title: Reliability of the i-STAT for the determination of blood electrolyte (K+, Na+, and CI-) concentrations in cattle.
abstract: BACKGROUND
  Rapid determination of blood electrolyte concentrations can help determine electrolyte status and delivery of effective volume of electrolyte solutions in field conditions.
  
  
  OBJECTIVE
  To evaluate reliability of the i-STAT, a point-of-care (POC) device, in measuring blood K(+), Na(+), and CI(-) concentrations in cattle.
  
  
  METHODS
  Ninety-eight cattle with various diseases.
  
  
  METHODS
  In this prospective study, blood samples collected from the jugular vein were processed for determination of K(+), Na(+), and CI(-) concentrations in blood and plasma using the i-STAT and auto-analyzer (Cobas C501), respectively. Blood and plasma electrolyte data were subjected to student t-test for comparison, the concordance analysis for agreement, accuracy, and precision, the Passing-Bablok regression and the Bland-Altman plot for reliability, and receiver operating characteristics curves for sensitivity (Se) and specificity (Sp).
  
  
  RESULTS
  Plasma concentrations of K(+) (4.39 versus 4.2 mmol/L; P < .0001) and CI(-) (100.30 versus 99.4 mmol/L; P < .04) were greater than their concentrations in blood. Plasma and blood Na(+) concentrations were similar (136.95 versus 136.8 mmol/L). The i-STAT results were highly correlated with the Cobas C501 results (r = 0.970, 0.922, and 0.866 for K(+), Na(+), and CI(-), respectively). Regression equations fitting blood (Y) and plasma (X) concentration did not deviate from the identity line for K(+) (Y = -0.10 + 0.98 × X), Na(+) (Y = X), and CI(-) (Y = 3.04 + 0.96 × X). The mean bias (blood concentration - plasma concentration) was -0.20 for K(+) (P = .03), -0.16 for Na(+) (P = .12), and -0.87 for CI(-) (P = .93). The i-STAT had 76-100% Se and 87.7-100% Sp for assessing electrolyte statuses.
  
  
  CONCLUSIONS
  The i-STAT yielded results that were in agreement with the auto-analyzer, with negligible biases in measurement of plasma K(+), Na(+), and CI(-) concentrations. The i-STAT is a reliable POC device and can be used in field condition to assess electrolyte status in cattle.
authors.affiliation: Department of Internal Medicine, Faculty of Veterinary Medicine, Firat University, Elazig, Turkey.
authors.forename: E
authors.initials: E
authors.lastname: Yildirim
authors.forename: T
authors.initials: T
authors.lastname: Karapinar
authors.forename: A
authors.initials: A
authors.lastname: Hayirli
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000097:blood* / Q000175:diagnosis; D002712:Chlorides / Q000097:blood*; D005260:Female; D006947:Hyperkalemia / Q000097:blood / Q000175:diagnosis / Q000662:veterinary; D006955:Hypernatremia / Q000097:blood / Q000175:diagnosis / Q000662:veterinary; D007008:Hypokalemia / Q000097:blood / Q000175:diagnosis / Q000662:veterinary; D007010:Hyponatremia / Q000097:blood / Q000175:diagnosis / Q000662:veterinary; D019095:Point-of-Care Systems; D011188:Potassium / Q000097:blood*; D012964:Sodium / Q000097:blood*
chemical_list: D002712:Chlorides; D012964:Sodium; D011188:Potassium
keywords: Accuracy; Bovine; Point-of-care device; Precision; Sensitivity; Specificity