Treatment of halothane arterial hypotension in equines with the use of 7.5% sodium chloride hypertonic solution

Abstract

7.5% sodium chloride hypertonic solution is widely employed to improve hemodynamic parameters mainly treatment of hemorrhagic shock. Its action is characterized by an increment of cardiac output, systemic blood pressure and plasmatic volume. The aim of this study was the evaluation of 7.5% sodium chloride hypertonic solution in the treatment of hypotension due to general anesthesia with halothane in horses. Fifteen adult horses of different breeds and weights submitted to elective
surgeries were allocated in this trial.The animals received detomidine as premedication. Induction of anesthesia was performed with guaifenesin, midazolam and ketamine. Halothane in 100% oxygen was used as the maintenance agent. When the mean arterial blood pressure fell below 60 mmHg, 4 ml/kg of 7.5% sodium chloride hypertonic solution were administered intravenously. Heart rate and rhythm, systolic, mean and diastolic blood pressure, respiratory rate, capillary refill time, blood gases, arterial pH, bicarbonate, oxyhaemoglobin saturation, sodium and chloride plasma levels, as well as packed cell volume were evaluated after 5,15, 30 and 60 minutes hypertonic infusion. A significant increase of arterial blood pressure was verified after hypertonic administration. Values of blood pressure remained above control during all the recording period. Packed cell volume decreased significantly showing the improvement of plasmatic volume caused by this solution. Discrete hypernatremia and hyperchloremia were observed. The other parameters remained unaltered. We can conclude that 7.5% sodium chloride hypertonic solution is effective and may be employed in the treatment of hypotension during halothane anesthesia in equines.