Novel equations for estimating intraperitoneal pressure among peritoneal dialysis patients

Background Increased intraperitoneal pressure (IPP) is associated with abdominal wall complications and technical failure in peritoneal dialysis (PD). Since the standard measurement of IPP is limited due to its cumbersome procedures, we aimed to develop and validate equations for estimating IPP. Methods We performed a cross-sectional study with a total of 200 prevalent PD patients who were divided into development and validation datasets after random sampling matched by body mass index. The IPPs were measured using the Durand method, with whole-body and abdominal anthropometry indices collected. Equations with 2.0-L and 1.5-L fill volumes were generated by stepwise linear regression modelling. The bias, accuracy and precision of the estimated IPP (eIPP) with 2-L and 1.5-L fill volumes were compared with actual IPPs by the Durand method. The eIPP for the 2-L fill volume was also compared with other existing equations. Results Two new equations incorporating waist circumference and height from the decubitus plane to mid-axillary line were generated. The eIPPs exhibited small biases in relation to the Durand method , with median differences of -0.24 cmH(2)O and -0.10 cmH(2)O for 2 L and 1.5 L, respectively. The precisions evaluated by the standard deviation of the absolute value of the differences were 2.59 cmH(2)O and 2.50 cmH(2)O, respectively. The accuracies evaluated by the value of the percentage of estimates that differed by >20% for the eIPP were 26% for 2.0 L and 27% for 1.5 L. Better bias, precision and accuracy were observed for the eIPP equation compared with other existing equations for the 2.0-L fill volume. Conclusions We provided two new equations developed from abdominal anthropometry indices to accurately estimate the IPP in the PD population. Lay Summary This article presents our work in developing and validating equations for evaluating intraperitoneal pressure (IPP) among peritoneal dialysis (PD) patients. We developed two novel equations to predict IPP with 2.0-L and 1.5-L fill volumes in adult PD patients. Our results showed that estimated IPP (eIPP) values using waist circumference and height from the decubitus plane to mid-axillary line were close to the actual IPP values measured by the Durand method. Compared with several existing equations, our newly derived equations have good performance in that they have smaller biases, better precision and greater accuracy. Whole-body anthropometry measurements such as body mass index and body surface area are generally considered to be major contributors to IPP. This study is the first to consider local anthropometry data relating to the volume of the peritoneal cavity when estimating the IPP. Our equations were verified to be a feasible and reliable approach to estimating IPP and therefore can assist in making individualized prescriptions for the PD population.