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Methods: During surgery, samples of cerebrospinal fluid and arterial blood were withdrawn simultaneously to evaluate lactate concentration.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.