title: [Qualification of the Stewart variables for the assessment of the acid-base status in healthy dogs and dogs with different diseases].
abstract: Peter Stewart criticized the traditional theory of the acid-base status by Henderson-Hasselbalch as too simple and incomplete. He developed a new model with 3 independent variables: (1) pCO2, (2) SID (strong ion difference) and (3) Atot (Acid total). In healthy and ill dogs the diagnostic usefulness of both acid-base models were compared. This study included n=58 healthy dogs and 3 clinical cases of sick dogs. The age of the healthy dogs was 5.0 (2.0-7.0) years (= median (1.-3. quartil)). The 3 clinical cases included (1) a dog with septic shock, (2) with acute renal insufficiency, and (3) with hypovolaemic shock due to gastric torsion. Venous blood was taken of all dogs and the acid-base parameters were determined within < or =30 minutes. Electrolytes and albumin were determined in blood serum and used for calculation of the Stewart variables. Limits of reference intervals (x+/-1.96 - s) were determined for the healthy dogs yielding pCO2 = 3.6-6.5 kPa, [SID3] = 33.1-50.9 mmol/l resp. [SID4] = 31.8-49.6 mmol/l and [Al = 8.5-13.1 mmol/l. In Case 1 the Henderson-Hasselbalch parameters demonstrated the presence of a strong metabolic acidosis with mild respiratory influence (pH, [HCO3-], [BE] and PCO2 at upper range of normal). Analysis of the Stewart variables [SID3] resp. [SID4] revealed an electrolyte imbalance with [Cl-] and [lactate-] as the reason for metabolic acidosis. Case 2 showed a metabolic acidosis with respiratory compensation (pH, [HCO3-], [BE] and PCO2). Analysis of the Stewart variables with [SID3] resp. [SID4 caused by [K+], [Na+] and [lactate-]demonstrated the acidotic metabolism due to a renal malfunction. Case 3 had a metabolic acidosis (pH-value in the lower range) caused by electrolyte imbalances ([SID4]. The Stewart variables allow a better understanding of the causes of acid-base-disturbances in animals with implications for successful therapy via infusion.
authors.affiliation: Institut for Veterinär-Physiologie, Fachbereich Veterinärmedizin, Freie Universität Berlin.
authors.forename: Christiane
authors.initials: C
authors.lastname: Siegling-Vlitakis
authors.forename: Barbara
authors.initials: B
authors.lastname: Kohn
authors.forename: Claudia
authors.initials: C
authors.lastname: Kellermeier
authors.forename: Rose
authors.initials: R
authors.lastname: Schmitz
authors.forename: Helmut
authors.initials: H
authors.lastname: Hartmann
mesh_terms: D000136:Acid-Base Equilibrium / Q000502:physiology*; D000138:Acidosis / Q000378:metabolism / Q000662:veterinary; D000465:Algorithms; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism; D001784:Blood Gas Analysis / Q000662:veterinary; D002245:Carbon Dioxide / Q000378:metabolism; D004283:Dog Diseases / Q000378:metabolism*; D004285:Dogs / Q000502:physiology*; D004573:Electrolytes / Q000378:metabolism; D006304:Health Status; D006863:Hydrogen-Ion Concentration; D008954:Models, Biological
chemical_list: D001639:Bicarbonates; D004573:Electrolytes; D002245:Carbon Dioxide