Flexible Catheter Research Articles

Soft Miniaturized Actuation and Sensing Units for Dynamic Force Control of Cardiac Ablation Catheters.

Recently, there has been active research in finding robotized solutions for the treatment of atrial fibrillation (AF) by augmenting catheter systems through the integration of force sensors at the tip. However, limited research has been aimed at providing automatic force control by also integrating actuation of the catheter tip, which can significantly enhance safety in such procedures. This article solves the demanding challenge of miniaturizing both actuation and sensing for integration into flexible catheters. Fabrication strategies are presented for a series of novel soft thick-walled cylindrical actuators, with embedded sensing using eutectic gallium-indium. The functional catheter tips have a diameter in the range of 2.6-3.6 mm and can both generate and detect forces in the range of < 0.4 N, with a bandwidth of 1-2 Hz. The deformation modeling of thick-walled cylinders with fiber reinforcement is presented in the article. An experimental setup developed for static and dynamic characterization of these units is presented. The prototyped units were validated with respect to the design specifications. The preliminary force control results indicate that these units can be used in tracking and control of contact force, which has the potential to make AF procedures much safer and more accurate.

Acute Peritoneal Dialysis in Premature Infants

This study aimed to investigate the underlying causes and outcomes of less than 1500 g birth weight infants who underwent acute peritoneal dialysis (PD). Case records of infants with birthweight less than 1500 g from January 2015 to June 2018 were reviewed. The median (range) birth weight and gestational age of the patients were 720 g (555-1055) and 26 weeks (23-27.5), respectively. Underlying factors for the development of acute kidney injury (AKI) were patent ductus arteriosus (PDA) (15 patients), necrotizing enterocolitis (NEC) (10 patients), sepsis (7 patients), asphyxia (2 patients) and hydrops fetalis (2 patients). Multifunctional 10 F flexible catheter was used for the procedure. Median PD onset time was 7 days (4.5-13.5) and median PD duration was 3 days (1.5-3.5). Overall mortality rate was 81 % (n=17). Despite high overall mortality, PD is technically feasible in very low birthweight (VLBW) and extremely low birthweight (ELBW) neonates using a multifunctional catheter.

Comparison of the new flexible tip bougie catheter and standard bougie stylet for tracheal intubation by anesthesiologists in different difficult airway scenarios: a randomized crossover trial

BackgroundIncidence of difficult endotracheal intubation ranges between 3 and 10%. Bougies have been recommended as an airway adjunct for difficult intubation, but reported success rates are variable. A new generation flexible tip bougie appears promising but was not investigated so far. We therefore compared the new flexible tip with a standard bougie in simulated normal and difficult airway scenarios, and used by experienced anesthesiologists.MethodsWe conducted a observational, randomized, cross-over simulation study. Following standardized training, experienced anesthesiologists performed endotracheal intubation using a Macintosh blade and one of the bougies in six different airway scenarios in a randomized sequence: normal airway, tongue edema, pharyngeal obstruction, manual cervical inline stabilization, cervical collar stabilization, cervical collar stabilization and pharyngeal obstruction. Overall success rate with a maximum of 3 intubation attempts was the primary endpoint. Secondary endpoints included number of intubation attempts, time to intubation and dental compression.ResultsThirty-two anesthesiologist participated in this study between January 2019 and May 2019. Overall success rate was similar for the flexible tip bougie and the standard bougie. The flexible tip bougie tended to need less intubation attempts in more difficult airway scenarios. Time to intubation was less if using the flexible tip bougie compared to the standard bougie. Reduced severity of dental compression was noted for the flexible tip bougie in difficult airway scenarios except cervical collar stabilization.ConclusionIn this simulation study of normal and difficult airways scenarios, overall success rate was similar for the flexible tip and standard bougie. Especially in more difficult airway scenarios, less intubation attempts, and less optimization maneuvers were needed if using the flexible tip bougie.Trial registrationclinicaltrials.gov Identifier: NCT03733158. 7th November 2018.

A novel noncontact detection method of surgeon's operation for a master-slave endovascular surgery robot.

Master-slave endovascular interventional surgery (EIS) robots have brought revolutionary advantages to traditional EIS, such as avoiding X-ray radiation to the surgeon and improving surgical precision and safety. However, the master controllers of most of the current EIS robots always lead to bad human-machine interaction, because of the difference in nature between the rigid operating handle and the flexible medical catheter used in EIS. In this paper, a noncontact detection method is proposed, and a novel master controller is developed to realize real-time detection of surgeon's operation without interference to the surgeon. A medical catheter is used as the operating handle. It is enabled by using FAST corner detection algorithm and optical flow algorithm to track the corner points of the continuous markers on a designed sensing pipe. A mathematical model is established to calculate the axial and rotational motion of the sensing pipe according to the moving distance of the corner points in image coordinates. A master-slave EIS robot system is constructed by integrating the proposed master controller and a developed slave robot. Surgical task performance evaluation in an endovascular evaluator (EVE) is conducted, and the results indicate that the proposed detection method breaks through the axial measuring range limitation of the previous marker-based detection method. In addition, the rotational detection error is reduced by 92.5% compared with the previous laser-based detection method. The results also demonstrate the capability and efficiency of the proposed master controller to control the slave robot for surgical task implementation. Graphical abstract A novel master controller is developed to realize real-time noncontact detection of surgeon's operation without interference to the surgeon. The master controller is used to remotely control the slave robot to implement certain surgical tasks.

Preventing peripheral intravenous catheter failure by reducing mechanical irritation

Peripheral intravenous catheter failure is a significant concern in the clinical setting. We investigated the effectiveness of care protocols, including an ultrasonographic “pre-scan” for selecting a large-diameter vein before catheterization, a “post-scan” for confirming the catheter tip position after catheterization with ultrasonography, and the use of a flexible polyurethane catheter to reduce the mechanical irritation that contributes to the incidence of catheter failure. This intervention study was a non-randomized controlled trial to investigate the effectiveness of the abovementioned care protocols, the effects of which were compared to the outcomes in the control group, which received conventional care. For both groups, participants were selected from patients in two wards at the University of Tokyo in Japan between July and November 2017. Inverse probability score-based weighted methods (IPW) using propensity score were used to estimate the effectiveness of care protocols. The primary outcome was catheter failure, which was defined as accidental and unplanned catheter removal. We used Kaplan-Meier survival curves to compare rates of time until catheter failure. We analysed 189 and 233 catheters in the intervention and control groups, respectively. In the control group, 68 catheters (29.2%) were determined to have failed, whereas, in the intervention group, only 21 catheters (11.1%) failed. There was a significant difference between each group regarding the ratio of catheter failure adjusted according to IPW (p = 0.003). The relative risk reduction of the intervention for catheter failure was 0.60 (95% CI: 0.47–0.71). Care protocols, including assessment of vein diameter, vein depth, and catheter tip location using ultrasound examination for reducing mechanical irritation is a promising method to reduce catheter failure incidence.

Flexible topological liquid diode catheter

Spontaneous and directional transport of various liquids in open and closed spaces is of great importance in various energy, water, and medical applications. Despite extensive progress in engineering diverse open surfaces to rectify liquid transport, the implementation of the diode-like liquid transport in a closed system is still rare. In this study, we present the design of flexible liquid diode catheters internally decorated with asymmetric reentrant structure that allows for the efficient and unidirectional transport of diverse liquids. We also elucidate that the hydrodynamic transport behaviors in the closed diode catheters are primarily dominated by the interplay between the surface effect and the bulk effect, which are distinctly different from those on open liquid diodes. The flexible liquid diode catheters can preserve their directional transport behaviors even under mechanical bending or twisting and under various liquids from low-surface-tension liquids, medical solutions to lubricant oils. The combination of extraordinary flexibility, durability, and stability promises the development of liquid transport devices that can work in various configurations and applications.

One-year Results of a Prospective, Multicenter, Observational Study of Thoracic Aortic Pathologies Treated with a Bare and Non-bare Stent Endograft and Dual-sheath Delivery System

Introduction: To report the results of RelayPlus (Terumo Aortic, Sunrise, FL, USA) which is CE-marked for the endovascular treatment of aneurysms of the descending thoracic aorta (DTA), aortic dissection (AD), aortic transection (AT) and penetrating aortic ulcers (PAU). This study was a postmarket surveillance requirement. The device is available in bare-stent (BS) and non-bare stent (NBS) configurations and a dual-sheath delivery system includes a flexible inner catheter. Methods: A prospective, non-randomized, observational study using a standard treatment and follow-up protocol enrolled consecutive patients treated with the device in 10 sites between January 2015 and December 2018. Standard endpoints (mortality, neurological deficits, endoleaks, all complications, migration, device integrity) are assessed at 30 days and through five years; one-year results are reported here. Results: The study enrolled 170 patients. Data from 148 patients with a mean follow-up of 379 days are reported here; mean age was 67.4 years (25−93), mostly male (n=104, 70%), 78 (52.7%) ASA ≥3. Patients were treated in 59 cases (40%) for DTA, 61 (41%) Type B AD, 16 (11%) AT, and 12 (8%) PAU. Average aneurysm diameter was 57 (28−106) mm. An average of 1.4 units was used per patent. BS or NBS was physician preference: NBS was more typical in AD (n=39, 64%) and AT (n=9, 56%). Landing was in Z0 (6%), Z1 (5%), Z2 (18%), Z3 (43%), and Z4 (28%). Revascularization of the innominate (n=1) and left subclavian (n=16) arteries were associated. There was no surgical conversion. At 30 days, mortality was 2.7%, there were no stroke, 0.6% paraplegia (n=2), no retrograde dissection and 6% type I endoleaks (7 Ia, 4 Ib). At one year, there were 2 non-TEVAR-related deaths (6 in total, all-cause mortality 4%), one type I endoleak, four type II and no conversion to open repair, migration or endograft collapse. There were 15 (10%) secondary interventions for endoleak (n=9, 6%), aneurysm expansion (n=5, 3%), and rupture (n=1, 0.6%). Average aneurysm diameter at one year was 46 (26−74) mm. Conclusion: Real world, standard clinical practice in the treatment of thoracic aortic pathologies with RelayPlus is highly predictable with a low number of units per patients and acceptable rates of mortality and reintervention in a challenging patient population. Disclosure: Nothing to disclose

3D cellular-resolution imaging in arteries using few-mode interferometry

Cross-sectional visualisation of the cellular and subcellular structures of human atherosclerosis in vivo is significant, as this disease is fundamentally caused by abnormal processes that occur at this scale in a depth-dependent manner. However, due to the inherent resolution-depth of focus tradeoff of conventional focusing optics, today’s highest-resolution intravascular imaging technique, namely, optical coherence tomography (OCT), is unable to provide cross-sectional images at this resolution through a coronary catheter. Here, we introduce an intravascular imaging system and catheter based on few-mode interferometry, which overcomes the depth of focus limitation of conventional high-numerical-aperture objectives and enables three-dimensional cellular-resolution intravascular imaging in vivo by a submillimetre diameter, flexible catheter. Images of diseased cadaver human coronary arteries and living rabbit arteries were acquired with this device, showing clearly resolved cellular and subcellular structures within the artery wall, such as individual crystals, smooth muscle cells, and inflammatory cells. The capability of this technology to enable cellular-resolution, cross-sectional intravascular imaging will make it possible to study and diagnose human coronary disease with much greater precision in the future.

Endoskopische Abtragung eines vernarbten Adenoms im Rektum mittels EndoRotor

Benign colorectal neoplasia are commonly resected using snare resection or endoscopic submucosal dissection (ESD). These methods are safe, but just the piecemeal resection in flat adenomas greater than 20 mm harbor a relevant risk of recurrence. Interventional endoscopic therapy of recurrent lesions can be challenging, even in expert hands due to a high risk of complications. While smaller, scarred recurrent adenomas less than 20 mm are suitable for endoscopic full-thickness resection, hitherto larger ones have had to be removed with more laborious, time-consuming and costly endoscopic methods, or had to undergo surgery. The EndoRotor is a novel non-diathermic resection system for benign neoplasia in the gastrointestinal tract. The tissue is aspirated into an opening at the tip of a flexible resection catheter, dissected by means of a rotating blade on the inside of the catheter and finally transported into a tissue trap. We present the case of a 79-year-old female patient with a large recurrent adenoma of a lateral-spreading tumor granular type in the rectum. Whereas a part of the adenoma could be resected with ESD, the scarred parts were not amenable to traditional endoscopic methods. By using EndoRotor, the scarred adenoma could be resected completely and without any complication. Scarred adenomas pose a challenge for interventional endoscopy. In this case study, EndoRotor proved to be a safe and viable method and a new resection option for complicated scarred rectal adenomas.

Cylindrical Transducer for Intravascular ARFI Imaging: Design and Feasibility

Intravascular acoustic radiation force impulse (IV-ARFI) imaging has the potential to identify vulnerable atherosclerotic plaques and improve clinical treatment decisions and outcomes for patients with coronary heart disease. Our long-term goal is to develop a thin, flexible catheter probe that does not require mechanical rotation to achieve high-resolution IV-ARFI imaging. In this work, we propose a novel cylindrical transducer array design for IV-ARFI imaging and investigate the feasibility of this approach. We present the construction of a 2.2-mm-long, 4.6-Fr cylindrical prototype transducer to demonstrate generating large ARFI displacements from a small toroidal beam, and we also present simulations of the proposed IV-ARFI cylindrical array design using Field II and a cylindrical finite-element model of vascular tissues and soft plaques. The prototype transducer was found to generate peak radial displacements of over [Formula: see text] in soft gelatin phantoms, and simulations demonstrate the ability of the array design to obtain ARFI images and distinguish soft plaque targets from surrounding, stiffer vessel wall tissue. These results suggest that high-resolution IV-ARFI imaging is possible using a cylindrical transducer array.

Gastroesophageal Reflux and Wheezing in Pediatry pH-metry studies

Analysis of esophageal pH is useful and recommended by specialists when the gastroesophageal reflux disease does not show specific symptoms such as chest pain or burnings, but a form of asthma and chronic cough. The investigation is performed after a mild anesthesia, inserting a thin and flexible catheter in the patient�s nostril; it reaches the esophagus, particularly the esophageal sphincter that connects the stomach to the esophagus. The catheter has a sensor that monitors the acidity level, the number of reflux episodes, their duration and the part of the esophagus reached by the acid in the stomach. Gastroesophageal reflux disease is frequently met in pediatric practice, rooting in the intrauterine life, a physiologic phenomenon in infants during the first semester of life.

New Flexible Tip Bougie catheter for difficult airway intubation. A randomized, crossover pilot study

INTRODUCTION: The ability to protect the airway is one of the basic skills that medical staff should have, especially those working within the Emergency Medical Service or Emergency Department. Endotracheal intubation under medical emergency conditions based on direct laryngoscopy is not effective enough; this effect is additionally reduced in the case of the difficult airway resulting from reduced visibility of the entrance to the glottis due to tongue or epiglottis oedema, trauma, etc. The aim of the study was to compare the intubation time and its effectiveness using two different stylets for difficult airway intubation. MATERIAL AND METHODS: The study involved 37 nurses who participated in training on advanced life support procedures. The experiment was designed as a randomized, cross-over simulation study. During the training, participants were instructed to perform endotracheal intubation using the tested intubation methods and had 20 minutes of practical training during which they were able to intubate with the tested stylets under normal airway. In the study, participants performed endotracheal intubation using a laryngoscope with a Macintosh blade and a difficult airway Bougie stylet (ONTEX, Chennai, India), or the Flexible Tip Bougie (MDSS GmbH, Hannover, Germany), which was designed to allow to guide the distal end of the anteriorly and posteriorly to facilitate entry into the larynx. RESULTS: The effectiveness of the first intubation attempt using a standard Bougie stylet was 37.8%, and that of the new Bougie stylet was 51.4% (p = 0.037). The mean intubation time was 55 s (IQR; 34–65) vs. 37 s (IQR; 25–41) (respectively, p = 0.021). The median ease of intubation was 7 (IQR; 5–9) points for a standard Bougie stylet and 5 (2.5–7) 2 points for a new Bougie stylet (p = 0.018). CONCLUSIONS: In a simulation study, the use of Flextip Bougie by nurses compared to a standard Bougie stylet was associated with higher efficacy and shorter intubation times in difficult airway.

Peripherally inserted central catheter design and material for reducing catheter failure and complications

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows: To assess the effectiveness of PICC material and design in reducing catheter failure and complications. Peripherally inserted central catheters (PICCs) are routinely inserted in adults and children who require intermediate intravascular therapy such as total parenteral nutrition (Russell 2014; Ullman 2017). PICCs are long (50 cm to 60 cm), flexible catheters usually constructed of polyurethane or silicone material. Typically inserted in the basilic, brachial or cephalic veins of the upper arm, the tip of the PICC terminates in a central vessel providing natural haemodilution of irritant infusates, such as chemotherapy. In recent decades, PICC use has increased due to perceived advantages in comparison to central venous catheters (CVCs), such as bedside placement by non‐medical staff and reduced complication profile during insertion (Bertoglio 2016; Chopra 2013a; Johansson 2013). PICCs are associated with greater patient‐reported satisfaction in adults requiring central venous access (Periard 2008). They have also been demonstrated to be a cost‐effective intervention, with the average cost of a PICC insertion estimated at USD 690 per patient (Periard 2008), compared to approximately USD 1500 for other central vascular access devices (Di Carlo 2012). However, despite these perceived benefits, PICC complications are common, with 30% of PICCs failing prior to the completion of therapy (Shen 2009; Ullman 2015).

Thymol reduces acetic acid-induced inflammatory response through inhibition of NF-kB signaling pathway in rat colon tissue.

The aim of the present study was to evaluate the anti-inflammatory effect of thymol in acetic acid-induced rat colitis through inhibiting the NF-κB signaling pathway. Colitis was induced by intra-rectal administration of 2mL of diluted acetic acid (4%) solution using a flexible plastic rubber catheter in Wistar rats. Colitis was induced on the first day and all treatments were applied 5days after the induction of colitis. Thymol was dissolved in 0.2% tween 80 in saline and administered orally at doses of 10, 30, and 100mg/kg per day. Macroscopic and histopathologic investigations were done. The expression of myeloperoxidase (MPO) and tumor necrosis factor-α (TNF-α) was determined by immunohistochemistry (IHC) assay. The protein expression level of pNF-κB p65 was measured by the Western blot technique. Treatment with thymol reduced mucosal and histological damages compared to the acetic acid group. Our results showed that thymol markedly inhibited the production of MPO and TNF-α in the colon tissue of the acetic acid-induced group. In addition, thymol decreased acetic acid-induced up-regulation of pNFκB p65 protein. The results of our study suggest that thymol exerts an anti-inflammatory effect in acetic acid-induced rat colitis by inhibiting the NF-κB signaling pathway and downregulating TNF-α and MPO expressions.

Mucosal impedance of the larynx: A technical report

IntroductionMucosal impedance testing measures changes in resistance to alternating electrical current. The purpose of this study is to establish the feasibility of mucosal impedance (MI) measurement in the pediatric larynx. MethodsA flexible plastic catheter, whose tip contains paired 2 mm mucosal impedance, is directly applied to the larynx under suspension microlaryngoscopy. Milliohms of resistance is relayed real-time from the catheter and output onto a PC. Results were obtained safely over the course of 5 min of intraoperative time for all 49 patients undergoing routine microlaryngoscopy at a tertiary care pediatric hospital. ResultsThe technique was successful in identifying MI values with reliable and reproducible results. The risk was minimal with no adverse events occurring. Impedance noise reduction was improved by the use of an aqueous gel coating on the probe and an emphasis on measurements of the interarytenoid space, which enabled the sensor rings to contact 360° of the mucosa. ConclusionLaryngeal MI can be safely and reliably performed with reproducible measurements and minimal added procedure time.

Randomized Controlled Trial of the Clinical Efficacy of Multiport Versus Uniport Wire-reinforced Flexible Catheters for Labor Epidural Analgesia

(Anesth Analg. 2018;126(2):537–544) When using epidural catheters that are not reinforced with a wire, multiport catheters provide improved epidural analgesia during labor (LEA) as compared with a single port catheter. Wire-reinforced flexible catheters, a recent advancement in epidural catheter design, have not been evaluated in this context. In the present study, the authors compared multiport and single-port wire-reinforced flexible catheters to determine whether the number of ports affects analgesia during lumbar epidural labor analgesia.

Auranofin Releasing Antibacterial and Antibiofilm Polyurethane Intravascular Catheter Coatings.

Intravascular catheter related bloodstream infections (CRBSIs) are a leading cause of hospital-acquired infections worldwide, resulting not only in the burden of cost and morbidity for patients but also in the over-consumption of medical resources for hospitals and health care organizations. In this study, a novel auranofin releasing antibacterial and antibiofilm polyurethane (PU) catheter coating was developed and investigated for future use in preventing CRBSIs. Auranofin is an antirheumatic drug with recently identified antimicrobial properties. The drug carrier, PU, acts as a barrier surrounding the antibacterial agent, auranofin, to extend the drug release profile and improve its long-term antibacterial and antibiofilm efficacy and potentially the length of catheter implantation within a patient. The PU+auranofin coatings developed here were found to be highly stretchable (exhibiting ~500% percent elongation), which is important for the compliance of the material on a flexible catheter. PU+auranofin coated catheters were able to inhibit the growth of methicillin-resistant Staphylococcus aureus (MRSA) for 8 to 26 days depending on the specific drug concentration utilized during the dip coating process. The PU+auranofin coated catheters were also able to completely inhibit MRSA biofilm formation in vitro, an effect that was not observed with auranofin or PU alone. Lastly, these coatings were found to be hemocompatible with human erythrocytes and maintain liver cell viability.

Brachytherapy utilising miniaturised X-ray tubes – clinical implementation and future applications

Electronic brachytherapy is an advanced radiation treatment technique specifically designed to deliver high doses of radiation inside or very close to the tumor-bearing tissues. Unlike the traditional radionuclide-based brachytherapy, electronic brachytherapy uses a miniaturised x-ray tube that can produce radiation when energised. Most of the electronic brachytherapy systems operate at 50 kVp, therefore posing less radiation exposure to both patients and staff when compared to the standard Cobalt-60 or Iridium-192 based brachytherapy systems. Electronic brachytherapy systems have broader applications that include the treatment of skin, brain, breast, spinal metastasis, endometrium, and cervix. The Axxent Xoft brachytherapy system is a unique system which houses a miniature X-ray tube of 2.25 mm diameter at the tip of a flexible catheter. As a mobile unit, the Xoft system requires less shielding and can be operated in remote centres with minimal radiation shielding facilities. The dose fall-off characteristics mimic those of the low energy isotopes, yet the unit still maintains the high dose rate property of an Ir-192 source. This study details the implementation and commissioning aspects of the Axxent system for intra-operative radiotherapy in Breast Cancer and future applications. Electronic brachytherapy systems have the potential to replace conventional radionuclide-based brachytherapy sources and systems.

Urgent start peritoneal dialysis.

Although historically peritoneal dialysis was widely used in nephrology, it has been underutilized in recent years. In this review, we present several key opportunities and strategies for revitalization of urgent start peritoneal dialysis use, and discuss the recent literature on clinical experience with peritoneal dialysis use in the acute and unplanned setting. Interest in using urgent start peritoneal dialysis to manage acute kidney injury (AKI) and unplanned chronic kidney disease (CKD) stage 5 patients has been increasing. To overcome some of the classic limitations of peritoneal dialysis use in AKI, such as a high chance of infectious and mechanical complications, and no control of urea, the use of cycles, flexible catheters, and a high volume of dialysis fluid has been proposed. This knowledge can be used in the case of an unplanned start on chronic peritoneal dialysis, and may be a tool to increase the peritoneal dialysis penetration rate among incident patients starting chronic dialysis therapy. Peritoneal dialysis should be offered in an unbiased way to all patients starting unplanned dialysis, and without contraindications to peritoneal dialysis. It may be a feasible, well tolerated, and complementary alternative to hemodialysis, not only in the chronic setting, but also in the acute.

Michele troya and flexible urethral catheters in XVIII century

Michele troya and flexible urethral catheters in XVIII century