| 摘要 |
<p>An obstetric vacuum extractor is disclosed for assisting the delivery of a baby. The extractor comprises a suction cup (11, see figure 1) for attaching to a portion of the baby's head and a conduit 14 which is coupled to the cup. The conduit 14 comprises a flow passage 16 which is arranged in fluid communication with an interior of the cup, wherein at least a portion of the conduit 14 comprises a flow passage 16 having a cross sectional profile in which a radius of the passage varies circumferentially of the passage. Ideally, the transverse cross-section profile is a trefoil, formed by longitudinal ridges or ribs 22 with apexes 23. The profile preserves the patentcy and strengthens the tube against collapse when the vacuum suction is applied, without restricting the flow of air. The profile may be only at a neck portion 15 or along the full length of the conduit.</p> |
