MO691CORRELATION OF INTRAPERITONEAL PRESSURE AND APEX TIME WITH ULTRAFILTRATION AND BIOCHEMICAL VARIABLES IN PATIENTS IN PERITONEAL DIALYSIS
Authors: Vargas Arispe Lionel Cristian , Amador Reyes Laura Gabriela , Valdez Ortiz Rafael , Perez Navarro Lucia Monserrat , Paredes Fernã¡ndez Carlos Mauricio 
Published: May 2021

Abstract

Background and Aims
Chronic Kidney Disease represents a growing and serious public health problem, which progresses to terminal stage with glomerular filtration rate &lt;15 ml/min/1.73m2. It makes it necessary to implement substitute therapies for renal function with hemodialysis (HD), peritoneal dialysis (PD) or kidney transplantation. It is known that the ultrafiltration (UF) capacity of PD is much lower than that of HD, which explains the higher incidence of overhydration in PD patients, which increases morbidity and mortality in this group of patients, being the second cause of change to HD. Due to this limitation, it is essential to know and fully exploit all the factors that influence the UF in PD. The net UF in DP is the result of 4 forces: 1) the osmotic force, the strongest and only one that is deliberately controlled; 2) intraperitoneal pressure (IPP) modulated by intraperitoneal volume (IPV), UF volume itself, posture, BMI, physical activity, etc.; 3) capillary hydrostatic pressure, modulated by the degree of fluid overload, and 4) capillary oncotic pressure proportional to hypoalbuminemia, in turn related to fluid overload. The IPP with typical values of 10-16 cm H2O, should not exceed 18 cmH2O, this excess leads to the development of mechanical, infectious and functional complications, among them, a decrease in UF. Elevated IPP is a little known cause of UF failure and, due to its easy diagnosis and application, it should be ruled out in cases of overhydration in PD. Another parameter to consider when favoring UF in PD is the residence time of the dialysate solution in the abdominal cavity through the APEX time calculation (functional test derived from the classic peritoneal balance test). In the present study, we intend to define the role of IPP and APEX time as diagnostic and adjunctive evaluation techniques to optimize UF in PD patients. We determined the correlation of IPP and APEX time with ultrafiltration and biochemical variables in PD patients.

Method
Pilot, observational, cross-sectional, analytical study.

Results
Thirty patients were included, 10 (33%) patients on PD in the IPD modality and 20 (66.7%) in the CAPD modality. Of which mostly men (53%). The mean residual uresis of the general population was 534.33 ml. The average UF with a 1.5% solution is 238.1, for a 2.5% solution the average UF is 296.2 and for a 4.25% solution the average UF is 535 ml. No statistically significant mean differences were found between both groups. (p ≤ 0.05). The average IPP in the supine position was 13.1 cmH2O, the sitting position was 22.8 cmH2O, and the vertical 25.4 cmH2O, the variability of the PIP in the prone position at 15.8 cmH2O is striking. No statistically significant differences were found between the averages of the analysis groups (p ≤ 0.05). The average calculated APEX time was 42.4 minutes. When performing the correlation of UF with IPP, APEX, Dif. Na, D/P and D/Do, as well as the correlation between APEX time and time in DP. Being able to determine that there is no correlation between the different variables. No statistically significant differences were found. (p ≤ 0.05).

Conclusion
It is the first study in Mexico that evaluates the usefulness of APEX and IPP time in Adult patients on CAPD and IPD. It was determined that Intraperitoneal Pressure does not influence Ultrafiltration levels. In our study we demonstrated that the APEX time, an index of the optimal ultrafiltration residence time, was not correlated with the UF volumes. Therefore, the adequacy of peritoneal dialysis must not only be based on functional tests, it must be personalized and be based in conjunction with clinical, biochemical, nutritional parameters and functional tests.