EPIDURAL SUFENTANIL AND BUPIVACAINE FOR LABOR ANALGESIA AND DOPPLER VELOCIMETRY OF THE UMBILICAL AND UTERINE ARTERIES

Background. The pain of parturition is associated with major physiologic alterations mediated by neurohumoral factors and increased activation of the sympathetic nervous system. Epidural local anesthetics abolish or alleviate many of the pain-mediated responses by reducing maternal catecholamine levels, inducing sympathectomy and consequent vasodilatation. The hormone response to surgical stress is not attenuated after epidural opioids as efficiently as after local anesthetics. Opioid receptors may modulate sympathetic outflow at a spinal level. This study was performed to compare the effects of epidural sufentanil and bupivacaine on the uterine and placental circulation. Methods: Utilizing a prospective randomized, double-blind study design, 30 healthy women at term were examined employing a color Doppler technique to assess and compare the effects of analgesia using sufentanil or bupivacaine epidurally during the first stage of labor on blood flow velocity waveforms in the uterine and umbilical arteries. Results: Effective analgesia was provided by both drugs, bupivacaine and sufentanil. Uterine and umbilical blood velocity waveform indices did not change significantly. There was, however, a significantly greater incidence of fetuses with changes in heart rate tracings in the sufentanil group, decreased variability being the most frequent. Maternal side effects attributable to sufentanil were common but mild. No patient became hypotensive in either group. Conclusions. Epidural sufentanil and bupivacaine provide effective analgesia with acceptable side effects during the first stage of labor in healthy parturients. Neither drug had any detrimental effects on blood flow indexes reflecting peripheral vascular resistance in the umbilical and uterine arteries in healthy parturients.