Observational pilot study of intra-abdominal pressure in different head of bed positions

Objectives The 2013 World Society of the Abdominal Compartment (WSACS) Guidelines state that intra-abdominal pressure (IAP) should be measured in the supine position. Since patients in the intensive care are preferably nursed in an elevated head of bed position, measuring IAP in more upright positions is more practical. However, measured IAP increases in more upright positions. This study aimed to evaluate the validity of the automatic IAP measurement in different HOB elevations in postoperative cardiothoracic surgery patients. Design Single-center observational study. Setting ICU of a university hospital . Participants 37 postoperative cardiothoracic surgery patients admitted to the ICU. Interventions IAP was measured by the Accuryn Monitoring System in 0°, 15°, 30°, 45° and 60° HOB elevation. Measurements and Main Results IAP measurements in 37 patients were analyzed. Mean IAP at 0° was 9.3 (SD 2.2). Mean IAP increased to 17.9 mmHg (SD 2.9) at 60°. A repeated measures ANOVA was conducted with a pairwise comparison for post-hoc analysis. Mean difference in IAP per 15° HOB elevation was: +1.8mmHg (95%CI 1.4-2.2) for 0°-15° , +2.4mmHg (2.0-2.8) for 15°-30°, +2.2mmHg (1.9-2.5) for 30°-45°, and +2.1mmHg (1.8-2.4) for 45°-60°. Conclusions This study demonstrates the increase of IAP by approximately 2 mmHg per 15 degree increase in HOB elevation using automatic measurements. This finding may facilitate more routine measurements of IAP and thereby earlier signalling of increases in IAP.