Objective evaluation of the shoulder dystocia phenomenon: effect of maternal pelvic orientation on force reduction.

摘要: This report describes the use of maternal pelvic and fetal models, a tactile sensing glove, microcomputer data acquisition system to measure shoulder extraction forces. Sixty-nine experiments were carried out in laboratory setting simulate vaginal delivery aftercoming shoulders. The tests conducted using variety biclavicular diameters (10-13 cm) angle positions (McRoberts, 10 degrees; lithotomy, 25 degrees). When comparing lithotomy versus McRoberts positioning, there was consistent reduction force needed extract shoulders with latter maneuver. No simulated clavicles fractured during until diameter 12.0 cm reached. At this point, five eight (63%) at degrees zero seven (0%) (P less than .025). For all 69 experiments, neck extension readings consistently lower total traction forces recorded by glove. suggests that, addition axially oriented forces, component flexion (lateral force) also present. As difficulty increased, impact these inadvertent became most pronounced level brachial plexus. is first study reproducibly model for dystocia describe pathophysiology specific neonatal injuries from perspective. results document objectively that positioning reduces plexus stretching, incidence clavicular fracture.