Department of Neuroanaesthesia, The National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK.
Neurocrit Care. 2013 Aug;19(1):65-8. doi: 10.1007/s12028-011-9633-5.
Nitric oxide (NO) is a compound with both protective and damaging effects on neurons. Quantification of NO metabolites in humans is limited by sample contamination with blood. In vivo cerebral microdialysis may offer an alternative approach as sampling of extracellular fluid (ECF) adjacent to neurons becomes possible. We investigate the prognostic value of brain ECF NO metabolites in patients with traumatic brain injury (TBI).
A prospective case cohort of 195 ECF samples collected from 11 cases over 4 days following TBI was collected. Nitrate and nitrite concentrations ([NO x ]) were quantified using a vanadium-based colorimetric assay.
Early ECF [NO x ] (<48 h post TBI) were significantly higher in non-survivors (median 59.2 μmol/l, n = 7) compared to survivors (23.3 μmol/l, n = 4) (P = 0.04). Late (48-96 h) ECF [NO x ] remained higher in non-survivors (47.9 μmol/l) compared to survivors (23.0 μmol/l) but this was not significant (P = 0.29). Receiver operator characteristic analysis shows an optimized cutoff level for ECF [NO x ] of 26.5 μmol/l measured <48 h post TBI for predicting non-survival (sensitivity 100%, specificity 75%).
Early ECF NO x concentrations are of prognostic value after TBI. ECF NO x may be a useful biomarker for treatment trials targeted at nitric oxide metabolism.
一氧化氮（NO）对神经元既有保护作用，也有损伤作用。由于血液会污染样本，因此人类 NO 代谢物的定量检测受到限制。在体内脑微透析可能提供一种替代方法，因为可以对神经元附近的细胞外液（ECF）进行采样。我们研究了外伤性脑损伤（TBI）患者脑 ECF NO 代谢物的预后价值。
对 11 例 TBI 患者 4 天内采集的 195 个 ECF 样本进行前瞻性病例队列研究。使用基于钒的比色测定法来定量硝酸盐和亚硝酸盐浓度（[NO x ]）。
与幸存者（n = 4）相比，非幸存者（n = 7）的早期 ECF [NO x ]（TBI 后 <48 h）明显更高（中位数 59.2 μmol/L）（P = 0.04）。非幸存者（47.9 μmol/L）的晚期（48-96 h）ECF [NO x ]仍高于幸存者（23.0 μmol/L），但无统计学意义（P = 0.29）。受试者工作特征分析显示，TBI 后 <48 h 测量的 ECF [NO x ]的优化截断值为 26.5 μmol/L，用于预测非存活（灵敏度 100%，特异性 75%）。
ECF NO x 浓度在外伤性脑损伤后具有预后价值。ECF NO x 可能是针对一氧化氮代谢的治疗试验的有用生物标志物。
