title: Clinical evaluation of hyponatremia and hypovolemia in critically ill adult neurologic patients: contribution of the use of cumulative balance of sodium.
abstract: OBJECTIVE
  Knowledge of the cumulative balance of sodium (CBS) is important for the diagnosis of salt disorders and water homeostasis and has the potential to predict hypovolemic status in acute neurological patients. However, an extensive application of the use of CBS is still lacking in the intensive care setting, where salt and water homeostasis represents a priority.
  
  
  METHODS
  Records of consecutive series of acute neurological patients admitted to a neurointensive care unit over a 6-month period were retrospectively reviewed. CBS was calculated at the admission to the Emergency Department. Discrimination between cerebral salt-wasting syndrome (CSWS) and the syndrome of inappropriate antidiuretic hormone secretion (SIADH) was performed on the basis of the classical criteria. Additionally, we used the findings of a negative CBS exceeding 2 mEq/kg for the diagnosis of CSWS. Two independent clinicians who were blinded to the CBS results performed diagnosis of the causes of hyponatremia and estimated the daily volemic status of the patients on the basis of clinical parameters. Logistic regression analysis was used to determine the independent prognostic factors of hypovolemia.
  
  
  RESULTS
  Thirty-five patients were studied for a total of 418 days. Four patients (11.4%) fitted the criteria of CSWS and three patients (8.5%) had SIADH. The unavailability of the CBS led to a wrong diagnosis in three of the eight hyponatremic patients (37.5%). The risk of developing hypovolemia in patients with negative CBS was 7.1 times higher (CI 3.86-13.06; p < 0.001). Multivariate analysis revealed that negative cumulative fluid balance, negative CBS >2 mEq/kg, and CVP ≤5 cmH2O were independent prognostic factors for hypovolemia.
  
  
  CONCLUSIONS
  CBS is likely to be a useful parameter in the diagnosis of CSWS and a surrogate parameter for estimating hypovolemia in acute neurological patients.
authors.affiliation: Department of Anesthesia and Intensive Care, Ospedale Papa Giovanni XXIII°, Bergamo, Italy, grittip@libero.it.
authors.forename: Paolo
authors.initials: P
authors.lastname: Gritti
authors.forename: Luigi Andrea
authors.initials: LA
authors.lastname: Lanterna
authors.forename: Lidia
authors.initials: L
authors.lastname: Rotasperti
authors.forename: Matteo
authors.initials: M
authors.lastname: Filippini
authors.forename: Simone
authors.initials: S
authors.lastname: Cazzaniga
authors.forename: Carlo
authors.initials: C
authors.lastname: Brembilla
authors.forename: Tatyana
authors.initials: T
authors.lastname: Sarnecki
authors.forename: Ferdinando Luca
authors.initials: FL
authors.lastname: Lorini
mesh_terms: D000328:Adult; D000368:Aged; D016638:Critical Illness; D005260:Female; D006801:Humans; D007010:Hyponatremia / Q000453:epidemiology* / Q000209:etiology; D020896:Hypovolemia / Q000453:epidemiology*; D007177:Inappropriate ADH Syndrome / Q000175:diagnosis* / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012964:Sodium / Q000378:metabolism*; D055815:Young Adult
chemical_list: D012964:Sodium