| Abstract: Aims: Accurate, repeatable measurements of intra-abdominal pressure (IAP) are necessary for proper patient management.[1] Manometry is one method for measuring intra-abdominal pressure.[2,3] This study evaluated intra-observer variability and the impact of variable fluid volume infusion on the accuracy of manometry in an IAP model.
Methods: A model consisting of a 210-liter container (the “Abdomen”) with a urinary
catheter exiting its base was designed to simulate IAP. The catheter tip was sealed within a 100 ml bag (the “bladder”). A water column measuring 10, 20, 30, 40 or 50 cm was placed within the container to simulate IAP. Pressure was measured using the manometry technique described by Sedrak.[3] Fluid volumes of 10, 20, 30, 40, and 50 ml were infused into the “bladder” and pressures were recorded. The gold standard was the water column height. Pressure differences of more/less than ± 3 cm water were considered clinically important in measured versus actual pressure.
Results: IAP measurements using manometry demonstrate clinically important variations from actual pressure (see table). Notable errors contributing to this variation include: Inadequate fluid volume infusion to create the proper fluid column height; failure to hold the drain tubing high enough resulting in a loop at the distal end which retains fluid and causes a siphon effect; failure to hold the tubing in an absolutely vertical position; pinching the Foley at the bend preventing fluid equilibration; and failure to straighten the natural curve in the tubing during measurement.
Discussion: Measuring IAP using manometry requires extreme attention to detail due to the high risk of human error. Inaccurate measurements occur if inadequate fluid volumes are used, if any fluid remains in the distal drain tubing or if the fluid column is not held perfectly upright. These variations are more pronounced at lower IAP then at higher IAP.
|
