Evaluation of two novel methods for the direct and continuous measurement of the intra-abdominal pressure in a porcine model

Intravesical bladder pressure (IVP) measurement is considered to be the gold standard for the assessment of intra-abdominal pressure (IAP). However, this method is indirect, discontinuous, and potentially infectious and relies on a physiological bladder function. This study evaluated two novel methods for direct, continuous IAP measurement. Experimental study in an animal research laboratory. 18 male domestic pigs. CO(2) was insufflated to increase the IAP to 30 mmHg for 18 and 24 h in six animals each. Another six animals served as controls. A piezoresistive (PRM) and an air-capsule (ACM) pressure measurement probe were placed intra-abdominally and of IAP was measured every 1 h (PRM/ACM) or every 2 h (IVP). The mean difference between insufflator readings and IAP values and limits of agreement (mean difference +/-2 SD) were calculated. In the presence of applied pressure IVP and PRM remained significantly below insufflator readings while ACM values showed no difference. Mean difference (and limits of agreement) were 4.5 (-2.1 to 11.1 mmHg), 1.6 (-8.0 to 11.2 mmHg), and 0.5 (-4.5 to 5.4 mmHg) for IVP, PRM, and ACM. The mean measurement-to-measurement drift of the ACM values was 9.0+/-10.2 mmHg. In this model agreement of PRM and ACM with insufflator readings was comparable to IVP. As both methods may be advantageous regarding continuous straightforward measurement of IAP, the employment in further experimental and clinical investigations is suggested.