A Comparative Study of Low Versus Standard Intraperitoneal Pressures in Gynaecological Laparoscopic Surgery

Background: Minimal access surgery in contrast to open surgery has quicker recovery during the postoperative period as well as reduced scores of pain. As a result of increased pressure in the abdominal cavity, laparoscopic surgery has many implications over a range of organ systems as well as their functioning. Laparoscopic surgery due to increased intraabdominal pressure also has many implications on various organ systems and their functioning. To overcome the consequences of increased intrabdominal pressure, a number of trials have been formulated to compare low- versus standard-pressure pneumoperitoneum. Aim: The aim of this study was to assess the effectivity of low intraperitoneal pressures v/s standard intraperitoneal pressure during laparoscopic hysterectomies. Study Design: Experimental study Materials and Methods: 40 cases with uncomplicated symptomatic benign uterine pathologies who were posted for laparoscopic hysterectomy were selected out of which 20-20 cases were randomized into low and standard pneumoperitoneum groups. Results: In patients in whom low pressure pneumoperitoneum is employed are better recovered in terms of pain than standard pressure pneumoperitoneum. This means hospital stay can be shortened in low pressure pneumoperitoneum groups which will be more economical and comfortable for patients. Conclusion: Laparoscopic hysterectomy can be done at 10 mmhg with the benefits of : Optimum visualization with low pressure Reduction in post operative pain helping the patient for early ambulation so that patient will get back to routine work and normal life earlier, it is the main purpose of minimal invasive surgery.

Imaging and leaks in peritoneal dialysis

Dialysate leaks are non-rare mechanical but dreaded complications in peritoneal dialysis (PD). They usually occur at the beginning of PD, with various clinical events depending on their location. Use of imaging tests such as computed tomography (CT) peritoneography, or magnetic resonance imaging (MRI) peritoneography, or scintigraphic peritoneography, can confirm the diagnosis and guide surgical intervention if needed. These simple, non-invasive, and accessible tests can be done in collaboration between the radiological et peritoneal teams. Depending on the leakage site, PD can be pursued with small volumes with a cycler. In other cases, it must be interrupted and the patient transferred to hemodialysis, in order to permit the peritoneal cavity to regain its integrity by cicatrization or with surgical intervention. Imaging can help to make sure peritoneal cavity has regained its integrity after this period of transition. Early leaks can be avoided by delaying PD start with by 14 days. Intraperitoneal pressure does not seem to contribute significantly. Prevention of PD leaks essentially depends on individual risk factors such as obesity or anterior abdominal surgeries. This article reviews the characteristics of dialysate leaks in PD and the imagery tests to limit transfer to hemodialysis.

MO694SWELLING OF PERITONEAL TISSUE DURING PERITONEAL DIALYSIS: COMPUTATIONAL ASSESSMENT USING POROELASTIC THEORY

Background and Aims Experimental studies and computational modeling show increased hydration of peritoneal tissue close to peritoneal surface after intraperitoneal (ip) administration of hypertonic dialysis fluid. This overhydration - due to fluid inflow from peritoneal cavity (driven by increased intraperitoneal pressure) and from blood (due to high interstitial concentration of osmotic agent diffusing from the cavity) - may lead to tissue swelling, as observed in experiments and in disturbed physiological conditions. We estimated the degree of swelling using linear poroelastic theory with fluid and solute transport parameters obtained from clinical studies. Method The spatially distributed model of peritoneal transport was extended by equations for tissue deformation and stress derived from linear poroelastic theory. The model describes also fluid and osmotic agent flows across tissue and capillary wall. We assumed that transport and deformation occur across a layer of tissue with initial intact width L0 and deformed width L; the deformation is described as the ratio L/L0. Transport parameters are assumed as average values estimated for intact tissue by Stachowska-Pietka (2019). As tissue stiffness (Lame coefficient) for muscle is not known, we examined stiffness ranging from 110 mmHg (connective tissue; interstitium) to 700 mmHg (solid tumor). We assumed that for initial periods of peritoneal dialysis when osmotic pressure of dialysis fluid is high: 1) osmotic pressure gradient across the capillary wall prevails over the combined Starling forces, 2) spatial profile of osmotic agent concentration in tissue (interstitial fluid) can be approximated by exponential function with the penetration depth ΛS. The model yields an equation for L/L0 to be solved numerically, but an approximated closed formula also works well for typical dialysis conditions. Results The model predicts that swelling of peritoneal tissue depends on factors such as tissue stiffness, tissue width, solute penetration depth, and transport parameters for tissue and capillary wall, and on the forces that induce fluid transport: intraperitoneal pressure and the increment of osmolality of dialysis fluid over plasma osmolality. Examples of L/L0 yielded by the model - with use of glucose 1.36% dialysis fluid and for two levels of ip hydrostatic pressure (Pip) - are shown. In Figure, left panel, for L0 = 1 cm representing human abdominal muscle, and solute diffusional penetration ΛS=ΛD=0.055 cm, or lower, as due to diffusion against fluid flow, ΛS=ΛD/2=0.027 cm, is plotted versus the tissue stiffness; the dialysis fluid with glucose 1.36% is applied (osmolality increment of 60 mmol/L at the beginning of peritoneal dwell, Waniewski et al, 1996) and Pip is 15 mmHg. As stiffness of abdominal and bowel muscles may be expected around 300 mm Hg, swelling might be up to 15%; it decreases with lower ip hydrostatic and osmotic pressures. Hypothetical dialysis at Pip = 0 (isobaric with interstitial fluid) would reduce swelling by factor 2, see Figure, right panel. The depth of osmotic agent penetration into the tissue impacts tissue hydration and swelling, see Figure 1 for L/L0 with twice reduced ΛS. The model and its approximation by the closed formula provide practically the same outcomes for clinical peritoneal dialysis, see Figure 1, but some discrepancy between them may occur for thin tissue, as rat abdominal wall. The approximate formula for L/L0 works well if ΛS is much shorter than L0. Nevertheless, for high degree of swelling a nonlinear theory should be constructed. Conclusion In peritoneal dialysis, exposure of peritoneal tissue to hypertonic dialysis fluid at increased hydrostatic pressure contributes to overhydration and swelling (by 5-15% after fluid infusion) of the tissue. The extent by which this swelling may contribute to changes in peritoneal tissue structure and function warrants further studies.

MO691CORRELATION OF INTRAPERITONEAL PRESSURE AND APEX TIME WITH ULTRAFILTRATION AND BIOCHEMICAL VARIABLES IN PATIENTS IN PERITONEAL DIALYSIS

Background and Aims Chronic Kidney Disease represents a growing and serious public health problem, which progresses to terminal stage with glomerular filtration rate <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.

Pressurized intra-peritoneal aerosol chemotherapy (PIPAC): increased intraperitoneal pressure does not affect distribution patterns but leads to deeper penetration depth of doxorubicin in a sheep model

Background Pressurized Intra-Peritoneal Aerosol Chemotherapy (PIPAC) is an innovative treatment against peritoneal carcinomatosis. Doxorubicin is a common intra-venous chemotherapy used for peritoneal carcinomatosis and for PIPAC. This study evaluated the impact of increased PIPAC intraperitoneal pressure on the distribution and cell penetration of doxorubicin in a sheep model. Methods Doxorubicin was aerosolized using PIPAC into the peritoneal cavity of 6 ewes (pre-alpes breed): N = 3 with 12 mmHg intraperitoneal pressure (“group 12”) and N = 3 with 20 mmHg (“group 20”). Samples from peritoneum (N = 6), ovarian (N = 1), omentum (N = 1) and caecum (N = 1) were collected for each ewe. The number of doxorubicin positive cells was determined using the ratio between doxorubicine fluorescence-positive cell nuclei (DOXO+) over total number of DAPI positive cell nuclei (DAPI+). Penetration depth (μm) was defined as the distance between the luminal surface and the location of the deepest DOXO+ nuclei over the total number of cell nuclei that were stained with DAPI. Penetration depth (μm) was defined as the distance between the luminal surface and the location of the deepest DOXO+ nuclei. Results DOXO+ nuclei were identified in 87% of samples. All omental samples, directly localized in front of the nebulizer head, had 100% DOXO+ nuclei whereas very few nuclei were DOXO+ for caecum. Distribution patterns were not different between the two groups but penetration depth in ovary and caecum samples was significantly deeper in group 20. Conclusions This study showed that applying a higher intra-peritoneal pressure during PIPAC treatment leads to a deeper penetration of doxorubicin in ovarian and caecum but does not affect distribution patterns.

Peritoneal physicochemical transport mechanisms: Hypotheses, models and controversies

This study answers criticisms by Waniewski et al. of the recent paper by Wolf on peritoneal transport kinetic models. Their criticisms centre on the accuracy of the data used for model fits, the hypothesis presented, which involves changes in glucose membrane parameters at high peritoneal glucose concentration and on the necessary techniques required to achieve accurate model parameter estimation. In response, this article shows that (1) the mean values previously captured from graphical depictions of Heimburger et al. are not different than those captured from the recent Waniewski et al. graphs, (2) a much simpler hypothesis is proposed, which centres on intraperitoneal pressure-induced lymph flow during the dialysis dwell and (3) the finding that the new model predictions, with only two constant parameter values, as estimated by the Powell algorithm, give a closer fit than the Waniewski model, which uses many time-varying parameters. The current findings again bring into question of the validity of their vasodilation hypothesis, leading to transient changes in capillary surface area during the dwell.

Pressurized Intra-Peritoneal Aerosol Chemotherapy (PIPAC): increased intraperitoneal pressure does not affect distribution patterns but leads to deeper penetration depth of doxorubicin in a sheep model

Background Pressurized Intra-Peritoneal Aerosol Chemotherapy (PIPAC) is an innovative treatment against peritoneal carcinomatosis. Doxorubicin is a common intra-venous chemotherapy used for peritoneal carcinomatosis and for PIPAC. This study evaluated the impact of increased PIPAC intraperitoneal pressure on the distribution and cell penetration of doxorubicin in a sheep model. Methods Doxorubicin was aerosolized using PIPAC into the peritoneal cavity of 6 ewes: N=3 with 12mmHg intraperitoneal pressure (group 1) and N=3 with 20mmHg (group 2). Samples from peritoneum (N=6), ovarian (N=1), omentum (N=1) and caecum (N=1) were collected for each ewe. The number of doxorubicin positive cells was determined using the ratio between doxorubicine fluorescence-positive cell nuclei (DOXO+) over total number of DAPI positive cell nuclei (DAPI+). Penetration depth (μm) was defined as the distance between the luminal surface and the location of the deepest DOXO+ nuclei over the total number of cell nuclei that were stained with DAPI. Penetration depth (μm) was defined as the distance between the luminal surface and the location of the deepest DOXO+ nuclei. Results DOXO+ nuclei were identified in 87% of samples. All omental samples, directly localized in front of the nebulizer head, had 100% DOXO+ nuclei whereas very few nuclei were DOXO+ for caecum. Distribution patterns were not different between the two groups but penetration depth in ovary and caecum samples was significantly deeper in group 2. Conclusions This study showed that applying a higher intra-peritoneal pressure during PIPAC treatment leads to a deeper penetration of doxorubicin in ovarian and caecum but does not affect distribution patterns.

The Factors Affectıng The Effıcıency Of Contınuous Ambulatory Perıtoneal Dıalysıs In Chıldren

Objective: Peritoneal dialysis is a complex and variable process. Many factors can affect efficiency of dialysis, and relevant mortality and morbidity rates. Efficient dialysis is important in improving quality of life as well as reducing the morbidity and mortality rates. Dialysis fill volume, intraperitoneal pressure and ultrafiltration (UF) are important variables that determine dialysis efficiency. We aimed to investigate the factors affecting dialysis efficiency and to determine necessities to develop a more effective dialysis program. Methods: Sixteen continuous ambulatory peritoneal dialysis (CAPD) patients between the ages of 7 and 19 years who were followed up in the Pediatric Nephrology Department were included in the study. Patients who had peritonitis, surgical or medical complications in the last 6 months were excluded from the study. Demographic data, duration of dialysis, hemogram, urea, creatinine, albumin, glucose levels, intraperitoneal pressures, peritoneal equilibration test (PET) and Kt/Vurea test results were recorded. Results: Mean Kt /Vurea, dialysis fill volume, UF, intraperitoneal pressure, Hb and serum albumin were found as 2.5±0.93 (1.22-4.64), 1123.4±126.86 (875-1360) ml/m2, 600.1±382.15 (85 -1375) ml, 12.9±2.77 (8.5-19) cm/H2O, 9.0±1.54 (6.3-11.8) gr/dl and 3.6±0.61 (2.45-4.8) gr/dl, respectively. A statistically significant relationship was shown between UF and Kt/Vurea (p=0.04). The mean duration of dialysis was 54±36 months. The majority of the cases had high (37.5%) and medium-high (31.25%) peritoneal permeability. High permeability was found to have a significant relationship with the duration of dialysis (p=0.04). Conclusion: Efficient peritoneal dialysis depends on preserved ultrafiltration. Therefore, the dialysate volume should be calculated according to the intraperitoneal pressure and dialysis should be adjusted according to the permeability properties of the peritoneal membrane.

Expediency of abdominal drainage after operative delivery in severe preeclampsia

One of the leading mechanisms for the development of severe preeclampsia in pregnant women is a decrease in perfusion pressure in the life-supporting organs, followed by the development of multiple organ failure. In recent years, there have been studies indicating the influence of intraperitoneal hypertension on the perfusion pressure of the pelvic and abdominal organs with the subsequent development of obstetric complications [ 4,2] according to the classification of JAN(2006), pregnancy is included in the list of conditions accompanied by an increase in intraperitoneal pressure. Thus, the prevention and treatment of increased intra-abdominal pressure in pathology accompanied by multiple organ dysfunction and insufficiency, which is observed in preeclampsia, is one of the important problems of modern medicine. The purpose of our study was to determine the feasibility of abdominal drainage during operative delivery for severe preeclampsia.

Intraperitoneal pressure: Stability over time and validation of Durand’s measurement method

Intraperitoneal pressure (IPP) is gaining consideration as a relevant parameter of peritoneal dialysis (PD) in adults, although many of its aspects are still pending clarification. We address here its stability over time and the validity of the usual method of clinical measurement, as proposed by Durand in 1992 but never specifically validated. We performed this validation by comparing Durand’s method and direct measurements with a central venous pressure system. We performed a total of 250 measurement pairs in 50 patients with different intraperitoneal volumes plus in-vitro measurements with a simulated peritoneum. Absolute differences between the two systems in vivo were 0.87 ± 0.91 cmH2O (range 0–5 cmH2O); only 6.4% of them were ≥3 cmH2O. In vitro results for both methods were identical. We also compared IPP measurements in the same patient separated by 1–4 h (514 measurement pairs in 136 patients), 1 week (92 pairs in 92 patients), and 2 years (34 pairs in 17 patients). Net differences of measurements separated by hours or 1 week were close to 0 cmH2O, with oscillations of 1.5 cmH2O in hours and 2.3 cmH2O in 1 week. IPP measured 2 years apart presented a net decrease of 2.5 ± 4.9 cmH2O, without correlation with body mass index changes or any other usual parameter of PD. In hours, 7% of IPP differences were >3 cmH2O, 22% in 1 week, and 50% in 2 years. In conclusion, Durand’s method is precise enough to measure IPP in peritoneal dialysis. This parameter is not stable over long timescales, so it is necessary to use recent measurements.