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Prigarin, Vladimir, Dmitry Karavaev und Viktor Protasov. „The cuFFT code for N-body simulation“. Journal of Physics: Conference Series 1336 (November 2019): 012023. http://dx.doi.org/10.1088/1742-6596/1336/1/012023.
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Rosenberg, Duane, Pablo D. Mininni, Raghu Reddy und Annick Pouquet. „GPU Parallelization of a Hybrid Pseudospectral Geophysical Turbulence Framework Using CUDA“. Atmosphere 11, Nr. 2 (08.02.2020): 178. http://dx.doi.org/10.3390/atmos11020178.
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An existing hybrid MPI-OpenMP scheme is augmented with a CUDA-based fine grain parallelization approach for multidimensional distributed Fourier transforms, in a well-characterized pseudospectral fluid turbulence code. Basics of the hybrid scheme are reviewed, and heuristics provided to show a potential benefit of the CUDA implementation. The method draws heavily on the CUDA runtime library to handle memory management and on the cuFFT library for computing local FFTs. The manner in which the interfaces to these libraries are constructed, and ISO bindings utilized to facilitate platform portability, are discussed. CUDA streams are implemented to overlap data transfer with cuFFT computation. Testing with a baseline solver demonstrated significant aggregate speed-up over the hybrid MPI-OpenMP solver by offloading to GPUs on an NVLink-based test system. While the batch streamed approach provided little benefit with NVLink, we saw a performance gain of 30 % when tuned for the optimal number of streams on a PCIe-based system. It was found that strong GPU scaling is nearly ideal, in all cases. Profiling of the CUDA kernels shows that the transform computation achieves 15% of the attainable peak FlOp-rate based on a roofline model for the system. In addition to speed-up measurements for the fiducial solver, we also considered several other solvers with different numbers of transform operations and found that aggregate speed-ups are nearly constant for all solvers.
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Chilingaryan, Suren, Andrei Shkarin, Roman Shkarin, Matthias Vogelgesang und Sergey Tsapko. „Benchmark for FFT Libraries“. Applied Mechanics and Materials 756 (April 2015): 673–77. http://dx.doi.org/10.4028/www.scientific.net/amm.756.673.
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There are various vendors of FFT libraries, but there is no software available for it automatic benchmarking on all available devices. In this article an application that allows easy measure the performance and precision of various FFT libraries on the available GPUs and CPUs is presented. This application has been used to find out the fastest FFT library for NVIDIA GTX TESLA and NVIDIA GTX TITAN. The obtained results shown that the best implementation is provided by cuFFT library developed by NVIDIA.
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Galletti, Ardelio, Livia Marcellino, Raffaele Montella, Vincenzo Santopietro und Sokol Kosta. „A virtualized software based on the NVIDIA cuFFT library for image denoising: performance analysis“. Procedia Computer Science 113 (2017): 496–501. http://dx.doi.org/10.1016/j.procs.2017.08.310.
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Feng, Chunsheng, Shi Shu, Jinchao Xu und Chen-Song Zhang. „Numerical Study of Geometric Multigrid Methods on CPU-GPU Heterogeneous Computers“. Advances in Applied Mathematics and Mechanics 6, Nr. 01 (Februar 2014): 1–23. http://dx.doi.org/10.4208/aamm.2013.m87.
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AbstractThe geometric multigrid method (GMG) is one of the most efficient solving techniques for discrete algebraic systems arising from elliptic partial differential equations. GMG utilizes a hierarchy of grids or discretizations and reduces the error at a number of frequencies simultaneously. Graphics processing units (GPUs) have recently burst onto the scientific computing scene as a technology that has yielded substantial performance and energy-efficiency improvements. A central challenge in implementing GMG on GPUs, though, is that computational work on coarse levels cannot fully utilize the capacity of a GPU. In this work, we perform numerical studies of GMG on CPU-GPU heterogeneous computers. Furthermore, we compare our implementation with an efficient CPU implementation of GMG and with the most popular fast Poisson solver, Fast Fourier Transform, in the cuFFT library developed by NVIDIA.
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Ganapathy, Aravindh S., Myron S. Powell und James L. Pirkle. „Extrusion of both Superficial and Deep Cuffs of a Functional Double-Cuff Peritoneal Dialysis Catheter after Significant Weight Loss“. Case Reports in Nephrology and Dialysis 11, Nr. 2 (09.07.2021): 190–94. http://dx.doi.org/10.1159/000515049.
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Extrusion of the superficial cuff of a peritoneal dialysis (PD) catheter is an uncommon complication that may be associated with infection or malfunction. However, extrusion of both the superficial and deep cuffs of a double-cuff catheter is rare and uniformly associated with failure and peritonitis. We report a case of a presternal-type PD double-cuff catheter with extrusion of both cuffs through an abdominal exit site after 6 years of use that has remained functional, which has not been previously reported. In this case, the patient had achieved a 60-kg weight loss resulting in retraction of the subcutaneous tissue around both cuffs, while the catheter was held in place by the titanium connector between the presternal extension tubing and the inner, coiled catheter. In such special circumstances, extrusion of both cuffs may not necessitate urgent catheter removal. A review of the literature revealed previous cases of superficial cuff extrusions with catheters remaining functional but not with deep cuff extrusion.
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Komasawa, Nobuyasu, Ryosuke Mihara, Kentaro Imagawa, Kazuo Hattori und Toshiaki Minami. „Comparison of Pressure Changes by Head and Neck Position between High-Volume Low-Pressure and Taper-Shaped Cuffs: A Randomized Controlled Trial“. BioMed Research International 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/386080.
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The present study compared changes in cuff pressure by head and neck position between high-volume low-pressure (HVLP) and taper-shaped (taper) cuffs in a prospective randomized clinical trial.Methods. Forty patients were intubated using tracheal tubes with either HVLP (n=20; HVLP group) or taper-shaped (n=20; Taper group) cuffs. Initial cuff pressure was adjusted to 15, 20, or 25 cmH2O in the neutral position. Cuff pressure was evaluated after changing the head and neck positions to flexion, extension, and rotation.Results. Cuff pressure significantly increased with flexion in both HVLP and Taper groups at all initial cuff pressures. It significantly increased with extension in the HVLP group, but not in the Taper group. Cuff pressure did not significantly differ with rotation in either group and was significantly smaller in the Taper group during flexion and extension than in the HVLP group, regardless of initial cuff pressure.Conclusion. Cuff pressure changes with head and neck flexion and extension were smaller in the Taper group than in the HVLP group. Our results highlight the potential for taper cuffs to prevent excessive cuff pressure increases with positional changes in the head and neck. This trial is registered withUMIN000016119.
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Younger, Alastair S. E., Timothy P. Kalla, James A. McEwen und Kevin Inkpen. „Survey of Tourniquet Use in Orthopaedic Foot and Ankle Surgery“. Foot & Ankle International 26, Nr. 3 (März 2005): 208–17. http://dx.doi.org/10.1177/107110070502600305.
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Background: Tourniquet technique varies among foot and ankle surgeons, and to establish a standard practice guideline the current standard of care should be examined. Methods: One hundred and forty responses were received after 253 surveys were mailed to American Orthopaedic Foot and Ankle Society (AOFAS) members, concerning type of tourniquets, location, and pressures used. Results: Cuff pressures most commonly used were 301 to 350 mmHg for thigh cuffs (49% of thigh cuff users) and 201 to 250 mmHG for calf and ankle cuffs (52% of calf cuff users, 66% of ankle cuff users). A substantial number of foot and ankle surgeons who use calf and ankle cuffs frequently use pressures above 250 mmHg (41% of calf cuff users, 19% of ankle cuff users). Only 9% use limb occlusion pressure when determining cuff pressure. Conclusion: Based on the existing evidence-based literature these pressures may be higher than necessary for many patients, and increased adoption of optimal pressure setting techniques as reported in the literature may help reduce tourniquet pressures used and risk of tourniquet injury. Respondents reported experiencing or hearing reports of breakthrough bleeding, nerve injury, and skin injuries under the cuff.
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Naqvi, Shenela, Muhammad Dawood Husain, Prasad Potluri, Parthasarathi Mandal und Philip Lewis. „Pressure distribution under different types of blood pressure measurement cuffs“. Journal of Industrial Textiles 47, Nr. 1 (16.03.2016): 89–103. http://dx.doi.org/10.1177/1528083716637868.
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The principal component of any non-invasive blood pressure measurement system is an inflatable cuff. Different types of fabrics are used for inflatable cuffs construction. In this study, sphygmomanometric blood pressure measurement using inflatable cuffs was simulated in Abaqus and validated through experimental results. The purpose of the simulation is to study the effect of variation in cuff fabric geometric and mechanical properties on pressure distribution and pressure transmission during blood pressure measurement by predicting the pressure at the interface of the blood pressure cuffs and a metal cylinder. Geometric and mechanical properties of the fabrics of four different cuff types were found experimentally. Interface pressure at the cuffs and metal cylinder surface was also found experimentally using Tekscan pressure sensing system for models validation. The results of the simulation showed that the interface pressure underneath the cuffs vary with variation in geometric and mechanical properties of their fabrics. The results of the simulation were found to be in good agreement with experimental findings. This research demonstrates that the pressure distribution under the cuffs is related to the cuffs' fabric geometric and mechanical properties. This means that variation in cuffs' fabric properties could ultimately incur variations in the blood pressure values of human subjects.
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Navarro, Lais Helena Camacho, José Reinaldo Cerqueira Braz, Giane Nakamura, Rodrigo Moreira e. Lima, Fredson de Paula e. Silva und Norma Sueli Pinheiro Módolo. „Effectiveness and safety of endotracheal tube cuffs filled with air versus filled with alkalinized lidocaine: a randomized clinical trial“. Sao Paulo Medical Journal 125, Nr. 6 (November 2007): 322–28. http://dx.doi.org/10.1590/s1516-31802007000600004.
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CONTEXT AND OBJECTIVE: High intracuff pressure in endotracheal tubes (ETs) may cause tracheal lesions. The aim of this study was to evaluate the effectiveness and safety of endotracheal tube cuffs filled with air or with alkalinized lidocaine. DESIGN AND SETTING: This was a prospective clinical study at the Department of Anesthesiology, Faculdade de Medicina de Botucatu, Universidade Estadual Paulista. METHODS: Among 50 patients, ET cuff pressures were recorded before, 30, 60, 90 and 120 minutes after starting and upon ending nitrous oxide anesthesia. The patients were randomly allocated to two groups: Air, with ET cuff inflated with air to attain a cuff pressure of 20 cmH2O; and Lido, with ET cuff filled with 2% lidocaine plus 8.4% sodium bicarbonate to attain the same pressure. ET discomfort before tracheal extubation, and sore throat, hoarseness and coughing incidence were studied at the time of discharge from the post-anesthesia care unit, and sore throat and hoarseness were studied 24 hours after anesthesia. RESULTS: Pressures in Lido cuffs were significantly lower than in Air cuffs (p < 0.05). Tracheal complaints were similar for the two groups, except for lower ET discomfort and sore throat incidence after 24 hours and lower systolic arterial pressure at the time of extubation in the Lido group (p < 0.05). CONCLUSION: ET cuffs filled with alkalinized lidocaine prevented the occurrence of high cuff pressures during N2O anesthesia and reduced ET discomfort and postoperative sore throat incidence. Thus, alkalinized lidocaine-filled ET cuffs seem to be safer than conventional air-filled ET cuffs.
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Sahan, Seda, und Elif Günay Ismailoğlu. „Nurse attıtudes towards cleanıng blood pressure cuffs: profile in Turkey“. Progress in Health Sciences 11, Nr. 1 (03.06.2021): 83–87. http://dx.doi.org/10.5604/01.3001.0014.9284.
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Purpose: Presenting how blood pressure cuffs are cleaned by nurses and which disinfectant agents are used in cleaning the cuffs will allow conducting detailed studies that can establish a standard procedure for cuff cleaning. However, there is no study on the views of nurses and application procedures regarding the cleaning of blood pressure cuffs. Therefore, this study aimed to determine nurses' attitudes regarding cleaning the blood pressure cuffs in Turkey. Materials and methods: The study sample was composed of nurses working in Turkey who were invited and agreed to participate in the study from February to March 2021. This study was completed with 286 nurses with 90% power. Research data were collected online via Google Forms. Results: In the study, 64.3% of the nurses stated that the cleaning staff should be responsible for cleaning the cuffs. 29.4% reported that the cuffs were cleaned several times a month, and 20.3% stated that cuffs were cleaned only when they were infected. 52.1% reported that alcohol was used for cleaning the cuffs. Conclusions: Nurses agreed on the necessity of cuff cleaning and that the cuffs could be a source of infection when they were not cleaned. Since nurses have an important role in infection control, they should play an active role in cuff cleaning and receive training on this issue.
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Araujo, Thelma Leite de, Marcos Venicíos de Oliveira Lopes, Nirla Gomes Guedes, Tahissa Frota Cavalcante, Rafaella Pessoa Moreira und Emília Soares Chaves. „Cuff dimension for children and adolescents: a study in a northeastern Brazilian city“. Revista Latino-Americana de Enfermagem 16, Nr. 5 (Oktober 2008): 877–82. http://dx.doi.org/10.1590/s0104-11692008000500013.
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The goal of this study was to measure the arm circumferences (AC) and appropriated cuff sizes for children and adolescents and to relate these dimensions to specific age ranges. This is a cross-sectional study, developed in Fortaleza, Ceará, Brazil, with 596 people between 6 and 17 years old. The AC was measured at the midpoint between the olecranon and the acromion. The selected cuff width followed the recommended ratio of 40% the AC. The more suitable cuff sizes were 7×14 cm, 8×16 cm and 9×18 cm, at 19.8%, 26.5% and 25%, respectively. A statistically significant association between AC and age range was found in both genders, as well as between the cuff and the age range, showing that the 7×14 cm (38.9%) and 8×16 cm (29.6%) cuffs were more suitable for children, and 8×16 cm (23.7%) and 9×18 cm (36.1 %) cuffs were better for adolescents. Adequate cuffs were concluded to be different from the standard cuffs used for children and adolescents.
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Conhaim, R. L., S. J. Lai-Fook und N. C. Staub. „Sequence of perivascular liquid accumulation in liquid-inflated dog lung lobes“. Journal of Applied Physiology 60, Nr. 2 (01.02.1986): 513–20. http://dx.doi.org/10.1152/jappl.1986.60.2.513.
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The peribronchovascular interstitium of the lung is a potential space that expands in pulmonary edema with the formation of large liquid cuffs. To study the time course of cuff formation we inflated nine isolated dog lung lobes with liquid to total lung capacity, rapidly froze them in liquid N2 after inflation periods of 1–300 min, then photographed 20 blocks of each lobe at X3 magnification. From the photographs we measured the ratio of cuff area to vessel area for arteries and veins of 0.05–8 mm diam. We found that the cuff-to-vessel area ratio attained a maximum value of 3–4, which was independent of vessel size. However, the first cuffs to reach maximum size were those around vessels of 0.1–0.5 mm diam, whereas cuffs around larger vessels filled more slowly. No cuffs were visible around vessels smaller than 0.1 mm diam. After 45 min cuffs had formed around 99% of all vessels larger than 0.5 mm diam but had formed around only 38% of veins and 91% of arteries of smaller diameter. We simulated the observed rate and pattern of cuff growth using electrical analog models. The filling pattern and model analyses suggest that liquid entered the interstitium from an air space site associated with arteries of approximately 0.1–1.0 mm diam, spread to adjacent sites, and eventually reached the lobe hilum. The estimated perivascular interstitial flow resistance decreased approximately 100-fold with cuff expansion.
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Pierce, I. T., P. D. Gatehouse, E. Kalodiki, C. Lattimer, G. Geroulakos, X. Y. Xu und D. N. Firmin. „Magnetic resonance venous velocity mapping during intermittent pneumatic compression of the calf and foot“. Phlebology: The Journal of Venous Disease 27, Nr. 7 (08.12.2011): 352–59. http://dx.doi.org/10.1258/phleb.2011.011053.
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Objective Assessment and optimization of intermittent pneumatic compression (IPC) devices for prophylaxis of deep vein thrombosis has previously used duplex ultrasound. The aim was to investigate novel magnetic resonance (MR) venous velocity mapping (VM) for IPC research and development. Methods Twelve normal subjects were scanned in the supine position using realtime MR VM with sequential foot and calf IPC (120 mmHg) at 1.5 T. Measurements were taken in the popliteal vein at baseline using both cuffs and each cuff individually recording 60 seconds continuously. Temporal resolution was 310 ms per independent image, at 1 ×1 mm spatial resolution. Results Peak velocity ( Vp) measurements: baseline, Vp = 2.1 cm/second (range = 1.1–3.5); using both compression cuffs, Vp = 41.5 cm/second (18.0–58.1); calf cuff alone, Vp = 40.6 cm/second (18.1–62.2); foot cuff alone, Vp = 7.9 cm/second (4.2–15.3). Flow volume measurements per compression cycle ( F): baseline, F = 2.3 cm3 (0.5–11.4); both compression cuffs, F = 7.1 cm3 (2.5–24.6); calf cuff only, F = 7.1 cm3 (2.4–24.5); foot cuff only, F = 2.6 cm3 (0.9–10.7). The foot cuff contribution was insignificant when combined with the calf cuff ( P < 0.01). The MR venous VM results were similar to those reported elsewhere using ultrasound. Conclusion This novel technique for MR venous VM can measure the realtime variations in venous blood flow during IPC.
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Saul, L., J. Smith und W. Mook. „The safety of automatic versus manual blood pressure cuffs for patients receiving thrombolytic therapy“. American Journal of Critical Care 7, Nr. 3 (01.05.1998): 192–96. http://dx.doi.org/10.4037/ajcc1998.7.3.192.
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BACKGROUND: Patients receiving thrombolytic therapy for acute myocardial infarction require frequent monitoring of blood pressure. Historically, many nurses have been reluctant to use automatic blood pressure cuffs during thrombolytic therapy because of concern that the automatic cuffs might increase risk of bleeding. This concern is not based on research findings but on case reports, anecdotal observations, and possible myths in clinical practice. OBJECTIVE: To determine the safety of using automatic blood pressure cuffs during thrombolytic therapy in patients with acute myocardial infarction. METHODS: Ninety-six patients with acute myocardial infarction who received thrombolytic therapy (streptokinase or tissue plasminogen activator) were randomized to have blood pressure measurements obtained with either automatic or manual blood pressure cuffs. Patients were checked at least every 2 hours for purpuric lesions (petechiae, ecchymoses, or hematomas). The study ended after 24 hours of measurements or when a purpuric lesion was noted. RESULTS: We found no significant difference in frequency of purpuric lesions between patients who had blood pressure measured with a manual cuff and patients who had blood pressure measured with an automatic cuff. The most common purpuric lesions noted were ecchymoses. A significant difference was noted in the frequency of purpuric lesions depending on which thrombolytic agent was used, regardless of cuff type. CONCLUSIONS: Automatic blood pressure cuffs are as safe as manual blood pressure cuffs in patients with acute myocardial infarction who are receiving thrombolytic therapy.
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Li, J., S. J. Lai-Fook und R. L. Conhaim. „Effect of hyaluronidase on interstitial cuff and pressure response in liquid-inflated rabbit lung“. Journal of Applied Physiology 72, Nr. 4 (01.04.1992): 1261–69. http://dx.doi.org/10.1152/jappl.1992.72.4.1261.
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The sequential pattern of perivascular interstitial cuff growth was studied in liquid-inflated rabbit lungs. Degassed isolated lungs were immersed in a saline bath and inflated to 5 cmH2O transpulmonary pressure with a 3% albumin solution or 3% albumin solution containing hyaluronidase. After inflation times varying between 1 and 7 h, the lungs were frozen in liquid N2. From blocks cut from the frozen lungs, interstitial cuff cross-sectional area was measured as a function of vessel size. No cuffs were observed around vessels less than 0.1 mm diam. At all inflation times, only approximately 50% of vessels less than 0.5 mm diam had cuffs, whereas virtually all vessels greater than 0.5 mm diam had cuffs. Cuff-to-vessel area ratio increased with inflation time, reaching a maximum of 1.0–1.4 by 5 h. The time constant of cuff growth was 1 h for the albumin-inflated lungs and was independent of vessel size. The time constant was reduced by 60% in the hyaluronidase-inflated lungs. The time constant for the response in perivascular interstitial pressure measured by micropuncture near the lung hilum was 2.5 h for albumin-inflated lungs and 1.2 h for hyaluronidase-inflated lungs. Electrical analog models were used to fit the experimental data of cuff growth and to determine interstitial liquid resistance. Interstitial resistance for the albumin-inflated rabbit lungs was 2- and 24-fold greater than values estimated previously for sheep and dog lungs, respectively.
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Phillips, R. J., und T. L. Powley. „Gastric volume rather than nutrient content inhibits food intake“. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 271, Nr. 3 (01.09.1996): R766—R769. http://dx.doi.org/10.1152/ajpregu.1996.271.3.r766.
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To evaluate the separate contributions of distension and nutrient stimulation of the stomach to the inhibition of short-term food intake and, particularly, to reassess previous analyses based on the inflatable gastrointestinal cuff, four experiments were performed. Rats equipped with pyloric cuffs and indwelling gastric catheters consumed a liquid diet ad libitum. Their consumption during short-term (30 min) feeding bout was measured after gastric infusions on cuff-open and cuff-closed trials. Animals taking meals (approximately 5 ml) with cuffs closed immediately after receiving intragastric infusions of 2.5, 5, 7.5, or 10 ml of normal saline exhibited both suppression at the smallest infusion and a dose-dependent reduction across the other volumes (experiment 1). Additionally, when the test diet concentration was varied, animals with their cuffs closed consumed a constant volume, not a constant number of calories (experiment 2). Furthermore, cuff-closed animals exhibited no more suppression to 5-ml intragastric infusions of nutrients (including, on different trials, 50 and 100% Isocal diet; 10, 20, and 40% glucose; and 40% sucrose and 40% fructose) than to the same volume of saline (experiments 3 and 4). In contrast, on cuff-open trials in which gastric contents could empty into the duodenum, these same nutrient loads were more effective (except fructose) than saline in producing suppression of food intake. In summary, although both limited gastric distension with the pylorus occluded and intestinal nutrient stimulation with the cuff open effectively reduced intake, cuff-closed gastric loads of mixed macronutrients or carbohydrate solutions of 2-8 kcal, pH from 5.8 to 6.7, and osmolarities between 117 and 2,294 mosM/kg produced only the distension-based suppression generated by the same volume of saline.
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Eley, Victoria, Aaron Khoo, Christine Woods und Andre van Zundert. „Improving Accurate Blood Pressure Cuff Allocation in Patients with Obesity: A Quality Improvement Initiative“. Healthcare 9, Nr. 3 (13.03.2021): 323. http://dx.doi.org/10.3390/healthcare9030323.
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Accurate noninvasive blood pressure (NIBP) measurement requires use of an appropriately sized cuff. We aimed to improve the perioperative allocation of NIBP cuffs in patients with Class II–III obesity. In the baseline evaluation, we measured the mid-arm circumference (MAC) of 40 patients with BMI > 35 kg/m2, documenting the corresponding cuff allocated by pre-operative nurses. The intervention consisted of the introduction of cuff allocation based on MAC measurement and augmented NIBP cuff supplies. We completed a re-evaluation and evaluation of the intervention by staff survey, using 5-point Likert scales and free text comments. At baseline, the correct cuff was allocated in 9 of 40 patients (22.5%). During the intervention, education occurred in 54 (69.2%) peri-operative nursing staff. Upon re-evaluation, the correct cuff was allocated in 30 of 40 patients (75.0%), a statistically significant improvement (χ2 = 22.1, p < 0.001). Ninety-three of 120 staff surveys were returned (78%). Eleven out of 18 preoperative staff surveyed (61.1%) felt confident measuring the arm and selecting the correct cuff. Six (33%) agreed that taking the arm measurement added a lot of extra work. Equipment shortages, accuracy concerns, and clinical workarounds were reported by staff. Our intervention increased the proportion of correct cuffs allocated, but equipment and practical issues persist with NIBP cuff selection in obese patients.
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Tong, Yuxin, Jamie M. Murbach, Vivek Subramanian, Shrirang Chhatre, Francisco Delgado, David C. Martin, Kevin J. Otto, Mario Romero-Ortega und Blake N. Johnson. „A Hybrid 3D Printing and Robotic-assisted Embedding Approach for Design and Fabrication of Nerve Cuffs with Integrated Locking Mechanisms“. MRS Advances 3, Nr. 40 (2018): 2365–72. http://dx.doi.org/10.1557/adv.2018.378.
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ABSTRACTThe ability to interface electronic materials with the peripheral nervous system is required for stimulation and monitoring of neural signals. Thus, the design and engineering of robust neural interfaces that maintain material-tissue contact in the presence of material or tissue micromotion offer the potential to conduct novel measurements and develop future therapies that require chronic interface with the peripheral nervous system. However, such remains an open challenge given the constraints of existing materials sets and manufacturing approaches for design and fabrication of neural interfaces. Here, we investigated the potential to leverage a rapid prototyping approach for the design and fabrication of nerve cuffs that contain supporting features to mechanically stabilize the interaction between cuff electrodes and peripheral nerve. A hybrid 3D printing and robotic-embedding (i.e., pick-and-place) system was used to design and fabricate silicone nerve cuffs (800 µm diameter) containing conforming platinum (Pt) electrodes. We demonstrate that the electrical impedance of the cuff electrodes can be reduced by deposition of the conducting polymer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) on cuff electrodes via a post-processing electropolymerization technique. The computer-aided design and manufacturing approach was also used to design and integrate supporting features to the cuff that mechanically stabilize the interface between the cuff electrodes and the peripheral nerve. Both ‘self-locking’ and suture-assisted locking mechanisms are demonstrated based on the principle of making geometric alterations to the cuff opening via 3D printing. Ultimately, this work shows 3D printing offers considerable opportunity to integrate supporting features, and potentially even novel electronic materials, into nerve cuffs that can support the design and engineering of next generation neural interfaces.
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Morris, Lue G., Richard A. Zoumalan, J. David Roccaforte und Milan R. Amin. „Monitoring Tracheal Tube Cuff Pressures in the Intensive Care Unit: A Comparison of Digital Palpation and Manometry“. Annals of Otology, Rhinology & Laryngology 116, Nr. 9 (September 2007): 639–42. http://dx.doi.org/10.1177/000348940711600902.
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Objectives: Tracheal tube cuff overinflation is a recognized risk factor for tracheal injury and stenosis. International studies report a 55% to 62% incidence of cuff overinflation among intensive care unit (ICU) patients. However, there are no data on tracheotomy tubes, and no recent data from ICUs in the United States. It is unknown whether routine cuff pressure measurement is beneficial. We sought to determine the incidence of cuff overinflation in the contemporary American ICU. Methods: We performed an Institutional Review Board-approved, prospective, observational study of endotracheal and tracheotomy tubes at 2 tertiary-care academic hospitals that monitor cuff pressure differently. At hospital A, cuff pressures are assessed by palpation; at hospital B, cuff pressures are measured via manometry. We audited cuff pressures in an unannounced fashion at these hospitals, using a handheld aneroid manometer. Cuffs were considered overinflated above 25 cm H2O. Results: We enrolled 115 patients: 63 at hospital A and 52 at hospital B. Overall, 44 patients (38%) were found to have overinflated cuffs. The incidence of overinflation was identical at the 2 hospitals (38%; p = .99). Of the endotracheal tubes, 43% were overinflated, as were 32% of the tracheotomy tubes (p = .24). Conclusions: Despite increasing awareness among intensivists and respiratory therapists, the incidence of tracheal tube overinflation remains high, with both endotracheal and tracheotomy tubes. Our finding that the use of manometry to assess cuff pressures did not reduce the incidence of overinflation suggests that a more vigilant management protocol may be necessary.
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Russell, Stephen M., Joshua Marcus und David Levine. „PATHOGENESIS OF RAPIDLY REVERSIBLE COMPRESSIVE NEUROPATHY“. Neurosurgery 65, suppl_4 (01.10.2009): A174—A180. http://dx.doi.org/10.1227/01.neu.0000335641.17914.4c.
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Abstract OBJECTIVE Using the sequential inflation of 2 sphygmomanometers, Lewis et al. (Heart 16:1–32, 1931) concluded that compressive neuropathy was secondary to ischemia of the compressed nerve segment. Despite subsequent animal studies demonstrating that compressive lesions are more likely the result of mechanical nerve deformation, disagreement remains as to the etiology of rapidly reversible compressive neuropathy. Our hypothesis is that, during the classic sphygmomanometer experiments, the areas of nerve compression at the cuff margins overlapped, so that a region of transient nerve deformation persisted during the second cuff inflation. If true, the original results by Lewis et al. would be consistent with a mechanical pathogenesis. METHODS In our study, 6 patients underwent sequential upper extremity dual-sphygmomanometer inflation with serial assessment by grip-dynamometer and 2-point discrimination. The order of cuff inflation, as well as the distance between cuffs, was varied. Mean grip force and 2-point discrimination values were statistically compared between conditions. RESULTS Patients with overlapping cuffs maintained their neurological deficits, whereas those with separated cuffs experienced an improvement in both grip force (P = 0.02) and 2-point discrimination (P < 0.001) when cuff inflation was switched. CONCLUSION Rapidly reversible compressive neuropathy seems to be secondary to mechanical nerve deformation at the margins of the compressive force rather than the result of ischemia of the compressed nerve segment. Overlap of the mechanically deformed nerve segments likely explains why neurological deficits persisted despite sequential cuff inflation in the classic experiments by Lewis et al.
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Moe, Sonja M., Robert L. Conhaim und Stephen J. Lai-Fook. „Interstitial albumin concentration measured during growth of perivascular cuffs in liquid-filled rabbit lung“. Journal of Applied Physiology 96, Nr. 1 (Januar 2004): 283–92. http://dx.doi.org/10.1152/japplphysiol.00581.2003.
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The growth rate and albumin concentration of interstitial fluid cuffs were measured in isolated rabbit lungs inflated with albumin solution (3 g/dl) to constant airway (Paw) and vascular pressures for up to 10 h. Cuff size was measured from images of frozen lung sections, and cuff albumin concentration (Cc) was measured from the fluorescence of Evans blue labeled albumin that entered the cuffs from the alveolar space. At 5-cmH2O Paw, cuff size peaked at 1 h and then decreased by 75% in 2 h. The decreased cuff size was consistent with an osmotic absorption into the albumin solution that filled the vascular and alveolar spaces. At 15-cmH2O Paw, cuff size peaked at 0.25 h and then remained constant. Cc rose continuously at both pressures, but was greater at the higher pressure. The increasing Cc with a constant cuff size was modeled as diffusion through epithelial pores. Initial Cc-to-airway albumin concentration ratio was 0.1 at 5-cmH2O Paw and increased to 0.3 at 15 cmH2O, a behavior that indicated an increased permeability with lung inflation. Estimated epithelial reflection coefficient was 0.9 and 0.7, and equivalent epithelial pore radii were 4.5 and 6.1 nm at 5- and 15-cmH2O Paw, respectively. The initial cuff growth occurred against an albumin colloid osmotic pressure gradient because a high interstitial resistance reduced the overall epithelial-interstitial reflection coefficient to the low value of the interstitium.
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Conhaim, R. L., S. J. Lai-Fook und A. Eaton. „Sequence of interstitial liquid accumulation in liquid-inflated sheep lung lobes“. Journal of Applied Physiology 66, Nr. 6 (01.06.1989): 2659–66. http://dx.doi.org/10.1152/jappl.1989.66.6.2659.
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In the initial stages of pulmonary edema, liquid accumulates in the lung interstitium and appears as cuffs around pulmonary vessels. To determine the pattern, rate, and magnitude of cuff formation, we inflated sheep lungs to capacity with liquid (inflation pressure 19 cmH2O) for 3–300 min. After freezing the lobes in liquid N2, we measured perivascular cuff size and total perivascular volume in frozen blocks of each lobe and compared the results with previous measurements in dog lungs. Total cuff volume in sheep lungs reached a maximum value of 5% of air space volume, compared with 9% in dog lungs. In sheep lungs 94% of vessels greater than or equal to 0.5 mm diam and 16% of smaller vessels were surrounded by cuffs. In dog lungs these values were 99 and 47%, respectively. The ratio of cuff area to vessel area reached a maximum of 2.3 in sheep lungs and 3.4 in dog lungs. In an electrical analogue model designed to simulate cuff growth, estimated interstitial resistance to liquid flow was 6–15 times higher than similar estimates in dog lungs. These species differences might be the result of differences in the composition of the interstitial gel or to differences in the mechanical linkage between the lung parenchyma and vessel wall.
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Wang, Chongyang, Wei Song, Bi Chen, Xudong Liu und Yaohua He. „Exosomes Isolated From Adipose-Derived Stem Cells: A New Cell-Free Approach to Prevent the Muscle Degeneration Associated With Torn Rotator Cuffs“. American Journal of Sports Medicine 47, Nr. 13 (27.09.2019): 3247–55. http://dx.doi.org/10.1177/0363546519876323.
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Background: Fatty infiltration, inflammation, and apoptosis are common degenerative changes in patients with chronic rotator cuff tears that can lead to muscle atrophy and can even result in massive irreparable rotator cuff tears. Some data have demonstrated the proregenerative, anti-inflammatory, and anti-apoptotic properties of stem cell–derived exosomes in some orthopaedic disorders, but their effect on torn rotator cuff muscles has never been investigated. Purpose: To study the effect of exosomes isolated from human adipose-derived stem cells (ASCs-Exos) on muscle degeneration, regeneration, and biomechanical properties in a rat model of a massive rotator cuff tear (MRCT). Study Design: Controlled laboratory study. Methods: A bilateral supraspinatus and infraspinatus tenotomy was performed on rats to create an MRCT model. Forty-two rats were randomly assigned to 3 groups: the sham surgery group, the saline group (lesions treated with a saline injection), and the ASCs-Exos group (lesions treated with an ASCs-Exos injection). Wet muscle weight, fatty infiltration, inflammation, vascularization, regeneration, and biomechanical properties were evaluated at 8 and 16 weeks after surgery. Results: The results revealed that the ASCs-Exos treatment could prevent the atrophy, fatty infiltration, inflammation, and vascularization of muscles in the MRCT model ( P < .001). Additionally, the myofiber regeneration and biomechanical properties of ASCs-Exos-treated rotator cuffs were significantly elevated compared with those in the saline-treated group ( P < .001). Conclusion: This study demonstrates that ASCs-Exos can effectively decrease atrophy and degeneration and improve muscle regeneration and biomechanical properties in torn rotator cuff muscles. Clinical Relevance: ASCs-Exos can be used as a new cell-free approach to prevent the muscle degeneration associated with torn rotator cuffs and may be helpful to repair torn rotator cuffs. Nevertheless, further work needs to be done in a large animal model owing to the inherent regenerative potential possessed by rodents.
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Chen, Ruo S., Laurel O’Connor, Matthew R. Rebesco, Kara L. LaBarge, Edgar J. Remotti und Joseph C. Tennyson. „Prehospital Intubations Are Associated with Elevated Endotracheal Tube Cuff Pressures: A Cross-Sectional Study Characterizing ETT Cuff Pressures at a Tertiary Care Emergency Department“. Prehospital and Disaster Medicine 36, Nr. 3 (05.04.2021): 283–86. http://dx.doi.org/10.1017/s1049023x21000297.
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AbstractIntroduction:Emergency Medical Services (EMS) providers are trained to place endotracheal tubes (ETTs) in the prehospital setting when indicated. Endotracheal tube cuffs are traditionally inflated with 10cc of air to provide adequate seal against the tracheal lumen. There is literature suggesting that many ETTs are inflated well beyond the accepted safe pressures of 20-30cmH2O, leading to potential complications including ischemia, necrosis, scarring, and stenosis of the tracheal wall. Currently, EMS providers do not routinely check ETT cuff pressures. It was hypothesized that the average ETT cuff pressure of patients arriving at the study site who were intubated by EMS exceeds the safe pressure range of 20-30cmH2O.Objectives:While ETT cuff inflation is necessary to close the respiratory system, thus preventing air leaks and aspiration, there is evidence to suggest that over-inflated ETT cuffs can cause long-term complications. The purpose of this study is to characterize the cuff pressures of ETTs placed by EMS providers.Methods:This project was a single center, prospective observational study. Endotracheal tube cuff pressures were measured and recorded for adult patients intubated by EMS providers prior to arrival at a large, urban, tertiary care center over a nine-month period. All data were collected by respiratory therapists utilizing a cuff pressure measurement device which had a detectable range of 0-100cmH2O and was designed as a syringe. Results including basic patient demographics, cuff pressure, tube size, and EMS service were recorded.Results:In total, 45 measurements from six EMS services were included with ETT sizes ranging from 6.5-8.0mm. Mean patient age was 52.2 years (67.7% male). Mean cuff pressure was 81.8cmH2O with a range of 15 to 100 and a median of 100. The mode was 100cmH2O; 40 out of 45 (88.9%) cuff pressures were above 30cmH2O. Linear regression showed no correlation between age and ETT cuff pressure or between ETT size and cuff pressure. Two-tailed T tests did not show a significant difference in the mean cuff pressure between female versus male patients.Conclusion:An overwhelming majority of prehospital intubations are associated with elevated cuff pressures, and cuff pressure monitoring education is indicated to address this phenomenon.
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Luchtel, D. L., L. Embree, R. Guest und R. K. Albert. „Extra-alveolar veins are contiguous with, and leak fluid into, periarterial cuffs in rabbit lungs“. Journal of Applied Physiology 71, Nr. 4 (01.10.1991): 1606–13. http://dx.doi.org/10.1152/jappl.1991.71.4.1606.
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We previously observed physiological evidence that arterial and venous extra-alveolar vessels shared a common interstitial space. The purpose of the present investigation was to determine the site of this continuity to improve our understanding of interstitial fluid movement in the lung. Orange G and Evans blue dyes were added to the arterial and venous reservoirs, respectively, of excised rabbit lungs as they were placed 20 cmH2O into zone 1 (pulmonary arterial and venous pressures = 5 cmH2O, alveolar pressure = 25 cmH2O). After 10 s or 4 h the lungs were fixed by immersion in liquid N2, freeze-dried, cut into 5-mm serial slices, and examined by light macroscopy. Serial sections of 0.25–0.5 mm were subsequently examined by scanning electron microscopy. In the animals subjected to the zone 1 stress for 4 h, arterial and venous extra-alveolar vessels were surrounded by cuffs of edema. The edema ratio (cuff area divided by vessel lumen area) was greater around arteries than veins and decreased with increasing vessel size. Periarterial cuffs usually contained orange dye and frequently contained both orange and blue dye. Lymphatics containing orange or blue dye were frequently seen in periarterial cuffs. Scanning electron microscopy demonstrated that extra-alveolar veins of approximately 100 microns diameter were anatomically contiguous with arterial extra-alveolar vessel cuffs. In rabbit lungs, both arterial and venous extra-alveolar vessels (and/or alveolar corner vessels) leak fluid into perivascular cuffs surrounding arterial extra-alveolar vessels, and lymphatics located in the periarterial cuff contain fluid that originates from both the arterial and venous extra-alveolar vessels.
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Niizeki, Kyuichi. „Intramuscular pressure-induced inhibition of cardiac contraction: implications for cardiac-locomotor synchronization“. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 288, Nr. 3 (März 2005): R645—R650. http://dx.doi.org/10.1152/ajpregu.00491.2004.
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The synchronization of cardiac and locomotor rhythms has been suggested to enhance the efficiency of arterial delivery to active muscles during rhythmic exercise, but direct evidence showing such a functional role has not been provided. In this study, we tested the hypothesis that the heartbeat is coupled with intramuscular pressure (IMP) changes so as to time the delivery of blood through peripheral tissues when the IMP is lower. To this end, we developed a computer-controlled, dynamic, thigh cuff occlusion device that enables bilateral thigh cuffs to repeatedly inflate and deflate, one side after the other, to simulate rhythmic IMP changes during bipedal locomotion. Nine healthy subjects were examined, and three different occlusion pressures (50, 80, and 120 mmHg) were applied separately to the thigh cuffs of normal subjects while they were sitting. Alternate occlusions of the bilateral thigh cuffs administered at the frequency of the mean heart rate produced significant phase synchronization between the cardiac and cuff-occlusion rhythms when 120 mmHg pressure was applied. However, synchronization was not observed when the occlusion pressure was 50 or 80 mmHg. During synchronization, heartbeats were most likely to occur in phases that did not include overlap between the peak arterial flow velocity in the thigh and elevated cuff pressure. We believe that phase synchronization occurs so that the cardiac cycle is timed to deliver blood through the lower legs when IMP is not maximal. If this can be extrapolated to natural locomotion, synchronization between cardiac and locomotor activities may be associated with the improved perfusion of exercising muscles.
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Grandiere Perez, Lucia, Céline Ramanantsoa, Aurélie Beaudron, Cyril Hoche Delchet, Pascale Penn und Pauline Comacle. „Efficacy of an Ethanol-Based Hand Sanitizer for the Disinfection of Blood Pressure Cuffs“. International Journal of Environmental Research and Public Health 16, Nr. 22 (07.11.2019): 4342. http://dx.doi.org/10.3390/ijerph16224342.
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Blood pressure cuffs (BP cuffs) have been implicated in some nosocomial outbreaks. We compared the efficacy of an ethanol-based hand sanitizer (EBHS) with a detergent/disinfectant for the disinfection of BP cuffs. The inner sides of 30 BP cuffs were sampled for bacterial culture. Then, the same area was divided into halves. One half was disinfected by a detergent/disinfectant and the other was disinfected by an EBHS. The bacterial count decreased significantly with both disinfectants (p < 0.0001 compared with before disinfection). The bacterial count decrease seemed greater with the EBHS compared with the detergent/disinfectant, but the difference was not significant. Therefore, within the limits of a single application, the EBHS was an efficacious means of BP cuff disinfection. However, the repeated exposure to emollients contained in EBHS may require further studies before validating these results.
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Twardowski, Zbylut J., James W. Dobbie, Harold L. Moore, W. Kirt Nichols, John D. DeSpain, Philip C. Anderson, Ramesh Khanna, Karl D. Nolph und Tim S. LoyS. „Morphology of Peritoneal Dialysis Catheter Tunnel : Macroscopy and Light Microscopy“. Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis 11, Nr. 3 (Juli 1991): 237–51. http://dx.doi.org/10.1177/089686089101100310.
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There is scanty knowledge of the morphology of peritoneal dialysis catheter tunnels in humans, even though such knowledge may impact on peritoneal catheter design, implantation and postimplantation care. Past descriptions of catheter tunnels are based mainly on data from animal experiments. Based on these data, it has been assumed that epidermal spreading is inhibited by collagen fibers ingrown into the cuff. Our preliminary investigation indicated that this may not be the case in humans and led us to study catheter tunnel morphology in more detail. Eighteen catheter tunnels (2 -Smm of tissue around the catheters) were removed in 17 peritoneal dialysis patients. The catheters were inserted 30 to 2013 days prior to removal (median 366 days). The catheters were removed electively or because of infectious or noninfectious complications. Contrary to the observations in animals, in only 1 case did epithelium extend to the cuff with only a minimal amount of granulation tissue present at the end of a 9 mm long sinus tract. In the remaining cases, the leading edge of the epithelium always met granulation tissue 1 −14 mm from the exit, and the cuffs were found 8 33 mm from the exit. In tunnels older than 197 days, dense fibrous tissue was ingrown into the cuffs, and a dense fibrous capsule surrounded the cuff. The uninfected intercuff segment formed a pseudosheath, indistinguishable from a tendon sheath or synovial membrane. Infection in the catheter tunnel propagates through the part of the cuff adjacent to the tubing inside the capsule, suggesting that the cuff per sedoes not constitute a major barrier for spreading infection. This observation, by exclusion, infers that the beneficial role of an external cuff in decreasing exit infections is by providing firm anchorage of the catheter resulting in restriction of its piston like movement and thereby minimizing trauma and inward conveyance of outer sinus tract flora.
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Blunt, Mark C., Peter J. Young, Anita Patil und Alan Haddock. „Gel Lubrication of the Tracheal Tube Cuff Reduces Pulmonary Aspiration“. Anesthesiology 95, Nr. 2 (01.08.2001): 377–81. http://dx.doi.org/10.1097/00000542-200108000-00019.
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Background Leakage of fluid occurs along the longitudinal folds within the wall of an inflated high-volume, low-pressure cuff. Theoretically, lubrication of the cuff with a water-soluble gel might prevent aspiration by plugging the channels in the cuff wall. Pulmonary aspiration during anesthesia has been linked with postoperative pneumonia and during critical illness causes ventilator-associated pneumonia. Methods Lubricated cuffs were compared with nonlubricated cuffs for leakage of dye placed in the subglottic space to the tracheobronchial tree in a benchtop model (n = 5) and in a prospective double-blinded randomized controlled trial of anesthetized patients (n = 36). The duration of the efficacy of the lubricant was determined in a prospective open observational study of critically ill patients with tracheostomies (n = 9). Dye was detected clinically by dye coloration of secretions during tracheal suctioning. Results In the benchtop model the incidence of leakage was 0% in the lubrication group and 100% in the nonlubrication group (P < 0.01). Dye leakage in anesthetized patients was 11% in the lubrication group and 83% in the nonlubrication group (P < 0.0001). In the critically ill patients with lubricated cuffed tracheostomy tubes, leakage first occurred after a median period of 48 h (range, 24-120 h). Conclusions Cuff lubrication with a water-soluble gel reduces pulmonary aspiration in anesthetized patients. In the critically ill patient with a tracheostomy the protective effect is lost after 24-120 h.
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Lee, M. E., T. N. Thrasher, L. C. Keil und D. J. Ramsay. „Cardiac receptors, vasopressin, and corticosteroid release during arterial hypotension in dogs“. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 251, Nr. 3 (01.09.1986): R614—R620. http://dx.doi.org/10.1152/ajpregu.1986.251.3.r614.
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The relative roles of cardiopulmonary and sinoaortic baroreceptors in the regulation of vasopressin and corticosteroid release were evaluated in conscious dogs. The dogs were prepared with inflatable cuffs around either the ascending aorta, proximal to the brachiocephalic trunk, or the pulmonary artery. Inflation of the cuffs was adjusted to cause a reduction of mean systemic arterial pressure (MAP) of 0, 5, 10, 20, or 30% of control for 1 h in separate experiments. In spite of the profound systemic hypotension caused by constriction of the ascending aorta, plasma vasopressin failed to increase and corticosteroids increased only in response to a 30% decrease in MAP. In contrast, a 5% reduction in MAP during pulmonary arterial constriction increased plasma vasopressin and corticosteroid concentrations significantly. The apparent paradox in these results is correlated with different effects of the two maneuvers on left atrial pressure. Left atrial pressure increased dose dependently during inflation of the ascending aortic cuff but decreased during inflation of the pulmonary arterial cuff. In contrast, graded inflation of the pulmonary arterial cuff caused dose-dependent increases in right atrial pressure, plasma vasopressin, and corticosteroids. Therefore, we conclude that powerful inhibitory signals, arising from the left heart, can inhibit vasopressin and hypotension release in response to systemic hypotension.
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Solà, Josep, Martin Proença, Fabian Braun, Nicolas Pierrel, Yan Degiorgis, Christophe Verjus, Mathieu Lemay, Mattia Bertschi und Patrick Schoettker. „Continuous non-invasive monitoring of blood pressure in the operating room: a cuffless optical technology at the fingertip“. Current Directions in Biomedical Engineering 2, Nr. 1 (01.09.2016): 267–71. http://dx.doi.org/10.1515/cdbme-2016-0060.
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AbstractRoutine monitoring of blood pressure during general anaesthesia relies on intermittent measurements with a non-invasive brachial cuff every five minutes. This manuscript provides first experimental evidence that a physiology-based pulse wave analysis algorithm applied to optical data (as provided by a standard fingertip pulse oximeter) is capable of accurately estimating blood pressure changes in-between cuff readings. Combined with the routine use of oscillometric cuffs, the presented novel approach is a candidate technology to increase patient safety by providing beat-to-beat hemodynamic measurements without the need of invasive monitoring procedures.
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Michel, C. C. „Oxygen Diffusion in Oedematous Tissue and through Pericapillary Cuffs“. Phlebology: The Journal of Venous Disease 5, Nr. 4 (Dezember 1990): 223–30. http://dx.doi.org/10.1177/026835559000500403.
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The effect of oedema upon the diffusion of oxygen from capillary blood into the surrounding metabolizing tissue is considered in calculations based on the Krogh-Erlang model. While diffusion distances are increased in oedema, the oxygen consumption per unit volume of tissue is correspondingly reduced and the increments of capillary Po2 necessary to meet the tissue oxygen requirements are small. Pericapillary cuffs of oedema fluid would appear to have minimal effects on oxygen diffusion. It appears unlikely that pericapillary cuffs containing fibrin act as diffusion barriers to oxygen unless the fibrin molecules occupy more than half the volume of the cuff.
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Ursino, Mauro, und Cristina Cristalli. „Mathematical Modeling of Noninvasive Blood Pressure Estimation Techniques—Part II: Brachial Hemodynamics“. Journal of Biomechanical Engineering 117, Nr. 1 (01.02.1995): 117–26. http://dx.doi.org/10.1115/1.2792259.
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The main biomechanical factors which may affect the accuracy of the oscillometric method for indirect blood pressure measurement are analyzed using a new model of brachial hemodynamics. In a first stage of this work, the model has been used to reproduce some well-known responses of collapsing arteries, such as the sharp increase in compliance, and the nonlinear pressure-flow characteristic with negative dynamic resistance. In a second stage the model has been linked to the arm tissue mechanics description presented in a previous work. The final model so obtained has then been employed to analyze the pattern of the main hemodynamic quantities (pressure pulsations in the cuffs, blood volume changes, blood flow upstream and downstream of the cuffs) during deflation manoeuvres. The simulation results agree with those found in the recent literature quite well. Results indicate that the cuff pressure value for maximum pulsations exhibits a large plateau, located approximately around the mean arterial pressure. However, stiffness of wall artery, or stretching of the cuff internal surface, may significantly alter the obtained results causing a phenomena of “pseudohypertension.”
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Braz, José Reinaldo Cerqueira, Lais Helena Camacho Navarro, Ieda Harumi Takata und Paulo Nascimento Júnior. „Endotracheal tube cuff pressure: need for precise measurement“. Sao Paulo Medical Journal 117, Nr. 6 (04.11.1999): 243–47. http://dx.doi.org/10.1590/s1516-31801999000600004.
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CONTEXT: High compliance endotracheal tubes cuffs are used to prevent gas leak and also pulmonary aspiration in mechanically ventilated patients. However, the use of the usual cuff inflation volumes may cause tracheal damage. OBJECTIVE: We tested the hypothesis that endotracheal tube cuff pressures are routinely high (above 40 cmH2O) in the Post Anesthesia Care Unit (PACU) or Intensive Care Units (ICU). DESIGN: Cross-sectional study. SETTING: Post anesthesia care unit and intensive care unit. PARTICIPANTS: We measured endotracheal tubes cuff pressure in 85 adult patients, as follows: G1 (n = 31) patients from the ICU; G2 (n = 32) patients from the PACU, after anesthesia with nitrous oxide; G3 (n = 22) patients from the PACU, after anesthesia without nitrous oxide. Intracuff pressure was measured using a manometer (Mallinckrodt, USA). Gas was removed as necessary to adjust cuff pressure to 30 cmH2O. MAIN MEASUREMENTS: Endotracheal tube cuff pressure. RESULTS: High cuff pressure (> 40 cmH2O) was observed in 90.6% patients of G2, 54.8% of G1 and 45.4% of G3 (P < 0.001). The volume removed from the cuff in G2 was higher than G3 (P < 0.05). CONCLUSION: Endotracheal tubes cuff pressures in ICU and PACU are routinely high and significant higher when nitrous oxide is used. Endotracheal tubes cuff pressure should be routinely measured to minimize tracheal trauma.
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Escobar, Pamela A., Gregory M. Gressel, Gary L. Goldberg und Dennis Yi-Shin Kuo. „Delayed Presentation of Vaginal Cuff Dehiscence after Robotic Hysterectomy for Gynecologic Cancer: A Case Series and Review of the Literature“. Case Reports in Obstetrics and Gynecology 2016 (2016): 1–5. http://dx.doi.org/10.1155/2016/5296536.
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Background. Vaginal cuff dehiscence after hysterectomy has varying incidence according to surgical approach, with highest rates associated with laparoscopic surgery. Comparative data on timing of diagnosis describe a wide range of clinical presentation from weeks to years after hysterectomy. Limited reports have focused specifically on delayed presentation of vaginal cuff dehiscence.Cases. All cases of vaginal cuff dehiscence at our institution between 2005 and 2015 were collectively reviewed and three cases were identified of women who presented with cuff dehiscence greater than 180 days from index surgery. Diagnosis occurred at 342 to 461 days after operation. One patient presented with abdominal pain, a second case presented with vaginal discharge, and the third case lacked clinical symptoms altogether. Prior to diagnosis, one case received chemotherapy and external beam radiation for Stage IB1 cervical cancer and another case received external beam radiation alone for Stage II endometrioid adenocarcinoma. All cuffs were repaired vaginally with interrupted, early absorbable suture.Conclusion. Robotic total laparoscopic hysterectomy may be associated with increased risk of vaginal cuff dehiscence. Further studies are needed to determine risk factors and patient characteristics associated with delayed presentation of vaginal cuff dehiscence in robotic total hysterectomy as well as all surgical approaches.
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Keller, Christian, Joseph Brimacombe, Micheal Boehler, Alexander Loeckinger und Friedrich Puehringer. „The Influence of Cuff Volume and Anatomic Location on Pharyngeal, Esophageal, and Tracheal Mucosal Pressures with the Esophageal Tracheal Combitube“. Anesthesiology 96, Nr. 5 (01.05.2002): 1074–77. http://dx.doi.org/10.1097/00000542-200205000-00008.
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Background The authors determined the influence of cuff volume and anatomic location on pharyngeal, esophageal, and tracheal mucosal pressures for the esophageal tracheal combitube. Methods Twenty fresh cadavers were studied. Microchip sensors were attached to the anterior, lateral, and posterior surfaces of the distal and proximal cuffs of the small adult esophageal tracheal combitube. Mucosal pressure for the proximal cuff in the pharynx was measured at 0- to 100-ml cuff volume in 10-ml increments, and for the distal cuff in the esophagus and trachea were measured at 0- to 20-ml cuff volume in 2-ml increments. The proximal cuff volume to form an oropharyngeal seal of 30 cm H2O was determined. In addition, mucosal pressures for the proximal cuff in the pharynx were measured in four awake volunteers with topical anesthesia. Results There was an increase in mucosal pressure in the trachea, esophagus, and pharynx at all cuff locations with increasing volume (all: P < 0.001). Pharyngeal mucosal pressures were highest posteriorly (50-ml cuff volume: 99 +/- 62 cm H2O; 100-ml cuff volume: 255 +/- 161 cm H2O). Esophageal mucosal pressures were highest posteriorly (10-ml cuff volume: 108 +/- 55 cm H2O; 20-ml cuff volume: 269 +/- 133 cm H2O). Tracheal mucosal pressures were highest anteriorly (10-ml cuff volume: 98 +/- 53 cm H2O; 20-ml cuff volume: 236 +/- 139 cm H2O). The proximal cuff volume to obtain an oropharyngeal seal of 30 cm H2O was 47 +/- 12 ml. Pharyngeal mucosal pressures were similar for cadavers and awake volunteers. Conclusion We conclude that mucosal pressures for the esophageal tracheal combitube increase with cuff volume, are highest where the cuff is adjacent to rigid anatomic structures, and potentially exceed mucosal perfusion pressure even when cuff volumes are limited to achieving an oropharyngeal seal of 30 cm H2O.
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Bulamba, Fred, Andrew Kintu, Nodreen Ayupo, Charles Kojjo, Lameck Ssemogerere, Agnes Wabule und Arthur Kwizera. „Achieving the Recommended Endotracheal Tube Cuff Pressure: A Randomized Control Study Comparing Loss of Resistance Syringe to Pilot Balloon Palpation“. Anesthesiology Research and Practice 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/2032748.
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Background. Both under- and overinflation of endotracheal tube cuffs can result in significant harm to the patient. The optimal technique for establishing and maintaining safe cuff pressures (20–30 cmH2O) is the cuff pressure manometer, but this is not widely available, especially in resource-limited settings where its use is limited by cost of acquisition and maintenance. Therefore, anesthesia providers commonly rely on subjective methods to estimate safe endotracheal cuff pressure. This study set out to determine the efficacy of the loss of resistance syringe method at estimating endotracheal cuff pressures. Methods. This was a randomized clinical trial. We enrolled adult patients scheduled to undergo general anesthesia for elective surgery at Mulago Hospital, Uganda. Study participants were randomized to have their endotracheal cuff pressures estimated by either loss of resistance syringe or pilot balloon palpation. The pressures measured were recorded. Results. One hundred seventy-eight patients were analyzed. 66.3% (59/89) of patients in the loss of resistance group had cuff pressures in the recommended range compared with 22.5% (20/89) from the pilot balloon palpation method. This was statistically significant. Conclusion. The loss of resistance syringe method was superior to pilot balloon palpation at administering pressures in the recommended range. This method provides a viable option to cuff inflation.
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Grieff, Marvin, Elizabeth Mamo, Gina Scroggins und Alexander Kurchin. „The ‘Pull’ Technique for Removal of Peritoneal Dialysis Catheters: A Call for Re-Evaluation of Practice Standards“. Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis 37, Nr. 2 (März 2017): 225–29. http://dx.doi.org/10.3747/pdi.2016.00152.
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BackgroundThe most commonly used peritoneal dialysis (PD) catheters have silicon tubing with attached Dacron cuffs. The current standard of care for PD catheter removal is by complete surgical dissection, withdrawing both the tubing and the cuffs. The intention is to avoid infection of any residual part of the catheter. We retrospectively analyzed our results with the alternative ‘pull’ technique, by which the silicon tube is pulled out, leaving the Dacron cuffs within the abdominal wall. This technique never gained popularity due to concern that the retained cuffs would get infected.MethodsWe reviewed our experience from an 18-month period, between January 2014 and June 2015. There were 46 catheter removals in 40 patients. All the catheters were of the double-cuffed coiled Tenckhoff type (Covidien, Dublin, Ireland).ResultsOf the 46 catheter removals by the ‘pull’ technique, there was only 1 case of retained cuff infection.ConclusionsThe ‘pull’ technique is a safe method for Tenckhoff catheter removal with low risk of infection. We strongly recommend it as the procedure of choice.
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Kwon, Jieun, Ye Hyun Lee, Sae Hoon Kim, Jung Hoon Ko, Byung Kyu Park und Joo Han Oh. „Delamination Does Not Affect Outcomes After Arthroscopic Rotator Cuff Repair as Compared With Nondelaminated Rotator Cuff Tears: A Study of 1043 Consecutive Cases“. American Journal of Sports Medicine 47, Nr. 3 (10.01.2019): 674–81. http://dx.doi.org/10.1177/0363546518817764.
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Background: Limited information is available regarding the characteristics of delaminated rotator cuff tears as compared with nondelaminated tears. Furthermore, there is conflicting information regarding the effects of delamination on the anatomic healing of repaired cuffs. Purpose: To evaluate the characteristics and anatomic outcomes of delaminated rotator cuff tears in comparison with nondelaminated tears to determine whether delamination is a negative prognostic factor affecting rotator cuff repair outcomes. Study Design: Cohort study; Level of evidence, 3. Methods: Between 2010 and 2014, 1043 patients were enrolled in the study to assess the prevalence of delamination. Among them, the findings from 531 patients who underwent magnetic resonance imaging or computed tomographic arthrography at least 1 year after surgery were included to determine whether delamination was a negative prognostic factor affecting the anatomic outcomes of arthroscopic rotator cuff repair. Delamination was assessed intraoperatively and defined by distinguishable edge cleavage tearing or interstitial horizontal gap between the articular and bursal surfaces of the torn tendon. One of 3 repair techniques (modified Mason Allen, single row, or double row) was used according to tear configuration and tendon mobilization. The authors evaluated visual analog scale scores for pain and satisfaction and American Shoulder and Elbow Surgeons scores to quantify clinical outcomes. Results: The incidence of delamination was 42.9% (447 of 1043). As compared with those with nondelaminated tears, patients with delaminated tears were older ( P < .001) and had longer symptom duration ( P = .019), larger tear sizes and retractions ( P < .001 for both), higher grades of fatty infiltration of the rotator cuff muscles (all P < .001), and poorer tendon quality ( P < .001). The overall healing failure rate was 19.0% (101 of 531). In univariate analysis, the rate of healing failure for the repaired cuffs was significantly higher in the delaminated group (delaminated tears, 60 of 238, 25.2%; nondelaminated tears, 41 of 293, 14.0%; P = .001). However, results of subgroup and multivariate analyses showed that the presence of delamination was ultimately not an independent risk factor for the failure of cuff healing. Between the delaminated and nondelaminated groups, there was no significant difference in postoperative functional outcomes. Conclusion: The results suggest that delaminated rotator cuff tears might represent chronic degenerative tears of longer symptom duration, with larger tear sizes and higher grades of fatty infiltration in older patients. It appears that delamination could be a confounding factor, not an independent prognostic factor, affecting rotator cuff healing.
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Monsel, Antoine, Qin Lu, Marine Le Corre, Hélène Brisson, Charlotte Arbelot, Corinne Vezinet, Marie-Hélène Fléron et al. „Tapered-cuff Endotracheal Tube Does Not Prevent Early Postoperative Pneumonia Compared with Spherical-cuff Endotracheal Tube after Major Vascular Surgery“. Anesthesiology 124, Nr. 5 (01.05.2016): 1041–52. http://dx.doi.org/10.1097/aln.0000000000001053.
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Abstract Background Patients undergoing major vascular surgery often develop postoperative pneumonia that impacts their outcomes. Conflicting data exist concerning the potential benefit of tapered-shaped cuffs on tracheal sealing. The primary objective of this study was to assess the efficiency of a polyvinyl chloride tapered-cuff endotracheal tube at reducing the postoperative pneumonia rate after major vascular surgery. Secondary objectives were to determine its impact on microaspiration, ventilator-associated pneumonia rate, and inner cuff pressure. Methods This prospective randomized controlled study included 109 patients who were randomly assigned to receive either spherical- (standard cuff) or taper-shaped (tapered cuff) endotracheal tubes inserted after anesthesia induction and then admitted to the intensive care unit after major vascular surgery. Cuff pressure was continuously recorded over 5 h. Pepsin and α-amylase concentrations in tracheal aspirates were quantified on postoperative days 1 and 2. The primary outcome was the early postoperative pneumonia frequency. Results Comparing the tapered-cuff with standard-cuff group, respectively, postoperative pneumonia rates were comparable (42 vs. 44%, P = 0.87) and the percentage (interquartile range) of cuff-pressure time with overinflation was significantly higher (16.1% [1.5 to 50] vs. 0.6% [0 to 8.3], P = 0.01), with a 2.5-fold higher coefficient of variation (20.2 [10.6 to 29.4] vs. 7.6 [6.2 to 10.2], P < 0.001). Although microaspiration frequencies were high, they did not differ between groups. Conclusion For major vascular surgery patients, polyvinyl chloride tapered-cuff endotracheal tubes with intermittent cuff-pressure control did not lower the early postoperative pneumonia frequency and did not prevent microaspiration.
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Kho, Chye L., Mark A. Brown, Sharon L. H. Ong und George J. Mangos. „Blood pressure measurement in pregnancy: the effect of arm circumference and sphygmomanometer cuff size“. Obstetric Medicine 2, Nr. 3 (September 2009): 116–20. http://dx.doi.org/10.1258/om.2009.090017.
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This study aimed to assess the difference in blood pressure readings between the standard and large cuff and to determine if such a difference applies over a range of arm circumferences (ACs) in pregnancy. We measured blood pressure on 219 antenatal women. Six blood pressure readings were taken, three with a standard ‘adult’ and three with a ‘large’ cuff, in random order. A random zero sphygmomanometer was used by a trained observer. Women with an AC >33 cm were similar in age, gestational age and parity but were heavier and had more hypertension than those with AC ≤33 cm. There was a systematic difference between the standard and large cuff of 5–7 mmHg with little effect due to AC. We were unable to demonstrate an association between the standard and large cuff blood pressure difference and increasing blood pressure. Our study has shown that both systolic and diastolic blood pressure measurements are more dependent on the cuff size used than AC and for the individual it is difficult to predict the magnitude of effect the different cuff sizes will have on blood pressure measurements. This study has shown the presence of an average difference in blood pressure measurement between standard and large cuffs in pregnancy, and does not support the arbitrary 33 cm ‘cut-off’ recommended in guidelines for the use of a large cuff in pregnancy.
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Kwon, Oh Soo, Young Yul Kim, Ji Yoon Ha und Han Bit Kang. „Changes in Matrix Metalloproteinase and Tissue Inhibitors of Metalloproteinase in Patients with Rotator Cuff Tears“. Clinics in Shoulder and Elbow 17, Nr. 2 (01.01.2014): 64–67. http://dx.doi.org/10.5397/cise.2014.17.2.64.
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BACKGROUND: The purpose of this study was to determine whether in patients with rotator cuff tears a correlation exists between molecular changes and clinical parameters such as age, duration of symptom, range of motion, and tear size. Molecular changes of matrix metalloproteinase (MMP) and tissue inhibitor of metalloproteinase (TIMP) were assessed by measuring messenger RNA (mRNA) levels of the two proteins.METHODS: The rotator cuff tissue from was obtained from the edge of a torn tendon revealed after debridement by a motorized shaver. Using the sample of rotator cuff tissue, the reverse transcription polymerase chain reaction was performed to quantify MMP-2 and TIMP-2 mRNA expression. To determine whether mRNA levels and the clinical variables, such as age, defect size, range of motion (ROM) of shoulder, and duration of symptoms, show any correlation, Spearman's correlation coefficients were used to test for significant differences.RESULTS: There was an inverse correlation between the mRNA levels of MMP-2 and TIMP-2 from the torn rotator cuff tendons regardless of the clinical variables. However, comparison of mRNA levels versus clinical parameters such as age, defect size, range of motion and duration of symptoms revealed a number of findings. We found a significant correlation between age and mRNA levels of MMP-2 from torn cuffs (r = 0.513, p = 0.021). Further, we found a significant correlation between defect size in the full thickness tears and mRNA levels of MMP-2 (r = 0.454, p = 0.045). Conversely, no significant association between mRNA levels of MMP-2 and ROM or duration of symptom was found.CONCLUSIONS: Our results suggest that both MMP-2 and TIMP-2 may be involved in the disease process of rotator cuff tears. Although the level of mRNA expression of MMP-2 and TMP-2 remain constant in torn rotator cuffs irrespective of the clinical variables, their levels may be influenced by age and defect size, which could account to change in tendon degradation and the healing process.
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Le Souef, P. N., D. M. Hughes und L. I. Landau. „Effect of compression pressure on forced expiratory flow in infants“. Journal of Applied Physiology 61, Nr. 5 (01.11.1986): 1639–46. http://dx.doi.org/10.1152/jappl.1986.61.5.1639.
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The effect of the force of compression on expiratory flow was evaluated in 19 infants (2-13 mo of age) with respiratory illnesses of varying severity. An inflatable cuff was used to compress the chest and abdomen. Expiratory flow and volume, airway occlusion pressure, cuff pressure (Pc), and functional residual capacity were measured. Transmission of pressure from cuff to pleural space was assessed by a noninvasive occlusion technique. Close correlations (P less than 0.001) were found between Pc and the change in pleural pressure with cuff inflation (delta Ppl,c). Pressure transmission was found to vary between two cuffs of different design and between infants. Several forced expirations were then performed on each infant at various levels of delta Ppl,c. Infants with low maximal expiratory flows at low lung volumes required relatively gentle compression to achieve flow limitation and showed decreased flow for firmer compressions. Flow-volume curves in each infant tended to become more concave as delta Ppl,c increased. These findings underline the importance of knowledge of delta Ppl,c in interpreting expiratory flow-volume curves in infants.
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Vigato, Estefanie Siqueira, und José Luiz Tatagiba Lamas. „Blood pressure measurement by oscillometric and auscultatory methods in normotensive pregnant women“. Revista Brasileira de Enfermagem 72, suppl 3 (Dezember 2019): 162–69. http://dx.doi.org/10.1590/0034-7167-2018-0314.
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ABSTRACT Objective: to compare blood pressure values obtained by auscultatory and oscillometric methods in different gestational periods, considering cuff width. Method: it is a cross-sectional and quasi-experimental study approved by the Research Ethics Committee. The sample consisted of 108 low-risk pregnant women. Blood pressure measurements were performed in gestational periods of 10-14, 19-22 and 27-30 weeks. Results: The oscillometric device presented values similar to the auscultatory method in systolic blood pressure, but overestimated diastolic blood pressure. Underestimation of blood pressure occurred when using the standard width cuff rather than the correct width cuff in both measuring methods. Conclusion: Verification of brachial circumference and use of adequate cuffs in both methods are indispensable to obtain reliable blood pressure values in pregnant women. We recommend performance of additional studies to evaluate diastolic blood pressure overestimation by the Microlife 3BTO-A.
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Biebl, Matthias, Albert G. Hakaim, Luk L. Lau, W. Andrew Oldenburg, Josef Klocker, Beate Neuhauser, Ricardo Paz-Fumagalli, J. Mark McKinney und Andrew Stockland. „Use of Proximal Aortic Cuffs as an Adjunctive Procedure during Endovascular Aortic Aneurysm Repair“. Vascular 13, Nr. 1 (Januar 2005): 16–22. http://dx.doi.org/10.1258/rsmvasc.13.1.16.
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The purpose of this study was to evaluate the incidence and durability of additional proximal cuffs during endovascular abdominal aortic aneurysm repair (EVAR). A retrospective review of 90 EVAR patients was conducted. Postoperative survival, proximal sealing zone–related complications, and secondary procedures were analyzed. Additional proximal cuffs were used in 11%. Their use did not affect postoperative survival ( p = .58), type I endoleak rate (4.4%; p = .19), or the need for sealing zone–related secondary procedures (6.3%; p = .38) compared with patients without cuff placement but was related to a higher cumulative graft migration rate (2.2% overall p = .02). Two patients (2.5%; p = .79) underwent conversion to open surgery, both for proximal sealing zone–related complications. Application of proximal cuffs appears to be an effective intraoperative adjunctive procedure to achieve a proximal seal during EVAR, with favorable midterm results. However, the risk of late endograft migrations may be elevated in this group.
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Zan, Peng, Guozheng Yan, Hua Liu, Banghua Yang, Yujuan Zhao und Nianting Luo. „Biomechanical Modeling of the Rectum for the Design of a Novel Artificial Anal Sphincter“. Biomedical Instrumentation & Technology 44, Nr. 3 (01.05.2010): 257–60. http://dx.doi.org/10.2345/0899-8205-44.3.257.
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Abstract This paper discusses biomechanical issues that are related to the option of a novel artificial anal sphincter around the human rectum. The prosthesis consists of a compression cuff system inside and a reservoir cuff system outside, which is placed around the debilitated sphincter muscle. The micro-pump shifts fluid between the cuffs and thus takes over the expansion and compression function of the sphincter muscle. However, the human rectum is not a rigid pipe, and motion in it is further complicated by the fact that the bowel is susceptible to damage. With the goal of engineering a safe and reliable machine, the biomechanical properties of the in-vivo porcine rectum are studied and the tissue ischemia is analyzed.
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Conhaim, R. L. „Growth rate of perivascular cuffs in liquid-inflated dog lung lobes“. Journal of Applied Physiology 61, Nr. 2 (01.08.1986): 647–53. http://dx.doi.org/10.1152/jappl.1986.61.2.647.
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In the early stages of pulmonary edema, excess liquid leaving the pulmonary exchange vessels accumulates in the peribronchovascular interstitium where it forms large peribronchovascular cuffs. The peribronchovascular interstitium therefore acts as a reservoir to protect the air spaces from alveolar flooding. The rate of liquid accumulation and the liquid storage capacity of the cuffs determine how quickly alveolar flooding is likely to follow once edema formation has begun. To measure the rate and capacity of interstitial filling we inflated 11 isolated degassed dog lung lobes with liquid to an inflation pressure of 14 cmH2O (total lung capacity) for 1–300 min, then froze the lobes in liquid N2. We made photographs of 20 randomly selected 12 X 8-mm cross sections from each lobe and measured cuff volume from the photographs by point-counting. We found that cuff volume increased from 2.2% of air-space volume after 1 min of inflation to 9.3% after 300 min. To measure the driving pressure responsible for cuff formation we used micropipettes to measure subpleural interstitial liquid pressure at the hilum of three additional lobes. With liquid inflation pressure set to 14 cmH2O interstitial pressure rose exponentially to 11.5 cmH2O. Interstitial compliance calculated from our volume and pressure measurements equaled 0.09 ml X cmH2O–1 X g wet wt-1, a value similar to that measured in air-inflated lungs. Goldberg [Am. J. Physiol. 239 (Heart Circ. Physiol. 8): H189-H198, 1980] has likened interstitial filling to the charging of a capacitor, a process that follows a monoexponential time course.(ABSTRACT TRUNCATED AT 250 WORDS)
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Klute, Lisa, Christian Pfeifer, Isabella Weiss, Agnes Mayr, Volker Alt und Maximilian Kerschbaum. „Displacement of the Greater Tuberosity in Humeral Head Fractures Does Not only Depend on Rotator Cuff Status“. Journal of Clinical Medicine 10, Nr. 18 (14.09.2021): 4136. http://dx.doi.org/10.3390/jcm10184136.
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It is assumed that dorsocranial displacement of the greater tuberosity in humeral head fractures is caused by rotator cuff traction. The purpose of this study was to investigate the association between rotator cuff status and displacement characteristics of the greater tuberosity in four-part humeral head fractures. Computed tomography scans of 121 patients with Neer type 4 fractures were analyzed. Fatty infiltration of the supra- and infraspinatus muscles was classified according to Goutallier. Position determination of the greater tuberosity fragment was performed in both coronary and axial planes to assess the extent of dorsocranial displacement. Considering non-varus displaced fractures, the extent of the dorsocranial displacement was significantly higher in patients with mostly inconspicuous posterosuperior rotator cuff status compared to advanced fatty degenerated cuffs (cranial displacement: Goutallier 0–1: 6.4 mm ± 4.6 mm vs. Goutallier 2–4: 4.2 mm ± 3.5 mm, p = 0.020; dorsal displacement: Goutallier 0–1: 28.4° ± 32.3° vs. Goutallier 2–4: 13.1° ± 16.1°, p = 0.010). In varus displaced humeral head fractures, no correlation between the displacement of the greater tuberosity and the condition of the posterosuperior rotator cuff could be detected (p ≥ 0.05). The commonly accepted theory of greater tuberosity displacement in humeral head fractures by rotator cuff traction cannot be applied to all fracture types.
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Katsogridakis, Emmanuel, Glen Bush, Lingke Fan, Anthony A. Birch, David M. Simpson, Robert Allen, John F. Potter und Ronney B. Panerai. „Detection of Impaired Cerebral Autoregulation Improves by Increasing Arterial Blood Pressure Variability“. Journal of Cerebral Blood Flow & Metabolism 33, Nr. 4 (12.12.2012): 519–23. http://dx.doi.org/10.1038/jcbfm.2012.191.
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Although the assessment of dynamic cerebral autoregulation (CA) based on measurements of spontaneous fluctuations in arterial blood pressure (ABP) and cerebral blood flow (CBF) is a convenient and much used method, there remains uncertainty about its reliability. We tested the effects of increasing ABP variability, provoked by a modification of the thigh cuff method, on the ability of the autoregulation index to discriminate between normal and impaired CA, using hypercapnia as a surrogate for dynamic CA impairment. In 30 healthy volunteers, ABP (Finapres) and CBF velocity (CBFV, transcranial Doppler) were recorded at rest and during 5% CO2 breathing, with and without pseudo-random sequence inflation and deflation of bilateral thigh cuffs. The application of thigh cuffs increased ABP and CBFV variabilities and was not associated with a distortion of the CBFV step response estimates for both normocapnic and hypercapnic conditions ( P = 0.59 and P = 0.96, respectively). Sensitivity and specificity of CA impairment detection were improved with the thigh cuff method, with the area under the receiver–operator curve increasing from 0.746 to 0.859 ( P = 0.031). We conclude that the new method is a safe, efficient, and appealing alternative to currently existing assessment methods for the investigation of the status of CA.