Intraperitoneal hydrostatic pressure and flow characteristics of peritoneal catheters in automated peritoneal dialysis

The prognostic values of estimating intraperitoneal pressure in the occurrence of abdominal wall complications in peritoneal dialysis patients

BACKGROUND

Increased intraperitoneal pressure is associated with abdominal wall complications and technical failure of peritoneal dialysis (PD). Several equations have been developed to estimate intraperitoneal pressure. We aimed to assess the prognostic yield of the intraperitoneal pressure as estimated by current equations on the occurrence of abdominal wall complications in peritoneal dialysis patients.

METHODS

This is a retrospective analysis of data from a prospective cohort which recruited 1207 incident PD patients. Estimated intraperitoneal pressure was calculated using four available equations (according to Sigogne, Castellanos, Scanziani and de Jesus Ventura). Abdominal wall complications were recorded during follow-up. Univariate analysis and multivariate analysis with competing risk regression were used to assess the predictive power of the estimates of intraperitoneal pressure in the occurrence of abdominal wall complications.

RESULTS

During a median follow-up of 30 months, 66 (5.5%) patients (1.6/100 patient-years) developed abdominal wall complications. The median time to the occurrence of abdominal wall complications was 5.7 months. Only the estimated intraperitoneal pressure by the de Jesus Ventura equation significantly predicted abdominal wall complications by using univariate analyses. Associations between estimated intraperitoneal pressure by the de Jesus Ventura equation and the occurrence of abdominal wall complications disappeared after adjusting for significant clinical factors.

CONCLUSIONS

We verified the prognostic value of estimation of intraperitoneal pressure by four available equations in predicting abdominal wall complications in our single-center PD cohort. Due to a low diagnostic yield, a novel equation for estimating the intraperitoneal pressure is urgently needed.

Relationship between intraperitoneal pressure and the development of hernias in peritoneal dialysis: confirmation for the first time of a widely accepted concept

BACKGROUND

Intraperitoneal pressure (IPP) in peritoneal dialysis (PD) is an individual characteristic that can be modified by posture and intraperitoneal volume (IPV). It is considered one of the predisposing factors for complications in the abdominal wall, such as the appearance of hernias. No studies to date have confirmed this. The main aim of this study was to assess the relationship between the development of hernia in incident PD patients and IPP measured at PD onset.

METHODS

A prospective observational study of incident patients in a PD programme between 2010 and 2020. IPP was measured using the Durand's method.

RESULTS

One hundred and twenty-four incident patients on PD, 68% male, mean age 62.1 ± 15.23 years, body mass index (BMI) 27.7 ± 4.82 kg/m2, 44% were diabetic. IPP in supine was 16.6 ± 4.60 cm H2O for a mean IPV of 2047.1 ± 359.19 mL. Hernias were reported in 18.5% of patients during PD follow-up: 57% were inguinal hernias, 33% umbilical, and a further 10% presented in a combined form. PD hernias correlated positively with IPP in supine position (p = 0.037), patient age (p = 0.008), BMI (p = 0.043), a history of prior hernia (0.016), laparoscopic catheter placement (p = 0.026), and technique failure (p = 0.012). In the multivariate analysis, a higher IPP was independently related to the development of hernias (p = 0.028).

CONCLUSIONS

The development of hernias in PD was related to a higher IPP at PD onset, older age, higher BMI, history of prior hernia, catheter placement by laparoscopy, and technique failure.

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 cmH2O and -0.10 cmH2O 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 cmH2O and 2.50 cmH2O, 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.

Pleural Effusion after Hepatic Radiofrequency Ablation with Artificial Ascites: Clinical Spectrum and Significance

PURPOSE

To retrospectively investigate incidence, clinical outcome, and risk factors of iatrogenic pleural effusion in patients with hepatic tumors undergoing radiofrequency (RF) ablation using artificial ascites (AA).

MATERIALS AND METHODS

Patients (N = 163) who underwent RF ablation using AA were classified into pleural effusion and non-pleural effusion groups according to the presence of pleural effusion on immediate follow-up CT and chest radiograph after RF ablation. The pleural effusion group included asymptomatic and symptomatic subgroups. The incidence and subsequent clinical outcomes of patients developing pleural effusion after RF ablation were evaluated.

RESULTS

Overall, 96 patients (58.9%) developed pleural effusion, which resolved in 4.4 d ± 3.1. Hospital length of stay in the pleural effusion group was longer than the non-pleural effusion group (6.5 d ± 2.6 vs 5.7 d ± 2.8, P < .01). The pleural effusion group had longer AA infusion time (P = .01), larger infused AA volume (P < .01), and longer ablation time (P < .01) than the non-pleural effusion group. Eighteen patients (18.8%) developed symptomatic pleural effusion and had a larger infused AA volume than asymptomatic patients with pleural effusion (P < .01). Pleural effusion duration and hospital length stay were also longer in the symptomatic pleural effusion subgroup than in the asymptomatic subgroup (P < .01). Infused AA volume was the only independent prognostic factor of pleural effusion duration in multivariate analysis (P = .038).

CONCLUSIONS

Pleural effusion frequently occurs after RF ablation using AA. Although generally considered negligible, pleural effusion could be a clinical problem and prolong hospitalization. Therefore, operators should be careful not to infuse too much AA when performing RF ablation.

Clinical relevance of marginal factors on ultrafiltration in peritoneal dialysis

BACKGROUND

Ultrafiltration (UF) in peritoneal dialysis (PD) is mainly driven by the osmotic gradient and peritoneal permeability, but other factors-such as intraperitoneal pressure (IPP)-also have an influence.

METHODS

To assess the clinical relevance of these marginal factors, we studied 41 unselected PD patients undergoing two consecutive 2 h, 2.27% glucose exchanges, first with 2.5 L and then with 1.5 L.

RESULTS

IPP, higher in the 2.5 L exchange, had a wide interpatient range, was higher in obese and polycystic patients and their increase with infusion volume was higher for women regardless of body size. UF with 2.5 L correlated inversely with IPP and was higher for patients with polycystosis or hernias, while for 1.5 L we found no significant correlations. The effluent had higher glucose and osmolarity in the 2.5 L exchange than in the 1.5 L one, similar for both sexes. In spite of this stronger osmotic gradient, only 21 patients had more UF in the 2.5 L exchange, with differences up to 240 mL. The other 20 patients had more UF in the 1.5 L exchange, with stronger differences (up to 800 mL, and more than 240 mL for 9 patients). The second group, with similar effluent osmolarity and peritoneal equilibration test (PET) parameters than the first, has higher IPP and preponderance of men. The sex influence is so intense that men decreased average UF with 2.5 L with respect to 1.5 L, while women increased it.

CONCLUSIONS

With 2.27% glucose, sex and IPP-modulated by obesity, polycystosis, hernias, and intraperitoneal volume-significantly affect UF in clinical settings and might be useful for its management.

Clinical Relevance of Intraperitoneal Pressure in Peritoneal Dialysis Patients

Introduction

Intraperitoneal pressure (IPP) in peritoneal dialysis (PD) increases in sitting and upright positions and is related to some individual characteristics. Adverse effects can appear with IPP > 20 cm H2O. Few studies about peritoneal transport or abdominal wall problems have directly measured IPP. We measured IPP in our prevalent PD patients to identify the clinical factors related to its variability and its possible association with peritoneal transport and abdominal wall complications.

Methods

We performed a retrospective, observational study of our stable PD patients. Intraperitoneal pressure was measured using the Durand's method in supine, sitting, and upright position.

Results

Forty-nine patients were included, 70% males, mean age 61.1 ± 15 years, body mass index (BMI) 27.9 ± 5.2 kg/m2. The mean of supine IPP was 18.0 ± 4.4 cm H2O. Intraperitoneal pressure in sitting and upright positions were similar and higher than in supine. Supine IPP showed a positive correlation with BMI ( p < 0.0005) and comorbidity ( p < 0.05). A multivariate linear regression analysis showed that BMI and comorbidity ( p < 0.005) had a positive correlation with IPP; time on PD and daily total ultrafiltration (UF) (p < 0.005) showed a negative correlation. Patients with an IPP ≥ 20 cm H2O had more hernias (35% vs 17%) and leakages (21% vs 8%) without statistical significance.

Conclusion

Our supine IPPs were higher than others published in adults. Intraperitoneal pressure has an individual value associated with body size. Greater IPP was correlated with lower daily total UF and more hernias and leakages. The measurement of IPP is a simple technique and can help with PD prescription, especially in obese patients.

Intraperitoneal pressure in peritoneal dialysis

The measure of intraperitoneal pressure in peritoneal dialysis is easy and provides clear therapeutic benefits. However it is measured only rarely in adult peritoneal dialysis units. This review aims to disseminate the usefulness of measuring intraperitoneal pressure. This measurement is performed in supine before initiating the drain of a manual exchange with "Y" system, by raising the drain bag and measuring from the mid-axillary line the height of the liquid column that rises from the patient. With typical values of 10-16 cmH₂O, intraperitoneal pressure should never exceed 18 cmH₂O. With basal values that depend on body mass index, it increases 1-3 cmH₂O/L of intraperitoneal volume, and varies with posture and physical activity. Its increase causes discomfort, sleep and breathing disturbances, and has been linked to the occurrence of leaks, hernias, hydrothorax, gastro-esophageal reflux and enteric peritonitis. Less known and valued is its ability to decrease the effectiveness of dialysis significantly counteracting ultrafiltration and decreasing solute clearance to a smaller degree. Because of its easy measurement and potential utility, should be monitored in case of ultrafiltration failure to rule out its eventual contribution in some patients. Although not yet mentioned in the clinical practice guidelines for PD, its clear benefits justify its inclusion among the periodic measurements to consider for prescribing and monitoring peritoneal dialysis.

Abdominal compliance: A bench-to-bedside review

Abdominal compliance (AC) is an important determinant and predictor of available workspace during laparoscopic surgery. Furthermore, critically ill patients with a reduced AC are at an increased risk of developing intra-abdominal hypertension and abdominal compartment syndrome, both of which are associated with high morbidity and mortality. Despite this, AC is a concept that has been neglected in the past.AC is defined as a measure of the ease of abdominal expansion, expressed as a change in intra-abdominal volume (IAV) per change in intra-abdominal pressure (IAP):AC = ΔIAV / ΔIAPAC is a dynamic variable dependent on baseline IAV and IAP as well as abdominal reshaping and stretching capacity. Whereas AC itself can only rarely be measured, it always needs to be considered an important component of IAP. Patients with decreased AC are prone to fulminant development of abdominal compartment syndrome when concomitant risk factors for intra-abdominal hypertension are present.This review aims to clarify the pressure-volume relationship within the abdominal cavity. It highlights how different conditions and pathologies can affect AC and which management strategies could be applied to avoid serious consequences of decreased AC.We have pooled all available human data to calculate AC values in patients acutely and chronically exposed to intra-abdominal hypertension and demonstrated an exponential abdominal pressure-volume relationship. Most importantly, patients with high level of IAP have a reduced AC. In these patients, only small reduction in IAV can significantly increase AC and reduce IAPs.A greater knowledge on AC may help in selecting a better surgical approach and in reducing complications related to intra-abdominal hypertension.

The interpretation of intra-abdominal pressures from animal models: the rabbit to human example

INTRODUCTION

The importance of the abdominal wall characteristics in intraabdominal pressure (IAP), intraabdominal hypertension (IAH) and abdominal compartment syndrome (ACS) are poorly understood. The applicability of laboratory research findings to human scenarios is unknown due to the potential differences in abdominal wall elastance (AWE) amongst species. The aims of the study are to describe the AWE curve in rabbits and to compare it to the available human data.

MATERIALS AND METHODS

Prospective experimental animal study in the setting of research laboratory. Male New Zealand White rabbits weighting 2.7 kg ± 0.1 kg, were anesthetized and the AWE was determined by infusion of lactated Ringer's solution into the peritoneal cavity whilst the IAP was measured. A meta-analysis of peer-reviewed studies was conducted to define human AWE.

RESULTS

The described AWE was lower in the rabbit than in humans. The function comparing human and rabbit was: log(e) human IAP = (0.58 log(e) rabbit IAP+1.6).

CONCLUSIONS

The AWE can vary amongst species. This study determined the relationship to allow the comparison of rabbit and human IAP. The proposed mathematical function is important for the advancement of interpretation and understanding of animal research into IAH and ACS. We recommend developing model-specific functions comparing individual animal models' IAP and that of humans.

Relationship between drain volume/fill volume ratio and clinical outcomes associated with overfill complaints in peritoneal dialysis patients

BACKGROUND

To better understand the spectrum of overfill reports and their corresponding clinical severity and etiology, we conducted a review of overfill reports from the Manufacturer and User Facility Device Experience (MAUDE) database, which is within the Food and Drug Administration (FDA) Web site (www.fda.gov).

METHOD

We searched the MAUDE database for events related to overfill reports between 1 January 1995 and 31 December 2008 and recorded drain volume (DV)/fill volume (FV), or DV/FV, and clinical symptoms and signs associated with the overfill report.

RESULTS

Among 462 MAUDE reports with a possible overfill event, 440 reports (95.2%) with a confirmed overfill event contained sufficient information to ascertain the clinical severity of the event. The number of reports with a clinical severity rating of minor, moderate, major, or death was 331, 71, 28, and 10, respectively. The median (range) DV/FV for a subgroup of 292 reports with a clinical severity rating of minor, moderate, major, or death was 1.63 (1.06 - 4.29), 1.71 (1.08 - 5.87), 2.14(1.64 - 2.61), and 2.50 (2.28 - 3.33), respectively. Insufficient drain accounted for a majority of overfill reports.

CONCLUSION

Our analysis of reports from the MAUDE database suggests an association between DV/FV and clinical severity of the reported overfill event, as well as significant patient-to-patient variability with respect to intraperitoneal volume tolerance.

Improving cycler prescriptions in peritoneal dialysis through informatic profiling

Cycler-based dialysis is the most common form of peritoneal dialysis in the United States of America, accounting for more than two thirds of patients on the modality. The advent of modern cyclers has enhanced the accessibility of therapy-delivery data. Cyclers have transformed peritoneal dialysis from an unobserved home therapy into an observable home therapy on many levels. We will discuss 3 of these levels herein. The ability to profile prescription behavior at a population level with attention to fill volume, number of cycles used per night, and total time on the cycler will be analyzed. Insights into the dynamics of flow during cycler therapy and the concept of transition point will then be explored. Finally, we will review the impact on patient care of making the delivery of the dialysis prescription easily observable to the medical team. It is our contention that these 3 levels of profiling offer practical lessons to enhance delivery of care for patients on cycler-based peritoneal dialysis.