Effects of 7.2% hypertonic saline solution on cardiovascular parameters and endogenous arginine vasopressin secretion in euvolemic isoflurane-anesthetized horses

Abstract

OBJECTIVE To compare the effects of 7.2% hypertonic and 0.9% isotonic saline (sodium chloride) solutions on cardiovascular parameters and plasma arginine vasopressin (AVP) concentrations in healthy, isoflurane-anesthetized horses. ANIMALS 8 healthy horses. PROCEDURES In a prospective, randomized, crossover study, horses were anesthetized with isoflurane twice with a 14-day wash-out period between anesthetic episodes. While anesthetized, horses received a bolus (4 mL/kg) of 7.2% hypertonic saline solution (HS) or 0.9% isotonic saline solution (IS). Heart rate; systolic, mean, and diastolic arterial blood pres-sures; and central venous and pulmonary artery pressures were measured every 5 minutes; cardiac output was measured by means of thermodilution every 15 minutes. Systemic vascular resistance (SVR) was calculated. Blood samples were collected before and during anesthesia, and plasma AVP concentrations were determined with a vali-dated ELISA. Data were analyzed with repeated-measures ANOVA and Pearson correlations. RESULTS HS caused an increase in systolic (P =.003) and mean (P =.023) arterial blood pressures that lasted for 30 minutes. The SVR was increased (P