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Water hammer is a principal cause of pipeline and equipment failure in pumping systems. The numerical method and experiments are used to investigate the dynamic interaction between the valve-closure water hammer wave and pump, to study the pressure variation and fluid-induced force on the pump components. The impeller-volute interaction and impeller position are taken into consideration. Results show that the valve-closure water hammer wave generates a substantial fluid-induced force on the pump and leads to a pressure surge in the pipeline. Meanwhile, the impeller-volute interaction also causes pressure and force variation in the pipeline and pump. The force amplitude caused by this factor in the axial direction is similar to that caused by the water hammer wave but is much smaller in the radial direction. The different interaction position of the water hammer wave on the blades can weaken the force, by 13.11% and 13.18% for the impeller and volute when the blades are under the most optimal position, respectively.

Background: The approach to peritoneal catheter malfunction consists usually in a diagnostic and therapeutic sequence of laxative prescription, abdominal radiography, brushing of the catheter, guide-wire manipulation or fluoroscopy and in the end of a videolaparoscopy (VLS) rescue intervention. Ultrasound (US) is able to find out major causes of peritoneal catheter malfunction, however without a clearly defined diagnostic value. The aim of the study was to validate the diagnostic capability of US in catheter malfunction compared to the diagnostic reference of VLS. Methods: US scans of the subcutaneous and intraperitoneal segment of the catheter were performed prior to a VLS intervention in 40 adult patients presenting persistent catheter malfunction within a prospective multicentre study. Laxative prescription and brushing of the catheter lumen were undertaken prior to US scan. US diagnosis was compared to the corresponding at VLS, kappa coefficient calculated and the causes of mismatch analysed. Results: In US, causes of persistent malfunction were catheter dislocation combined with omental wrapping in 21 cases, omental wrapping without dislocation in 11 cases, dislocation only in 4 cases, adherences to non-omental structures in 3 cases and entrapment in the lateral inguinal fossa in 1 case. The US diagnosis corresponded to the respective at VLS in 36 of 40 cases, resulting in a kappa coefficient of 0.89 (95% CI: 0.78–1.00). The discrepancies were due to improper visualization of the catheter between omentum and intestinal loops, resulting in an erroneous US diagnosis of omental wrapping. Conclusions: This study suggests that US might have a pivotal role in the diagnostic approach to peritoneal catheter dysfunction.

Background:Patients with COVID-19 and ARDS on prolonged mechanical ventilation are at risk for developing endotracheal tube (ETT) obstruction that has not been previously described in patients with ARDS due to other causes. The purpose of this report is to describe a case series of patients with COVID-19 and ARDS in which ETT occlusion resulted in significant clinical consequences and to define the pathology of the obstructing material.Methods:Incidents of ETT occlusion during mechanical ventilation of COVID-19 patients were reported by clinicians and retrospective chart review was conducted. Statistical analysis was performed comparing event rates between COVID-19 and non-COVID 19 patients on mechanical ventilation over the predefined period. Specimens were collected and submitted for pathological examination.Findings:Eleven COVID-19 patients experienced endotracheal tube occlusion over a period of 2 months. Average age was 69 (14.3, range 33-85) years. Mean APACHE III score was 73.6 (17.3). All patients had AKI and cytokine storm. Nine exhibited biomarkers for hypercoagulability. Average days on mechanical ventilation before intervention for ETT occlusion was 14 (5.18) days (range of 9 to 23 days). Five patients were discharged from the ICU, and 4 expired. Average documented airway resistance on admission was 14.2 (3.0) cm H2O/L/sec. Airway resistance before tube exchange was 28.1 (8.0) cm H2O /L/sec. No similar events of endotracheal tube occlusion were identified in non-COVID patients on mechanical ventilation during the same time period. Microscopically, the material consisted of mucin admixed with necrotic cell debris, variable numbers of degenerated inflammatory cells, oral contaminants and red blood cells.Interpretation:Patients with COVID-19 and ARDS on prolonged mechanical ventilation are at risk for developing ETT obstruction due to deposition of a thick, tenacious material within the tube that consists primarily of mucin and cellular debris. Clinicians should be aware of this dangerous but treatable complication.

Industry has long fought the battle to design a vascular catheter that is less thrombogenic. Indwelling catheters provide long-term central venous access, but they develop fibrin sheaths as the vascular system recognizes them as foreign bodies. Peripheral catheters and central catheters can be changed over a guidewire when they form a fibrin sheath or otherwise malfunction. However, totally implantable venous access devices such as a port cannot be easily exchanged over a wire. Therefore, when a port malfunctions, thrombolytics are usually the only option attempted before the port is explanted and a new site is prepared for access. We present a minimally invasive technique demonstrating port salvage that does not require explant.

Omental wrapping is a common cause of peritoneal catheter malfunction. This diagnosis should be confirmed by radiography before proceeding with surgical omentectomy. We report two cases of peritoneal dialysis (PD) catheter outflow obstruction from our developing PD program in Grenada, in which contrast studies accurately diagnosed omental wrap, allowing for prompt surgical correction. In both cases, the contrast study indicated the presence of omental wrapping, confirmed at time of surgical correction. Radiographic features of omental wrap are distinctive, which allows for reliable differentiation from other causes of obstruction. Radiographic contrast study reliably diagnoses the cause of peritoneal catheter obstruction, permitting prompt diagnosis and treatment. This is vital for regions with limited access to haemodialysis.

Background. Surgical stapling devices are known for their reliability and convenience. A letter to health care professionals published by the US Food and Drug Administration in March 2019 highlighted the increasing number of adverse events associated with surgical staplers. Driven by a case of stapler malfunction during an elective laparoscopic sleeve gastrectomy, we performed a literature review to investigate the incidence of primary stapler malfunction. We also discuss the common types and an approach to its management. Methods. PubMed, MEDLINE, and EMBASE databases were searched for articles discussing surgical stapler malfunction. Twelve studies were selected that described the incidence and/or consequences of primary stapler malfunction. A narrative synthesis was performed. Results. From observational studies, the incidence ranged from 0.022% to 2.3%. A prospective survey reported that 86% of laparoscopic surgeons either had personal experience with or knew of surgeons who experienced stapler malfunction, implying a higher incidence. Underreporting has been an issue as manufacturers can get exemptions from public reporting. Significantly, higher malfunctions have been reported after exemptions were lifted. The most common types of stapler malfunction are stapler misfire and stapler locking. Major morbidity and mortality have been reported. Conclusion. Surgeons are increasingly reliant on technological innovations. Stapling failure occurs and it is imperative to be aware of this. Given the high volume of stapler use, a high percentage of surgeons are likely to encounter this problem in their career. It is important to have an approach to the prevention and management of this potentially catastrophic complication.

Background: Expanded applications and increasing volumes of complex endovascular procedures have increased the risk of unintended intraoperative fragmentation and retention of catheters and sheaths. We describe a series of retained or fragmented endovascular devices, a quality improvement program to address this unmet need for improved detection of catheter fragmentation, and the results of this program. Methods: Cases utilizing endovascular devices that resulted in a retained catheter fragment were identified and analyzed during divisional quality improvement review. One consistent area of concern was operating room (OR) staff unfamiliarity with verifying the integrity of an endovascular device. In response, a slide-based training protocol of focused, endovascular nursing education was implemented. Following perceived lack of improvement after this approach, we developed a handheld visual reference display of the tips of common catheters and sheaths. Staff was surveyed before and after intervention to assess the educational value of the display and the impact on staff device familiarity. Results: All 4 described cases resulted in an unplanned return to the OR for retrieval of the fragmented catheter or sheath. No thromboembolic complications were observed, although associated intra-arterial thrombus was noted in 2 cases. Thirty-four OR nurses were polled to trial the visual reference display initiative, with 70% of those reporting primary surgical assignments outside of cardiovascular ORs. Introduction of the new visual reference display improved staff confidence in their ability to identify a broken device (2.4-3.7, P < .001). This improvement was most significant in OR staff with primary assignments in noncardiovascular services. Conclusion: Current OR standard operating procedures fail to address the potential for unintentionally retained catheters and wires during endovascular procedures. Our novel visual reference display of common endovascular items rather than conventional in-service training improved the ability of staff to identify device fragmentation at the time of the index procedure.

New female condom (FC) products, different in design and materials that have the potential to lower cost and improve acceptability are being developed. A pilot study of the Panty Condom was conducted among experienced FC users in Durban, South Africa. This pilot function trial enrolled 19 women who were asked to use five Panty Condoms each and collect information on use in a condom diary at home, followed by one follow-up interview. Primary endpoints were total clinical failure and total female condom failure. Non-inferiority of component modes, clinical breakage, non-clinical breakage, slippage, misdirection, and invagination were also determined. Frequencies and percentages were calculated for each failure mode. The mean age of the participants was 27.8 years (SD 4.9). Safety and acceptability data were also assessed. In 95 condom uses nine failure events occurred in eight condoms. Clinical breakage occurred in 8.4% (n = 8) of condoms and slippage in one condom. Total FC failure was 8.4% of all condom uses. Of the eight breakage events there were two reports of the condom ripping during sex and six reports of the condom detaching from the panty. Fifteen women either liked very much or liked somewhat using the Panty Condom. Total clinical failure was approximately twice that seen in other FC functionality studies.

Objective This research evaluated Automated Driving Systems (ADSs) involved collisions to identify factors relevant to future ADS research and development. Background Rapidly developing ADSs promise improved safety, among other benefits. Properly applied collision research can inform ADS development, to minimize future collisions. Errors and failures that result in collisions come from sources including the system, ADS operators, and external factors including other drivers. Partially automated systems incorporate new equipment and procedures creating new sources of human error. Fully autonomous systems represent a new class of drivers that interact in unique ways. Method ADS collision reports from the California Department of Motor Vehicles and the National Transportation Safety Board were collected. An expert in human factors and collision investigation analyzed and categorized the crashes while extracting common factors. Results ADS vehicles were never at fault but were often affected from the rear during braking, turning, and gap acceptance maneuvers. Side impacts to ADS vehicles were related to passing vehicles and lane keeping behaviors. Unique incidents also provided additional insights. ADS collision rates cannot yet be determined with confidence. Conclusion Conflicts that lead to collision-involvement with ADSs may be caused by differences between ADS and human driving behavior. Conservative ADS behavior may violate the expectations of other nearby human road users. Application The findings from this work help inform the future development of ADS, as well as potentially the testing of ADS and the formation of policy to guide their future deployment.

Background Little evidence exists regarding optimal peritoneal dialysis (PD) access insertion pathways, benchmarking for patency targets, and definitions of access dysfunction. Methods This quality improvement (QI) project evaluated patients with PD catheters inserted at a single center in Toronto, Canada, following: establishment of PD catheter insertion protocols, a PD access coordinator, PD access operator training, and outcomes reporting. We define primary vs secondary PD catheter dysfunction by presentation before/after initial home PD treatment. We report catheter dysfunction rates, interventions restoring PD catheter patency (interventional radiology [IR] vs advanced laparoscopic [AL]) (embedded vs non-embedded) between 2012 and 2017. Results A total of 297 first PD catheters were inserted between January 2012 and December 2017. Interventional radiology PD catheters ( n = 94) were placed in older patients with greater comorbidities and less prior abdominal surgery than AL-placed catheters. Indications for IR insertion included need for urgent dialysis given resource availability (36.2% [ n = 34]) and prohibitive surgical risk (26.6% [ n = 25]). Interventional radiology-inserted catheters had overall (primary and secondary) dysfunction rates of 17%. Non-embedded AL catheters had 16.1% overall dysfunction. Embedded AL-inserted PD catheters had a 24.6% overall dysfunction rate. Among all dysfunctional catheters, IR manipulation was successful in 31% ( n = 11), and surgical revision was necessary in all unsuccessful cases with either lysis of adhesions or omentopexy to establish patency. Conclusion Our PD catheter QI initiative involved tracking, outcome reporting, defining PD catheter dysfunction and PD access insertion pathway development, yielding important insights into opportunities for program improvement. Multicenter research initiatives are needed to further improve PD access dysfunction definitions and to establish the best benchmarks for these metrics.

Introduction:Long-term use of peritoneal dialysis catheter is associated with complications such as infection and malfunction, necessitating removal of catheter with subsequent reinsertion or permanent transfer to haemodialysis. This study aims to investigate the outcome in patients who underwent reinsertion.Methods and materials:A single-centre retrospective study was performed in Singapore General Hospital for all adult incident peritoneal dialysis patients between January 2011 and January 2016. Study data were retrieved from patient electronic medical records up till 1 January 2017.Results:A total of 470 patients had peritoneal dialysis catheter insertion with median follow-up period of 29.2 (interquartile range = 16.7–49.7) months. A total of 92 patients required catheter removal. Thirty-six (39%) patients underwent catheter reinsertion. The overall technique survival at 3 and 12 months were 83% and 67%. Median time to technique failure of the second catheter was 6.74 (interquartile range = 0–50.2) months. The mean survival for patients who converted to haemodialysis and re-attempted peritoneal dialysis was comparable (54.9 ± 5.5 vs 57.3 ± 3.6 months; p = 0.75). Twelve (13%) patients had contraindication for peritoneal dialysis and were excluded from analysis. Of 11 patients who required catheter removal due to malfunction, 7 (64%) underwent catheter reinsertion and 6 (86%) patients ultimately converted to haemodialysis during study period. Of the 69 patients who had catheter removal due to infection, 29 (42%) underwent catheter reinsertion and 8 (28%) patients eventually converted to haemodialysis during the study period.Conclusion:Patient survival was comparable between patients who re-attempted peritoneal dialysis and patients who transferred to haemodialysis. Patients who had previous catheter removal due to infections had favourable technique survival than those due to catheter malfunction.

Background: For subcutaneously implanted central venous ports, some complications due to prolonged placement have been reported. We investigated the appropriate puncture points and port placement sites to prevent catheter fracture in right internal jugular port placement. Methods: This retrospective study included 709 patients who underwent right internal jugular vein puncture and port implantation in the right precordium between 1 May 2012 and 31 March 2018. The cases were divided into undamaged catheter group and damaged catheter group comprising normal and fracture cases, respectively. The catheter angle, distance from the clavicle, tip position, and curvature radius were measured from fluoroscopic images obtained at the time of implantation. The t-test was used in statistical analysis. Results: Median angles were 91.6° in the undamaged catheter group and 58.0° in the damaged catheter group. Median distances were 26.0 mm in the undamaged catheter group and 36.6 mm in the damaged catheter group. Median tip positions were 51.6 mm in the undamaged catheter group and 37.5 mm in the damaged catheter group. Median curvature radii were 9.2 R in the undamaged catheter group and 7.1 R in the damaged catheter group. Significant differences were found in the angle, height, and curvature radius between the two groups. Conclusion: Our results indicate that a venipuncture as close to the clavicle as possible (less than 3 cm) and a gentle catheter curve (close to 90° angle) are associated with a lower risk of catheter fracture.

Background Lanreotide and octreotide acetate suspension for injectable (LAR) are both recommended for clinical use in patients with locally advanced or metastatic gastroenteropancreatic neuroendocrine tumors. However, each agent possesses unique attributes in terms of their drug-delivery characteristics. The study objective was to compare overall drug-delivery efficiency between lanreotide and octreotide LAR in gastroenteropancreatic neuroendocrine tumor patients. Methods This study employed an observational time and motion design among patients treated with lanreotide or octreotide LAR across five US cancer centers. Baseline patient data collection included age, disease grade and duration, prior therapies and performance status. Drug-delivery time (drug preparation and administration), total patient time and resource use data were collected for gastroenteropancreatic neuroendocrine tumors receiving lanreotide (n = 22) or octreotide LAR (n = 22). Following each administration, qualitative data on the drug-delivery experience was collected from patients and nurses. Results Lanreotide was associated with a significant reduction in mean delivery time (2.5 min; 95% CI:2.0 to 3.1) compared to octreotide LAR (6.2 min; 95%CI: 4.4 to 7.9; p = 0.004). The mean total patient time for lanreotide and octreotide LAR was comparable between groups (32.1 vs. 36.6 minutes; p = 0.97). Nurses reported increased concerns with octreotide LAR related to needle clogging ( p = 0.034) and device failures ( p = 0.057). Overall, lanreotide had a median satisfaction score of 5.0 compared to a score of 4.0 with octreotide LAR ( p = 0.03). Conclusions Lanreotide was associated with significant reductions in drug-delivery time compared to octreotide LAR, which contributed to an improvement in overall healthcare efficiency. Trial registration clinicaltrials.gov Identifier: NCT03017690.

At present, central venous access devices (CVADs) are widely used in clinical practice. The reasons for CVAD obstruction caused by precipitated medication or lipids are increasingly complex. However, there is no clear treatment program for CVAD obstruction caused by precipitated medication or lipids. The target of this study was to analyze data regarding obstruction caused by precipitated medication or lipids in CVADs and to calculate the efficacy of different treatment methods. A systematic review with meta-analysis was conducted in alignment with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. The PubMed, Web of Science, EMBASE, Cochrane Library, CINAHL, and China National Knowledge Internet databases were searched for original research published before 2018. There were 1356 publications initially screened, with one additional study identified through snowballing. Seven studies met the inclusion criteria. The reasons for obstruction, except for clot formation, primarily included the following: mechanical complications; lipid deposition; mineral deposition; or drug precipitation. Meta-analysis showed that sodium hydroxide resulted in the highest recanalization rate in lipid deposition, followed by ethanol, and the difference was significant. The efficacy analysis revealed that hydrochloric acid and l-cysteine have similar effects on mineral deposition and drug precipitation. According to this review, the most effective methodology was shown to be the intravenous perfusion of sodium hydroxide in several treatments when the obstruction is caused by lipid deposition. In contrast, mineral deposition and drug deposition are best treated with l-cysteine to recover the patency of central venous access devices.

Background The weighted catheter has shown promising results in retrospective and randomized studies. We examined its usefulness in patients with previous failed non-weighted peritoneal dialysis (PD) catheters or previous abdominal surgery. Methods The insertion, start, end, and removal dates were recorded for all-type catheter insertions from 2011 to 2016. Primary and secondary failure rates were recorded, defined as failure to ever establish flow (primary) or failure after a period of successful PD (secondary). Patients were censored from analysis if PD ended due to death, transfer of care, transfer to hemodialysis, transplantation, or if the patient recovered renal function. Results There were 44 weighted, 75 non-weighted open surgical, and 143 percutaneous catheters. There was previous abdominal surgery in 29% and 6% of patients receiving surgically inserted and percutaneous catheters, respectively ( p < 0.0001). Primary failure rates were 4/44 (9%), 20/75 (27%), and 26/143 (18%) in weighted, non-weighted surgical, and percutaneous catheters, respectively. There were reduced primary and secondary failure rates in the weighted (9% primary and 15% secondary) versus non-weighted surgically inserted group (27% primary and 46% secondary) ( p = 0.04). There was no difference between primary ( p = 0.15) and secondary ( p = 0.5) failure rates between weighted and percutaneously inserted catheters. Kaplan-Meier survival analysis revealed overall increased catheter survival in the weighted group ( p = 0.02). Conclusion Weighted catheters were associated with increased survival and decreased failure rates compared with non-weighted surgical catheters, despite usage in patients at higher risk of catheter failure due to previous failed catheters and abdominal surgery.

Objective: Patients on extracorporeal membrane oxygenation are frequently in need for sedation. Use of propofol has been associated with impaired oxygenator function due to adsorption to the membrane as well as lipid load. The aim of our retrospective analysis was to compare two different sedation regimens containing either propofol or midazolam with respect to oxygenator running time. Methods: Midazolam was used in 73 patients whereas propofol was used in 49 patients, respectively. In the propofol group, veno-arterial–extracorporeal membrane oxygenation was used predominantly (84%), while veno-venous–extracorporeal membrane oxygenation was used more often in the midazolam group (64%). Results: Oxygenator running time until first exchange was 7 days in both groups ( p = 0.759). No statistically significant differences could be observed between the subgroup of patients receiving lipid-free (n = 24) and lipid-containing (n = 31) parenteral nutrition, respectively. Laboratory parameters like triglycerides, free hemoglobin, fibrinogen, platelets, and activated partial thromboplastin time were not significantly different between both sedation regimens ( p = 0.462, p = 0.489, p = 0.960, p = 0.134, and p = 0.843) and were not associated with oxygenator running time. Conclusion: The use of propofol as sedative seems suitable in patients undergoing extracorporeal membrane oxygenation therapy.

Introduction:Vascular access devices are commonly inserted devices that facilitate the administration of fluids and drugs, as well as blood sampling. Despite their common use in clinical settings, these devices are prone to occlusion and failure, requiring replacement and exposing the patient to ongoing discomfort/pain, local vessel inflammation and risk of infection. A range of insertion and maintenance strategies are employed to optimize device performance; however, the evidence base for many of these mechanisms is limited and the mechanisms contributing to the failure of these devices are largely unknown.Aims/objectives:(1) To revisit existing understanding of blood, vessel physiology and biological fluid dynamics; (2) develop an understanding of the implications that different clinical practices have on vessel health, and (3) apply these understandings to vascular access device research and practice.Method:Narrative review of biomedical and bioengineering studies related to vascular access practice.Results/outcomes:Current vascular access device insertion and maintenance practice and policy are variable with limited clinical evidence to support the theoretical assumptions underpinning these regimens. This review demonstrates the physiological response to vascular access device insertion, flushing and infusion on the vein, blood components and blood flow. These appear to be associated with changes in intravascular fluid dynamics. Variable forces are at play that impact blood componentry and the endothelium. These may explain the mechanisms contributing to vascular access failure.Conclusion:This review provides an update to our current knowledge and understanding of vascular physiology and the hemodynamic response, challenging some previously held assumptions regarding vascular access device maintenance, which require further investigation.

Endovascular thrombectomy is now the standard of care for large vessel occlusion stroke. The aim is to achieve rapid and complete recanalisation while avoiding complications. Apart from the conventional complications of neurointerventional procedures, mechanical thrombectomy has its unique set of complications, inherent to the disease pathophysiology. We describe an unusual complication of catheter fracture and subsequent distal embolisation into the cerebral vasculature, which was noticed 24 hours after the procedure. Due to a lack of clinical consequences, we decided to manage it conservatively. The patient died within the following few days from respiratory complications unrelated to the stroke or the endovascular thrombectomy procedure. Consequently, we were able to retrieve the fractured segment and carry out histopathological analysis, which helped us to identify exactly its origin from the guide catheter. We believe that systematic reporting and database compilation of such device-related complications will aid in the design and development of neurointerventional devices in the future.

The goal of this study was to examine how interruptions affect the acquisition of laparoscopic skills among novices. Undergraduate students with no prior laparoscopic experience completed a basic laparoscopic training task requiring them to pick up and transfer colored objects in a predetermined sequence. The number of colored objects in the sequence was varied to produce three levels of task demand. During execution of the primary task, participants were exposed to a visual interruption by having their video display go blank. The length of interruptions was also varied to examine its effect on memory for the sequence of object moves. Results show greater perceived workload and sequence errors as the demand of the ring transfer task increased. Interruptions from simulated equipment failure were not found to negatively impact recollection of the predetermined color sequences.

Objective To analyse medical device-related pressure ulcer (MDRPU) management modes and their possible risks and provide references to treat MDRPUs. Methods The Australian/New Zealand Standard (AS/NZS) 4360:2004 risk management standard is the first national risk management standard in the world. Zhongshan Hospital adopted the standard to establish risk management modes to improve the MDRPU risk management process and to register, assess and analyse the key risks for MDRPUs. Eight risk types were identified and registered: organization management risk, environment risk, patient safety risk, human resource risk, infection risk, occupational safety risk, legal risk and reputational risk. Results Following the implementation of the AS/NZS 4360:2004 risk management standard in our institution, the organization management risk value decreased from 25 to 5; the environment risk value decreased from 25 to 5; the patient safety risk value decreased from 20 to 3; the human resource risk value decreased from 16 to 4; the infection risk value decreased from 9 to 1; the occupational risk value decreased from 9 to 6; the legal risk value decreased from 9 to 4; and the reputational risk value decreased from 12 to 2. Conclusion The AS/NZS 4360:2004 risk management standard was effective in managing the risk of MDRPUs.

Urinary catheters have been used on an intermittent or indwelling basis for centuries, in order to relieve urinary retention and incontinence. Nevertheless, the use of urinary catheters in the clinical setting is fraught with complication, the most common of which is the development of nosocomial urinary tract infections, known as catheter-associated urinary tract infections. Infections of this nature are not only significant owing to their high incidence rate and subsequent economic burden but also to the severe medical consecutions that result. A range of techniques have been employed in recent years, utilising various technologies in attempts to counteract the perilous medical cascade following catheter blockage. This review will focus on the current advancement (within the last 10 years) in prevention of encrustation and blockage of long-term indwelling catheters both from engineering and medical perspectives, with particular emphasis on the importance of stimuli-responsive systems.

Introduction: The use of left ventricular assist device (LVAD) has grown rapidly. Adverse events do continue to occur. In recent years, analysis of LVAD sound recordings emerged as a means to monitor pump function and detect pump thrombosis. The aim of this study was to characterize the sounds from HeartMate II and to evaluate the use of handheld iOS devices for sound recordings. Method: Signal analysis of LVAD sound recordings, with dedicated recording equipment and iOS devices, was performed. Two LVADs running in mock loop circuits were compared to an implanted LVAD. Spectral analysis and parametric signal models were explored to quantify the sound and potentially detect changes in it. Results: The sound recordings of two LVADs in individual mock loop circuits and a third one implanted in a patient appeared to be similar. Qualitatively, sound characteristics were preserved following changes in pump speed. Recordings using dedicated equipment showed that HeartMate II sound comprises low-frequency components corresponding to pump impeller rotation, as well as high-frequency components due to a pulse width modulation of the electric power to the pump. These different signal components interact and result in a complicated frequency spectrum. The iPhone and iPod recordings could not reproduce the sounds as well as the dedicated equipment. In particular, lower frequencies were affected by outside disturbances. Discussion: This article outlines a systematic approach to LVAD sound analysis using signal processing methods to quantify and potentially detect changes, and describes some of the challenges, for example, with the use of inexpensive recording devices.

Introduction: The use of cyanoacrylate glue as sealant on the exit site of peripherally inserted central catheters (PICCs) may offer some important clinical advantages. However, concerns exist about the potential interaction between cyanoacrylate and the material of the catheter itself. The aim of this study was to investigate the possibility of damage to the catheter secondary to a long-term contact with a two-component skin glue (N-butyl + octyl cyanoacrylate). Methods: Twelve PICCs of different brands and types were selected (11 made of polyurethane and one made of silicon). PICCs were glued onto artificial skin pads, slightly wetted with Earle solution. The pads were kept in an egg incubator at 34°C and 60% humidity, for up to twelve weeks. Possible signs of degradation were monitored by surface analyses and mechanical tests. Scanning electron microscopy observations, surface roughness measurements, pressure strength and uniaxial tests were performed. Results: Samples were analyzed after 4, 8 and 12 weeks of contact with the glue. No chemical reaction between the glue and the material of the catheters was evident. The mechanical strength of PICCs was consistently within the ranges of ISO standards. An expected increase in the stiffness of the samples covered with glue was observed in uniaxial tests. The silicon catheter was weaker than the polyurethane catheters and was damaged while trying to remove it from the pad for tests. Conclusions: The long-term use of N-butyl + octyl cyanoacrylate glue on polyurethane PICCs is not expected to be associated to any damage to the catheter.

Background: SAR342434 (U100; SAR-Lis; insulin lispro) is a biosimilar/follow-on to insulin lispro (U100; Ly-Lis). Similar pharmacokinetics/pharmacodynamics between the two products has been demonstrated in a hyperinsulinemic euglycemic clamp study. The current study evaluated the safety of SAR-Lis and Ly-Lis when administered by continuous subcutaneous insulin infusion (CSII; insulin pumps). Methods: This was a randomized, open-label, 2 × 4-week, two-arm crossover study in 27 patients with type 1 diabetes mellitus (NCT02603510). The main outcome was the incidence of infusion set occlusions (ISOs), defined as failure to correct hyperglycemia (plasma glucose ≥≥ 300 mg/dl) by 50 mg/dl within 60 minutes by insulin bolus via the pump. Secondary outcomes included intervals between infusion set changes, treatment-emergent adverse events (TEAEs) including infusion site, hypersensitivity reactions and hypoglycemic events, and safety. Results: The number of patients reporting at least one ISO was small: 6/25 patients on SAR-Lis reported 14 ISOs and 4/27 on Ly-Lis reported nine ISOs. The estimated difference in ISO risk for SAR-Lis versus Ly-Lis was 7.9% (95% CI, –1.90 to 17.73). Mean interval between infusion set changes for any reason was similar with SAR-Lis (3.09 days) and Ly-Lis (2.95 days). The event rate (events/patient-month) of any hypoglycemia was similar with SAR-Lis (7.15) and Ly-Lis (7.98), as was the percentage of patients who experienced any TEAE (12.0% and 14.8%). Conclusion: Both SAR-Lis and Ly-Lis were well tolerated by patients using insulin pumps. The results do not suggest a clinically significant difference in the risk of ISO between SAR-Lis and Ly-Lis when used in CSII.

Background Intracranial atherosclerotic disease may result in ischemic infarction and has a high rate of recurrent ischemic strokes despite medical therapy. Patients who fail medical therapy may undergo endovascular treatment with cerebral artery angioplasty and possible Wingspan stent placement. We present a unique case of Wingspan delivery microcatheter fracture that resulted in a retained foreign body and an endovascular salvage maneuver. Case description An elderly patient presented with an acute ischemic stroke due to a severe stenosis in the proximal left middle cerebral artery (MCA). The patient failed non-invasive medical treatment and underwent endovascular treatment with angioplasty and Wingspan stent placement. Following Wingspan stent deployment, the stent delivery catheter fractured, and the retained catheter fragment resulted in MCA occlusion. The foreign body was retrieved by balloon catheter inflation within an intermediate catheter adjacent to the proximal end of the fractured catheter and removal of the entire construct (TRAP technique). Conclusions Wingspan delivery microcatheter fracture is a rare event. The TRAP technique may be used for successful retrieval of a retained foreign body.

Introduction In a previous paper, the authors investigated the mechanical behavior of several commercial polyurethane peripherally inserted central venous catheters (PICCs) in their ‘brand new’ condition. The present study represents a second step of the research activity and aims to investigate possible modifications of the PICC mechanical response, induced by long-term conservation in in vivo-like conditions, particularly when used to introduce oncologic drugs. Methods Eight 5 Fr single-lumen catheters from as many different vendors, were examined. Several specimens were cut from each of them and kept in a bath at 37°C for 1, 2, 3 and 6 months. Two fluids were used to simulate in vivo-like conditions, i.e. ethanol and Ringer-lactate solutions, the first being chosen in order to reproduce a typical chemical environment of oncologic drugs. The test plan included swelling analyses, uniaxial tensile tests and dynamic mechanical thermal analysis (DMTA). Results and conclusions All tested samples were chemically and mechanically stable in the studied conditions, as no significant weight variation was observed even after six months of immersion in ethanol solution. Uniaxial tensile tests confirmed such a response. For each PICC, very similar curves were obtained from samples tested after different immersion durations in the two fluid solutions, particularly for strains lower than 10%.

This work is set in the context of perioperative practice in difficult airway management. It integrates a root cause analysis and fish bone technique to investigate a critical incident in temporary yet crucial equipment failure. Risk management and incident reporting is analysed alongside human factors in the operating theatre environment. Finally, recommendations for risk reduction, vigilance and checking vital airway equipment are made in anaesthetic practice.

Introduction Central venous catheter (CVC) access is commonplace in intensive care units. Patients undergoing computed tomographic angiography require injection of contrast at high flow rates (4.5 mL/s), often CVC access is not used due to safety concerns. The CVC might rupture at high flow rates, resulting in CVC fragmentation and embolization or contrast extravasation. The objective of this study is to determine the pressure required to burst a CVC under static load and compare this to the pressure generated by injection of contrast at high flow rates (dynamic load) through the distal (16-g) lumen of a triple-lumen CVC. Methods We gathered 16-cm long triple-lumen CVCs (n = 14) from patients with an average dwell time of 5.2 days (±2.7 days). Half the CVCs (n = 7) were subjected to static testing, where the distal lumen was occluded with the guidewire and super glue at the distal end of the catheter. The CVC was then placed into a 10-cm deep water bath at 37°C to simulate in vivo conditions and water was injected until catheter rupture. Dynamic pressure testing was done with the remaining catheters, with radio-contrast injected through the unoccluded distal lumen at flow rates of 4.5 mL/s, then 7 mL/s. Pressures were recorded throughout injection. Results During static testing, 6/7 CVCs burst at the distal lumen where the glue was applied, the remaining CVC burst proximal to the hub. PSI at burst during static testing was 184.2 PSI (95% confidence interval [CI] 174.3-194.1 PSI). During dynamic testing the mean peak pressures at 7 mL/s was 81.1 PSI (95% CI 73-89.2 PSI). At 4.5 mL/s the mean peak pressure was 47.9 PSI (95% CI 42.9-52.9 PSI). Conclusions No CVCs failed under dynamic loading with injection of contrast at flow rates (4.5 and 7 mL/s) high enough to support computed tomographic angiography. This suggests 16-cm triple-lumen CVCs can be used safely.

Provision of extracorporeal membrane oxygenation as part of support escalation in severe refractory acute respiratory failure in England is provided by five specialist centres that operate within a well-defined quality and safety framework. We conducted a qualitative study of the extracorporeal membrane oxygenation retrieval service provided by one of the five centres. We analysed 176 consecutive debrief reports written between October 2013 and April 2018 by the consultant. Main identified issues were short delays in retrieval predominantly due to insufficient communication or equipment failure. All issues were addressed in subsequent practice. Our results suggest a need for improved communication between the referring intensive care unit and retrieving team. Our findings highlight the value of regular reflection-based evaluation to ensure continued provision of safe and efficient service.

Objective: To evaluate the effect of synchronous water irrigation on the fatigue resistance of nickel-titanium instrument. Methods: A standardized cyclic fatigue test models were established, and five types of nickel-titanium instruments (PTU F1, WO, WOG, RE, and M3) were applied. Each instrument was randomly divided into two groups ( N = 12). There was synchronous water irrigation in the experimental group, and no water irrigation in the control group. Besides, ProTaper Universal F1 was randomly divided into 10 groups ( N = 20). In the static group, nickel-titanium instruments were divided into one control group (no irrigation, N = 20) and six experimental group (irrigation, N = 20) based on different flow rate, angle and position; while in the dynamic group, instruments were divided into one control group (no irrigation, N = 20) and two experimental group (irrigation, N = 20) based on different flow rate. The rotation time (Time to Failure, TtF) of instruments was recorded and analyzed. Results: According to the static experiments, the TtF of instruments in all experimental groups was significantly higher than that in the static control group. Besides, the dynamic tests of PTU F1 showed that the TtF in the experimental group was significantly higher than that in the dynamic control group. Compared with control group, the TtF in the experimental groups increased by at least about 30% and up to 160%. The static and dynamic tests of PTU F1 showed that the TtF of nickel-titanium instrument in all experimental groups was significantly higher than that in the control group. However, there was no significant difference between any two experimental groups. Conclusion: Regardless of dynamic or static model, TtF with irrigation was longer than that with non-irrigation, indicating that synchronous irrigation can increase the fatigue resistance of nickel-titanium instrument. However, different irrigation conditions may have the same effect on the fatigue resistance.

Background: We report our experience of an unexpected complication of internalization of a pulmonary artery (PA) band in the vascular lumen, which occurred in a chronic porcine model of repaired tetralogy of Fallot (TOF). Methods: Twelve piglets were divided into 3 groups: (1) TOF model animals (PA band plus pulmonary valvotomy, n = 4), (2) pulmonary insufficiency (PI) animals (pulmonary valvotomy, n = 4), and (3) control animals (n = 4). A nonabsorbable, coated braided polyester tape was used to perform the main pulmonary artery banding. Echocardiography was performed 4 months postoperatively. After each animal was euthanized, PA histological analysis was performed in animals with band internalization. Results: Significant postsurgical pulmonary regurgitation and right ventricular enlargement were present in the TOF and PI, compared with control animals, whereas no significant pulmonary stenosis was observed in TOF animals when compared with PI group. Postmortem examination of all TOF animals revealed the constricting band to be intact but partially internalized into the PA lumen, allowing blood flow around the stenosis. Histological sections of the banded PA in the area of internalization showed a significant disorganization of the medial layer, with significant scarring and fibrotic reaction surrounding the outside of the band and the presence of inflammatory cells suggesting a significant inflammatory response during band internalization. Conclusions: Band internalization may occur after PA banding using a nonabsorbable, coated braided polyester tape in a chronic porcine model of repaired TOF. This unusual complication was likely due to the type of material used for banding.

Background There are no large studies that have examined ultra-short break-in period with a blind, bedside, midline approach to Tenckhoff catheter insertion. Methods Observational cohort study of 245 consecutive adult patients who underwent percutaneous catheter insertion for chronic peritoneal dialysis (PD) at our center from January 2009 to December 2013. There were 132 (53.9%) diabetics and 113 (46.1%) non-diabetics in the cohort. Results The mean break-in period for the percutaneous group was 2.68 ± 2.6 days. There were significantly more males among the diabetics (103 [78%] vs 66 [58.4%], p = 0.001). Diabetics had a significantly higher body mass index (BMI) (23.9 ± 3.7 kg/m2 vs 22.2 ± 4 kg/m2, p < 0.001) and lower serum albumin (33.1 ± 6.3 g/L vs 37 ± 6 g/L, p < 0.001) compared with non-diabetics. Poor catheter outflow was present in 6 (4.5%) diabetics and 16 (14.2%) non-diabetics ( p = 0.009). Catheter migration was also significantly more common in the non-diabetic group (11 [9.7%] vs 2 [1.5%], p = 0.004). Primary catheter non-function was present in 17(15%) of the non-diabetics and in 7(5.3%) of the diabetics ( p = 0.01). There were no mortality or major non-procedural complications during the catheter insertions. Among patients with 1 year of follow-up data, catheter survival (93/102 [91.2%] vs 71/82 [86.6%], p = 0.32) and technique survival (93/102 [91.2%] vs 70/82 [85.4%], p = 0.22) at 1 year was comparable between diabetics and non-diabetics, respectively. Conclusions Percutaneous catheter insertion by practicing nephrologists provides a short break-in period with very low mechanical and infective complications. Non-diabetic status emerged as a significant risk factor for primary catheter non-function presumed to be due to more patients with lower BMI and thus smaller abdominal cavities. This is the first report that systematically compares diabetic and non-diabetic patients.

Background: Insulin infusion set failure resulting in prolonged hyperglycemia or diabetic ketoacidosis can occur with pump therapy in type 1 diabetes. Set failures are frequently characterized by variable and unpredictable patterns of increasing glucose values despite increased insulin infusion. Early detection may minimize the risk of prolonged hyperglycemia, an important consideration for automated insulin delivery and closed-loop applications. Methods: A novel algorithm designed to alert the patient to the onset of infusion set failure was developed based upon continuous glucose sensor values and insulin delivered from an insulin pump. The method was calibrated on 12 weeks of infusion set wear without failures recorded by 4 patients in ambulatory conditions and prospectively validated on 18 weeks of infusion set wear with and without failures belonging to 9 other subjects in ambulatory conditions. Results: The algorithm, evaluated retrospectively, identified a failure 2.52 ± 1.91 days ahead of the actual event as recorded by the clinical team, corresponding to 50% sensitivity, 66% specificity and 55% accuracy. If set failure alarms had been activated in real time, the average time >180 mg/dl would be reduced from 82.7 ± 40.9 hours/week/subject (without alarm) to 58.8 ± 31.1 hours/week/subject (with alarm), corresponding to a potential 29% reduction in time spent >180mg/dl. Conclusion: The proposed method for early detection of infusion set failure based on glucose sensor and insulin data demonstrated favorable results on retrospective data and may be implemented as an additional safeguard in a future fully automated closed-loop system.

IntroductionNeonates admitted to a neonatal intensive care unit (NICU) rely highly on intravenous (IV) therapy, for which the peripheral intravenous cannula (PIVC) is the preferred device to allow such therapies to proceed. Placement of a PIVC is a painful procedure and repeated attempts for successful insertion should therefore be limited. We aimed to quantify the incidence, complications, and factors associated with these complications.MethodsWe conducted a prospective observational study to examine PIVC-related complications in level III NICUs of two university medical centers (UMC) in The Netherlands. We performed descriptive analyses and binary logistic regression analysis to identify factors associated with PIVC complications.ResultsA total of 518 catheters were inserted in 235 infants. The first-time success rate was 45%. The predominant reason for non-elective removal due to complications was infiltration (N = 193; 67%). No significant association was found between discipline of the inserter, vein visualization device and location of the PIVC and whether or not a catheter needed to be removed due to a complication.ConclusionsIn this study the majority of PIVCs were removed after the occurrence of a complication. The most common complication was infiltration. Strategies to identify and prevent infiltration in an NICU population are required. Future interventional studies should attempt to improve first-time insertion success and reduce PIVC failure from infiltration in the neonate. Based on the results of the present study, neonatologists and physician assistants are the preferential PIVC inserters. Advanced training of all members of vascular access specialist teams and ongoing monitoring of PIVC-related complications are recommended.

Objective Even though roughly 90% of all implanted cardiac implantable electronic devices leads can be removed through conventional techniques, presence of large vegetations or thrombi, fractured leads, previous failed extraction, or long duration from implantation often impede classical transvenous extraction. In these cases, laser-assisted procedures represent a highly successful alternative and have a low procedural complication rate with major adverse events in less than 2% of cases. Unfortunately, most encountered complications are potentially fatal, which prompted us to develop a novel approach that adds additional safety measures by allowing for real-time intrathoracic visualization and intervention. Methods Five consecutive patients classified as high-risk patients received concomitant laser sheet extraction and right-sided uniportal video-assisted thoracic surgery for real-time intrathoracic visualization. Results Complete extraction was achieved in all cases without observing major intraoperative events, and on-table extubation was feasible in all cases. No chest tube-associated or incision-related complications were encountered. Conclusions Concomitant laser sheet extraction and video-assisted thoracoscopy are feasible and may offer benefits in high-risk patients. Further studies to document the actual safety and clinical value of our procedure are warranted.

Introduction Exchange procedures involve tunneled dialysis catheter (TDC) removal and exchange over a wire, using the same exit site and venotomy site. Diagnostic imaging or intervention was generally not performed in exchange procedures. Revision procedures involve placement of new TDC using the previous venotomy site and a new tunnel and exit site. The majority of revisions usually include diagnostic imaging and intervention in the central circulation if needed. Methods A retrospective single review of 70 patients who underwent 97 TDC replacements from 2010 to early 2012 because of catheter malfunction was evaluated for either infection or malfunction within 30 days of the procedure. Results There were 41 exchanges and 56 revisions out of the 97 procedures performed. There were eight infections (documented by positive blood culture) in the exchanges (19.5%) and one in the revision group (1.8%). The need for an additional procedure due to malfunction was 10 in the exchange (24.4%) and 10 (17.8%) in the revision group. Conclusions Revision is a clearly superior procedure with regard to infection and more data need to be gathered as to whether it will decrease repeat procedures.

♦ ObjectivesPeritoneal dialysis (PD) catheters are critical to the success of the technique. However, few studies provide evidence about which design helps to reduce complications. Self-locating catheters (SLCs) are used to avoid displacement of the catheter tip. The incidence of mechanical and infectious complications and catheter survival rate were assessed in Tenckhoff PD catheters.♦ DesignThe prospective randomized study compared drainage problems in 40 incident PD patients using a single-cuff SLCs and 38 patients using a single-cuff, straight Tenckhoff catheter (TC).♦ResultsNo significant differences were observed in the number of complications in the Pre period (from the insertion of the catheter to the start of the technique); however, the number of complications was lower in the SLC group during Post ( p = 0.021) and Total period ( p = 0.048). The number of problems related to catheter malfunction for each period: Pre, Post, and Total, was significantly lower with SLCs vs TCs ( p = 0.018, p = 0.001 and p = 0.003, respectively). Problems were solved more easily with SLCs, using laxatives, with less need for fluoroscopic placement and no need for surgical replacement, as opposed to the TC group: Pre (not significant), Post ( p = 0.007), and Total ( p = 0.011). Median survival was 39.6 months (30.9 – 48.3) for SLCs and 30.1 months (22.6 – 37.5) for TCs, which is not a significant difference. However, SLCs have a higher malposition-free survival rate. Multivariate logistic regression models only included the variable “type of catheter” as a predictor of malfunction during the Pre period (odds ratio [OR] = 4.154). The Post period included the variables, “type of catheter” (OR = 7.701) and “age” (OR = 1.047), and the Total period only included the variable “type of catheter” (OR = 4.487), which indicates an increased probability of malfunction with the use of TCs vs SLCs. The variables (gender, previous intra-abdominal surgery, body mass index (BMI) and diabetes mellitus) did not add predictive value to the models ( p > 0.05).♦ ConclusionThe study confirms the hypothesis that TCs have more malfunctions and a lower malposition-free survival rate than SLCs, and TCs are considered as the highest risk factor for malfunction during all study periods.

Intravascular foreign bodies can cause serious complications and catheter fracture with or without embolization is a rare, serious event. Intravascular fragments from broken catheters can be retrieved percutaneously or surgically, and should be removed as soon as possible to prevent further lethal complications. A gooseneck loop snare is the most popular device for endovascular retrieval of intravascular foreign bodies. Herein, we present the first report of successful percutaneous retrieval of a fractured catheter using a balloon.

Introduction Patients with cancer need stable venous access using central vascular devices like central venous ports and peripherally inserted central catheters that can be used for a wide range of indications. Numerous flushing protocols exist including different frequencies for catheter locking to maintain catheter patency. The aim of this retrospective study was to evaluate the incidence of lumen occlusion of central venous ports in a group of adult cancer patients, adopting a policy of locking with normal saline every three months. Methods This is a single-center retrospective observational study. During follow-up, we analyzed adult cancer patients who had undergone port insertion from January 1st, 2007 to August 31st, 2014. Flushing and locking were performed every three months with a syringe containing normal saline. Results We collected data from 381 patients with ports inserted in subclavian vein (379 patients) and in the right jugular vein (2 patients). Locking was performed during 3-monthly follow-up visits. Median follow-up was 810 days (90-2700 days). Among 381 ports, 59 were removed; the reasons for removal were: end of use (45 cases), catheter rupture (9 cases), dislocation (3 cases) and catheter-related bloodstream infection (2 cases). We had no reports of lumen occlusion. Conclusions Our data suggest that locking ports with normal saline every three months is not associated with an increased risk of lumen occlusion.

Background The relationship between bridging thrombolysis and femoral access site complications after mechanical thrombectomy remains contested. Use of a closure device could minimise bleeding complications. This study aimed to elucidate the rate of access site complications in a cohort of patients treated using an 8F groin sheath with subsequent closure using the Angio-Seal to assess safety and the impact of bridging thrombolysis on access site complication rate. Methods All patients with large vessel occlusive stroke treated between 2014 and 2017 with thrombectomy with or without bridging thrombolysis were reviewed. A prospectively acquired departmental database was used to obtain baseline data, and the radiology information and haematology reporting systems were used to record imaging or transfusion relating to subsequent access site complications. Results Seventy-five patients treated with thrombectomy alone were compared to 70 patients treated with prior intravenous thrombolysis. All had an 8F femoral sheath placed for arterial access, and all underwent attempted haemostasis with an 8F Angio-Seal. Two patients (1.14%) suffered Angio-Seal device failure necessitating manual pressure. One patient (0.6%) suffered a small femoral pseudo-aneurysm. No retroperitoneal haemorrhage, haematoma requiring transfusion, ipsilateral deep-vein thrombosis or ipsilateral acute limb ischaemia was encountered. There was no significant difference in the rate of haemorrhagic, ischaemic or infective complications between those treated with bridging thrombolysis or thrombectomy alone. Conclusion Use of the Angio-Seal closure device for 8F femoral access is safe in acute stroke patients. Intravenous thrombolysis prior to endovascular thrombectomy does not significantly alter femoral access site complication rate if this approach is used.