title: Strong ion and weak acid analysis in severe preeclampsia: potential clinical significance.
abstract: BACKGROUND
  The influence of common disturbances seen in preeclampsia, such as changes in strong ions and weak acids (particularly albumin) on acid-base status, has not been fully elucidated. The aims of this study were to provide a comprehensive acid-base analysis in severe preeclampsia and to identify potential new biological predictors of disease severity.
  
  
  METHODS
  Fifty women with severe preeclampsia, 25 healthy non-pregnant- and 46 healthy pregnant controls (26-40 weeks' gestation), were enrolled in this prospective case-control study. Acid-base analysis was performed by applying the physicochemical approach of Stewart and Gilfix.
  
  
  RESULTS
  Mean [sd] base excess was similar in preeclamptic- and healthy pregnant women (-3.3 [2.3], and -2.8 [1.5] mEq/L respectively). In preeclampsia, there were greater offsetting contributions to the base excess, in the form of hyperchloraemia (BE(Cl) -2 [2.3] vs -0.4 [2.3] mEq/L, P<0.001) and hypoalbuminaemia (BE(Alb) 3.6 [1] vs 2.1 [0.8] mEq/L, P<0.001). In preeclampsia, hypoalbuminaemic metabolic alkalosis was associated with a non-reassuring/abnormal fetal heart tracing (P<0.001). Quantitative analysis in healthy pregnancy revealed respiratory and hypoalbuminaemic alkalosis that was metabolically offset by acidosis, secondary to unmeasured anions and dilution.
  
  
  CONCLUSIONS
  While the overall base excess in severe preeclampsia is similar to that in healthy pregnancy, preeclampsia is associated with a greater imbalance offsetting hypoalbuminaemic alkalosis and hyperchloraemic acidosis. Rather than the absolute value of base excess, the magnitude of these opposing contributors may be a better indicator of the severity of this disease. Hypoalbuminaemic alkalosis may also be a predictor of fetal compromise.
  
  
  BACKGROUND
  clinicaltrials.gov: NCT 02164370.
authors.affiliation: Department of Anesthesiology and Pain Medicine, University of Washington, 1959 NE Pacific Street, Suite BB1415, Box 356540, Seattle, WA 98195-6540, USA clemens.ortner@meduniwien.ac.at.
authors.forename: C M
authors.initials: CM
authors.lastname: Ortner
authors.affiliation: Department of Anaesthesia, University of Cape Town and New Groote Schuur Hospital, Cape Town, South Africa.
authors.forename: B
authors.initials: B
authors.lastname: Combrinck
authors.affiliation: Department of Obstetrics and Gynaecology, University of Cape Town and New Groote Schuur Hospital, Cape Town, South Africa.
authors.forename: S
authors.initials: S
authors.lastname: Allie
authors.affiliation: Anaesthesia, Perioperative and Pain Medicine Unit, Melbourne Medical School, The University of Melbourne, Melbourne, Australia.
authors.forename: D
authors.initials: D
authors.lastname: Story
authors.affiliation: Department of Anesthesiology and Pain Medicine, University of Washington, 1959 NE Pacific Street, Suite BB1415, Box 356540, Seattle, WA 98195-6540, USA.
authors.forename: R
authors.initials: R
authors.lastname: Landau
authors.affiliation: Department of Biostatistics, School of Public Health, University of Washington.
authors.forename: K
authors.initials: K
authors.lastname: Cain
authors.affiliation: Department of Anaesthesia, University of Cape Town and New Groote Schuur Hospital, Cape Town, South Africa.
authors.forename: R A
authors.initials: RA
authors.lastname: Dyer
mesh_terms: D000137:Acid-Base Imbalance / Q000209:etiology*; D000471:Alkalosis / Q000209:etiology; D001639:Bicarbonates / Q000097:blood; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D034141:Hypoalbuminemia / Q000150:complications; D011225:Pre-Eclampsia / Q000378:metabolism*; D011247:Pregnancy; D011446:Prospective Studies
chemical_list: D001639:Bicarbonates
keywords: acid-base balance; pre-eclampsia; pregnancy