title: Vacuum sources in obstetrics.
abstract: OBJECTIVE
  To characterize the performance of vacuum equipment used in operative vaginal deliveries.
  
  
  METHODS
  We measured wall suction in eight Cleveland area labor-and-delivery units. Additionally, we tested samples of hand-operated and electric vacuum pumps. For each apparatus we recorded vacuum in millimeters of mercury using a calibrated, diaphragm-type gauge. We calculated mean maximal vacuum. Work required to produce 500 mm Hg of vacuum was determined for the hand-operated pumps. At increments of vacuum, we compared the vacuum displayed by the gauge head included with the device to our standard.
  
  
  RESULTS
  Mean wall suction was 494 mm Hg (range, 248-655). As compared to the Mity-vac, the CMI hand-operated pump needed significantly more work to generate 500 mm Hg of vacuum. Electric pumps produced a reliable and consistent vacuum. Gauges included with the pump had an average error of 4% over 400-600 mm Hg.
  
  
  CONCLUSIONS
  Wall suction was an unreliable source of vacuum. The two hand-operated pumps tested required significantly different amounts of work to achieve an adequate vacuum. Addition of a fluid trap does not affect the vacuum, and head gauges supplied with vacuum pumps are accurate.
authors.affiliation: Department of Obstetrics and Gynecology, University MacDonald Womens Hospital, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA.
authors.forename: D W
authors.initials: DW
authors.lastname: Wiper
authors.forename: M A
authors.initials: MA
authors.lastname: Duchon
authors.forename: K L
authors.initials: KL
authors.lastname: Muise
mesh_terms: D036861:Delivery, Obstetric / Q000379:methods*; D004867:Equipment Design; D005260:Female; D006801:Humans; D011247:Pregnancy; D014618:Vacuum; D014620:Vacuum Extraction, Obstetrical / Q000295:instrumentation / Q000592:standards*