Agreement of measured and calculated serum osmolality during the infusion of mannitol or hypertonic saline in patients after craniotomy: a prospective, double-blinded, randomised controlled trial

Abstract

BackgroundMannitol and hypertonic saline are used to ameliorate brain edema and intracranial hypertension during and after craniotomy. We hypothesized that the agreement of measured and calculated serum osmolality during the infusion of hypertonic saline would be better than mannitol. The objective was to determine the accuracy of serum osmolality estimation by different formulas during the administration of hyperosmolar agent.MethodsA prospective, randomized, double-blinded, controlled trial was conducted in a 30-bed neurosurgical intensive care unit at a university hospital. Thirty-five adult patients requiring the use of hyperosmolar agents for prevention or treatment of brain edema after elective craniotomy were enrolled, and randomly assigned 1:1 to receive 125 mL of either 20 % mannitol (mannitol group) or 3.1 % sodium chloride solution (hypertonic saline group) in 15 min. Serum osmolality, serum sodium and potassium concentration, blood urea nitrogen and blood glucose concentration were measured during the study period. The primary outcome was the agreement of measured and estimated serum osmolality during the infusion of the two experimental agents. We used Bland and Altman’s limits of agreement analysis to clarify the accuracy of estimated serum osmolality. Bias and upper and lower limits of agreement of bias were calculated.ResultsFor each formula, the bias was statistically lower in hypertonic saline group than mannitol group (p < 0.001). Within group comparison showed that the lowest bias (6.0 [limits of agreement: −18.2 to 30.2] and 0.8 [−12.9 to 14.5] mOsml/kg in mannitol group and hypertonic saline group, respectively) was derived from the formula ‘2 × ([serum sodium] + [serum potassium]) + [blood urea nitrogen] + [blood glucose]’.ConclusionsCompared to mannitol, a better agreement between measured and estimated serum osmolality was found during the infusion of hypertonic saline. This result indicates that, if hypertonic saline is chosen to prevent or treat brain edema, calculated serum osmolality can be used as a reliable surrogate for osmolality measurement.Trial registrationClinicalTrials.gov identifier: NCT02037815

Prediction of Mortality in Pediatric Traumatic Brain Injury: Implementations from a Tertiary Pediatric Intensive Care Facility

“…[21] We confirmed that the medication were initiated with the admission to PICU in a majority of the children, and the duration to reach the target serum osmolality extended to 8.5 h (3.5-40 h). In the prospective randomized double blind study, Li et al [22] demonstrated the serum osmolality for mannitol and 3% NaCl infusion was as 292.4±9.1 mosm/L and 294.1±6.6 mosm/L, respectively, and both these values were below the threshold levels at 6 h. As shown by Francony et al, [23] 20% Mannitol and 7.4% NaCl infusions elevated serum osmolality only by 2%. Delays in achieving the target osmolality result in prolonged exposure to elevated ICP which are directly related to negative prognosis, and a multidisciplinary approach towards TBI management (medical staff responding in the field, ER physicians, and neurosurgeons) contributes to positive prognosis.…”

Retrospective evaluation of the association between hyponatremia and neurological dysfunction in hospitalized foals (2012‐2016): 109 cases

“…This assumption was supported by the fact that calculated efOsmol was significantly lower in foals with neurological signs compared with those without. Ideally, efOsmol is measured, rather than calculated, but in most clinical situations good correlation between both can be assumed . Exceptions are cases with the presence of unidentified osmoles that remain undetected unless osmolality is measured .…”

A teaspoon of sugar and a pinch of salt

“…Typical sodium goals for lowering elevated ICPs range from 145 to 155 mmol/L, which correlates to the estimated 10 mOsmol/ kg difference needed to create the gradient necessary to cause fl uid shifts. 14 If these sodium values are exceeded or are achieved too rapidly, patients are at risk for seizures, altered mental status, and potentially central pontine myelinolysis. Recently, data have suggested that chloride may have a larger effect on patients being treated with hypertonic saline than originally thought.…”