SRS350 - Organ protection in high-risk open thoracoabdominal aortic aneurysm repair: single-centre outcomes and the role of cerebrospinal fluid microdialysis(MD) as real-time spinal cord metabolic monitoring

Abstract Background Open thoracoabdominal aortic aneurysm (TAAA)repair carries high risk of organ ischaemia.We assessed mortality, survival, and the effect of standardised organ and spinal cord protection bundle in high-risk single-centre cohort. Methods Analysis of 124 consecutive repairs (2017–2021): open 98, endovascular 26; non-elective 26; Extent II 69; redo 51. Risk factors were analysed. The bundle comprised left-heart bypass (LHB), selective coeliac and renal perfusion (Custodiol/cold blood), cerebrospinal fluid drainage (CSFD), paraspinal NIRS, cMEP, selective intercostal reimplantation. In a feasibility subset, lactate, pyruvate, and glucose CSF/MD were measured serially;lactate-pyruvate-ratio(LPR > 25) was pre-specified as a metabolic ischaemia threshold. Results In-hospital mortality was 17.7% (open 16.9%; endovascular 0.8%). Stroke 6.5%; SCI 11.3% (permanent 8.9%). Haemofiltration was required in 41.9% (permanent 4.0%). Five-year survival was 79.8%. Bundle delivery: LHB > 90%, CSFD 79.8%, coeliac/SMA perfusion 88%, renal perfusion 82%, CSFD/MD 5% (feasibility). Haemofiltration (HR 14.89, P = 0.020) and paraplegia (HR 4.30, P = 0.027) predicted in-hospital death, whereas SMA perfusion was protective (HR 0.023, P = 0.036). Serial MD showed metabolic derangement during ischaemia (rising lactate, falling glucose, LPR > 25), normalising with reperfusion. Lactate rose fivefold, peaking six hours postoperatively (P = 0.001). Intraoperative SCI (two patients with >50% cMEP reduction) was associated with 200% LPR increase. Conclusions In this high-risk Extent II, non-elective/redo cohort,multimodal protection achieved acceptable survival. Mortality was driven by renal replacement therapy and SCI, underscoring the need for rigorous spinal protocols and standardised bundles. CSF microdialysis offers actionable real-time metabolic surveillance with potential to improve outcomes.