Blood glucose, acid–base and electrolyte changes during loading doses of alpha2-adrenergic agonists followed by constant rate infusions in horses

Abstract

The aim of the present study was to investigate changes in blood glucose concentration ([Glu]B), acid-base status and electrolyte concentrations during constant rate infusions (CRI) of two alpha2-adrenergic agonists in seven horses treated in a blinded, randomised, crossover design with xylazine or romifidine. An intravenous (IV) bolus of xylazine (1mg/kg) or romifidine (80g/kg) was administered followed by an IV CRI of xylazine (0.69mg/kg/h) or romifidine (30g/kg/h) for 2h. Blood samples were collected from the pulmonary artery before and after loading doses, during the CRI, and for 1h after discontinuing drugs. Blood glucose, base excess (BE), pH, partial pressure of carbon dioxide (Pv¯CO2), strong ion difference (SIDest) and bicarbonate concentration ( [Formula: see text] ) increased significantly during the CRI with both alpha2-adrenergic agonists. Chloride concentration ([Cl-]B) and anion-gap (AG) decreased significantly compared to baseline. The decrease in sodium concentration ([Na+]B) was only significant with xylazine. From 1h after starting the CRI onwards, [Glu]B was significantly higher with romifidine compared to xylazine. Except [Glu]B, SIDest, and Pv¯CO2, all variables returned to normal values 1h after discontinuing xylazine. After stopping romifidine, all variables except pH remained altered for at least 1h. It was concluded that loading doses of alpha2-adrenergic agonists followed by CRIs produce [Glu]B, acid-base and electrolyte changes. The clinical significance of the reported changes remains to be investigated and absolute values should be interpreted with caution, as fluid boli were used for cardiac output measurements, but may become important during prolonged infusion and in critically ill patients. a b s t r a c tThe aim of the present study was to investigate changes in blood glucose concentration ([Glu] B ), acidbase status and electrolyte concentrations during constant rate infusions (CRI) of two alpha 2 -adrenergic agonists in seven horses treated in a blinded, randomised, crossover design with xylazine or romifidine.An intravenous (IV) bolus of xylazine (1 mg/kg) or romifidine (80 lg/kg) was administered followed by an IV CRI of xylazine (0.69 mg/kg/h) or romifidine (30 lg/kg/h) for 2 h. Blood samples were collected from the pulmonary artery before and after loading doses, during the CRI, and for 1 h after discontinuing drugs. Blood glucose, base excess (BE), pH, partial pressure of carbon dioxide (P vCO 2 ), strong ion difference (SID est ) and bicarbonate concentration (½HCO It was concluded that loading doses of alpha 2 -adrenergic agonists followed by CRIs produce [Glu] B , acid-base and electrolyte changes. The clinical significance of the reported changes remains to be investigated and absolute values should be interpreted with caution, as fluid boli were used for cardiac output measurements, but may become important during prolonged infusion and in critically ill patients.

Behavioral and cardiopulmonary effects of dexmedetomidine alone and in combination with butorphanol, methadone, morphine or tramadol in conscious sheep

“…Horses administered a 3 hour infusion of xylazine or romifidine had documented increases in pH, bicarbonate and BE, probably from a urinary loss of chloride (Ringer et al. ). In our study there were no significant chloride changes and we cannot corroborate this hypothesis in sheep and the cause remains unclear.…”

Cardiopulmonary effects of dexmedetomidine and ketamine infusions with either propofol infusion or isoflurane for anesthesia in horses

“…Blood glucose was higher than found in conscious horses and can be attributed to the inhibition of insulin by the use of alpha 2 ‐adrenergic agonists and use of 5% dextrose for cardiac output measurements (Ringer et al. ). Measured ionized and pH‐corrected calcium concentrations decreased over time in both groups, but was significant only in group ISOKD, and this has been previously reported with dexmedetomidine infusions in isoflurane‐anesthetized cats, and in horses anesthetized with halothane or isoflurane (Grubb et al.…”

Evaluation of sedative, analgesic, physiological, and laboratory effects of two doses off medetomidine and xylazine in dromedary calves

“…Many side effects, particularly changes of acid–base, electrolytes, hepatic and renal biomarkers, and hematological parameters, are associated with α 2 ‐adrenergic agonists and have been reported in buffalo calves (Khan, Ashraf, Pervez, Hashmi, & Mahmood, ; Singh et al, ), rams (Aminkov & Hubenov, ), and horses (Ringer et al, ). To the best of our knowledge, there is no published study documenting the comparison between the effects of medetomidine and xylazine in dromedary camels.…”