title: Physicochemical Approach to Determine the Mechanism for Acid-Base Disorders in 793 Hospitalized Foals.
abstract: BACKGROUND
  The quantitative effect of strong electrolytes, unmeasured strong anions (UAs), pCO2, and plasma protein concentrations in determining plasma pH can be demonstrated using the physicochemical approach. Plasma anion gap (AG) and strong ion gap (SIG) are used to assess UAs in different species.
  
  
  OBJECTIVE
  Strong ions are a major factor influencing changes in plasma pH of hospitalized foals. AG and SIG accurately predict severe hyper-L-lactatemia ([L-lac(-)] > 7 mmol/L).
  
  
  METHODS
  Seven hundred and ninety three hospitalized foals < 7 days old.
  
  
  METHODS
  Retrospective study. The relationship between measured pH and physicochemical variables, and the relationship between plasma [L-lac(-)] and AG and SIG, were determined using regression analyses. Optimal AG and SIG cut points to predict hyper-L-lactatemia were identified using an ROC curve analysis.
  
  
  RESULTS
  Combined, the measured strong ion difference and SIG accounted for 54-69% of the changes in the measured arterial pH of hospitalized foals. AG and SIG were significantly associated with plasma [L-lac(-)] (P < .0001). The receiver operator characteristics (ROC) AUC of AG and SIG for prediction of severe hyper-L-lactatemia were 0.89 (95%CI, 0.8-0.95; P < .0001) and 0.90 (95%CI, 0.81-0.96; P < .0001), respectively. Severe hyper-L-lactatemia was best predicted by AG > 27 mmol/L (sensitivity 80%, 95%CI, 56-94, specificity 85%, 95%CI, 73-93; P < .0001) and SIG <-15 mmol/L (sensitivity 90%, 95%CI, 68-98; specificity 80%; 95%CI, 68-90; P < .0001).
  
  
  CONCLUSIONS
  Altered concentrations of strong ions (Na(+), K(+), Cl(-)) and UAs were the primary cause of acidemia of hospitalized foals. AG and SIG were good predictors of hyper-L-lactatemia and could be used as surrogate tests.
authors.affiliation: Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada.
authors.forename: D E
authors.initials: DE
authors.lastname: Gomez
authors.affiliation: Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada.
authors.forename: N M
authors.initials: NM
authors.lastname: Biermann
authors.affiliation: Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA.
authors.forename: L C
authors.initials: LC
authors.lastname: Sanchez
mesh_terms: D000136:Acid-Base Equilibrium; D000137:Acid-Base Imbalance / Q000097:blood / Q000175:diagnosis / Q000662:veterinary*; D000818:Animals; D000831:Animals, Newborn / Q000097:blood; D002712:Chlorides / Q000097:blood; D005260:Female; D006734:Horse Diseases / Q000097:blood / Q000175:diagnosis*; D006736:Horses; D006863:Hydrogen-Ion Concentration; D007773:Lactates / Q000097:blood; D008297:Male; D011188:Potassium / Q000097:blood; D012189:Retrospective Studies; D012964:Sodium / Q000097:blood
chemical_list: D002712:Chlorides; D007773:Lactates; D012964:Sodium; D011188:Potassium
keywords: Anion gap; Nonvolatile weak acids; Strong ion difference; Strong ion gap; Unmeasured anions