Prevention Unintentional Mechanical Birth Injuries

这项建议的目的是阐明在称为肩部难产的产科急症后发生的机械性出生损伤的机制，并开发实际干预措施来控制或预防这种损伤，其中一些可能导致终身残疾。影响高达15%的阴道分娩的肩部难产是一种自然发生的机械性梗阻，在头部分娩后，胎儿的肩膀被压在母亲耻骨后面，如果没有临床医生的具体干预，躯干就无法分娩，临床医生必须采取方便的措施防止窒息，同时避免胎儿颈部过度拉伸。后者可能导致骨骼骨折和/或臂丛神经损伤--高达30%的肩部发育困难的意外后果。 用于解决肩部难产的标准产科手法包括操纵母亲或胎儿。一种手法相对于另一种手法的优越性尚未得到证实；但生物力学考虑支持这样一种假设，即胎儿操纵分娩所需的力量比母亲操纵少20%至30%，如果优先考虑，可以减少受伤的发生率。然而，大多数临床医生不太熟悉胎儿的操作和 推迟它们的使用，以支持重复使用母性的。这项研究计划的目的是证明在实现肩部难产的无创解决方面，胎儿手法相对于母体手法的机械优势，并使临床医生熟悉胎儿手法作为一种公共卫生措施来减少和预防新生儿损伤。 为了实现这些目标，生物医学工程将通过5个具体目标与临床产科相结合： 1.使用自制的肩难产模拟器测量临床医生对胎头的牵引力，并将这种牵引力的方向、大小和速率与胎儿的颈伸、屈、转、臂丛伸展和骨骼骨折相关联； 2.在实验室环境下，客观评估子宫和母体排出力以及不同肩难产手法对临床医生施力、胎儿颈部运动参数和臂丛神经伸展的影响； 3.利用实验室模拟器和测力系统，对临床医生进行有关肩难产手法操作的教育计划，并评估其对临床医生在分娩期间估计牵引量的能力的影响； 4.测量临床医生应用的活体牵引力，并将其与实验室得出的力参数进行比较； 5.进行一项小型随机临床试验，比较McRoberts手法(母体手法)和Rubin手法(胎儿手法)后临床医生施加的力。

The objective of this proposal is to elucidate mechanisms involved in mechanical birth injuries that occur following an obstetric emergency known as shoulder dystocia and to develop practical interventions to control or prevent such injuries, some of which can lead to lifelong disability. Affecting up to 15% of vaginal deliveries, shoulder dystocia is a naturally-occurring mechanical obstruction in which, after the head delivers, the fetal shoulders become impacted behind the mother's pubic bone and the trunk cannot deliver without specific intervention by the clinician who must act expediently to prevent asphyxia while simultaneously avoiding undue stretch on the fetal neck. The latter can result in skeletal fractures and/or brachial plexus nerve injury -- unintended outcomes of up to nearly 30% of shoulder dystocias. Standard obstetric maneuvers used to resolve shoulder dystocia involve manipulation of either the mother or the fetus. The superiority of one maneuver over another has not been proven; yet biomechanical considerations support the hypothesis that fetal manipulation requires 20% to 30% less force to deliver the infant than maternal manipulation and, if prioritized, could reduce the incidence of injury. However, most clinicians are less familiar with fetal maneuvers and defer their use in favor of repeating maternal ones. The goals of this research proposal are to demonstrate the mechanical advantage of fetal over maternal manipulation in accomplishing atraumatic resolution of shoulder dystocia and to familiarize clinicians with fetal maneuvers as a public health measure to reduce and prevent neonatal injury. To achieve these objectives, biomedical engineering will be integrated with clinical obstetrics through 5 specific aims: 1. to measure clinician-applied traction on the fetal head using a custom-designed shoulder dystocia birthing simulator and correlate direction, magnitude and rate of this force with fetal neck extension, flexion and rotation, brachial plexus stretch and skeletal fracture; 2. to objectively assess, in a laboratory setting, the effect of uterine and maternal expulsive forces and of different shoulder dystocia maneuvers on clinician-applied force, fetal neck motion parameters and brachial plexus stretch; 3. to conduct an educational program for clinicians on the performance of shoulder dystocia maneuvers, employing the laboratory simulator and force-measuring systems, and assess its effect on clinicians' ability to estimate the amount of traction they apply during delivery; 4. to measure clinician-applied traction in vivo and compare this with laboratory-derived force parameters; 5. to conduct a small, randomized clinical trial comparing clinician-applied forces following McRoberts' maneuver (a maternal manipulation) and following Rubin's maneuver (a fetal manipulation).