title: Importance of vacuum for breastmilk expression.
abstract: OBJECTIVE
  To determine the effect of the strength of applied vacuum on the flow rate and yield of breastmilk using an electric breast pump.
  
  
  METHODS
  Twenty-one breastfeeding mothers and two expressing mothers expressed their breastmilk for 15 minutes using an electric breast pump set at their own maximum comfortable vacuum, and at one to three softer vacuums. Milk yield and flow rate were measured.
  
  
  RESULTS
  At the maximum comfortable vacuum (-190.7 +/- 8.8 mm Hg) 4.3 +/- 0.4 milk ejections occurred during 15 minutes of expression and yielded 118.5 +/- 11.4 mL of milk (65.5 +/- 4.1% of the available milk). Softer vacuums yielded less milk volume (p < 0.05) and less of the available milk (p < 0.01). Milk flow rate was greater during the first milk ejection than the third or subsequent milk ejections (p < 0.001). Cream content of the milk was highest after expressing for 15 minutes using the mother's maximum comfortable vacuum.
  
  
  CONCLUSIONS
  Use of the mother's maximum comfortable vacuum enhances milk flow rate and milk yield. The cream content of the milk at the end of the expression period was an indicator of how effectively the breast had been drained.
authors.affiliation: Biochemistry and Molecular Biology, School of Biomedical, Biomolecular and Chemical Sciences, Faculty of Life and Physical Sciences, The University of Western Australia, Crawley, Western Australia, Australia. Jacqueline.Kent@uwa.edu.au
authors.forename: Jacqueline C
authors.initials: JC
authors.lastname: Kent
authors.forename: Leon R
authors.initials: LR
authors.lastname: Mitoulas
authors.forename: Mark D
authors.initials: MD
authors.lastname: Cregan
authors.forename: Donna T
authors.initials: DT
authors.lastname: Geddes
authors.forename: Michael
authors.initials: M
authors.lastname: Larsson
authors.forename: Dorota A
authors.initials: DA
authors.lastname: Doherty
authors.forename: Peter E
authors.initials: PE
authors.lastname: Hartmann
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007774:Lactation / Q000502:physiology*; D008055:Lipids / Q000032:analysis*; D008893:Milk Ejection / Q000502:physiology*; D008895:Milk, Human / Q000737:chemistry* / Q000378:metabolism*; D013396:Suction; D013997:Time Factors; D014618:Vacuum
chemical_list: D008055:Lipids