Dialysis Line Research Articles

#1664 Assessing vascular access thrombectomy service adherence to GIRFT recommendations: single centre experience

Abstract Background and Aims Studies showed that early thrombectomy of dialysis vascular access (VA) is associated with better outcomes [1], especially for native VA [2]. Timely treatment of VA thrombosis within 24-48 hours is recommended by GIRFT to minimize access loss and requirement for dialysis line insertion [3]. Our centre has approximately 430 HD patients but has no on-site vascular surgery or vascular access interventional radiology (IR) service. Wait time for elective VA surgery or fistuloplasty is >8 weeks and VA surveillance is based on routine clinical monitoring. VA prevalence is 62% AV fistula (AVF), 2% AV graft (AVG), 36% central venous catheter (CVC). Fistula thrombectomy is provided at another centre, with increasing waiting times over recent years due to shortage of interventional radiologists. This study evaluates adherence to GIRFT recommendations for patients at our centre requiring thrombectomy and will identify potential local strategies to reduce fistula thrombosis and CVC use. Method In a 24-months’ retrospective cohort analysis of maintenance HD patients with permanent VA, we obtained data on: Results 44 patients with permanent VA developed VA thrombosis. The median waiting time for thrombectomy was 8 days (Fig. 1). Post-intervention primary patency rate was 71% at 3-months and 60% at 6-months (Fig. 2). 61% of patients required hospital admission with a 12-day median length of stay, with total inpatient admission days of 403 days over 2 years (2022-2023), and total cost of £246,065 (Figs. 3 and 4). The median CFD-extended was 356 days, i.e. 9 days/patient/year with VA-related complications (Fig. 5). Conclusion This study shows that our centre's VA thrombectomy service falls far outside the GIRFT recommendation of intervention within 24-48 hours. The high associated rates of CVC use, inpatient bed days and avoidable costs place a heavy burden on patient outcomes and NHS resources. The ideal solution of an on-site thrombectomy service is difficult to achieve due to lack of vascular IR support. In response to this study, we now aim to reduce thrombosis rates by training additional interventional nephrologists in elective fistuloplasty, implementing a robust VA surveillance to improve early detection of malfunctioning VA suitable for elective intervention and improving staff education on fistula care.

#2722 Hemodialysis vascular access flow assessment by ultrasound dilution method (NephroFlow™) and ultrafiltration method with NIKKISO DBB-EXA™

Abstract Background and Aims A functioning vascular access (VA) is needed to ensure optimal dialysis. Reduced or falling levels of VA flow volume (Qa) indicate VA dysfunction and predict thrombosis. Qa can be measured by a number of different techniques, most of all using dilution techniques such as ultrasound dilution to measure the amount of recirculation induced by reversal of blood lines. The NephroFlow™ hemodialysis monitor estimates Qa using ultrasound velocity measurements of flowing blood and their dilution with 0.9% NaCl. Nikisso DBB-EXATM dialysis machine has the capacity to measure the VA recirculation rate by photometry performing a controlled rise on ultrafiltration rate; Qa is subsequently estimated using the Krivitski formula. There is little literature on the comparison of the different methodologies, but it was described that the DBB-EXATM method underestimates Qa compared to others techniques [1]. Our study aims to compare the Qa between the NephroFlow™ ultrasound dilution technique and the Nikisso DBB-EXATM ultrafiltration method. Method We performed an observational study that included 45 hemodialysis patients followed at our unit. Measurements of VA flow using the NephroFlow® device and the Nikisso-EXATM Ultrafiltration method were performed in patients with a native arteriovenous fistula or a graft. They were hemodynamically stable without acute clinical conditions. Both studies were undertaken during the first 90 minutes of a mid-week dialysis session, under a constant dialysis blood pump flow with the ultrafiltration interrupted during the procedure after having reversed the dialysis lines. For each patient we calculated the average of two Qa evaluations conducted at Nikisso-EXATM, spaced 15 days apart, with an additional evaluation using NephroFlow® conducted between these assessments. Results Forty-five patients (male: 71.1%) with a mean age of 73.2 ± 8 years were selected. The main CKD causes were diabetic kidney disease (n = 13, 28.9%) and uncertain etiology (n = 13, 28.9%). The dialysis vintage of these patients was 142.6 months (minimum 19, maximum 168). An arteriovenous fistula was present in 38 patients (84.4%) and an arteriovenous graft in 7 patients (15.6%). In the entire group, the mean flow with NephroFlow™ was 986.9 ± 515 ml/min and with DBB-EXATM 859.7 ± 522 ml/min. The measured values of the two methods presented a significant positive correlation (by Pearson) (R = 0.822, P < 0.01) (Fig. 1). In the group of patients with arteriovenous fistula (n = 38, 84.4%), the mean flow with NephroFlow™ was 961.8 ± 395 ml/min and with DBB-EXATM 839.1 ± 577 ml/min. The measured values of the two methods presented a significant positive correlation (by Pearson) (R = 0.844, P < 0.01). In the group of patients with arteriovenous graft (n = 7, 15.6%), the mean flow with NephroFlow™ was 1017.3 ± 401 ml/min and with DBB-EXATM 909.2 ± 604 ml/min. The measured values of the two methods presented a significant positive correlation (by Pearson) (R = 0.906, P < 0.01). Conclusion We found a significantly positive correlation between the Qa measurements obtained using both methods. The measurement of Qa using the ultrafiltration method on Nikisso DBB-EXATM seems to be a valuable and easily implementable tool for VA surveillance in both arteriovenous fistula and grafts. However, a bigger number of studies are required in this field in order to clarify this correlation with an additional comparative analysis to assess the reproducibility of measurements.

Axillary necklace graft salvage of a locally infected Haemodialysis with Reliable Outflow (HeRO®) graft.

A 48-year-old patient presented 4 months after insertion of a right sided Haemodialysis with Reliable Outflow (HeRO®, Merit Medical) graft with a discharging abscess at the site of the brachial artery anastomosis. There was localised involvement of the arterial Gore® Acuseal inflow graft that necessitated its removal. The venous outflow component was thought salvageable as infection was well localised to the region of the antecubital fossa. Alternative access options were limited so we sought to preserve the venous outflow portion of the patient's original graft - minimising tissue damage and avoiding the need for a dialysis line. The infected arterial graft was excised, leaving behind the original SuperHero® connector and venous graft. A left sided tunnelled axillary necklace technique was utilised to restore arterial inflow. After a four-day recovery, the patient went on to successfully resume their usual haemodialysis regimen without any complications. Convalescent imaging, repeat blood cultures, and monitoring of inflammatory markers showed no signs of residual infection at 6 weeks. The originality of this case was the way in which an axillary necklace inflow graft was connected to the pre-existing venous outflow portion of the HeRO® haemodialysis graft system, allowing the excision of the infected inflow graft at the brachial anastomosis. This technique could be viewed as an effective salvage procedure as it allowed the venous outflow portion of the original graft to remain in situ, minimised tissue damage and enabled the patient to swiftly resume haemodialysis without the need for a line.

Removal of stuck tunnelled dialysis line requiring cardiopulmonary bypass and venous repair.

Tunnelled central venous dialysis catheters can usually be removed easily. However, their removal can become rarely complicated requiring more invasive techniques. We report a case in which cardiopulmonary bypass and repair of great veins was required for safe removal. A 38-year-old female with end-stage renal failure and a 3-year-old Hickman line inserted into her right internal jugular vein was referred to our cardiac surgical unit following failed attempts of line removal by local vascular surgical team using open vascular surgical techniques. As a result, an MDT decision was made that it was safer to proceed to a cardiothoracic surgical approach rather than other techniques. Investigations showed significant calcification surrounding the line which was adherent to the venous wall. Removal of the retained catheter required median sternotomy and the use of cardiopulmonary bypass as the great veins had to be opened to free the line and allow complete removal. The line was successfully removed with its encircling calcified sheath, and the veins were closed primarily without needing a patch repair. The integrity of the great veins was maintained to meet the on-going need this young patient has for central venous access. The patient made an uneventful recovery. When other measures fail, sternotomy and cardiopulmonary bypass provide a safe option for complete removal of stuck central venous catheters with low risk to the patient.

#6211 THE OPPORTUNITY COSTS EXPERIENCED BY PATIENTS WHO INJECT DRUGS UNDERGOING HAEMODIALYSIS: A CASE SERIES

Abstract Background and Aims Patients who inject drugs (PWIDs) represent a uniquely difficult population to manage with haemodialysis, often with reliance on tunneled venous access. This population is historically difficult to reach, and their care is usually associated with higher per capita healthcare costs [1], unsurprisingly poor outcomes are reported [2] with a multitude of likely causes. Here we show the time associated opportunity costs these patients experience including the significant complication of tunnelled dialysis line infection in a person who actively injects drugs. Method This study follows on from the work by Burns [3]. In this retrospective observational study, the electronic health records of patients who were known to be ongoing users of recreational drugs were reviewed from January 2015 – August 2021. Patients were reviewed from their first tunneled line placement until either their death or until the end of the study time period. Stata 14 was used to generate descriptive statistics. Results 6 Patients were identified, 5 had a primary diagnosis of AA Amyloidosis with the other being IgA. This cohort of patients did poorly, 5 out of 6 of the cohort had died with a mean survival of 27 months. Patients were followed for an average of 769 days (range 485 - 1052). The majority of this time alive was spent as an inpatient with the mean percentage of time as an inpatient being 55% (Range 35–81%) with a mean of 411 total inpatient days. The first confirmed bacteraemia occurred within the first 100 days in 4 out of 6 of the patients. Conclusion With this case series we demonstrate the opportunity cost PWIDs experience in the form of time spent as an inpatient. This cost is further added to by the burden of outpatient maintenance haemodialysis. Consideration should also be given to the excess burden their care places on over-stretched healthcare systems. Infections and dialysis compliance are key components in the care of PWIDs and while moving away from tunneled access should be sought whenever possible a multidisciplinary approach should also be considered; these patients commonly lead chaotic lifestyles and in-center dialysis is usually the only option. Including addiction, social and psychiatric services alongside dialysis may be a way to engage with this historically difficult to reach population. The hope is that this study provides the incentive for further studies focusing on the opportunity costs and the quality of life this population can expect when embarking on haemodialysis. This would provide patients with realistic expectations while also aiding clinicians in navigating this difficult ethical situation.

Surgical Site and Blood Stream Infections in Children with Delayed Sternal Closure after Cardiopulmonary Bypass Surgery: A Single-Center Experience

Abstract Objective Delayed sternal closure (DSC) is a frequent strategy for optimizing hemodynamics for patients after complicated cardiac surgery. However, this practice is associated with increased risk for infection and mortality. Despite the importance of antibiotic prophylaxis during open chest management, no clear recommendations are available. We sought to describe our practice with single-agent prophylactic antibiotic treatment for children with DSC. Methods We retrospectively reviewed the electronic medical record of children with delayed chest closure after stage 1 palliative surgery, between January 2009 and December 2020. Demographics, antibiotic treatment, and data regarding postoperative infection occurrence were collected. The primary outcomes were surgical site infection (SSI) and blood stream infection (BSI) rates within 28 days of repair. Results Sixty-eight patients were identified with single ventricle physiology, who underwent Damus–Kaye–Stansel or a modified Norwood procedure, remained with an open chest postoperatively, and were treated with prophylactic cefazolin. Sixty-three percent (43/68) of the children were male with a median (interquartile range) age of 9 (6–16) days. Eleven patients (16%) had an SSI or BSI identified postoperatively. Those with infections were significantly older (8 vs. 14 months, p = 0.037), had longer central line time (11 vs. 7 days, p = 0.004), had a central line location other than internal jugular (p = 0.022), and had a dialysis line (p = 0.022). Conclusion Our study demonstrates a relatively low occurrence rate of postoperative SSIs and bacteremia with prophylactic cefazolin therapy among children with DSC suggesting that single-agent, narrow antimicrobial treatment may be sufficient in this high-risk population.

A Case of Acute Intravascular Hemolysis During Dialysis: A Quiz

A Case of Acute Intravascular Hemolysis During Dialysis: A Quiz

Application of regional citrate anticoagulation in patients at high risk of bleeding during intermittent hemodialysis: a prospective multicenter randomized controlled trial

Safe and effective anticoagulation is essential for hemodialysis patients who are at high risk of bleeding. The purpose of this trial is to evaluate the effectiveness and safety of two-stage regional citrate anticoagulation (RCA) combined with sequential anticoagulation and standard calcium-containing dialysate in intermittent hemodialysis (IHD) treatment. Patients at high risk of bleeding who underwent IHD from September 2019 to May 2021 were prospectively enrolled in 13 blood purification centers of nephrology departments, and were randomly divided into RCA group and saline flushing group. In the RCA group, 0.04 g/mL sodium citrate was infused from the start of the dialysis line during blood draining and at the venous expansion chamber. The sodium citrate was stopped after 3 h of dialysis, which was changed to sequential dialysis without anticoagulant. The hazard ratios for coagulation were according to baseline. A total of 159 patients and 208 sessions were enrolled, including RCA group (80 patients, 110 sessions) and saline flushing group (79 patients, 98 sessions). The incidence of severe coagulation events of extracorporeal circulation in the RCA group was significantly lower than that in the saline flushing group (3.64% vs. 20.41%, P<0.001). The survival time of the filter pipeline in the RCA group was significantly longer than that in the saline flushing group ((238.34±9.33) min vs. (221.73±34.10) min, P<0.001). The urea clearance index (Kt/V) in the RCA group was similar to that in the saline flushing group with no statistically significant difference (1.12±0.34 vs. 1.08±0.34, P=0.41). Compared with saline flushing, the two-stage RCA combined with a sequential anticoagulation strategy significantly reduced extracorporeal circulation clotting events and prolonged the dialysis time without serious adverse events.

POS-124 Traveler diarrhea in 2 patients, is it Cholera or no Cholera, That is the question

Cholera is gastroenteritis caused by Vibrio cholerae. It presents with vomiting, severe secretory diarrhoea, and dehydration. It presents as watery, rice-water stools with a fishy odour. It can cause severe complications with severe electrolyte imbalances such as hyponatraemia, hypernatraemia, and hypokalaemia and oligoanuric acute kidney injury (AKI) due to acute tubular necrosis (ATN). Case 1: A 19-year-old arrived few days back from Bangladish was admitted with altered mental status, vomiting and diarrhea, His labs on admission showed creatinine 713 micromol/L, urea 21.6 mmol/L, bicarbonate 13 mmol sodium 148 mmol/L, potassium 3.6 mmol/L, chloride 109 mmol/L. WBC 28 x 109, Hb 154 g/L , lactate was normal,urine analysis showed positive leucocyte esterase, negative nitrates, positive blood, WBCs 756 cells/microL, RBCs 12,759 cells/microL, PH 6.5, specific gravity 1.019 with granular casts, procalcitonin 813 ng/dL. Urine albumin was > 400 mg/L. On day 3 of admission creatinine peaked to 1,104 micromol/L, urea 38mmol/L, he became anuric with development of pulmonary edema, he received 2 short sessions of hemodialysis. Stool PCR showed positive Vibrio,Enteroaggregative E.coli (EAEC), Enteropathogenic E.coli (EPEC), Enterotoxigenic E. coli (ETEC) lt/ st, Shigella/ Enteroinvasive E. coli (EIEC) Norovirus, Sapovirus, C.diff, and campylobacter. During hospitalization patient was afebrile and maintained his blood pressure, he received intravenous fluids for resuscitation and completed a course of ceftriaxone, azithromycin and doxycycline. Creatinine on discharge was 110microcol/L, urea 6.4 mmol/L. Case 2: 47 years old male patient previously healthy, arrived from Bangladesh 2 days prior to admission, presented with uncountable episodes of watery diarrhea associated with central abdominal pain, nausea, and vomiting. Patient was severely dehydrated, anuric, labs in ED showed creatinine 456 micromol/L , bicarbonate 11 mmol/L , urea 10.8 mmol/L, no hyperkalemia, Albumin 55g/L ( normal range 32-52), venous PH 7.16, hemoglobin 180 g/L , WBCs 17.7 x109. repeated labs within 12 hours showed worsening acidosis despite starting sodium bicarbonate intravenous boluses and infusion. Venous PH 7.04, patient was initiated on hemodialysis via temporary dialysis line due to refractory worsening acidosis,. Peak creatinine reached 635 micromol/L and bicarbonate 9 mmol/L, protein creatinine ration 2 g/g. He received 2 short session of hemodialysis with aggressive fluid resuscitation, urine output in day was 1.4 L, on day 10 of hospitalization, creatinine continue to improve and reached 94 micromol/L and patient was discharged home. His stool PCR was negative for Campylobacter (jejuni, coli and upsalien ), Clostridium difficile (toxin A/ B), Plesiomonas shigelloides, salmonella, Yersinia enterocolitica,Vibrio (parahaemolyticus, vulnificus, and Vibrio cholerae), EAEC, EPEC, ETEC all were not detected. He completed 1 week course of Ceftriaxone, Metronidazole, and Azithromycin. The cause of his traveler diarrhea was not known but the patient responded well to supportive measures, hemodialysis and antibiotics. Both patients were discharged home with improving renal function. Traveler diarrhea from endemic areas can be due to multiple pathogens. supportive treatment including vigorous hydration and initiation of hemodialysis may be required in sever cases of AKI.

Tunneled dialysis line‐associated hemorrhagic shock following self‐inflicted trauma in a hemodialysis patient: A case report

Complications of tunneled central venous catheters (CVCs) for hemodialysis are frequent, and most commonly include bacteremia, thrombosis, and stenosis. While bleeding is a relatively rare complication of dialysis lines overall, tunneled CVCs may present a unique bleeding risk given their ability to be displaced or damaged as patients have direct access to the equipment in place. Here, we describe the case of a 68-year-old man with end-stage renal disease and neurocognitive disorder, who developed hemorrhagic shock following self-inflicted laceration of his tunneled dialysis catheter proximal to the Y. Examination of the catheter tunnel revealed that the cuff was palpable proximal to the exit site, but the opening was well retracted. In such cases, hemorrhage is particularly difficult to control because the cuff is rigid and poorly amenable to compression, in addition to being difficult to access. This case demonstrates the risk of significant hemorrhage when a tunneled CVC is damaged at this location and the potential need for the urgent removal of the retained component to prevent recurrence of bleeding. It also highlights important patient safety considerations given the risk of self-inflicted trauma in patients with a neurocognitive disorder and a language barrier affecting communication.

MO771: Haemodialysis Access Flow Measurement: Comparison of Ultrasound Dilution and Ultrafiltration Method on Nikisso DBB-EXA™ Dialysis Machine

Abstract BACKGROUND AND AIMS The regular measurement of the haemodialysis vascular access (VA) flow demonstrates a protective effect over thrombotic complications [1]. Transonic® Ultrasound dilution technique was first introduced in 1995 and progressively became a method of reference for recirculation and blood flow measurement on haemodialysis VA [2]. It is based on the technique of haemodilution with a certain volume of 0.9% NaCl and the measure of recirculation with inversed lines using the ultrasound technique. Consecutively the VA flow is estimated with a certain formula. Nikisso DBB-EXA™ dialysis machine has the capacity to measure the VA recirculation rate by photometry performing a controlled rise on ultrafiltration rate. The aim of the present study is to compare the VA flow rate between the Transonic® Ultrasound dilution technique and the Nikisso DBB-EXA™ Ultrafiltration method. METHOD The primary outcome of the study is the association of VA flow measured by Transonic® and the Nikisso DBB-EXA™. During the first half of the same dialysis session, we measured the VA recirculation and flow rate twice with the two methods under a constant dialysis blood pump flow of 250–300 mL/min with the ultrafiltration and haemodiafiltration interrupted during the procedure after having reversed the dialysis lines. RESULTS The values are represented as mean ± SD. A total of 18 chronic haemodialysis patients (13 male: 5 female, mean age: 70 ± 14 years) participated in the study. They were haemodynamically stable without acute clinical conditions and were dialysed with a well-functioning arteriovenous fistula for at least 6 months. The mean value of recirculation with inverted dialysis lines for the Transonic® method was 20.79 ± 7.58% and for the Nikisso DBB-EXA™ was 24.43 ± 7.77. The mean values of VA blood flow with the Transonic® method were 1229 ± 588 mL/min and for the Nikisso DBB-EXA™ 1096 ± 490 mL/min. The measured values of the two methods presented a significant positive correlation (by Pearson) (R = 0.920, P &amp;lt; 0.001) (Figure). CONCLUSION There is a significantly positive correlation concerning the VA flow measurement between the reference method of Transonic® and the Ultrafiltration method offered by the Nikisso DBB-EXA™. Larger studies are needed to confirm this correlation with an additional comparative analysis of the reproducibility of measurements.

EP.WE.555Impact of COVID 19 on Renal access surgery

AimsTo assess the impact of COVID -19 on renal access surgery.MethodsElectronic patient records and renal ware were accessed to obtain data of all renal access activity during the COVID period.ResultsThere as a shutdown of all elective activity which affected the renal access surgery as well. No new Arterio venous fistulas (AVFs) were created in the time period 14 March to 05th May 2020. No pre-fistula mapping scans were performed. All new starters started with a tunneled dialysis line. In the recovery phase special theatre sessions were asked for and procedures carried out in Day surgery and in independent sector (n-18). A total of 203 new AVF’s were created compared to 272 the year before a fall of 25%. There were 48 patients admitted with blocked access, 70% of whom underwent radiological intervention compared to 52% in 2019. Surgical intervention was offered to just 4% compared to 25% in 2019. The number of access abandoned was 27% in 2020 vs 19% in 2019.ConclusionCOVID-19 adversely affected the renal access population and none of the British Renal access surgery targets were met for 2020.

A144 ISOLATED UPPER ESOPHAGEAL VARICES DUE TO SUPERIOR VENA CAVA SYNDROME: A CASE OF UPPER GI BLEEDING

Abstract Background Esophageal varices represent a cause of upper gastrointestinal bleeding (UGI) with significant associated morbidity and mortality. The majority of variceal bleeds are due to portal hypertension and cirrhosis. In some very rare cases isolated upper esophageal varices may occur. These present management challenges, as typical management options for varices in cirrhosis are not applicable due to differences in pathophysiology. Infusions to decrease portal pressure and TIPS procedures may be used in cirrhosis, but are not effective in patients with SVC syndrome. Aims We present a literature review on isolated upper esophageal varices due to SVC syndrome, and present a case that provides further confirmation that surgical vascular reconstruction is a viable option in these cases. Methods The case of a 49 year old female with variceal hemorrhage secondary to SVC syndrome was reviewed. A search of the literature was undertaken using the terms “varices + superior vena cava syndrome” and “upper esophageal varices + management.” Results Overall, the majority of cases of isolated upper esophageal varices are secondary to SVC syndrome. They typically occur in cases of benign, rather than malignant SVC syndrome. Only one previous case was reported to be managed with surgical vascular reconstruction. We present the case of a 49-year old woman with SVC syndrome secondary to a thrombosed dialysis line who went on to develop isolated upper esophageal varices and large volume UGI bleeding. The pathophysiology of these “downhill” varices differs enough from portal hypertension that typical variceal management options may not be appropriate. Given a previous history of unsuccessful balloon angiography and the risk associated with variceal bleeding, she was taken back to the operating room for surgical vascular reconstruction. A surgical bypass was performed. She did well post-surgery and was discharged. She had no recurrence of bleeding and had a resolution of her edema at 6 month follow up. Conclusions Isolated upper esophageal varices are a potentially serious complication of SVC syndrome, and should be considered in cases of upper GI bleeding in patients with dialysis lines as they can have limited management options. This case was successfully managed by surgical vascular reconstruction, which represents an important treatment option in these difficult cases. Funding Agencies None

An iterative run-to-run learning model to derive continuous brachial pressure estimates from arterial and venous lines during dialysis treatment

Objective:Non-invasive continuous blood pressure monitoring is not yet part of routine practice in renal dialysis units but could be a valuable tool in the detection and prevention of significant variations in patient blood pressure during treatment. Feasibility studies have delivered an initial validation of a method which utilises pressure sensors in the extra-corporeal dialysis circuit, without any direct contact with the person receiving treatment. Our main objective is to further develop this novel methodology from its current early development status to a continuous-time brachial artery pressure estimator. Methods:During an in vivo patient feasibility study with concurrent measurement validation by Finapres Nova experimental physiological measurement device, real-time continuous dialysis line pressures, and intermittent occluding arm cuff pressure data were collected over the entire period of (typically 4-hour) dialysis treatments. There was found to be an underlying quasi-linear relationship between arterial line and brachial pressure measurements which supported the development of a mathematical function to describe the relationship between arterial dialysis line pressure and brachial artery BP. However, unmodelled non-linearities, dynamics and time-varying parameters present challenges to the development of an accurate BP estimation system. In this paper, we start to address the problem of physiological parameter time variance by novel application of an iterative learning run-to-run modelling methodology originally developed for process control engineering applications to a parameterised BP model. Results:The iterative run-to-run learning methodology was applied to the real-time data measured during an observational study in 9 patients, supporting subsequent development of an adaptive real-time BP estimator. Tracking of patient BP is analysed for all the subjects in our patient study, supported only by intermittent updates from BP cuff measurements. Conclusion:The methodology and associated technology is shown to be capable of tracking patient BP non-invasively via arterial line pressure measurement during complete 4-hour treatment sessions. A robust and tractable method is demonstrated, and future refinements to the approach are defined.

Microscopic and chemical characterization of PVC tube used for dialysis lines: A new approach.

Polyvinylchloride is universally agreed upon to be the material of choice for tubings and for containers for medical application. Many alterations of the chemical/physical surface conditions, mainly due to an altered extrusion process, could influence its biocompatibility by promoting platelet aggregation. Biocompatibility and safety of the medical device must be preserved, also monitoring the migration of additives within polyvinylchloride during the diffusion process. A large variety of methods are used to verify the correct composition and extrusion of polyvinylchloride but, generally, they need long experimental time and are expensive. The aim of the study is to propose a simple, economic and rapid approach based on Fourier transform-infrared spectroscopy and Coomassie Blue staining. The method has been used to detect chemical and morphological defects caused by an altered extrusion process on 20/75 polyvinylchloride tubings in a blind test. This approach positively identified altered samples in 80% of the cases. The suggested approach represents a reliable and versatile method to detect and monitor surface defects by an easy, inexpensive and reproducible method.

Abstract 322: The Mayo Cardiac Intensive Care Unit Admission Risk Score Predicts Resource Utilization During Hospitalization

Background: With the rising cost of critical care and limited availability of critical care resources, improvements are need in the current cardiac intensive care unit (CICU) triage process. We sought to determine whether the Mayo Clinic Intensive Care Unit Admission Risk Score (M-CARS) could be used to predict which CICU patients will require critical care resources. Methods: Adult patients admitted to our CICU from 2007 to 2018 were retrospectively reviewed. The M-CARS was calculated using data from the time of admission. Groups were compared using Wilcoxon test for continuous variables and chi-squared test for categorical variables. Results: We included 12,428 patients with a mean age of 67 ± 15 years (37% females). The mean M-CARS was 2.1 ± 2.1, including 5,890 (47.4%) patients with M-CARS &lt;2 and 644 (5.2%) patients with M-CARS &gt;6. Critical care therapies were frequently used, including mechanical ventilation in 28.0%, vasoactive medications in 25.5%, dialysis in 4.8% and invasive lines in 44.3%. The low-risk cohort with M-CARS &lt;2 was less likely to require invasive or noninvasive mechanical ventilation (8.0% vs. 46.1%), vasoactive medications (10.1% vs. 38.8%), dialysis (1.0% vs. 8.2%) or invasive lines (34.6% vs. 53.0%), as compared to patients with M-CARS ≥2 (all p&lt;0.001). A higher M-CARS was associated with greater use of critical care therapies and longer CICU and hospital length of stay. Conclusions: In addition to predicting hospital mortality, the M-CARS predicts resource utilization during CICU admission and could be used in the triage of critically ill cardiac patients. Patients with M-CARS &lt;2 infrequently require critical care resources and have extremely low mortality, yet account for nearly half of all CICU admissions, suggesting a potential to avoid CICU admission in many patients.

Totally percutaneous endoluminal ballooning of stuck hemodialysis catheters: One-year experience of a referral center.

The stuck catheter is an uncommon but dreaded complication of dialysis line placement. It always finds the operator unaware and often requires procedure modification or reschedule. Hong pioneered the technique of endoballooning to expand a stuck central venous catheter, thus freeing it from wall adhesions. The purpose of the current study was to present a totally percutaneous variation of endoluminal stuck catheters ballooning, along with our experience in terms of safety and feasibility. A major difference presented in respect to previous techniques is that this modification does not require isolation of the distal line stump at the venous entry point by tissue dissection, thus reducing procedural time and difficulty. We presented a case series of five lines that were ballooned by navigating low-profile material directly from the cutaneous exit of the lines, with optimal results (100% success). The findings of this investigation provide additional evidence with respect to the safety and effectiveness of endoluminal ballooning of Tesio lines and offer a new variation of endoluminal ballooning which we found easy to perform, safe, and effective.

Heart transplant complicated by metformin induced lactic acidosis

Introduction Mild lactic acidosis following heart transplant is a known laboratory finding that generally does not require treatment. However, we encountered a case in which a diabetic patient on metformin underwent a heart transplant and developed a profound rise in lactate which caused a severe anion gap metabolic acidosis and refractory vasoplegia. Methods Case Report. Results A 52 year old man with a past medical history of type 2 diabetes mellitus managed with metformin, chronic kidney disease, and coronary artery disease underwent an LVAD explant and a heart transplant utilizing bicaval anastomosis technique. Twenty minutes after separating from bypass, an arterial blood gas was notable for a lactate of 7.8 mmol/L. Over the next two hours, the patient developed vasoplegia and a severe anion gap metabolic acidosis with a lactate that peaked at 18.0 mmol/L. TEE and surgical visualization agreed that cardiac function was excellent and without evidence of tamponade. The patient's hyperdynamic cardiac function was confirmed by the cardiac output values nearing 14 L/m via Swan-Ganz thermodilution. The patient's preoperative medication history was once more analyzed and metformin induced lactic acidosis was added to our working differential diagnosis. A dialysis line was placed, and continuous veno-venous hemofiltration (CVVH) was initiated in the OR, followed by a downtrend of lactate and improvement in hemodynamics. CVVH was continued in the ICU resulting in resolution of lactemia. Discussion Metformin induced lactic acidosis is rare and a diagnosis of exclusion. We ruled out hypovolemia due to a CVP of 14-15 mmHg and ischemic bowel by benign abdominal exam and normal AST, ALT, amylase, and lipase. Sepsis was considered less likely due to lack of infectious source/fever and maintenance of scheduled antibiotic prophylaxis. We had established that the donor cardiac function was excellent. Due to the unpredictable nature of heart transplant, our patient received metformin within 48 hours of surgery. The patient's known chronic kidney disease, potentially exacerbated by cardiopulmonary bypass, likely contributed to metformin induced lactic acidosis.

First-in-human evaluation of a hand-held automated venipuncture device for rapid venous blood draws.

Obtaining venous access for blood sampling or intravenous (IV) fluid delivery is an essential first step in patient care. However, success rates rely heavily on clinician experience and patient physiology. Difficulties in obtaining venous access result in missed sticks and injury to patients, and typically require alternative access pathways and additional personnel that lengthen procedure times, thereby creating unnecessary costs to healthcare facilities. Here, we present the first-in-human assessment of an automated robotic venipuncture device designed to safely perform blood draws on peripheral forearm veins. The device combines ultrasound imaging and miniaturized robotics to identify suitable vessels for cannulation and robotically guide an attached needle toward the lumen center. The device demonstrated results comparable to or exceeding that of clinical standards, with a success rate of 87% on all participants (n = 31), a 97% success rate on nondifficult venous access participants (n = 25), and an average procedure time of 93 ± 30 s (n = 31). In the future, this device can be extended to other areas of vascular access such as IV catheterization, central venous access, dialysis, and arterial line placement.

A rare case of oesophageal variceal bleed secondary to dialysis catheter-induced superior vena cava stenosis and thrombosis

We are presenting a case of bleeding oesophageal varices secondary to superior vena cava stenosis caused by a permanent dialysis line. A 67-year-old female with chronic kidney disease (CKD) stage V on haemodialysis, secondary to chronic pyelonephritis and secondary focal segmental