Perfusion Tube Research Articles

Assessing Discomfort in American Adult Intensive Care Patients.

While in the intensive care unit, critically ill patients experience a myriad of distressing symptoms and stimuli leading to discomfort, a negative emotional and/ or physical state that arises in response to noxious stimuli. Appropriate management of these symptoms requires a distinct assessment of discomfort-causing experiences. To assess patient-reported discomfort among critically ill patients with the English-language version of the Inconforts des Patients de REAnimation questionnaire, and to explore relationships between demographic and clinical characteristics and overall discomfort score on this instrument. This study had a cross-sectional, descriptive, single-cohort design. The convenience sample consisted of alert and oriented patients aged 18 years or older who had been admitted to intensive care units at a Midwestern tertiary referral hospital and were invited to participate. An 18-item questionnaire on physiological and psychological stimuli inducing discomfort was administered once. Each item was scored from 0 to 10, with the total possible discomfort score ranging from 0 to 100. Descriptive statistics were used to analyze participants' demographic and clinical characteristics and questionnaire responses. A total of 180 patients were enrolled. The mean (SD) overall discomfort score was 32.9 (23.6). The greatest sources of discomfort were sleep deprivation (mean [SD] score, 4.0 [3.4]), presence of perfusion catheters and tubing (3.4 [2.9]), thirst (3.0 [3.3]), and pain (3.0 [3.0]). Intensive care unit patients in this study reported mild to moderate discomfort. Additional research is needed to design and test interventions based on assessment of specific discomfort-promoting stimuli to provide effective symptom management.

Improving Circulatory Support in Cases of Acute DeBakey Type I Aortic Dissection: A Novel Arterial Cannulation Approach and Its Effects on Perfusion and Minimizing Complications

Objective. Proposing a novel arterial cannulation technique for acute DeBakey type I aortic dissection with severe aortic arch and branch involvement to enhance CPB effectiveness and reduce organ malperfusion complications. Methods. The technique involves retrograde insertion of an arterial perfusion tube into the aortic arch through the left common carotid artery. Extracorporeal circulation is established, and total aortic arch replacement with deep hypothermic systemic circulation and a frozen elephant trunk stent placement are performed to restore lower body perfusion. Results. Six patients with severe aortic arch and branch involvement underwent the new arterial cannulation technique. All patients had smooth postoperative recoveries without significant complications. Conclusion. The novel arterial cannulation technique shows promise in managing acute DeBakey type I aortic dissection with extensive vascular involvement, reducing complications, and enhancing patient outcomes. Further validation with a larger patient cohort is needed to confirm its effectiveness and safety. If successful, this technique could become a valuable addition to treatment strategies for improved outcomes.

Pulse pressure loss after extracorporeal cardiopulmonary resuscitation is an independent predictor of ECMO weaning failure

To analyze the predictors of successful weaning off extracorporeal membrane oxygenation (ECMO) after extracorporeal cardiopulmonary resuscitation (ECPR). The clinical data of 56 patients with cardiac arrest who underwent ECPR in Hunan Provincial People's Hospital (the First Affiliated Hospital of Hunan Normal University) from July 2018 to September 2022 were retrospectively analyzed. According to whether ECMO was successfully weaning off, patients were divided into the successful weaning off group and the failed weaning off group. The basic data, duration of conventional cardiopulmonary resuscitation (CCPR, the time from cardiopulmonary resuscitation to ECMO), duration of ECMO, pulse pressure loss, complications, and the use of distal perfusion tube and intra-aortic balloon pump (IABP) were compared between the two groups. Univariate and multivariate Logistic regression analyses were performed to identify the risk factors for weaning failure of ECMO. Twenty-three patients (41.07%) were successfully weaned from ECMO. Compared with the successful weaning off group, patients in the failed weaning off group were older (years old: 46.7±15.6 vs. 37.8±16.8, P < 0.05), higher incidence of pulse pressure loss and ECMO complications [81.8% (27/33) vs. 21.7% (5/23), 84.8% (28/33) vs. 39.1% (9/23), both P < 0.01], and longer CCPR time (minutes: 72.3±19.5 vs. 54.4±24.6, P < 0.01), shorter duration of ECMO support (hours: 87.3±81.1 vs. 147.7±50.8, P < 0.01), and worse improvement in arterial blood pH and lactic acid (Lac) levels after ECPR support [pH: 7.1±0.1 vs. 7.3±0.1, Lac (mmol/L): 12.6±2.4 vs. 8.9±2.1, both P < 0.01]. There were no significant differences in the utilization rate of distal perfusion tube and IABP between the two groups. Univariate Logistic regression analysis showed that the factors affecting the weaning off ECMO of ECPR patients were pulse pressure loss, ECMO complications, arterial blood pH and Lac after installation [pulse pressure loss: odds ratio (OR) = 3.37, 95% confidence interval (95%CI) was 1.39-8.17, P = 0.007; ECMO complications: OR = 2.88, 95%CI was 1.11-7.45, P = 0.030; pH after installation: OR = 0.01, 95%CI was 0.00-0.16, P = 0.002; Lac after installation: OR = 1.21, 95%CI was 1.06-1.37, P = 0.003]. After adjusting for the effects of age, gender, ECMO complications, arterial blood pH and Lac after installation, and CCPR time, showed that pulse pressure loss was an independent predictor of weaning failure in ECPR patients (OR = 1.27, 95%CI was 1.01-1.61, P = 0.049). Early loss of pulse pressure after ECPR is an independent predictor of failed weaning off ECMO in ECPR patients. Strengthening hemodynamic monitoring and management after ECPR is very important for the successful weaning off ECMO in ECPR.

Chinese experts consensus on the prevention and treatment of complications caused by intraperitoneal perfusion chemotherapy for gastrointestinal tumors (2022 edition)

Peritoneal metastasis is one of the common metastasis of gastrointestinal malignancy. Intraperitoneal chemotherapy (including hyperthermic intraperitoneal chemotherapy and intraoperative intraperitoneal chemotherapy) not only can effectively increase the peritoneal drug concentration, but also can reduce side effects of systemic chemotherapy. It can significantly prolong the long term survival of patients with peritoneal metastasis and improve the quality of life. In order to standardize the popularization and application of intraperitoneal chemotherapy, relevant professional committees have formulated expert consensus on intraperitoneal chemotherapy. However, there is no systematic guidance on the prevention and treatment of related complications of intraperitoneal chemotherapy. Under the guidance of the Complications Management Committee of the Colorectal Cancer Professional Committee of the Chinese Medical Association and the Colorectal Cancer Professional Committee of the Chinese Anti-cancer Association, we organized domestic experts in relevant fields to formulate this consensus according to the procedural specifications and relevant literature reports. This consensus aims to summarize the causes of common complications of intraperitoneal chemotherapy such as pneumonia, intraperitoneal hemorrhage, fever, peritonitis, ileus, intestinal dysfunction, anastomotic bleeding, anastomotic leakage, leakage or infection of perfusion tube, nausea and vomiting, myelosuppression, hepatic or nephritic dysfunction. After repeatedly soliciting the opinions of domestic authoritative experts and their discussion and modification, a consensus was formed to provide effective reference for the prevention and treatment of complications.

Optimisation of Volume Flow Rates when Using Endovascular Shunting Techniques: An Experimental Study in Different Bench Flow Circuits

Acute tissue ischaemia may arise due to arterial emergencies or during more complex vascular procedures and may be mitigated by temporary shunting techniques. Endovascular shunting (ES) techniques enable percutaneous access and shunting from the donor artery without the need to completely interrupt the arterial flow in the donor artery. An endoshunt system may also cover longer distances than most conventional shunts. The aim was to investigate and optimise the flow rates in different endovascular shunt systems. Step 1: The flow capacity of different ES configurations was compared with the flow capacity of a 9 Fr Pruitt-Inahara shunt (PIS). An intravenous bag with 0.9% NaCl, pressurised to 90mmHg, was connected simultaneously to a PIS and to one of the tested ES configurations. The two shunt systems were then opened at the same time. The delivered fluid volumes from the shunt systems were collected and measured. The volume flow rate was subsequently calculated. Steps 2 and 3: Within a heart lung machine circuit, pressure-flow charts were constructed for the individual ES components and for the fully connected optimised endoshunt systems. The flow rate was increased in steps of 40-50 mL/min while monitoring the driving pressure, enabling the creation and comparison of the pressure-flow charts for the individually tested components. In total, seven individual inflow and outflow potential ES components were investigated with inflow and outflow diameters ranging from 6 to 15 Fr. ES systems based on standard donor introducers led to substantially lower volume flow than the corresponding PIS volume flow, whereas ES systems based on dedicated 6 or 8 Fr dialysis access introducers (Prelude Short Sheet, Merit Medical) matched PIS flow rates. The introduction of 30 cm long ¼'' perfusion tubing within the ES system did not affect volume flow for any of the tested ES configurations. Endoshunting techniques can match PIS volume flow rates over short and long distances. The achieved ES flow rate is highly dependent on the components used within the ES system.

Perfuse and Reuse: A Low-Cost Three-Dimensional-Printed Perfusion Bioreactor for Tissue Engineering.

This article describes fabrication of a customizable bioreactor, which comprises a perfusion system and coverslip-based tissue culture chamber that allow centimeter-scale vascularized or otherwise canalized tissue constructs to be maintained in weeks long static and/or perfusion culture at an exceptionally low cost, with intermittent live imaging and media sampling capabilities. The perfusion system includes a reusable polydimethylsiloxane (PDMS) lid generated from a three-dimensional (3D)-printed poly-lactic acid (PLA) mold and several lengths of perfusion tubing. The coverslip tissue culture chamber includes PDMS components built with 3D-printed PLA molds, as well as 3D-printed PLA frames and glass coverslips that house perfusable hydrogel constructs. As proof of concept, we fabricated a vascularized hydrogel construct, which was subjected to static and perfusion tissue culture, as well as flow studies using fluorescent beads and widefield fluorescent microscopy. This system can be readily reproduced, promoting the advancement of tissue engineering and regenerative medicine research.

Interprofessional veno-veno bypass simulation improved team confidence

BackgroundRarely performed procedures can cause stress and communication challenges in emergency situations. A simulation was developed to practice and improve team performance and procedural workflow when it has been determined that a liver transplant patient will need veno-veno bypass. The scenario involved a patient predetermined to need veno-veno bypass to allow team members to practice procedural workflow and communication. The simulation used a checklist outlining steps of the procedure and expected communication needed among surgeon, anesthesiologist, nurses, and perfusion team members. Perfusion and nursing supplied equipment to simulate the veno-veno bypass. Debriefing and a brief survey followed the simulation. ResultsDuring the simulation participants performed steps outlined in the checklist. During debriefing, discussion occurred regarding equipment usage, step order, time documentation, and medication use. Additional discussions occurred regarding modifying perfusion tubing and supplies. Participants rated their confidence in understanding communication (4.2), ability to work with others (4.6), knowledge of supplies (4.4), and use of closed-loop communication (4.4) on a scale of 1 (not at all confident) to 5 (extremely confident) (n = 5). ConclusionParticipants concluded going through veno-veno bypass steps was a positive experience. Surgeons acknowledged there were multiple ways to perform this procedure and agreed it should be done the same way each time for standardization. Nursing staff commented they liked reviewing equipment in a nonemergency situation. The checklist will be turned into a resource for future operating room procedures. The perfusion team made modifications to their equipment based on surgeon recommendations. Future training is planned when new members join the team.

Optimizing Different Conditions to Develop a Single Stranded Phage-Lambda DNA (λDNA) Tightrope

λDNA tightrope can be referred to as λDNA is suspended between two beads above the surface of the flow cell which allows the λDNA to be viewed extended rather than in collapse form. It is use for DNA studies such DNA repairs, but when using the normal protocol (at a velocity of 300 µl/minutes, beads size of 5 µm and concentration of 500.0 µg/ml of 1.0 λDNA) it results to multiple tightropes forming on the beads which interference with a many studies. In this study, different conditions were optimized to develop a single stranded λDNA tight rope by taking into consideration the following conditions, velocity (100 to 600), beads size (3 µm and 5µm), concentration (500.0 µg/ml, 375.0 µg/ml and 250.0 µg/ml) and time. To form the tightrope, beads were added into water in an eppendorf tube, centrifuged and sonicated before putting into the flow cell. The flow cell, syringe pump and perfusion tube were all fixed together, where ABC buffer and λDNA were put into the perfusion tube and set according to protocol to make the tightropes. YOYO-1 dye was used to stain the λDNA before using atomic force microscopy to image the tightropes, the same procedure was repeated for the different conditions and all dispense readings of the flow rate were taken at not less than 3.0 µl/minutes. λDNA on the surface of the flow cell was observed at the velocity of 100 and 200 µl/minutes for all the conditions. The optimized result was at velocity of 300µl/ml, concentration 375.0 µg/ml of 1.0 μλDNA and beads size of 3 µl which lasted for 15 minutes which gave the best result of single stranded λDNA tightrope compared to all the conditions and the normal protocol.

The effect on early renal function of various dynamic preservation strategies in a preclinical pig ischemia-reperfusion autotransplant model.

The aims of this study were to determine the most optimal timing to start machine perfusion during kidney preservation to improve early graft function and to evaluate the impact of temperature and oxygen supply during machine perfusion in a porcine ischemia-reperfusion autotransplant model. The left kidney of an approximately 40-kg female Belgian Landrace pig was exposed to 30 minutes of warm ischemia via vascular clamping and randomized to 1 of 6 study groups: (1) 22-hour static cold storage (SCS) (n = 6), (2) 22-hour hypothermic machine perfusion (HMP) (n = 6), (3) 22-hour oxygenated HMP (n = 7), (4) 20-hour HMP plus 2-hour normothermic perfusion (NP) (n = 6), (5) 20-hour SCS plus 2-hour oxygenated HMP (n = 7), and (6) 20-hour SCS plus 2-hour NP (n = 6). Graft recovery measured by serum creatinine level was significantly faster for continuous HMP preservation strategies compared with SCS alone and for all end-ischemic strategies. The active oxygenated 22-hour HMP group demonstrated a significantly faster recovery from early graft function compared with the 22-hour nonactive oxygenated HMP group. Active oxygenation was also found to be an important modulator of a faster increase in renal flow during HMP preservation. Continuous oxygenated HMP applied from the time of kidney procurement until transplant might be the best preservation strategy to improve early graft function.

Conducting Polymer Scaffolds for Hosting and Monitoring 3D Cell Culture

This work reports the design of a live‐cell monitoring platform based on a macroporous scaffold of a conducting polymer, poly(3,4‐ethylene dioxythiophene):poly(styrenesulfonate). The conducting polymer scaffolds support 3D cell cultures due to their biocompatibility and tissue‐like elasticity, which can be manipulated by inclusion of biopolymers such as collagen. Integration of a media perfusion tube inside the scaffold enables homogenous cell spreading and fluid transport throughout the scaffold, ensuring long term cell viability. This also allows for co‐culture of multiple cell types inside the scaffold. The inclusion of cells within the porous architecture affects the impedance of the electrically conducting polymer network and, thus, is utilized as an in situ tool to monitor cell growth. Therefore, while being an integral part of the 3D tissue, the conducting polymer is an active component, enhancing the tissue function, and forming the basis for a bioelectronic device with integrated sensing capability.

Pyrolysis kinetics of perfusion tubes under non-isothermal and isothermal conditions

The waste-to-energy (WTE) conversion of solid waste including perfusion tubes becomes interesting, with potential advantages of reducing the volume and mass of solid waste, and exploiting new energy sources. First, the non-isothermal pyrolysis experiments of perfusion tubes with the heating rates (β) of 5, 10, 20, 40°Cmin−1 were conducted in a thermogravimetric analyzer (TGA) under nitrogen atmosphere. The TGA results indicated that the pyrolysis temperature of perfusion tubes is mainly between 200°C and 500°C, and the pyrolysis process of perfusion tubes under non-isothermal conditions can be divided into two stages. Next, the isothermal pyrolysis experiments of perfusion tubes were carried out on a batch fluidized bed at four temperatures (850, 875, 900, 925°C), which is close to the practical pyrolysis processes of perfusion tubes. The batch fluidized bed results demonstrated that the pyrolysis process of perfusion tubes under isothermal conditions only has a rapid conversion stage, which is dissimilar to that under non-isothermal conditions (two-stage conversion). Last, the pyrolysis kinetic parameters of perfusion tubes under non-isothermal and isothermal conditions were calculated, respectively by the isoconversional methods (the Flynn–Wall–Ozawa (FWO) method and the Kissinger–Akahira–Sunose (KAS) method) and the isothermal model fitting methods. Noted that the isothermal pyrolysis kinetics of perfusion tubes were for the first time investigated according to the gas compositions at different isothermal conditions, and the contracting volume (R3) mechanism model was determined as the most probable model to describe the pyrolysis process of perfusion tubes among six potential mechanism models. The apparent activation energies of perfusion tube pyrolysis under non-isothermal conditions were between 97.81 and 209.62kJmol−1 using the FWO method and between 85.63 and 214.28kJmol−1 using the KAS method, while it was calculated as 74.54kJmol−1 under isothermal conditions. The decrease of apparent activation energy in isothermal fluidized bed experiments could be due to less limitation to external transfer of mass and heat. Overall, these results suggested that this research can provide an understanding of pyrolysis kinetics of perfusion tubes and some useful information for the design of pyrolytic processing system using perfusion tubes as feedstock.

Application of homemade vein puncture module on the practice course of 'Fundamental Nursing’

Objective To explore the application effect of homemade vein puncture (made by wast resources) module on the practice course of 'Fundamental Nursing’, so as to enhance the quality of teaching, and save expenditure. Methods We utilized the waste of silicone tube, perfusion tube and other waste resources to do homemade vein puncture practice module. Two classes of Grade 2011 nursing undergraduate students had been selected by convenient. Students of the control group underwent routine vein puncture practice, while students of the experimental group received homemade vein puncture practice module, and the the result of vein puncture practice and expenditure were compared between two groups. Results The average score of experimental group were (91.920±4.618), the success rate of puncture at first time 92.0%, while the scores were (89.040±5.087) and 68.0% in the control group (P<0.05). Conclusions The homemade vein puncture (made by waste resources) can effectively promote the practice skill of nursing students, minimize expenditure, achieve resources cycle utilization, and be benefits practice teaching. Key words: Education, nursing; Waste resources; Vein puncture module; Fundamental nursing

Lab-scale preparations of Candida albicans and dual Candida albicans–Candida glabrata biofilms on the surface of medical-grade polyvinyl chloride (PVC) perfusion tube using a modified gravity-supported free-flow biofilm incubator (GS-FFBI)

The assembly of a man-made gravity-supported free-flow biofilm incubator (GS-FFBI) was described, which was composed of a gas cushion injector and four incubators. The GS-FFBI had the characteristics of (i) a bottom-up flow direction, and (ii) lab-scale biofilm preparation without the use of a multichannel pump. Two opportunistic fungal strains, namely Candida albicans and Candida glabrata, were employed to incubate C. albicans and dual C. albicans–C. glabrata biofilms on the surface of medical-grade polyvinyl chloride perfusion tube. In terms of the results from {2, 3-bis (2-methoxy-4-nitro-5-sulfo-phenyl)-2H-tetrazolium-5-carboxanilide} (XTT) assay, dry weight measurement, colony-forming unit counting, susceptibility test, and scanning electron microscopy, it was demonstrated that GS-FFBI could form both stable single and dual Candida biofilms with no significant variations among the four incubators or the three daily incubations within 21h, and could operate for at least 96h smoothly with no contamination of stock medium. The results also indicated, for the first time, that C. albicans and C. glabrata might be co-existent competitively and symbiotically in the dual biofilms with flowing media. GS-FFBI would be a useful device to study in vitro morphological and physiological features of microbial biofilms in the medical settings.

Computational Analysis and Design of Heating Perfusion Tube

Computational Analysis and Design of Heating Perfusion Tube

Retrospective analysis of outcome data with regards to the use of Phisio®-, Bioline®- or Softline®-coated cardiopulmonary bypass circuits in cardiac surgery

Numerous cardiopulmonary bypass circuits with various coatings designed to reduce the inflammatory response and to provide better hemocompatibility are available. The aim of this study was to compare the effect of phosphorylcholine-coated, albumin-heparin-coated and synthetic polymer-coated perfusion tubing systems on patient outcome. We performed a retrospective database review of elective patients between January 1st 2010 and December 31st 2010. Demographics, preoperative, operative, postoperative data and follow-up were collected and statistically analysed. We identified 201 patients and formed three groups: Group 1 with phosphorylcholine coating (n=133), Group 2 with albumin-heparin coating (n=32) and Group 3 synthetic polymer coating (n=36). Mean age was 68 ± 11 years, additive Euroscore 5.8 ± 2.7. In-hospital outcomes were comparable between the groups without statistically significant differences. The overall 30-day and 1-year late survival were 98.5% and 96.7 ± 1.9%, respectively. Our findings suggest that in-hospital and follow-up outcomes are comparable in cardiac surgery patients after using either phosphorylcholine-coated, albumin-heparin-coated or synthetic polymer-coated circuits during cardiopulmonary bypass.

The effect of pH and concentration on alpha-methyldopa absorption in man.

An open crossover study of the absorption of alpha-methyldopa has been conducted in normal healthy adult male volunteers in whom a triple lumen perfusion tube had been placed. Three volunteers were perfused on separate occasions with 0.1 mM alpha-methyldopa at pH 4.5, 6.0 and 7.4. Three other volunteers were perfused on separate occasions with 0.1, 1.0 and 10 mM alpha-methyldopa at pH 6.0. Two additional subjects were perfused with 0.1 mM alpha-methyldopa at pH 6.0. Absorption was not a linear function of concentration above 1 mM alpha-methyldopa. There was also a weak trend toward greater absorption near pH 6.0. At higher concentrations of drug in the perfusion solution (10 vs 1 mM), the free fraction of alpha-methyldopa in plasma samples was increased significantly. Thus, although absorption of alpha-methyldopa is more efficient at lower concentrations, bioavailability may not be substantially enhanced due to increased sulphation in the gut wall. Comparison of permeabilities with previous results from our laboratories suggests the rat is a good model for predicting the behaviour of alpha-methyldopa after its oral administration to man.

A simple bypass technique for superior vena cava reconstruction☆

Superior vena cava (SVC) clamping can be required during thoracic surgery for SVC replacement or repair. In such cases, bypass techniques can be necessary to avoid hemodynamic instability, cerebral venous hypertension and hypoperfusion. Here, we report a novel and simple SVC bypass technique which does not require full systemic heparinization, specialized cannulation techniques or pumping devices and which can be applied percutaneously in the preoperative phase or intraoperatively. The preoperative shunt consisted in two Swan-Ganz catheters inserted in the jugular and femoral veins and connected by perfusion tubing with a three way stopcock. The intraoperative shunt consisted of a Pruitt(®)-catheter inserted in the left innominate vein and connected to a femoral Swan-Ganz catheter by perfusion tubing. We validated our system in seven patients undergoing SVC reconstruction. We monitored the systemic arterial blood pressures, the heart rate and vasoactive peptide requirements throughout the procedure. We also determined the neurological status and the in-hospital morbidity and mortality for each patient. Using this bypass, SVC clamping caused no hemodynamic instability, no neurological impairments and no in-hospital complications or deaths. This simple temporary SVC bypass procedure is safe and avoids hemodynamic instability and cerebral venous hypertension.

Outcomes of midterm circulatory support by left ventricular assist device implantation with descending aortic anastomosis

For some patients undergoing left ventricular assist device (LVAD) implantation, the perfusion tube is anastomosed to the descending aorta instead of the currently more prevalently used ascending aorta. Purpose of this study was to assess retrospectively the outcomes of LVAD patients with descending aortic anastomosis. Between March 2007 and March 2010, six patients underwent LVAD implantation with descending aortic anastomosis with Toyobo or Jarvik 2000 LVAD at our institute. Their average circulatory support time was 434(range 82-751)days. Both types of LVAD afforded adequate circulatory support, and inotrope treatment and mechanical ventilation were discontinued relatively early. Echocardiograms of the three patients with Jarvik 2000 LVAD revealed antegrade flow in the ascending aorta during the intermittent low-speed period. Among them, one patient developed infarction in the right brain hemisphere because of thromboembolism, whereas another patient developed pneumonia in the left lung followed by a lethal systemic infection. One patient on Toyobo LVAD support reached heart transplantation without morbidity. Another patient implanted with Toyobo LVAD, whose left ventricular function was too poor to generate forward flow through aortic valve, developed thrombus in the ascending aorta. No embolic events were observed in the organs below the diaphragm. In conclusion, descending aortic anastomosis of the perfusion tube can be used for LVAD implantation for some patients, but considerable risks of morbidities, including thromboembolic events and/or infection, should be recognized.

An optimized recording method to characterize biophysical and pharmacological properties of acid-sensing ion channel

To re-confirm and characterize the biophysical and pharmacological properties of endogenously expressed human acid-sensing ion channel 1a (hASIC1a) current in HEK293 cells with a modified perfusion methods. With cell floating method, which is separating the cultured cell from coverslip and putting the cell in front of perfusion tubing, whole cell patch clamp technique was used to record hASIC1a currents evoked by low pH external solution. Using cell floating method, the amplitude of hASIC1a currents activated by pH 5.0 in HEK293 cells is twice as large as that by the conventional method where the cells remain attached to coverslip. The time to reach peak at two different recording conditions is (21+/-5) ms and (270+/-25) ms, respectively. Inactivation time constants are (496+/-23) ms and (2284+/-120) ms, respectively. The cell floating method significantly increases the amiloride potency of block on hASIC1a [IC50 is (3.4+/-1.1) micromol/L and (2.4+/- 0.9) micromol/L, respectively]. Both recording methods have similar pH activation EC50 (6.6+/-0.6, 6.6+/-0.7, respectively). ASICs channel activation requires fast exchange of extracellular solution with the different pH values. With cell floating method, the presence of hASIC1a current was re-confirmed and the biophysical and pharmacological properties of hASIC1a channel in HEK293 cells were precisely characterized. This method could be used to study all ASICs and other ligand-gated channels that require fast extracellular solution exchange.

Airway stenosis associated with a mycotic pseudoaneurysm of the common carotid artery

A 56-year-old woman was seen who had been under hemodialysis treatment. In September 2003, the patient was sent to our hospital with fever and dyspnea, and artificial respiration was initiated. Bronchoscopy detected stenosis due to compression of the bronchus. Contrast computed tomography and angiography detected a pseudoaneurysm of the right common carotid artery. We performed emergency excision of the mycotic pseudoaneurysm, which was closed with an autologous pericardial patch. We also performed median sternotomy to obtain an adequate surgical view. A perfusion tube was inserted into the internal carotid artery. The inflammatory findings and dyspnea resolved postoperatively.