Intrathecal lactate as a predictor of early- but not late-onset spinal cord injury in thoracoabdominal aneurysmectomy

Objective To evaluate the role of intrathecal lactate as an early predictor of spinal cord injury during thoracoabdominal aortic aneurysmectomy. Design Observational study. Setting University hospital. Participants Forty-four consecutive patients scheduled to undergo thoracoabdominal aortic aneurysmectomy. Two patients had a type-B dissecting aneurysm while the other 42 patients suffered from degenerative aneurysm. Interventions None. Methods During surgery, samples of cerebrospinal fluid and arterial blood were withdrawn simultaneously to evaluate lactate concentration. Samples were collected at 4 fixed times during and after surgery: T1 (beginning of the intervention), T2 (15 minutes after aortic cross-clamping), T3 (just before unclamping), T4 (end of surgery). Measurements and Main Results Mean lactate levels in cerebrospinal fluid rose consistently and steadily from the beginning of the intervention until after surgery (T1 = 1.83 mmol/L), T2 = 2.10 mmol/L, T3 = 2.72 mmol/L, T4 = 3.70 mmol/L). Seven patients developed spinal cord injury; two of them had delayed injury occurring 24 hours after the end of surgery; the remaining 5 had early onset. In this group of 5 patients, preoperative cerebrospinal fluid lactate levels were significantly (p = 0.04) higher than those of the other 37 patients preoperatively (2.12 ± 0.35 v 1.79 ± 0.29 mmol/L). Conclusions Preoperative cerebrospinal lactate concentration is elevated in patients who will develop early-onset spinal cord injury after thoracoabdominal aortic aneurysmectomy. This may allow a better stratification of these patients, suggesting a more aggressive strategy of spinal cord function preservation, such as systematic reimplanting of intercostal arteries, and possibly obtaining a better outcome.