Hypothermia Decreases Cerebrospinal Fluid Asymmetric Dimethylarginine Levels in Children With Traumatic Brain Injury.
OBJECTIVES:: Pathological increases in asymmetric dimethylarginine, an endogenous nitric oxide synthase inhibitor, have been implicated
in endothelial dysfunction and vascular diseases. Reduced nitric oxide early after traumatic brain injury may contribute to
hypoperfusion. Currently, methods to quantify asymmetric dimethylarginine in the cerebrospinal fluid have not been fully explored.
We aimed to develop and validate a method to determine asymmetric dimethylarginine in the cerebrospinal fluid of a pediatric
traumatic brain injury population and to use this method to assess the effects of 1) traumatic brain injury and 2) therapeutic
hypothermia on this mediator.
DESIGN, SETTING, AND PATIENTS:: An ancillary study to a prospective, phase II randomized clinical trial of early hypothermia in a tertiary care pediatric intensive care unit for children with Traumatic brain injury admitted to Children's Hospital of Pittsburgh.
MEASUREMENTS AND MAIN RESULTS:: A UPLC-MS/MS method was developed and validated to quantitate asymmetric dimethylarginine. A total of 56 samples collected over 3 days with injury onset were analyzed from the cerebrospinal fluid of consented therapeutic hypothermia (n = 9) and normothermia (n = 10) children. Children undergoing diagnostic lumbar puncture (n = 5) were enrolled as controls. Asymmetric dimethylarginine was present at a quantifiable level in all samples. Mean asymmetric dimethylarginine levels were significantly increased in normothermic Traumatic brain injury children compared with that in control (0.19 ± 0.08 µmol/L and 0.11 ± 0.02 µmol/L, respectively, p = 0.01), and hypothermic children had significantly reduced mean asymmetric dimethylarginine levels (0.11 ± 0.05 µmol/L) vs. normothermic (p = 0.03) measured on day 3. Patient demographics including age, gender, and nitric oxide levels (measured as nitrite and nitrate using liquid chromatography coupled with Griess reaction) did not significantly differ between normothermia and hypothermia groups. Also, nitric oxide levels did not correlate with asymmetric dimethylarginine concentrations.
CONCLUSIONS:: Asymmetric dimethylarginine levels were significantly increased in the cerebrospinal fluid of traumatic brain injury children. Early hypothermia attenuated this increase. The implications of attenuated asymmetric dimethylarginine on nitric oxide synthases activity and regional cerebral blood flow after traumatic brain injury by therapeutic hypothermia deserve future study.
1Department of Pharmaceutical Sciences, School of Pharmacy, University of Pittsburgh, Pittsburgh, PA. 2Edward Via College of Osteopathic Medicine, Blacksburg, VA. 3Safar Center for Resuscitation Research, School of Medicine, University of Pittsburgh, Pittsburgh, PA. 4Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center and Department of Critical Care Medicine, School of Medicine, University of Pittsburgh, Pittsburgh, PA. 5Department of Neurological Surgery, School of Medicine, University of Pittsburgh, Pittsburgh, PA. 6Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix, AZ. 7Department of Critical Care Medicine, School of Medicine and Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA.
SourcePediatric critical care medicine : a journal of the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies 14:4 2013 May pg 403-412
Pub Type(s)JOURNAL ARTICLE