Novel Aspects of the Immune Response Involved in the Peritoneal Damage in Chronic Kidney Disease Patients under Dialysis.

Chronic kidney disease (CKD) incidence is growing worldwide, with a significant percentage of CKD patients reaching end-stage renal disease (ESRD) and requiring kidney replacement therapies (KRT). Peritoneal dialysis (PD) is a convenient KRT presenting benefices as home therapy. In PD patients, the peritoneum is chronically exposed to PD fluids containing supraphysiologic concentrations of glucose or other osmotic agents, leading to the activation of cellular and molecular processes of damage, including inflammation and fibrosis. Importantly, peritonitis episodes enhance peritoneum inflammation status and accelerate peritoneal injury. Here, we review the role of immune cells in the damage of the peritoneal membrane (PM) by repeated exposure to PD fluids during KRT as well as by bacterial or viral infections. We also discuss the anti-inflammatory properties of current clinical treatments of CKD patients in KRT and their potential effect on preserving PM integrity. Finally, given the current importance of coronavirus disease 2019 (COVID-19) disease, we also analyze here the implications of this disease in CKD and KRT.

Peritoneal Oxygenation as a Novel Technique for Extrapulmonary Ventilation; A Review and Discussion of the Literature.

The COVID-19 crisis has highlighted the difficulties that might occur when attempting to oxygenate patients who have suffered a severe pulmonary insult, including in the development of acute respiratory distress syndrome (ARDS). Traditional mechanical ventilation (MV) is effective; however, in severe cases of hypoxia, the use of rescue therapy, such as extracorporeal membrane oxygenation (ECMO), may be required but is also associated with significant complexity and complications. In this review, we describe peritoneal oxygenation; a method of oxygenation that exploits the peritoneum's gas exchange properties in a fashion that is similar to peritoneal dialysis and has shown considerable promise in animal models. We have conducted a review of the available literature and techniques, including intraperitoneal perfluorocarbons, intraperitoneal jet ventilation, a continuous low-pressure oxygen system (PEROX) and the use of phospholipid-coated oxygen microbubbles (OMBs) through peritoneal microbubble oxygenation (PMO). We conclude that peritoneal oxygenation is a promising technique that warrants further investigation and might be used in clinical settings in the future.

Angiogenic Role of Mesothelium-Derived Chemokine CXCL1 During Unfavorable Peritoneal Tissue Remodeling in Patients Receiving Peritoneal Dialysis as Renal Replacement Therapy.

Peritoneal dialysis (PD) is a valuable 'home treatment' option, even more so during the ongoing Coronavirus pandemic. However, the long-term use of PD is limited by unfavourable tissue remodelling in the peritoneal membrane, which is associated with inflammation-induced angiogenesis. This appears to be driven primarily through vascular endothelial growth factor (VEGF), while the involvement of other angiogenic signaling pathways is still poorly understood. Here, we have identified the crucial contribution of mesothelial cell-derived angiogenic CXC chemokine ligand 1 (CXCL1) to peritoneal angiogenesis in PD. CXCL1 expression and peritoneal microvessel density were analysed in biopsies obtained by the International Peritoneal Biobank (NCT01893710 at www.clinicaltrials.gov), comparing 13 children with end-stage kidney disease before initiating PD to 43 children on chronic PD. The angiogenic potential of mesothelial cell-derived CXCL1 was assessed in vitro by measuring endothelial tube formation of human microvascular endothelial cells (HMECs) treated with conditioned medium from human peritoneal mesothelial cells (HPMCs) stimulated to release CXCL1 by treatment with either recombinant IL-17 or PD effluent. We found that the capillary density in the human peritoneum correlated with local CXCL1 expression. Both CXCL1 expression and microvessel density were higher in PD patients than in the age-matched patients prior to initiation of PD. Exposure of HMECs to recombinant CXCL1 or conditioned medium from IL-17-stimulated HPMCs resulted in increased endothelial tube formation, while selective inhibition of mesothelial CXCL1 production by specific antibodies or through silencing of relevant transcription factors abolished the proangiogenic effect of HPMC-conditioned medium. In conclusion, peritoneal mesothelium-derived CXCL1 promotes endothelial tube formation in vitro and associates with peritoneal microvessel density in uremic patients undergoing PD, thus providing novel targets for therapeutic intervention to prolong PD therapy.

SARS-CoV-2 During Abdominal Operations: Are Surgeons at Risk?

BACKGROUND: The safety of surgery in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-positive patients remains unclear. On the basis of data from other viral diseases, it has been assumed that coronavirus disease 2019 (COVID-19) has the potential risk of transmission during surgery. The presence of the virus within the peritoneal fluid and the peritoneal tissues is not known. MATERIALS AND METHODS: This is a prospective cross-sectional study including adult patients with confirmed COVID-19 who underwent surgery at a single institution. Using specific real-time reverse transcriptase-polymerase chain reaction, the presence of SARS-CoV-2 was determined in abdominal fluid samples. RESULTS: Six patients with COVID-19 underwent abdominal surgery. Five patients were asymptomatic, and 1 had severe disease. SARS-CoV-2 was tested in 20 different samples, all of which resulted negative. CONCLUSIONS: SARS-CoV-2 was not found in the peritoneal cavity of 6 patients undergoing abdominal surgery. The risk of transmissibility of COVID-19 during surgery is still unclear.

Massive intraperitoneal hemorrhage in patients with COVID-19: a case series.

Coronavirus disease (COVID-19) initiates several life-threatening complications including coagulopathies with a unique characteristic that made this problem challenging. Here we presented 4 cases of RT-PCR positive patients that have experienced deadly intraperitoneal hemorrhage with fourth WHO Bleeding Grade after overcoming their respiratory phase. COVID-19 could induce several coagulopathies with different features that besides iatrogenic interventions increases its mortality and morbidity due to lack of clinical evidence based on well-designed randomized clinical trials on anticoagulation therapies (AT) and administration of varieties of newly approved and non-approved medicines. This report showed the urgent need for investigation on the pathophysiology of COVID-19-associated coagulopathy esp. in hemorrhagic events which are needed to make the best therapeutic decision.

ISPD recommendations for the evaluation of peritoneal membrane dysfunction in adults: Classification, measurement, interpretation and rationale for intervention.

GUIDELINE 1: A pathophysiological taxonomy: A pathophysiological classification of membrane dysfunction, which provides mechanistic links to functional characteristics, should be used when prescribing individualized dialysis or when planning modality transfer (e.g. to automated peritoneal dialysis (PD) or haemodialysis) in the context of shared and informed decision-making with the person on PD, taking individual circumstances and treatment goals into account. (practice point). GUIDELINE 2A: Identification of fast peritoneal solute transfer rate (PSTR): It is recommended that the PSTR is determined from a 4-h peritoneal equilibration test (PET), using either 2.5%/2.27% or 4.25%/3.86% dextrose/glucose concentration and creatinine as the index solute. (practice point) This should be done early in the course dialysis treatment (between 6 weeks and 12 weeks) (GRADE 1A) and subsequently when clinically indicated. (practice point). GUIDELINE 2B: Clinical implications and mitigation of fast solute transfer: A faster PSTR is associated with lower survival on PD. (GRADE 1A) This risk is in part due to the lower ultrafiltration (UF) and increased net fluid reabsorption that occurs when the PSTR is above the average value. The resulting lower net UF can be avoided by shortening glucose-based exchanges, using a polyglucose solution (icodextrin), and/or prescribing higher glucose concentrations. (GRADE 1A) Compared to glucose, use of icodextrin can translate into improved fluid status and fewer episodes of fluid overload. (GRADE 1A) Use of automated PD and icodextrin may mitigate the mortality risk associated with fast PSTR. (practice point). GUIDELINE 3: Recognizing low UF capacity: This is easy to measure and a valuable screening test. Insufficient UF should be suspected when either (a) the net UF from a 4-h PET is <400 ml (3.86% glucose/4.25% dextrose) or <100 ml (2.27% glucose /2.5% dextrose), (GRADE 1B) and/or (b) the daily UF is insufficient to maintain adequate fluid status. (practice point) Besides membrane dysfunction, low UF capacity can also result from mechanical problems, leaks or increased fluid absorption across the peritoneal membrane not explained by fast PSTR. GUIDELINE 4A: Diagnosing intrinsic membrane dysfunction (manifesting as low osmotic conductance to glucose) as a cause of UF insufficiency: When insufficient UF is suspected, the 4-h PET should be supplemented by measurement of the sodium dip at 1 h using a 3.86% glucose/4.25% dextrose exchange for diagnostic purposes. A sodium dip ≤5 mmol/L and/or a sodium sieving ratio ≤0.03 at 1 h indicates UF insufficiency. (GRADE 2B). GUIDELINE 4B: Clinical implications of intrinsic membrane dysfunction (de novo or acquired): in the absence of residual kidney function, this is likely to necessitate the use of hypertonic glucose exchanges and possible transfer to haemodialysis. Acquired membrane injury, especially in the context of prolonged time on treatment, should prompt discussions about the risk of encapsulating peritoneal sclerosis. (practice point). GUIDELINE 5: Additional membrane function tests: measures of peritoneal protein loss, intraperitoneal pressure and more complex tests that estimate osmotic conductance and 'lymphatic' reabsorption are not recommended for routine clinical practice but remain valuable research methods. (practice point). GUIDELINE 6: Socioeconomic considerations: When resource constraints prevent the use of routine tests, consideration of membrane function should still be part of the clinical management and may be inferred from the daily UF in response to the prescription. (practice point).

A Prospective Study to Identify Rates of SARS-CoV-2 Virus in the Peritoneum and Lower Genital Tract of Patients Having Surgery: An Observational Study.

STUDY OBJECTIVE: The risks to surgeons of carrying out aerosol-generating procedures during the coronavirus disease 2019 (COVID-19) pandemic are unknown. To start to define these risks, in a systematic manner, we investigated the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus in the abdominal fluid and lower genital tract of patients undergoing surgery. DESIGN: Prospective cross-sectional observational study. SETTING: Single, large United Kingdom hospital. PATIENTS: Total of 113 patients undergoing abdominal surgery or instrumentation of the lower genital tract. INTERVENTIONS: We took COVID-19 swabs from the peritoneal cavity and from the vagina from all eligible patients. Results were stratified by preoperative COVID-19 status. MEASUREMENTS AND MAIN RESULTS: In patients who were presumed COVID-19 negative at the time of surgery, SARS-CoV-2 virus RNA was detected in 0 of 102 peritoneal samples and 0 of 98 vaginal samples. Both cohorts included 4 patients who were antibody positive but nasopharyngeal swab test negative at the time of surgery. Peritoneal and vaginal swabs were also negative in 1 patient who had a positive nasopharyngeal swab immediately before surgery. CONCLUSION: The presence of SARS-CoV-2 RNA in the abdominal fluid or lower genital tract of presumed negative patients is nil or extremely low. These data will inform surgeons of the risks of restarting laparoscopic surgery at a time when COVID-19 is endemic in the population.