title: The effect of different reference transducer positions on intra-abdominal pressure measurement: a multicenter analysis.
abstract: OBJECTIVE
  To investigate the effect of different reference transducer positions on intra-abdominal pressure (IAP) measurement. Three reference levels were studied: the symphysis pubis; the phlebostatic axis; and the midaxillary line at the level of the iliac crest.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  The intensive care units of participating hospitals
  
  
  METHODS
  One hundred thirty-two critically ill patients at risk for intra-abdominal hypertension (IAH).
  
  
  METHODS
  In each patient, three sets of IAP measurements were obtained in the supine position, using the different reference levels. The IAP measurements obtained at the different reference levels were compared using a paired t-test and Bland-Altman statistics were calculated.
  
  
  RESULTS
  IAP(phlebostatic) (9.9 +/- 4.67 mmHg) and IAP(pubis) (8.4 +/- 4.60 mmHg) were significantly lower that IAP(midax) (12.2 +/- 4.66 mmHg; p < 0.0001 for both comparisons). The bias between the IAP(midax) and IAP(pubis) was 3.8 mmHg (95% CI 3.5-4.1) and 2.3 mmHg (95% CI 1.9-2.6) between the IAP(midax) and the IAP(phlebostatic). The precision was 3.03 and 3.40, respectively.
  
  
  CONCLUSIONS
  In the supine position, IAP(midax) is higher than both IAP(phlebostatic) and IAP(pubis), differences found to be clinically significant; therefore, the symphysis pubis or phlebostatic axis reference lines are not interchangeable with the midaxillary level.
authors.affiliation: Surgical Intensive Care Unit, Ghent University Hospital, De Pintelaan 185, 9000, Gent, Belgium. jan.dewaele@UGent.be
authors.forename: Jan J
authors.initials: JJ
authors.lastname: De Waele
authors.forename: Inneke
authors.initials: I
authors.lastname: De Laet
authors.forename: Bart
authors.initials: B
authors.lastname: De Keulenaer
authors.forename: Sandy
authors.initials: S
authors.lastname: Widder
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Kirkpatrick
authors.forename: Adrian B
authors.initials: AB
authors.lastname: Cresswell
authors.forename: Manu
authors.initials: M
authors.lastname: Malbrain
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Bodnar
authors.forename: Jorge H
authors.initials: JH
authors.lastname: Mejia-Mantilla
authors.forename: Richard
authors.initials: R
authors.lastname: Reis
authors.forename: Michael
authors.initials: M
authors.lastname: Parr
authors.forename: Robert
authors.initials: R
authors.lastname: Schulze
authors.forename: Sonia
authors.initials: S
authors.lastname: Compano
authors.forename: Michael
authors.initials: M
authors.lastname: Cheatham
mesh_terms: D000005:Abdomen; D003161:Compartment Syndromes / Q000175:diagnosis* / Q000503:physiopathology; D016638:Critical Illness; D006801:Humans; D007362:Intensive Care Units; D011312:Pressure