# Effect of Body Position on the Development of Intra-abdominal Hypertension and Abdominal Compartment Syndrome in Patients in Critical Condition

## TL;DR

This study shows that elevating the head of the bed in critically ill patients increases intra-abdominal pressure, raising the risk of intra-abdominal hypertension.

## Contribution

The study reveals that body position significantly affects intra-abdominal pressure and highlights the risk for patients with higher BMI.

## Key findings

- Intra-abdominal hypertension and abdominal compartment syndrome were most prevalent at 45° head-of-bed elevation.
- Abdominal perfusion pressure and filtration gradient were significantly lower at elevated positions compared to the supine position.
- Higher BMI was strongly associated with increased risk of intra-abdominal hypertension at elevated head-of-bed angles.

## Abstract

Background

Measurement of intra-abdominal pressure (IAP) in the supine position (SP-0o) is the cornerstone for preventing intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS). However, mechanically ventilated patients (MVP) are nursed with a head-of-bed angle (HOB) at 30o-45o for ventilator-associated pneumonia (VAP) prevention. The aim of the study was to evaluate the impact of HOB positioning of MVP on IAH and ACS.

Methods

A prospective observational cohort study was conducted at 150 MVP who had completed 24 hours with at least one risk factor for IAH in the mixed medical and surgical Intensive Care Unit (ICU). IAP, abdominal perfusion pressure (APP), and filtration gradient (FG) were measured via the bladder at SP-0o, 20°, 30°, and 45° HOB three times daily for 3 days.

Results

Mean Body Mass Index (BMI) was 30.4 (SD=6.4), while pulmonary infection was the leading admission cause. Out of 1800 registrations, IAP was reported 757 times (42.1%) and ACS 51 times (2.8%). Fourteen patients developed ΙΑΗ. IAH and ACS percentages differed significantly among the four body positions, with the lowest percentage being in SP-0o and the highest at 45°. APP and FG in SP-0o were significantly higher compared to 20o, 30o, and 45o (p<0.001 for all comparisons). Greater BMI (OR=1.14; p<0.001) at 20o, 30o, and 45o of HOB elevation was significantly associated with a greater risk of IAH than SP-0o.

Conclusion

Elevation of HOB increases IAP and risk of IAH. It is recommended that MVPs with increased BMI and with at least one risk factor for IAH have their IAP measured daily.