title: Effect of airway pressure on lumbar epidural pressure during positive pressure ventilation.
abstract: BACKGROUND
  The purpose of this study was to measure lumbar epidural pressure (EP) during the insertion of a Tuohy needle under general anesthesia and to evaluate the influence of airway pressure on EP.
  
  
  METHODS
  Lumbar EP was measured directly through a Tuohy needle during intermittent positive pressure ventilation in fifteen patients. Mean and peak EP were recorded after peak inspiratory pressures (PIP) of 0, 15, and 25 cmH(2)O.
  
  
  RESULTS
  All measured lumbar EPs were positive, with the pressure increasing during inspiration and decreasing during expiration. Median EP was 6.0 mmHg (interquartile range, 4.0-8.0) at 0 cmH(2)O of PIP, 6.5 mmHg (4.5-8.5) at 15 cmH(2)O, and 8.5 mmHg (6.0-10.5) at 25 cmH(2)O, increasing significantly at 15 cm H(2)O PIP, and further increasing at 25 cmH(2)O (P < 0.001).
  
  
  CONCLUSIONS
  We demonstrate the influence of increased airway pressure on lumbar EP measured directly through a Tuohy needle. Lumbar EPs were positive, and increasing PIP levels significantly increased lumbar EP.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, Seoul, Korea.
authors.forename: Sun Sook
authors.initials: SS
authors.lastname: Han
authors.forename: Young Jin
authors.initials: YJ
authors.lastname: Lim
authors.forename: Yunseok
authors.initials: Y
authors.lastname: Jeon
authors.forename: Kyoung-Beom
authors.initials: KB
authors.lastname: Min
authors.forename: Won-Sik
authors.initials: WS
authors.lastname: Ahn
authors.forename: Sang Chul
authors.initials: SC
authors.lastname: Lee