THE EFFECTS OF MEDETOMIDINE ON MATERNAL AND FETAL CARDIOVASCULAR AND PULMONARY-FUNCTION, INTRAUTERINE PRESSURE AND UTERINE BLOOD-FLOW IN PREGNANT GOATS

To investigate the effects of medetomidine on late pregnant goats, med etomidine induced changes in maternal or fetal circulation and acid-ba se balance, as well as changes in intrauterine pressure (IUP) and uter ine blood flow (UBF), were studied. Intramuscular administration of me detomidine (40 mu g/kg b.w.) decreased the heart rate (HR) and arteria l blood pressure (ABP) of the mother, and the change in HR was signifi cant statistically (p<0.05). In the fetus, HR and ABP showed a transie nt decrease and increase (p<0.05), respectively. A decrease in materna l arterial blood pH and oxygen partial pressure (PO2) and an increase in carbon dioxide partial pressure (PCO2) were recorded after the inje ction, but none was significant. In the fetus, arterial blood PO2 decr eased significantly (p<0.05) after 5 min of administration, and a sign ificant metabolic acidemia supported by a decrease in base excess was observed. Within 1 to 4 min after the administration of medetomidine, IUP began to rise and remained high for 10 to 14 min. Thereafter, the rise in IUP was frequent and periodical. After the injection, UBF sign ificantly (p<0.05) decreased, and the fall in UBF was associated with a rise in IUP. The maternal and fetal serum medetomidine concentration increased remarkably after the injection of medetomidine into the mot her. These observations in late pregnant goats suggested that medetomi dine induced a decrease in maternal cardiac output, a decrease in UBF arising from the induction of uterine contractions, and transplacental medetomidine can have a suppressive effect on the fetus.