Influence of Semi-Recumbent Position on Intra-Abdominal Pressure as Measured by Bladder Pressure

Intra-abdominal pressure (IAP) obtained by bladder pressure measurement is used to detect impending abdominal compartment syndrome (ACS), but, while it is recommended to use a supine position, the literature describes IAP measurement in varying positions. This study evaluated the impact of body position at differing head-of-bed (HOB) elevations on bladder pressure when planned to be used as a surrogate IAP measurement.Forty-five trauma patients admitted to a surgical intensive care unit underwent bladder pressure measurements at 0, 15, 30, 45 degrees HOB position and 30 degrees HOB position plus 15 degrees of reverse Trendelenburg tilt; these measurements were performed in counterbalanced fashion and assessed by built-in angle indicators on the bed rails of each bed. Study participants were connected to an IAP monitoring kit via their indwelling Foley catheter.A total of 675 bladder pressure measurements were obtained with 135 measurements at each of five HOB elevations (0 degrees , 15 degrees , 30 degrees , 45 degrees , 30 degrees +15 degrees tilt). Statistically significant differences occurred between all HOB elevations. Statistically significance differences also occurred at different BMI statuses.Elevating HOB significantly increases bladder pressure measurement. Bladder pressure measurements in nonsupine positions may not provide valid interpretation for IAP, and more so in cases of increased body mass index.