title: Transvesical intra-abdominal pressure measurement using minimal instillation volumes: how low can we go?
abstract: OBJECTIVE
  To determine the minimal instillation volume at which an intra-abdominal pressure (IAP) curve can be obtained and to compare this with the IAP measured at 20 ml instilled volume.
  
  
  METHODS
  Prospective cohort study in the Intensive Care Unit of Ghent University Hospital.
  
  
  METHODS
  Twenty-five critically ill sedated and ventilated patients at risk for intra-abdominal hypertension (IAH).
  
  
  METHODS
  IAP was measured transvesically using a custom-designed IAP monitoring set. Measurement was started without any additional instillation of saline and was continued at 1-ml increments up to 10 ml. Finally, IAP was measured with 20 ml instillation volume.
  
  
  RESULTS
  After each instillation an "oscillation test" was performed. The minimal volume at which the oscillation test was positive was recorded. These values were compared to the IAP obtained using 20 ml saline (IAP20 ml). At 2 ml installed saline volume an oscillation curve could be obtained in all patients. Mean IAP2 ml) was 11.2+/-3.2 mmHg, IAP10 ml) 11.4+/-3.7 mmHg, and IAP20 ml) 11.7+/-3.2 mmHg. In four patients (16%) there was a clinically significant difference of 2 mmHg or more between IAP2 ml and IAP20 ml. The mean difference between IAP20 ml) and IAP2 ml was 0.60+/-0.91 mmHg (95% CI 0.22-0.98).
  
  
  CONCLUSIONS
  In this sample of patients at risk for IAH 2 ml saline was sufficient for IAP signal transduction. Higher volumes for transvesical IAP measurement resulted in higher pressure readings in some patients.
authors.affiliation: Intensive Care Unit, Ghent University Hospital, De Pintelaan 185, 9000, Ghent, Belgium.
authors.forename: I
authors.initials: I
authors.lastname: De laet
authors.forename: E
authors.initials: E
authors.lastname: Hoste
authors.forename: Jan J
authors.initials: JJ
authors.lastname: De Waele
mesh_terms: D000005:Abdomen; D000283:Administration, Intravesical; D003161:Compartment Syndromes / Q000175:diagnosis*; D016638:Critical Illness; D006801:Humans; D007362:Intensive Care Units; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results