Buhimschi C, Garfield R E
Division of Reproductive Sciences, Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston 77555-1062, USA.
Am J Obstet Gynecol. 1996 Feb;174(2):744-53. doi: 10.1016/s0002-9378(96)70459-3.
The primary aim of this study was to develop a noninvasive method for recording uterine contractile activity during pregnancy by systematically evaluating whether abdominal surface electromyography is representative of uterine electrical and contractile events. A secondary purpose was to use these techniques to determine when the uterus is in a state of preparedness for labor.
Electrical activity was acquired by use of unipolar electrodes attached simultaneously to the uterine wall and to the abdominal surface of pregnant rats. Intrauterine pressure was recorded with a pressure transducer inserted in the uterine cavity. Computer-acquired records of electrical events (electromyography) and pressure were compared on different days of gestation, during spontaneous labor at term, or during preterm birth induced with an antiprogestin. Similarly, electrical activity was assessed after administration of agents that either stimulate (oxytocin) or inhibit (isoproterenol) contractility. Correlation analyses were performed between uterine electromyographic activity, surface electromyographic activity, and concomitant intrauterine pressure. The effects of vaginal wall stimulation were also evaluated at different times of pregnancy.
The electrical activity recorded early in pregnancy (day 18) from the uterus consisted of irregular electrical bursts with little correspondence to the signals recorded from the surface (R2=0.006). Later in gestation (days 19 through 21) the electrical activity of the uterus became more regular, consisting of frequent bursts with accordance between the signals recovered from the uterus and those collected from the surface (R2=0.95). During labor (preterm or term) bursts recorded from either the uterus or the abdominal surface were of large amplitude and corresponded to ample changes in intrauterine pressure. Correlation coefficients between uterus and surface and uterus and pressure were R2=1 and 0.96, respectively. Similarly, during preterm labor the coefficients were R2=1 for uterine electromyographic activity versus surface electromyographic activity and R2=0.99 for uterine electromyographic activity versus intrauterine pressure. Vaginal stimulation in early gestation was not followed by subsequent signal conduction to the uterus, whereas during delivery activity induced in the vagina propagated to the uterus and consequently to the abdominal surface.
Abdominal surface recording of uterine electrical events are representative of the activity generated by the muscle cells of the uterus. During term and preterm labor uterine electrical activity and intrauterine pressure achieve maximum activity. Electromyographic monitoring with vaginal stimulation of the uterus may allow prediction of when the uterus is in a state required for labor.
本研究的主要目的是通过系统评估腹部表面肌电图是否能代表子宫电活动和收缩活动，来开发一种在孕期记录子宫收缩活动的非侵入性方法。次要目的是使用这些技术来确定子宫何时处于分娩准备状态。
使用单极电极同时连接到妊娠大鼠的子宫壁和腹部表面来获取电活动。用插入子宫腔的压力传感器记录子宫内压力。在妊娠的不同天数、足月自然分娩期间或用抗孕激素诱导的早产期间，对计算机获取的电活动记录（肌电图）和压力进行比较。同样，在给予刺激（催产素）或抑制（异丙肾上腺素）收缩力的药物后评估电活动。对子宫肌电图活动、表面肌电图活动和伴随的子宫内压力进行相关性分析。还在妊娠的不同时间评估阴道壁刺激的效果。
妊娠早期（第18天）从子宫记录的电活动由不规则的电爆发组成，与从表面记录的信号几乎没有对应关系（R2 = 0.006）。在妊娠后期（第19至21天），子宫的电活动变得更加规则，由频繁的爆发组成，子宫恢复的信号与从表面收集的信号一致（R2 = 0.95）。在分娩期间（早产或足月），从子宫或腹部表面记录的爆发幅度很大，并且与子宫内压力的大幅变化相对应。子宫与表面以及子宫与压力之间的相关系数分别为R2 = 1和0.96。同样，在早产期间，子宫肌电图活动与表面肌电图活动的系数为R2 = 1，子宫肌电图活动与子宫内压力的系数为R2 = 0.99。妊娠早期的阴道刺激之后没有随后的信号传导至子宫，而在分娩期间，阴道诱导的活动传播至子宫并因此传播至腹部表面。
子宫电活动的腹部表面记录代表子宫肌细胞产生的活动。在足月和早产期间，子宫电活动和子宫内压力达到最大活动。通过阴道刺激子宫进行肌电图监测可能有助于预测子宫何时处于分娩所需的状态。
