title: Effect of frusemide and hypertonic saline on electrolytes during post exercise anaesthesia.
abstract: This study evaluated the effects of pre-exercise frusemide administration and hypertonic saline (H) infusion during anaesthesia on arterial pH, blood gases and electrolytes in 6 Thoroughbred horses anaesthetised immediately post exercise. Horses received either frusemide (F) (0.5 mg/kg, i.v.) or a saline placebo (P) injection 4 h prior to treadmill exercise. Exercise consisted of a 3 min warm-up at 40% VO2max followed by exercise to fatigue. Detomidine (40 micrograms/kg, i.v.) was given within 5 min of stopping and followed 5 min later by zolazepam-tiletamine (1.25 mg/kg, i.v.) to induce anaesthesia. During maintenance of anaesthesia using isoflurane in O2, either isotonic saline solution (I) or 7.5% H (4 ml/kg, i.v.) was administered. Arterial blood was sampled at the following times: prior to (Pre-F/P) and 4 h after (Pre-ex) F or P administration, 1 min after fatigue (Fatigue), 5 min after induction of anaesthesia (Post-ind), and just prior to and 15, 30 and 60 min after beginning isoflurane (ISFL) anaesthesia. Arterial pH and blood gas tensions, pulmonary arterial blood temperature, plasma [lactate], total protein and plasma [Na+], [K+], and [Cl-] were measured. Data were analyzed using 2-way ANOVA for repeated measures (P < 0.05). There were significant differences over time for all variables except total protein. Plasma [Na+] increased at Fatigue compared to Pre-F/P or Pre-ex in all treatment groups. Plasma [Na+] and [Cl-] increased during ISFL anaesthesia compared to Pre-F/P and Pre-ex in horses given H. During ISFL anaesthesia, plasma [Cl-] decreased compared to Pre-F/P in Group F+I horses. We conclude that acid-base, blood gas, and electrolyte changes associated with F are unlikely to influence management of horses anaesthetised immediately following supramaximal exercise to fatigue. Hypertonic saline infusion may help restore plasma [Cl-] faster in hypochloraemic horses requiring anaesthesia immediately after strenuous exercise.
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, USA.
authors.forename: S
authors.initials: S
authors.lastname: Greene
authors.forename: R
authors.initials: R
authors.lastname: Keegan
authors.forename: J
authors.initials: J
authors.lastname: Brown
authors.forename: J
authors.initials: J
authors.lastname: Kingston
authors.forename: W M
authors.initials: WM
authors.lastname: Bayly
mesh_terms: D000136:Acid-Base Equilibrium / Q000187:drug effects; D000758:Anesthesia / Q000662:veterinary*; D000818:Animals; D004232:Diuretics / Q000494:pharmacology*; D004573:Electrolytes / Q000097:blood*; D005260:Female; D005665:Furosemide / Q000494:pharmacology*; D006736:Horses / Q000502:physiology*; D008297:Male; D010101:Oxygen Consumption; D010805:Physical Conditioning, Animal; D012462:Saline Solution, Hypertonic; D012964:Sodium / Q000097:blood
chemical_list: D004232:Diuretics; D004573:Electrolytes; D012462:Saline Solution, Hypertonic; D005665:Furosemide; D012964:Sodium