Noninvasive Assessment of Intra-Abdominal Pressure by Measurement of Abdominal Wall Tension¹

Background

Sustained increased intra-abdominal pressure (IAP) has negative effects. Noninvasive IAP measurement could be beneficial to improve monitoring of patients at risk and in whom IAP measurements might be unreliable. We assessed the relation between IAP and abdominal wall tension (AWT) in vitro and in vivo.

Materials and Methods

The abdomens of 14 corpses were insufflated with air. IAP was measured at intervals up to 20 mm Hg. At each interval, AWT was measured five times at six points. In 42 volunteers, AWT was measured at five points in supine, sitting, and standing positions during various respiratory manoeuvres. Series were repeated in 14 volunteers to measure reproducibility by calculating coefficients of variation (CV). ANOVA was used for analyses.

Results

In corpses, all points showed significant correlations between IAP and AWT (P < 0.001 for points 1–4 in the upper abdomen, P = 0.017 for point 5 and P = 0.008 for point 6 in the lower abdomen). Mean slopes were greatest at points across the epigastric region (points 1–3). In vivo measurements showed that AWT was on average 31% higher in men compared to women (P < 0.001), and increased from expiration to inspiration to Valsalva's manoeuvre (all P < 0.001). AWT was highest at points 1 and 2 and in standing position, followed by supine and sitting positions. BMI did not influence AWT. Mean CV of repeated measurements was 14%.

Conclusions

AWT reflects IAP. The epigastric region appears most suitable for AWT measurements. Further longitudinal clinical studies are needed to assess usefulness of AWT measurements for monitoring of IAP.

Key Words: intra-abdominal pressure, abdominal wall tension, abdominal hypertension, compartment syndrome, measurement, noninvasive, surgery, trauma, complications, bladder pressure