Background: 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.
Materials and methods: 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.
Results: 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.
Conclusions: 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.