specificity, and accuracy of the L4 SpEP in predicting neurologic dysfunction was 92.8% (13 abnormal/14 predicted), 90.9% (20/22), and 91.7% (33/36).(ABSTRACT TRUNCATED AT 250 WORDS)

Monitoring of intrathecal oxygen tension during experimental aortic occlusion predicts ultrastructural changes in the spinal cord

“…Predicting the degree of spinal cord ischemia during thoracic aortic clamping is of importance to obtain better neurologic outcome. Various neurophysiologic monitoring methods have been successfully used during aortic replacement [4][5][6][7][8][9][10][11] but are still controversial [12][13][14][15] and not universally accepted. We 14 have recently described the use of a flexible multiparameter intrathecal catheter for continuous monitoring of cerebrospinal PO 2 , PCO 2 , and pH.…”

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Protective Effect of Sildenafil (Viagra) in Transient Spinal Cord Ischemia

“…Latency and amplitude are two important parameters that are carefully monitored in this technique. In previous studies, a 15–20% decrease in amplitude has been recognized as a significant indicator of SEP variations [1, 22, 23]. Such variations in SEP are measured as extensions of the period of distal latency and decreases in amplitude [24,25,26,27,28,29,30,31,32,33,34].…”

Intra-aortic injection of propofol prevents spinal cord injury during aortic surgery☆

“…In clinical settings, the detection of MEP changes after aortic cross-clamping often necessitates more than 15 min [9,10,23], as seen group 1. The ischemic injury in the spinal cord progresses during the diagnostic process.…”

“…Transcranial spinal motor-evoked potentials (MEPs) enable an evaluation of spinal cord function during general anesthesia and an early diagnosis of spinal cord ischemia during TAAA surgery [8][9][10]. We monitored the attenuation of MEP amplitudes in the current practice of TAAA repair to determine whether intercostal or lumbar arteries in clamped segments of aortas should be reconstructed [8].…”