Management of infected arteriovenous grafts for haemodialysis: Outcomes and strategies using a novel objective scoring system.

BACKGROUND: In haemodialysis patients with exhausted autogenous options, prosthetic arteriovenous grafts (AVGs) are frequently utilised as tertiary vascular access. However, the prosthetic nature of AVGs precipitates an increased risk of infection which may translate to excess morbidity and life-threatening complications. The current evidence remains divided on the optimal treatment strategy for arteriovenous graft infections (AVGi) with arguments for conservative management by antibiotics, salvaging with graft revision or total/subtotal excision. To address this gap, we assessed the outcomes of AVGi patients treated in our institution, developing an AVGi severity classification model and a proposed treatment algorithm to guide AVGi management. METHODS: We conducted a single centre retrospective review of outcomes of patients with AVGi managed either by sole antibiotics therapy, graft revision or surgical excision between June 2016 and May 2021. Outcomes of AVGi patients across differing treatment groups were compared, including 1-year mortality, 6-month and 1-year functional vascular access. We also analysed the outcomes of tunnelled haemodialysis lines (THL), which were used as a temporary vascular access in several AVGi patients in our study. RESULTS: A total of 34 AVGi patients were managed within that time frame and included in the study (5 conservatively management by antibiotics, 5 graft revisions and 24 surgical excision) with a mean age of 60.4 ± 14.4 years (67.6% males). Overall 1-year mortality was 14.7%. A 6-month functional vascular access status across the three groups stood at 60%, 60% and 10% while 1-year functional vascular access status was 60%, 75% and 42% respectively. CONCLUSIONS: When clinically appropriate, conservative management by antibiotics or salvage/graft revision can present as prudent AVGi treatment options. The adoption of our proposed severity classification system and treatment algorithm provides a more thorough objective assessment of the infection and helps guide the clinical decision-making process.

The management of dialysis access thrombosis during the COVID-19 pandemic.

BACKGROUND: Maintaining patent access is essential for haemodialysis dependent end stage renal failure patients. The COVID-19 pandemic has significantly affected surgical and interventional radiology services worldwide. We aimed to review the impact COVID-19 has caused to the management of acute dialysis access thrombosis. METHODS: We conducted a single centre retrospective review of outcomes of patients with arteriovenous fistula and arteriovenous graft thrombosis between March and May 2020, which coincided with the first peak of the COVID-19 pandemic in London, and a similar period in the previous year, March-May 2019. Outcomes in both cohorts of patients were compared, including attempts at salvage, salvage success, 1-month patency rates after salvage and subsequent surgery on the same access. We also analysed the use of tunnelled haemodialysis lines (THL), either due to failed salvage attempts or when salvage was not attempted. RESULTS: There was a similar incidence of access thrombosis in both periods (26 cases in 2019, 38 in 2020). There were 601 patients dialysing via an arteriovenous fistula or graft in 2019, and 568 patients in 2020. Access salvage, when attempted, had similar success rates and 1-month patency (salvage success 74% vs 80%, p = 0.39; 1-month patency 55% vs 62%, p = 0.69). The proportion of patients where access salvage was not attempted and a THL inserted was significantly higher in 2020 compared to 2019 (32% vs 4%, p = 0.007). There were more patients who subsequently had surgery to salvage or revise the same access in 2019 compared to 2020 (62% vs 13%, p < 0.001). CONCLUSIONS: During the peak of the COVID-19 pandemic, there were fewer attempts at access salvage. This was a conscious decision due to increased pressure on the healthcare system, access to emergency interventional radiology or operative theatres and the perceived risk/benefit ratio of access salvage. The long-term effects of this change in practice remain unknown.

Outcomes of Renal Transplant Recipients With SARS-CoV-2 Infection in the Eye of the Storm: A Comparative Study With Waitlisted Patients.

BACKGROUND: Patients with chronic kidney disease stage 5 and those on immunosuppression are particularly vulnerable and are shielded as per public health strategy. We present our experience of coronavirus disease 2019 (COVID-19) transplant patients in one of the most affected parts of the UK with direct comparison to waitlisted patients. METHODS: A single-center prospective study of symptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) positive waitlisted and transplant patients was undertaken to compare these groups and assess clinical outcomes. RESULTS: A total of 60 consecutive symptomatic SARS-CoV-2 positive patients were identified with 32 active waitlisted patients and 28 functioning renal transplants. Demographics were similar. The incidence of symptomatic COVID-19 in the waitlisted group was 9.9% compared to 1.9% in renal transplant patients (P < 0.001). Immunosuppression did not influence initial symptomology. Fifteen percent of patients in the waitlisted and 32% in the transplant groups died (P = 0.726). Mortality as proportion of total waitlisted (321 patients) and transplant population (1434 patients) of our centre was 1.5% and 0.6% (P < 0.001), respectively. C-reactive protein (CRP) at 48 h and peak CRP were associated with mortality in both groups while quick sequential organ failure assessment score at 48 h (P = 0.036) was associated with mortality for transplant patients. CONCLUSIONS: Incidence of COVID-19 is higher in the waitlisted population but transplant patients have more severe disease, reflected by higher mortality. CRP at 48 h can be used as a predictive tool. In the absence of effective treatments, the current strategy of shielding is arguably the most important factor in protecting patients while resuming transplantation.

Extending anatomic barriers to right laparoscopic live donor nephrectomy.

OBJECTIVE: To analyze the effects of a right-sided-complex laparoscopic live donor nephrectomy, defined as bifurcation of the right renal artery behind the inferior vena cava. Right-sided laparoscopic live donor nephrectomy is now a widely accepted procedure when complex anatomy is encountered on the left. TECHNICAL CONSIDERATIONS: The present retrospective case note review involved 59 of 303 laparoscopic live donor nephrectomy procedures performed in a single center from January 2001 to April 2010 (group 1, simple, n=48; and group 2, complex, n=11). The effect of a donor right procedure on warm ischemia, graft function, and donor/recipient complications was analyzed. RESULTS: No difference in donor or recipient age or first and second warm ischemic times was found between the 2 groups. No difference was found in the estimated glomerular filtration rate or serum creatinine at 1 week and 3 and 6 months [estimated glomerular filtration rate (6/12), 49±15 vs 60±9 mL/min, P=.087; and serum creatinine (6 months), 159±116 vs 120±25 µmol/L; P=.356]. No cases of delayed graft function were reported, and none of the grafts developed vascular thrombosis. The cumulative estimated glomerular filtration rate at 6/12 was 51±15 mL/min and the serum creatinine was 153±108 µmol/L. Two patients (4%) required conversion to open surgery in group 1, and the cumulative conversion rate was 3.3%. In the complex group with retrocaval dissection, 8 kidneys were retrieved with a single artery and 3 had multiple vessels (2 with 2 vessels and 1 with 3 vessels; anastomotic time 26±6 minutes). CONCLUSION: Complex vasculature in a right-sided donation should not be considered a contraindication, because the kidneys procured had excellent function compared with those with single vasculature with no increase in the conversion or vascular thrombosis rate. In addition, the described techniques permit improved arterial length and, importantly, organs procured with a single artery.

Axillary-axillary loop graft for hemodialysis access.

BACKGROUND: Vascular access in hemodialysis patients can be challenging especially in those with failed primary, secondary and/or tertiary procedures. We present a technique which utilizes the axillary artery and vein to fashion a synthetic loop graft. METHOD: A synthetic arteriovenous loop graft is formed using the axillary artery and vein under general anesthesia following pre-operative contrast venograms. DISCUSSION: This method allows the use of the upper arm vessels, thereby preserving vessels in the legs; it also facilitates immediate access for dialysis. CONCLUSION: The axillary-axillary loop graft is a valuable salvage option in patients with complex vascular access.

The two layer method does not improve the preservation of porcine kidneys.

BACKGROUND: The Two layer method (TLM) has been extremely successful in the preservation of the pancreas. However, this has not been thoroughly investigated in other organs or in clinically relevant large animal models. The aim of this study was to assess the effects of TLM in a large animal model of kidney preservation. MATERIAL/METHODS: Porcine kidneys were retrieved after 10 minutes of warm ischaemic injury and flushed with 300 ml UW solution at 4°C. Kidneys were then either placed in University of Wisconsin solution (UW) or TLM using pre-oxygenated perfluorodecalin and UW. Kidneys were stored for 18 hours at 4°C then reperfused with oxygenated autologous blood to assess renal function. RESULTS: Renal blood flow (RBF) was significantly lower and intra-renal resistance (IRR) higher in TLM compared to UW group [Area under the curve (AUC) RBF, UW; 427±168 vs TLM; 247±55 ml/min/100g.h; P=0.041, AUC IRR, UW; 7.7±2.2 vs TLM; 10.5±1.9 ml/min/mmHg; P=0.041]. Levels of creatinine clearance (CrCl) were significantly lower in TLM group [AUC CrCl, UW; 1.8±1.0 vs TLM; 0.6±0.4 ml/min/100 g.h; P=0.034]. Levels of lipid peroxidation were significantly lower in TLM group [8-isoprostane/Cr ratio 3h; UW 3338±896 vs TLM 2072±886 pg/ml/mmol/L; P=0.04]. Levels of total nitric oxide were significantly higher in TLM group (P=0.009). CONCLUSIONS: TLM did not improve the preservation condition of porcine kidneys. Furthermore, there appeared to be increased inflammation, endothelial injury and reduced renal function compared to preservation with UW. Further experimental work is needed to determine the role of PFC in kidney preservation.

A comparison of hypothermic machine perfusion versus static cold storage in an experimental model of renal ischemia reperfusion injury.

INTRODUCTION: There is increasing support for the use of hypothermic machine perfusion (HMP) in an attempt to reduce preservation injury. However, experimental evidence is needed to further examine the effects of HMP on renal ischemia reperfusion injury. METHODS: Porcine kidneys were subjected to 10 min of warm ischemia followed by 18 hr of static cold storage with hyperosomolar citrate (HOC), histidine-tryptophan-ketoglutarate (HTK), or University of Wisconsin (UW) solutions or 18 hr HMP with Kidney Perfusion Solution using the Lifeport perfusion system. Renal function, oxidative damage, and morphology were assessed during 3 hr of reperfusion with autologous blood using an isolated organ perfusion system. RESULTS: During reperfusion, intrarenal resistance was significantly lower in the HMP group compared with HOC and UW (area under the curve; HMP 3.8+/-1.7, HOC 9.1+/-4.3, UW 7.7+/-2.2, HTK 5.6+/-1.9 mm Hg/min; P=0.006), and creatinine clearance was significantly higher compared with the UW group (area under the curve creatinine clearance; HMP 9.8+/-7.3, HOC 2.2+/-1.7, UW 1.8+/-1.0, HTK 2.1+/-1.8 mL/min/100 g; P=0.004). Tubular function was significantly improved in the HMP group (P<0.05); however, levels of lipid peroxidation were significantly higher (P=0.005). CONCLUSION: HMP demonstrated a reduced level of preservation injury compared with the static techniques resulting in improved renal and tubular function and less tubular cell inflammation during reperfusion.