title: Cognitive changes after saline or plasmalyte infusion in healthy volunteers: a multiple blinded, randomized, cross-over trial.
abstract: BACKGROUND
  In an incidental finding, during a study of plasma chemistry after crystalloid infusion, participants reported subjective cognitive changes, particularly slower thinking, after saline but not Hartmann's (Ringer's lactate) solution. The authors tested the hypothesis that saline infusion would produce greater adverse cognitive changes than Plasmalyte infusion.
  
  
  METHODS
  The authors conducted a randomized, cross-over, multiple blinded study of healthy adult volunteers. On separate days, participants received 30 ml/kg over 1 h of either 0.9% saline or Plasmalyte with the order randomly allocated. Plasma chemistry was tested on venous samples. As part of a battery of cognitive tests our primary endpoint was the reaction time index after infusion.
  
  
  RESULTS
  The authors studied 25 participants. Plasma chloride was greater after saline than after Plasmalyte: mean difference 5.4 mM (95% CI, 4.1-6.6 mM; P < 0.001). Saline was also associated with greater metabolic acidosis: base-excess 2.5 mM more negative (95% CI, 1.9-3.0 mM more negative; P < 0.001). There was no evidence of a difference in the reaction time index between the two interventions: mean reaction time index 394 ms (SD, 72) after saline versus 385 ms (SD, 55) after Plasmalyte. Difference: saline 9 ms slower (95% CI, 30 ms slower to 12 ms faster; P = 0.39). There were minimal differences in the other cognitive and mood tests.
  
  
  CONCLUSIONS
  Despite expected differences in plasma chemistry, the authors found that measures of cognition did not differ after infusions of Plasmalyte or saline.
authors.affiliation: Perioperative and Pain Medicine Unit, Melbourne Medical School, The University of Melbourne, Melbourne, Victoria 3010, Australia. david.story@austin.org.au
authors.forename: David A
authors.initials: DA
authors.lastname: Story
authors.forename: Lucy
authors.initials: L
authors.lastname: Lees
authors.forename: Laurence
authors.initials: L
authors.lastname: Weinberg
authors.forename: Soon-Yee
authors.initials: SY
authors.lastname: Teoh
authors.forename: Katherine J
authors.initials: KJ
authors.lastname: Lee
authors.forename: Sarah
authors.initials: S
authors.lastname: Velissaris
authors.forename: Rinaldo
authors.initials: R
authors.lastname: Bellomo
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Wilson
mesh_terms: D000138:Acidosis / Q000139:chemically induced; D000328:Adult; D003071:Cognition / Q000187:drug effects*; D018592:Cross-Over Studies; D005260:Female; D005942:Gluconates / Q000009:adverse effects; D006801:Humans; D015636:Magnesium Chloride / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D011189:Potassium Chloride / Q000009:adverse effects; D011930:Reaction Time / Q000187:drug effects; D019346:Sodium Acetate / Q000009:adverse effects; D012965:Sodium Chloride / Q000009:adverse effects*
chemical_list: D005942:Gluconates; C012499:Plasma-lyte 148; D015636:Magnesium Chloride; D012965:Sodium Chloride; D019346:Sodium Acetate; D011189:Potassium Chloride