Anesthetic safety evaluation of Enflurane on pregnant dogs and their fetuses

The safety and feasibility of anesthesia during pregnancy are the public concern to human and veterinary medicines,respiratory and cardiac suppression is the most serious side effect of anesthetic. In order to evaluate the effects of Enflurane on pregnant dogs their fetuses,we established the animal model of the artery catheterization,and investigated the maternal and fetal anesthetic concentrations as well as blood gases in the pregnant dogs anesthetized by inhalation of Enflurane. In this experiment,the femoral artery catheterization of 12 pregnant dogs and their 12 fetuses were performed through the anterior tibia artery by using 17 G and 18 G arterial puncture needle,4F expanded tube,3 F induction tube and the C-arm monitoring system. The results showed that the fetuses survived in uterus for 36 h (two cases),4 ~ 5 d (two cases),6 ~7 d (three cases),8 ~10 d (three cases) and 12 ~14 d (two cases) after operation,respectively. 10 fetuses that survived over 4 days in uterus after the operation were successfully delivered. The fetuses were healthy and their catheters were kept well,the other two pregnant dogs aborted their fetuses. After establishing the model successfully,Atropine sulfate in dose of 0. 04 mg/kg bw were injected into cutaneous muscle of dogs in right clinostatism. 15 minutes later after application of Atropine sulfate,the induced anesthesia was carried out by vein injection of 2. 5% Pentothal sodium (10 mg/kg/bw). The tracheal cannula was performed and the dogs were anesthetized for 10 min by Enflurane inhalation from anesthetic machine. Subsequently,the respiratory rate of experimental animals was controlled to 20-22 times/min by a mechanical ventilator,and the tidal volume was 13 ~ 15 mL/kg/bw. The maternal and fetal arterial anesthetic concentrations and blood gases including pH,PO 2,PCO 2,TCO 2,HCO 3-,SB,BEb and Sat. O 2 were measured after Enflurane inhalation anesthesia. The results showed Enflurane can cross placenta and reach fetal blood. The arterial anesthetic concentrations in fetuses were lower than that in their mothers,but the changes of anesthetic concentrations in fetuses were very similar to their mothers. The pH and BEb in the maternal and fetal blood were significantly lower (P 【 0. 01 or 0. 05),PO 2,PCO 2,and Sat. O 2 were significantly higher (P 【 0. 01 or 0. 05),compared to the prior anesthesia. SB decreased,HCO 3-and T-CO 2 increased (P 】 0. 05) in the early stage of anesthesia,but there were no significant difference after and before anesthesia. These results indicated that Enflurane crosses the placenta very quickly in dogs and is characterized by the quick induction anesthesia and elimination in the body. There were slight respiratory and metabolic acidosis in the period of anesthesia in both pregnant dogs and their fetus and the state were gradually restored to normal with the elimination of the Enflurane in blood. Taken together,Enfluence should be considerated the candidate for the induction and maintenance anesthesia for veterinary and human medicine.