Research Reports - The prognostic value of brain nitric oxide metabolites after traumatic brain injury
Neurocrit Care. 2013 Aug;19(1):65-8
Tisdall MM, Rejdak K, Kitchen ND, Smith M, Petzold A
BACKGROUND: 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).
METHODS: 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.
RESULTS: 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%).
CONCLUSION: 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