Effects of Opioids on the Contractility of Isolated Human Pregnant Uterine Muscle / 대한마취과학회지

BACKGROUND: Effects of fentanyl, sufentanil, meperidine, and morphine on the spontaneous contractility of isolated human pregnant uterine muscle strips were determined. METHODS: Uterine specimens were obtained from normal full-term parturients undergoing elective lower-segment cesarean section. Longitudinal muscle strips were made and mounted individually and vertically in tissue chambers to record their isometric tension. After establishment of rhythmic contractions in the buffer solution, opioid concentration-response curves were constructed. The responses to opioids were repeated in the presence of opioid receptor blocker, nitric oxide synthase inhibitor, beta-adrenoceptor blocker, or cyclo-oxygenase inhibitor. RESULTS: Fentanyl and meperidine caused concentration-dependent decreases of the uterine contractility, their IC50 (concentration which causes 50% inhibition of the amplitude of spontaneous contractions) being 6.8 x 10(-6) M and 2.2 x 10(-3) M, respectively. On the contrary, sufentanil and morphine were without significant effects on the contractility. Pretreatment with either naloxone, N(G)-nitro-L-arginine methyl ester, atenolol, or indomethacin did not affect the uterine responses to opioids. CONCLUSIONS: These results demonstrate that fentanyl and meperidine may have direct inhibitory effects on the contractility of the human uterus. However, the opioid concentrations needed to significantly reduce the uterine contractility were at a supraclinical range.

Hemodynamic Changes Associated with Uterine Contraction under Obstetric Analgesia / 대한마취과학회지

BACKGROUND: Continuous epidural analgesia is the most widely used technique in obstetric analgesia today. Hemodynamic changes during pregnancy were most remarkable during the uterine contractions of the first stage of labor. The aim of this study was to compare the difference in hemodynamics between two groups with and without obstetric analgesia. METHODS: Twenty healthy parturients were divided into two groups as follows: Group 1; 10 parturients under epidural analgesia, Group 2; 10 parturients without epidural analgesia,and hemodynamic changes were monitored throughout labor. For the purpose of analysis, the course of labor was divided into three categories according to the degree of dilation of the cervix: 4 cm, 4~7 cm and above 7cm. Hemodynamic parameters were obtained during and in-between contractions over the course of labor through transcutaneous impedence cardiography and a noninvasive automatic blood pressure monitor. RESULTS: Heart rate (HR) in Group 2 were more increased than that in Group 1 during uterine contraction. In Group 1, the end-diastolic volume index (EDVI) and stroke volume index (SVI) at 4 cm dilation and SVI at above 7 cm dilation of the cervix were increased during the contraction. In Group 2, HR increased throughout the first stage of delivery and systolic blood pressure (SBP), EDVI at 4~7 cm and above 7 cm dilation and SVI at above 7 cm dilation were increased during contractions. CONCLUSIONS: Our study showed more stability in hemodynamic parameters in parturients under epidural analgesia as compared to those without analgesia. From these results, we conclude that continuous epidural analgesia is very safe to the fetus as well as mother since the technique dose not cause significant hemodynamic change during uterine contractions.