title: Polyuria in relation to dysnatraemias in neurocritical care.
abstract: BACKGROUND
  Polyuria has the potential to cause severe water and sodium imbalance. We studied the epidemiology of polyuria in association with dysnatraemias and whether polyuria is an independent risk factor for higher mortality and poorer outcome in neurocritical care.
  
  
  METHODS
  We performed an analysis of a 3-year prospective database containing 902 neurocritical care patients. Polyuria was defined as diuresis above 4000 ml/day, hyponatraemia as a serum sodium (SeNa) < 135 mmol/l and hypernatraemia as SeNa > 150 mmol/l.
  
  
  RESULTS
  We identified polyuria in 236 (26.2%) patients (639 days). Polyuric patients stayed in the neurointensive care unit (NICU) longer than those without polyuria (mean: 10.7 vs. 3.5 days, p < 0.001). These patients also had more frequent cerebral complications (p < 0.001) and a poorer outcome upon discharge from the NICU (p = 0.032). NICU mortality had borderline significance in relation to whether the patients were polyuric (p = 0.055). There were only 49 (20.8%) patients with dysnatraemia who were shown to have a significantly higher NICU mortality (p = 0.006). There were no differences in frequency between hyponatraemic and hypernatraemic polyuric patients (p = 0.127). Polyuric patients with hypernatraemia suffered poorer outcomes (p = 0.009) and higher NICU mortality (p < 0.001), but they had a lower Glasgow Coma Scale or GCS recorded at the onset of polyuria (p < 0.001). Cerebral salt wasting (CSW) was thought to be the cause of polyuria in 7 (3.0%) patients and central diabetes insipidus (CDI) in another 5 (2.1%) patients. Univariate models showed polyuria to be a risk factor for poor outcome (odds ratio [OR] = 1.39, p = 0.032) and had a borderline significance for mortality during their NICU stay (OR = 1.83, p = 0.055). These factors did not appear as significant following multivariate logistic regression analysis.
  
  
  CONCLUSIONS
  Polyuria often occurred in neurocritical care patients, but was not usually associated with sodium imbalance, CSW or CDI. We did not find that polyuria was a significant predictor of increased mortality or poorer outcome in NICU patients.
authors.affiliation: a Neurocenter, Neurointensive care unit, Regional Hospital , Liberec , Czech Republic.
authors.forename: Vera
authors.initials: V
authors.lastname: Spatenkova
authors.affiliation: b Department of Neurosurgery , Central Military Hospital and Charles University , Prague , Czech Republic.
authors.forename: Ondrej
authors.initials: O
authors.lastname: Bradac
authors.affiliation: c Department of Neurosurgery , Royal Hallamshire Hospital , Sheffield , UK.
authors.forename: Patricia
authors.initials: P
authors.lastname: de Lacy
authors.affiliation: d Department of Clinical Biochemistry , Regional Hospital , Liberec , Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Skrabalek
mesh_terms: D000368:Aged; D003422:Critical Care / Q000379:methods*; D005260:Female; D015600:Glasgow Coma Scale; D017052:Hospital Mortality; D006801:Humans; D006955:Hypernatremia / Q000209:etiology / Q000628:therapy*; D007010:Hyponatremia / Q000209:etiology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D009422:Nervous System Diseases / Q000150:complications / Q000628:therapy; D019635:Neurosurgical Procedures; D011141:Polyuria / Q000150:complications / Q000628:therapy*; D011182:Postoperative Care; D011237:Predictive Value of Tests; D011446:Prospective Studies; D016896:Treatment Outcome; D014883:Water-Electrolyte Imbalance / Q000209:etiology
keywords: CSW; central diabetes insipidus; hypernatraemia; hyponatraemia; polyuria