Both piezoresistive measurement and water-capsule measurement had smaller confidence intervals than intravesical pressure measurement, indicating higher precision, whereas water-capsule measurement had a significant offset. Piezoresistive measurement could be the most suitable device for continuous direct intra-abdominal pressure monitoring in specific patients.

Parameters derived from the PV curve may help in characterizing the lung aeration of the lung and in indicating recruitment. In the presence of lung-protective ventilator settings, the stress index derived from the Paw-t curve was not able to indicate recruitment.

Pulmonary pressure-volume curves (P-V curves) of patients with acute lung injury are commonly analyzed using a parametric algorithm with symmetrical properties. Some of the aspects observed after performing nonlinear regression for two models capable of fitting symmetric, respectively asymmetric data are discussed.One analyzed aspect was the algebraic complexity of the asymmetric model that does not allow for an estimation of the boundaries of the zone of maximal compliance directly from the parameter estimates in contrast to the symmetric model. Moreover, mathematical evidence is provided.Using a sigmoid equation for analysis of P-V curves a systematic deviation caused by asymmetrical distribution was encountered, leading to non-robust definitions of lower and upper inflection points. Increasing the number of parameters to fit asymmetric data does not increase physiological expression.We conclude that some of the drawbacks in using P-V curves may be attributed to imprecise analysis tools. To increase the value of P-V curves other forms of mathematical analysis should be investigated.