scholarly journals A framework of current based defibrillation improves defibrillation efficacy of biphasic truncated exponential waveform in rabbits

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Weiming Li ◽  
Jingru Li ◽  
Liang Wei ◽  
Jianjie Wang ◽  
Li Peng ◽  
...  
Keyword(s):  
Pulse Duration ◽  
Rabbit Model ◽  
Constant Current ◽  
Shock Duration ◽  
Peak Voltage ◽  
Peak Current ◽  
High Impedance ◽  
Shock Impedance ◽  
Energy Peak ◽  
The Right

AbstractDefibrillation is accomplished by the passage of sufficient current through the heart to terminate ventricular fibrillation (VF). Although current-based defibrillation has been shown to be superior to energy-based defibrillation with monophasic waveforms, defibrillators with biphasic waveforms still use energy as a therapeutic dosage. In the present study, we propose a novel framework of current-based, biphasic defibrillation grounded in transthoracic impedance (TTI) measurements: adjusting the charging voltage to deliver the desired current based on the energy setting and measured pre-shock TTI; and adjusting the pulse duration to deliver the desired energy based on the output current and intra-shock TTI. The defibrillation efficacy of current-based defibrillation was compared with that of energy-based defibrillation in a simulated high impedance rabbit model of VF. Cardiac arrest was induced by pacing the right ventricle for 60 s in 24 New Zealand rabbits (10 males). A defibrillatory shock was applied with one of the two defibrillators after 90 s of VF. The defibrillation thresholds (DFTs) at different pathway impedances were determined utilizing a 5-step up-and-down protocol. The procedure was repeated after an interval of 5 min. A total of 30 fibrillation events and defibrillation attempts were investigated for each animal. The pulse duration was significantly shorter, and the waveform tilt was much lower for the current-based defibrillator. Compared with energy-based defibrillation, the energy, peak voltage, and peak current DFT were markedly lower when the pathway impedance was > 120 Ω, but there were no differences in DFT values when the pathway impedance was between 80 and 120 Ω for current-based defibrillation. Additionally, peak voltage and the peak current DFT were significantly lower for current-based defibrillation when the pathway impedance was < 80 Ω. In sum, a framework of adjusting the charging voltage and shock duration to deliver constant energy for low impedance and constant current for high impedance via pre-shock and intra-shock impedance measurements, greatly improved the defibrillation efficacy of high impedance by lowering the energy DFT.

scholarly journals Comparative study of inflammatory response and adhesions formation after fixation of different meshes for inguinal hernia repair in rabbits

2005 ◽  
Vol 20 (5) ◽  
pp. 347-352 ◽  
Author(s):  
Alberto Goldenberg ◽  
Jacques Matone ◽  
Wagner Marcondes ◽  
Fernando Augusto Mardiros Herbella ◽  
José Francisco de Mattos Farah
Keyword(s):  
Inflammatory Response ◽  
Abdominal Wall ◽  
Peritoneal Cavity ◽  
Abdominal Cavity ◽  
Mesh Fixation ◽  
Rabbit Model ◽  
Laparoscopic Approach ◽  
Preperitoneal Space ◽  
Similar Amount ◽  
The Right

PURPOSE: Compare, in a rabbit model, the inflammatory response and adhesions formation following surgical fixation of polypropilene and Vypro mesh in the inguinal preperitoneal space. METHODS: Fourteen male New Zealand rabbits, weighing between 2.000 to 2.500 g were used. A midline incision was made and the peritoneal cavity was exposed. The 2,0X1,0 cm polypropylene mesh was fixed in the left flank and secured to the margins with 3-0 prolene in a separate pattern. In the right flank, a 2,0X1,0 cm Vypro II mesh was sewn in the same way. After the post surgical period, the animals were again anesthetized and underwent laparoscopic approach, in order to identify and evaluate adhesions degree. Both fixed prosthesis were excised bilaterally with the abdominal wall segment, including peritoneum, aponeurosis and muscle and sent to a pathologist RESULTS: Operative time ranged from 15 to 25 minutes and no difficulties in applying the mesh were found. From the 14 polypropylene meshes fixed to the intact peritoneum, 11 had adhesions to the abdominal cavity (78,6%). Concerning Vypro mesh, 12 animals developed adhesions from the 14 with mesh fixation (85,7%). Histological examination of tissues harvested revealed fibroblasts, collagen, macrophages and lymphocytes between the threads of the mesh. CONCLUSION: Polypropylene and Vypro mesh, when implanted in the peritoneal cavity of rabbits provoke similar amount of adhesions. Vypro mesh tissues had higher fibrosis resulting in better mesh incorporation to the abdominal wall.

scholarly journals Effects of bone cement filling in rabbit proximal femoral medullary cavity on distal femoral blood flow and metabolism

2018 ◽  
Vol 46 (12) ◽  
pp. 5237-5244
Author(s):  
Li-Cheng Xi ◽  
Hong-Yu Li ◽  
Ming Zhang ◽  
Si-Cheng Huang
Keyword(s):  
Blood Flow ◽  
Bone Cement ◽  
Rabbit Model ◽  
Experimental System ◽  
Medullary Cavity ◽  
Marrow Cavity ◽  
Femoral Blood Flow ◽  
Femoral Blood ◽  
The Right ◽  
Time Point

Objective A rabbit model was used to evaluate the effects of bone-cemented hip arthroplasty on distal femoral blood flow and metabolism relative to that of the non-cemented contralateral leg. Methods The marrow cavity of the right hind femur was filled with bone cement. At each of the following time points, rabbits were randomly selected to receive an injection of one dose of 99mTc-methylene diphosphonate and then immediately scanned using a gamma camera: immediately postoperatively and at 4 and 8 weeks postoperatively. A BL-410 model biofunction experimental system was used to analyze the acquired images and determine the radioactive counts of each hind leg. Results The X-ray and photographic images of the right femoral bones confirmed successful filling of the marrow cavity with bone cement. The radioactive counts were significantly lower in the experimental than control legs at each time point. The ratio of the radioactive count of the experimental to control leg increased considerably at each time point, but each ratio was <1. Conclusion Blocking the proximal femoral medullary cavity with bone cement was associated with significant lowering of the blood circulation of the femur and marrow, decreasing the distal femoral blood flow and bone metabolic rate.

Cerebral angiography using transauricular access in a rabbit model: a new technique

2020 ◽  
pp. 028418512091567
Author(s):  
Hak Jin Kim ◽  
Seon Hee Choi ◽  
So-Hyeon Kim ◽  
Yong-Woo Kim ◽  
Byung Hak Jhun ◽  
...  
Keyword(s):  
Aortic Arch ◽  
Femoral Artery ◽  
Cerebral Angiography ◽  
Guide Wire ◽  
Cerebral Arteries ◽  
Rabbit Model ◽  
Cardiac Chamber ◽  
A New Technique ◽  
The Right ◽  
Selection Of

Background Cerebral angiography in a rabbit model is widely used in the field of interventional radiology. Conventionally, the femoral artery is used for cerebral angiography in radiology departments. However, angiographic studies require surgical cutdown of the femoral artery, which is technically difficult. Purpose To evaluate a new cerebral angiography technique involving a transauricular approach in a rabbit model. Material and Methods In each of 10 rabbits, central auricular arteries were punctured in the right or left ear with a 20-gauge i.v. catheter. A microcatheter (2.0 F) with a 0.016-inch guide wire was introduced through the i.v. catheter and advanced to the aortic arch. The microcatheter and guide wire were advanced selectively into cerebral arteries and angiography was performed. Results Central auricular arteries were successfully punctured with 20-gauge i.v. catheters. After approaching the aortic arch, microcatheter tips and guide wires were advanced manually to cerebral arteries on both sides. Difficulties in selecting the carotid arteries were resolved by using a looping technique within the cardiac chamber. Microcatheter loops within the cardiac chamber disappeared or remained during artery superselection. Conclusion Transauricular cerebral angiography appears to be a feasible technique for brain or carotid intervention studies in rabbits. In addition, vertebral angiography using a transauricular approach is possible using the looping technique. Selection of carotid or vertebral arteries on each side was not difficult when the microcatheter and guide wire were looped within the cardiac chamber. The ear chosen for the initial puncture does not appear to be important.

scholarly journals A novel fusiform aneurysmal model in a rabbit carotid: a combination of pericarotid calcium chloride and elastase incubation

2015 ◽  
Vol 42 (S1) ◽  
pp. S12-S12 ◽  
Author(s):  
A Alaqeel ◽  
C Meek ◽  
J Wong ◽  
A Mitha
Keyword(s):  
Calcium Chloride ◽  
Rabbit Model ◽  
Vessel Diameter ◽  
Therapeutic Interventions ◽  
Effective Technique ◽  
New Zealand White Rabbits ◽  
Histopathological Studies ◽  
Carotid Aneurysms ◽  
The Right ◽  
Digital Subtraction Angiography Imaging

Background: The purpose of this study was to develop a novel, simple and effective model of fusiform artery aneurysms in rabbits using a combination of periaortic calcium chloride (CaCl2) and elastase incubation. Methods: Fusiform aneurysms were developed in three New Zealand White rabbits by exposing a 2 cm segment of the right carotid artery to CaCl2 (0.5 mol/L) and pancreatic porcine elastase (75 U) for 20 minutes. The left carotid was used as a control. Vessel diameter was measured by serial digital subtraction angiography imaging at weeks 2, 4 and 6. Animals were sacrificed on week 6 and histopathological studies were performed. Results: All rabbits developed a fusiform aneurysm, with an average dilation ratio of 105%±10% by week 6. No mortality was reported. Histopathological studies revealed pathological features consistent with fusiform aneurysms. Conclusions: This novel rabbit model of fusiform carotid aneurysms is the first in the literature by using a combination of periaortic CaCl2 and elastase incubation. This is a simple, reliable, and effective technique and results in a potentially valuable model for the study of fusiform aneurysms and possible therapeutic interventions, such as flow diversion.

scholarly journals Empirical Modeling of Average Cutting Speed during WEDM of Hastelloy C22

2018 ◽  
Vol 249 ◽  
pp. 02003 ◽  
Author(s):  
Bhupinder Singh ◽  
Joy Prakash Misra
Keyword(s):  
Process Parameters ◽  
Cutting Speed ◽  
Performance Measure ◽  
Empirical Modeling ◽  
Workpiece Material ◽  
Peak Current ◽  
The Right ◽  
Pulse On Time ◽  
Pulse Off Time ◽  
Wedm Process

Cutting speed (CS) is a key performance measure to achieve optimal utilization of the WEDM process. However, input process parameters of WEDM and combination of wire and workpiece material greatly hamper CS and hence productivity and machining efficiency. Therefore, it is essential to pick the right combination of parameters and wire and workpiece material to obtain better CS. In this paper, four process parameters: Pulse-on time, Pulse-off time, Spark-gap voltage, and Peak current were chosen to develop an empirical model for CS during WEDM of Hastelloy C22 to provide a guideline to the potential users of the technique. This paper describes the response surface methodology (RSM) based mathematical modeling for average cutting speed. Furthermore, analysis of variance (ANOVA) was applied to find out significant process parameters and it was depicted that pulse on time and peak current were the major parameters affecting CS.

Improved Healing of Transected Rabbit Achilles Tendon after a Single Injection of Cartilage-Derived Morphogenetic Protein-2

2003 ◽  
Vol 31 (4) ◽  
pp. 555-559 ◽  
Author(s):  
Carina Forslund ◽  
Per Aspenberg
Keyword(s):  
Achilles Tendon ◽  
Single Injection ◽  
Rabbit Model ◽  
Tendon Healing ◽  
Radiographic Examination ◽  
Morphogenetic Protein ◽  
Tendon Ruptures ◽  
The Right ◽  
Callus Size ◽  
Positive Effect

Background Achilles tendon ruptures in humans might be treated more efficiently with the help of a growth factor. Cartilage-derived morphogenetic protein-2 has been shown to induce formation of tendon-like tissue. Hypothesis Cartilage-derived morphogenetic protein-2 has a positive effect on mechanical parameters for tendon healing in a rabbit model with Achilles tendon transection. Study Design Controlled laboratory study. Methods The right Achilles tendon of 40 rabbits was transected without tendon suture. Cartilage-derived morphogenetic protein-2 (10 μg) or vehicle control (acetate buffer) was injected locally 2 hours postoperatively. All tendons were tested biomechanically at 8 and 14 days, and treated tendons were histologically and radiographically evaluated at 56 days. Results At 14 days, both failure load and stiffness of treated tendons were increased by 35%. The treated tendons had significantly larger callus size at 8 and 14 days. Histologic and radiographic examination showed no signs of ossification in the treated tendons after 56 days. Conclusions A single injection of cartilage-derived morphogenetic protein-2 led to a stronger and stiffer tendon callus than that in the controls without inducing bone formation. Clinical Relevance Similar results from a larger animal model would suggest a possible future use of cartilage-derived morphogenetic protein-2 in the treatment of human Achilles tendon ruptures.

Wire Electro Discharge Machining of Al/SiC Metal Matrix Composite

2011 ◽  
Vol 121-126 ◽  
pp. 564-567
Author(s):  
Bao Ji Ma ◽  
Yu Quan Zhu ◽  
Xiao Li Jin
Keyword(s):  
Surface Roughness ◽  
Current Pulse ◽  
Pulse Duration ◽  
Cutting Speed ◽  
Machining Performance ◽  
Peak Current ◽  
Positive Effects ◽  
Electro Discharge Machining ◽  
Input Variables ◽  
Pulse On Time

The machining characteristics of SiC/Al composite using wire electro discharge machining (WEDM) were investigated in this study. Material cutting speed and surface roughness value were adopted to evaluate the machinability. Peak current, pulse on time, pulse duration and working voltage were selected as the input variables to investigate the machining performance. Effects of input variables on the cutting speed and surface roughness were experimentally tested. Peak current, pulse on time and working voltage were confirmed to have positive effects on cutting speed and surface roughness value. Whereas the cutting speed and surface roughness value decrease with the increase of pulse duration.

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