A concise overview of non-invasive intra-abdominal pressure measurement techniques: from bench to bedside

Abstract

This review presents an overview of previously reported non-invasive intra-abdominal pressure (IAP) measurement techniques. Each section covers the basic physical principles and methodology of the various measurement techniques, the experimental results, and the advantages and disadvantages of each method. The most promising non-invasive methods for IAP measurement are microwave reflectometry and ultrasound assessment, in combination with an applied external force.

Keywords: Abdominal compartment syndrome; Intensive care unit; Intra-abdominal pressure; Microwave reflectometry; Non-invasive measurement; Ultrasound.

Fig. 1

Wheatstone bridge strain gauge. In this circuit, V_in is the input voltage, R₁, R₂, R₃, and R_S are resistors and V_out is the output voltage that fluctuates according to the changes in R_S

Fig. 2

Summary of results of the study about the effect of IAP on the human spine (adapted with permission from Hodges et al. [10]). a Experimental set-up used in the study. By stimulating phrenic nerve, IAP is increased and the extensor torque around mid-lumbar level is measured by means of a strain gauge. Peak IAP values are achieved by using a pressure catheter which is known as the intragastric method b Normalized peak extensor torque as a function of peak IAP (R = 0.86, P < 0.01) (adapted from Hodges et al. [10])

Fig. 3

The general principle of respiratory inductance plethysmography (RIP). Firstly, the coils should be positioned around the rib cage (RC) and abdomen (AB). Finally, by data acquisition, the changes in the length of AB and RC coils will be achieved (adapted with permission from Chen et al. [11])

Fig. 4

The tracings achieved by respiratory inductance plethysmography (RIP). The first signal shows IAP in mmHg versus time in seconds. Peso is the esophageal pressure in mmHg that is shown as the second signal. The last two signals are related to thorax and abdominal volume changes that have been assessed by thorax and abdominal respiratory inductance plethysmography (RIP). Sample tracings obtained with BiCore monitor (Cardinal Health, Dublin, Ohio, United States)

Fig. 5

Abdominal wall tensiometry. Tensiometry is performed by measuring force and distance (indentation) at the site where the punctual force is applied (adapted with permission from van Ramshorst et al. [20]). a Initial abdominal wall tension (AWT) measurement device b Seven points were measured during the initial study: three on the linea alba, three on the rectus abdominis muscle and finally one over the lateral transverse muscle. The measurements were solely performed on one half of the abdomen, assuming abdominal symmetry

Fig. 6

Abdominal wall tension (AWT) measurement prototype used by van Ramshorst et al. (adapted with permission from van Ramshorst et al. [21]). a New prototype of tensiometer connected to smartphone b Six measurement points, derived from anatomical structures, were marked on each abdominal wall: 5 cm caudal to the xiphoid bone (point 1), 5 cm cranial to the umbilicus (point 2), 5 cm left to point 2 (point 3), 10 cm left to point 2 (point 4), 5 cm cranial to the pubic bone (point 5), and an extra point, 5 cm left to point 5 (point 6)

Fig. 7

Abdominal wall tensiometer. Tensiometer used by Chen et al. to measure the required thrust (N) to produce displacement (mm) (adapted with permission from Chen et al. [22])

Fig. 8

Correlation between abdominal wall tension (AWT) and urinary bladder pressure (UBP), performed by tensiometry. As can be seen, an almost linear correlation was found between abdominal wall thickness and the urinary bladder pressure (adapted from Chen et al. [22])

Fig. 9

Veinpress system mounted on an ultrasound probe (adapted with permission from Bloch et al. [24])

Fig. 10

Ultrasound-tonometry set-up. Tonometry was performed in combination with ultrasound for intra-compartmental pressure (ICP) assessment with an applied pressure of 40 mmHg (right panel) compared to the situation without applied pressure (left panel) (d1, d2: compartment diameters, T: tibia, V: veinpress) (adapted from Bloch et al. [24])

Fig. 11

Elastic ratio (ER) as a function of the intra-compartmental pressure (ICP) for different external pressure values (adapted with permission from Bloch et al. [24])

Fig. 12

Elastic ratio (ER) as a function of the intra-compartmental pressure (ICP). The 95% confidence interval was seen at 40 mmHg external pressure (adapted with permission from Bloch et al. [24])

Fig. 13

Ultrasound tonometry concept for intra-abdominal pressure assessment. Labels “a” and “b” denote the vertical chamber diameter in two different intra-abdominal pressure (IAP) values (adapted from Bloch et al. [25])

Fig. 14

Vertical chamber diameter in relation to intra-abdominal prerssure. Chamber diameter is expressed as a function of intra-abdominal pressure (IAP) stages at an external pressure of 22.5 mmHg and 37.5 mmHg, assessed with ultrasound tonometry (adapted from Bloch et al. [25])

Fig. 15

Peritoneal rebound visualized by ultrasound assessment in combination with external pressure. Loss of peritoneal rebound visualization happens when IAP is equal to or more than external pressure (adapted with permission from See et al. [26])

Fig. 16

Block diagram of a Doppler tonometry system (adapted with permission from Akinin et al. [27])

Fig. 17

Relationship between applied force and measured velocity as a function of time (adapted with permission from Akinin et al. [27])

Fig. 18

Doppler ultrasound. Relation between intra-abdominal pressure (IAP) and venous transit time blood flow, performed by Doppler ultrasound. (adapted with permission from Gudmundsson et al. [28]). a Blood flow in the inferior vena cava vein and blood flow in the right femoral vein b as a function of intra-abdominal pressure. * significant difference from the nearest left observation, ** significant difference from the final IAP measurement (P < 0.05)

Fig. 19

Laser ultrasound. Schematic representation of the optical sensor and Fabry-Pérot etalon as the main concept of laser ultrasound (adapted with permission from Preisser et al. [29])

Fig. 20

Experimental data for permittivity and conductivity of muscle at body temperature (adapted with permission from Gabriel et al. [30])

Fig. 21

Bioimpedance analysis. Results of the measured absolute impedance for different induced values of IAP. Drastically reduced sensitivity for values over 7 mmHg is observed (adapted with permission from David et al. [31])

Fig. 22

Microwave reflectometry. Values of S11 (scattering parameter) as a function of IAP for the selected frequency of 4.25 GHz, measured based on microwave reflectometry (adapted with permission from David et al. [31])

Fig. 23

Digital image correlation. Set-up of digital image correlation (DIC) test for a uniaxial tensile test of a cylindrical specimen. (adapted with permission from [34])

Fig. 24

Markers placement on the abdominal skin for digital image correlation a Markers configuration in normal IAP b Markers configuration in IAH (adapted with permission from Song et al. [35])

Fig. 25

Wireless motility capsule. Components of a motility capsule for intragastric pressure measurement consists of a solid plastic head and a soft polyurethane body incorporating the batteries and sensors (adapted with permission from Fernandes et al. [37])

Fig. 26

Intragastric pressure changes in an individual pig model during 24 h measured by wireless motility capsule (adapted from Rauch et al. [36])

Fig. 27

Summary of characteristics of the different non-invasive IAP measurement techniques. (DIC: digital image correlation, US: ultrasound)