Block Failure Research Articles

P1807Manifestations and outcome of cardiac sarcoidosis - does gender matter?

Abstract Background Sarcoidosis is characterized by the formation of inflammatory epithelioid-cell granulomas in various organs with cardiac involvement as its most ominous manifestation. A female preponderance in the prevalence of cardiac sarcoidosis (CS) is well known but other possible gender differences remain poorly studied. Purpose We set out to evaluate gender-related differences in the manifestations and long-term outcome of CS. Methods We reviewed the history, diagnostic procedures, details of treatment and outcome of 158 consecutive patients with histologically confirmed CS diagnosis between 1988 and 2017 at our hospital. Follow-up data were collected up to the end of 2018. Results The study population consisted of 51 men and 107 women (68%). At presentation, men were younger than women (mean age 47 years vs 51 years, p=0.045) and had more often a history of pre-existing extracardiac sarcoidosis (25% vs 10%, p=0.013). Isolated CS remained less common in men even after the complete diagnostic process (50% vs 75%, p=0.001). The main presenting CS manifestations were atrioventricular block, ventricular tachyarrhythmias and heart failure in 39%, 30% and 18% of men vs in 54%, 23% and 17% of women, respectively (p=0.183). Left ventricular ejection fraction at presentation averaged 49±11% in men and 49±13% in women (p=0.845). Troponin T was elevated more often in men at the presentation (46% vs 26%, p=0.024). At magnetic resonance imaging, pathological myocardial late gadolinium enhancement was observed in 87% of men and 84% of women (p=0.615). Myocardial “hot spot” at 18-F fluorodeoxyglucose positron emission tomography was also equally common (87% in men, 92% in women, p=0.468). An intracardiac cardioverter-defibrillator was implanted in 78% of men and 75% of women (p=0.693) and nearly all patients (99%, no gender difference) received immunosuppressive therapy. During the mean follow-up of 64 months, 10 of 51 men versus 30 of 107 women either died of a cardiac cause, suffered an aborted sudden cardiac death or underwent transplantation. The composite event-free survival did not differ between genders (Figure 1. Log-rank p=0.852). Conclusions Two thirds of CS patients are women. At disease presentation, women are older than men and their sarcoidosis is more often isolated to the heart but the clinical manifestations, diagnostic findings and long-term outcome are comparable in the two genders.

Stability analysis and design of stabilization measures for Chenab railway bridge rock slopes

This article presents the challenges encountered during the stability analysis and stabilization of two Himalayan rock slopes supporting the Chenab Railway Bridge in India, which will be the highest railway bridge in the world after completion. Owing to the importance of the project, extensive geological investigations, in situ and laboratory tests were carried out using conventional and advanced methods to evaluate various intact rock, rock joints, rock mass properties and rock mass quality present at the site. Once the conclusive results were made regarding these properties, stability of slopes were evaluated against both structurally controlled and stress-controlled failures using the developed probabilistic approach due to the presence of high variability in intact rock, rock mass and rock joints properties. It was observed that while the slopes were stable against stress-controlled failures, the possibility of structurally controlled failures exists as observed in the probabilistic approach in which the conventional deterministic approach was not able to detect. Different stabilization measures, i.e. rock bolts, slope flattening, grouting, drainage and shotcreting, were designed at the site to reduce the probability of failures for the slopes, deformability of rocks present due to cavities and high aperture joints, shallow block failures along the slope surface and pore-pressure build-up. To check the efficiency of the stabilization measures, cross-hole seismic tomography is carried out at the site and further in situ measured displacements are compared with the displacements estimated using the developed probabilistic approach. The case study used in this paper is a real-time ongoing bridge project of global interest and the data and analysis presented will be of great benefit to the researchers and practitioners working on similar problems.

Setting and solving the game confrontation problem of the hardware-redundant dynamic system with an attacking enemy operating under incomplete information in the conflict process

The game task of confrontation of the attacked hardware-redundant dynamic system with an attacking enemy operating in conditions of incomplete information about the behavior of the attacked enemy in the process of conflict was posed and solved numerically and analytically.The attacking party aspires to increase the intensity of the failures of the components of the attacked system at the expense of its attack resources, up to its total failure. The attacked party, due to the corresponding strategy of redistribution of reserve blocks of the hardware-redundant dynamic system between the failed main blocks at the appropriate instants of time, strives to maximize the probability of failure-free operation of the attacked system at the end of the confrontation (game) with the attacking enemy.Behavior of the system under attack in the process of conflict is approximated by the Markov process, and the number of operable states is equal to the number of failed functional blocks that do not exceed the number of standby blocks. As a payment function in the game in question, the probability of failure-free operation of the attacked system is used by the time the game ends. The solution of the game is the vector of the system setup moments after the corresponding failures of the functional blocks and the set of reservation vectors corresponding to the instantaneous settings of the system being attacked, which maximizes the probability of system failure during the conflict.The differential game model is reduced to a multi-step matrix model with given probabilities of the states of the attacking enemy. Numerical algorithms for calculating the vector of reservation for the attacked system that maximizes the probability of its trouble-free operation by the end of the game and for solving the game problem in question are presented in a form convenient for implementation on a personal computer.

EFFECTIVENESS OF CAUDAL EPIDURAL ANAESTHESIA IN ANORECTAL SURGERY.

Objectives: To assess the effectiveness of caudal epidural anaesthesia in patients with anorectal surgical condition. Study Design: Prospective randomized study. Setting: Department of Surgery, Jinnah Hospital, Lahore. Period: 1st August 2016 to 31st July 2017. Materials and Methods: One hundred and eighty patients with general anorectal surgical conditions were recruited in this study with their consent. Patients were subject to surgery planned beneath caudal block. Results: One hundred and fifty eight patients (87%) satisfy with the technique of anaesthesia and one hundred sixty six (92.22%) patients demonstrate satisfaction with the postoperative pain control. One hundred and fifty two patients (84.44%) were resisted with pre-operative information and 158 (87%) patients show their consent to select this kind of anaesthesia if needed again. In 20 patients there was block failure caused about 11.11% failure rate. Conclusion: Satisfactory anaesthesia, minimal requirements, cost effectiveness and high patients acceptability make caudal anaesthesia a suitable choice for trivial and surgery.

Regional anaesthesia is associated with less patient satisfaction compared to general anaesthesia following distal upper extremity surgery: a prospective double centred observational study

BackgroundPatient satisfaction is a well-established indicator to evaluate the quality of medical care and there is an increasing support for the use of patient-reported experience measures (PREMs) to evaluate satisfaction. To anesthetize the upper limb for surgery, both general and regional plexus anaesthesia are appropriate techniques. However, the best technique in the anaesthesiologist’s perspective might not necessarily result in the highest patient satisfaction. The aim of this study is to investigate patient satisfaction following general and regional anaesthesia, and to identify areas where anaesthesiologists can focus on improving patient care.MethodsPatients scheduled for elective distal upper extremity surgery under either general or regional plexus anaesthesia were prospectively included. On the first postoperative day, patient satisfaction and main reason for dissatisfaction with the anaesthesia technique were investigated during a telephone interview.ResultsOf the 243 patients included in the current study, 79.8% report being “fully satisfied” with their anaesthesia technique. 32.1% of the patients who received regional anaesthesia reported not feeling “fully satisfied”. This figure is 5.5% following general anaesthesia. Main reason for dissatisfaction following regional anaesthesia are reported as “insufficient anaesthesia prior to surgery”, and “the discomfort of having a long-lasting insensate extremity postoperatively”.ConclusionsFollowing regional plexus anaesthesia, a third of the patients are not “fully satisfied”. To optimize patient satisfaction following regional anaesthesia techniques, we advocate stronger focus on patient counselling preoperatively, addressing the issues of block failure and prolonged postoperative sensory and motor block.

Anesthesia for muscle biopsy to test susceptibility to malignant hyperthermia

IntroductionMalignant hyperthermia is an autosomal dominant pharmacogenetic disorder, characterized by hypermetabolic crisis triggered by halogenated anesthetics and/or succinylcholine. The standard method for diagnosing malignant hyperthermia susceptibility is the in vitro muscle contracture test in response to halothane-caffeine, which requires muscle biopsy under anesthesia. We describe a series of anesthetic procedures without triggering agents in malignant hyperthermia, comparing peripheral nerve block and subarachnoid anesthesia. MethodWe assessed the anesthetic record charts of 69 patients suspected of malignant hyperthermia susceptibility who underwent muscle biopsy for in vitro muscle contracture in the period of 7 years. Demographic data, indication for malignant hyperthermia investigation, in vitro muscle contracture test results, and surgery/anesthesia/recovery data were analyzed. ResultsSample with 34±13.7 years, 60.9% women, 65.2% of in vitro muscle contracture test positive. Techniques used: peripheral nerve blocks — lateral femoral and femoral cutaneous, latency 65±41min — (47.8%); subarachnoid anesthesia (49.3%), and total venous anesthesia (1.4%). There was 39.4% failure of peripheral nerve block and 11.8% of subarachnoid anesthesia. Adverse events (8.7%) occurred only with subarachnoid blockade (bradycardia, nausea, and transient neurological syndrome). All patients remained in the post-anesthesia care unit until discharge. Age and weight were significantly higher in patients with blockade failure (ROC cut-off point of 23.5 years and 59.5kg) and blockade failure was more frequent in the presence of increased idiopathic creatine kinase. ConclusionAnesthesia with non-triggering agents has been shown to be safe in patients with malignant hyperthermia susceptibility. Variables such as age, weight, and history of increased idiopathic creatine kinase may be useful in selecting the anesthetic technique for this group of patients.

Anestesia durante biópsia muscular para teste de suscetibilidade à hipertermia maligna

IntroductionMalignant hyperthermia is an autosomal dominant pharmacogenetic disorder, characterized by hypermetabolic crisis triggered by halogenated anesthetics and/or succinylcholine. The standard method for diagnosing malignant hyperthermia susceptibility is the in vitro muscle contracture test in response to halothane‐caffeine, which requires muscle biopsy under anesthesia. We describe a series of anesthetic procedures without triggering agents in malignant hyperthermia, comparing peripheral nerve block and subarachnoid anesthesia. MethodWe assessed the anesthetic record charts of 69 patients suspected of malignant hyperthermia susceptibility who underwent muscle biopsy for in vitro muscle contracture in the period of 7 years. Demographic data, indication for malignant hyperthermia investigation, in vitro muscle contracture test results, and surgery/anesthesia/recovery data were analyzed. ResultsSample with 34±13.7 years, 60.9% women, 65.2% of in vitro muscle contracture test positive. Techniques used: peripheral nerve blocks — lateral femoral and femoral cutaneous, latency 65±41minutes — (47.8%); subarachnoid anesthesia (49.3%), and total venous anesthesia (1.4%). There was 39.4% failure of peripheral nerve block and 11.8% of subarachnoid anesthesia. Adverse events (8.7%) occurred only with subarachnoid blockade (bradycardia, nausea, and transient neurological syndrome). All patients remained in the post‐anesthesia care unit until discharge. Age and weight were significantly higher in patients with blockade failure (ROC cut‐off point of 23.5 years and 59.5kg) and blockade failure was more frequent in the presence of increased idiopathic creatine kinase. ConclusionAnesthesia with non‐triggering agents has been shown to be safe in patients with malignant hyperthermia susceptibility. Variables such as age, weight, and history of increased idiopathic creatine kinase may be useful in selecting the anesthetic technique for this group of patients.

Providing multidisciplinary scientific advice for coastal planning in Kitimat Arm, British Columbia

Abstract A 6.3 m tsunami swept through Kitimat Arm, British Columbia in 1974. An even larger wave struck and damaged the Northlands Navigation dock at Kitimat and the Haisla First Nation docks at Kitamaat Village the following year. Further down the fjord, two large coastal block failures were observed on the fjord walls across from the Gitga'at village of Hartley Bay. Several large infrastructure projects have recently been proposed for the Kitimat Arm coastal areas. The Geological Survey of Canada has therefore embarked on a five-year project to understand the magnitude and frequency of submarine mass movements in this fjord system to provide information regarding the risks from these events and to propose mitigation measures that may reduce these risks. We provide here an overview and the main results to date of an ongoing multidisciplinary study, which includes palaeotsunami studies, geomorphological and sub-seabed mapping, subaerial landslide hazard assessment, tsunami modelling, in situ and laboratory geotechnical testing, and the real-time tracking of seismic activity and seafloor movement. Some of these activities are reported in greater detail elsewhere in this book. The results of this research are summarized as a list of conclusions and recommendations to the Government of Canada.

Engineering Geological and Geotechnical Approaches for the Construction of Powerhouse Cavern of Tehri Pumped Storage Plant (1000 MW) - A Case Study

Construction of underground Cavern in the Himalayan region is full of challenges and uncertainties. Experience has shown that construction in Himalayan regions requires good understanding of geology, adequate site investigations, proper design and selection of suitable construction methodology and technology. The most commonly encountered geological problems during excavation of underground structure in Hydroelectric Projects are, Fault/Thrust/Shear Zones squeezing and swelling, wedge block failure etc. Tehri Pumped Storage Plant (PSP) is located at the left bank of river Bhagirathi in the state of Uttarakhand in Northern India. This case study indicates about the geological challenges faced and their remedial measures during the construction of Tehri PSP Powerhouse Cavern having dimension of 203m x 24m x 58m.3D-geological mapping with 1:100 scales was carried out in excavated central drift of powerhouse to evaluate the rock composition, behavior of rock mass, structural features and further investigation to finalize the layout and orientation. During the investigation Sheared Phyllite with bands of thinly Phyllite Quartzite rock were encountered in the end portion of central drift of powerhouse which had posed a mammoth challenge in designing the powerhouse cavern. Keeping in view the recommendations of geotechnical experts and the design consultants, decision were made to shift the cavern further by 50 m to avoid Sheared Phyllite bands. The shifting of cavern led to the reorientation of structures like control room, service bay and location of units etc. This paper briefly describes the Engineering Geological and Geotechnical set up of powerhouse with proper investigation approaches and excavation sequences highlighting the importance of orientation and Sheared Phyllite Zone.

Implantable loop recorders in patients with unexplained syncope: Clinical predictors of pacemaker implantation.

Implantable loop recorders (ILR) are a valuable tool for the investigation of unexplainedsyncopal episodes. The aim of this retrospective single center study was to identify predictive factors for pacemaker implantation in patients with unexplained syncope who underwent ILR insertion. One hundred six patients were retrospectively analyzed (mean age 59.1 years; 47.2% male) with unexplained syncope and negative conventional testing who underwent ILR implantation. The pri- mary study endpoint was detection of symptomatic or asymptomatic bradycardia requiring pacemaker implantation. The average follow-up period after ILR implantation was 20 ± 15 months. Pacemaker im- plantation according to current guidelines was necessary in 22 (20.8%) patients, mean duration until index bradycardia was 81 ± 88 (2-350) days. Ten (45.5%) patients received a pacemaker due to sinus arrest, 7 (31.8%) patients due to third-degree atrioventricular block, 2 (9.1%) patients due to second- degree atrioventricular block and 1 (4.5%) patient due to atrial fibrillation with a slow ventricular rate. Three factors remained significant in multivariate analysis: obesity, which defined by a body mass index above 30 kg/m2 (OR: 7.39, p = 0.014), a right bundle branch block (OR: 9.40, p = 0.023) and chronic renal failure as defined by a glomerular filtration rate of less than 60 mL/min (OR: 6.42, p = 0.035). Bradycardia is a frequent finding in patients undergoing ILR implantation due to un- explained syncope. Obesity, right bundle branch block and chronic renal failure are independent clinical predictors of pacemaker implantation.

A Retrospective Study of the Incidence and Management of Complications Associated With Regional Nerve Blocks in Equine Dental Patients.

Regional anesthesia of the equine head is commonly performed to allow oral extraction of diseased teeth in the standing horse. The use of 4 blocks (infraorbital nerve, maxillary nerve, mental nerve, and mandibular nerve) is well documented for desensitization of dental quadrants for oral surgery for exodontia, but descriptions of associated complications are limited. A total of 270 regional nerve blocks were performed on 162 equine patients in a second opinion referral hospital setting. Criteria for inclusion in the study included a 24-hour stay in hospital, that the blocks be performed by one clinician and at minimum, a 2-week follow-up examination be performed. A total of 8 complications were identified in 7 patients representing a 2.96% incidence of complication. Complications included supraorbital hematoma (3), local hematoma (2), lingual self-trauma (2), and nerve block failure to desensitize (1). Treatment and management of complications are discussed. Complications associated with regional anesthesia may be reduced by reducing anesthetic volumes, precise needle placement, familiarity with the facial anatomy relevant to nerve blocks, adequate restraint, aseptic technique, postprocedural muzzling, and the use of a newly opened bottle of local anesthetic.

Optimization of Lead Placement in the Right Ventricle During Cardiac Resynchronization Therapy. A Simulation Study.

Patients suffering from heart failure and left bundle branch block show electrical ventricular dyssynchrony causing an abnormal blood pumping. Cardiac resynchronization therapy (CRT) is recommended for these patients. Patients with positive therapy response normally present QRS shortening and an increased left ventricle (LV) ejection fraction. However, around one third do not respond favorably. Therefore, optimal location of pacing leads, timing delays between leads and/or choosing related biomarkers is crucial to achieve the best possible degree of ventricular synchrony during CRT application. In this study, computational modeling is used to predict the optimal location and delay of pacing leads to improve CRT response. We use a 3D electrophysiological computational model of the heart and torso to get insight into the changes in the activation patterns obtained when the heart is paced from different regions and for different atrioventricular and interventricular delays. The model represents a heart with left bundle branch block and heart failure, and allows a detailed and accurate analysis of the electrical changes observed simultaneously in the myocardium and in the QRS complex computed in the precordial leads. Computational simulations were performed using a modified version of the O'Hara et al. action potential model, the most recent mathematical model developed for human ventricular electrophysiology. The optimal location for the pacing leads was determined by QRS maximal reduction. Additionally, the influence of Purkinje system on CRT response was assessed and correlation analysis between several parameters of the QRS was made. Simulation results showed that the right ventricle (RV) upper septum near the outflow tract is an alternative location to the RV apical lead. Furthermore, LV endocardial pacing provided better results as compared to epicardial stimulation. Finally, the time to reach the 90% of the QRS area was a good predictor of the instant at which 90% of the ventricular tissue was activated. Thus, the time to reach the 90% of the QRS area is suggested as an additional index to assess CRT effectiveness to improve biventricular synchrony.

Failed spinal anaesthesia by intrathecal ropivacaine

Ropivacaine is a newly used local anaesthetic in Iran. Replacing this newer developed drug instead of older bupivacaine has many clinically significant benefits. Block failure is reported repeatedly by Iranian anaesthesiologists in spinal anaesthesia by intrathecal ropivacaine. A few theories can explain the reason for higher block failure with intrathecal ropivacaine compared with bupivacaine. Non-commitment to using intravenous sedative medications may be the most justifiable reason for this phenomenon.

Randomized controlled trial of a simplified adductor canal block performed for analgesia following total knee arthroplasty

Background and objectivesThe objective of the study was to determine if injection of local anesthetic into the vastus medialis and sartorius muscles adjacent to the adductor canal produces sensory changes...

Detection and analysis of mass wasting events in chalk sea cliffs using UAV photogrammetry

Coastal cliff recession represents a significant risk to both people and infrastructure, it is therefore important that we are able to efficiently monitor these environments to inform future management decisions. Through the use of UAV digital photogrammetry, we obtain point clouds to develop monthly models of the sea cliffs at Telscombe, East Sussex, UK between August 2016 and July 2017. The models captured were accurate to 0.05 m and had an average point density of 351 pts./m2. Using the methodology presented we were able to automatically detect rockfalls by undertaking a 2.5D surface change detection which populated monthly inventories through volumetric estimations. A total of 10,085 failures were observed with an estimated volumetric flux of 3889.4 m3 over the 12 month period of data collection. Due to the high frequency of data capture, successive block failures in the Newhaven Chalk formation were observed. The largest failure within the 12 month period was estimated at 2546.8 m3 and followed significant toe erosion due to wave action. The steepening of the cliff face was modelled through limit equilibrium analysis to determine the reduction in factor of safety for the months preceding failure. We then present a magnitude-frequency analysis using negative power laws from the monthly rockfall inventories for the entire study area. The negative power law models produced a strong correlation across all months with r2 values ranging from 0.97 to 0.99. The normalised power law scaling parameters ranged from 1.421 to 1.955 for β and from 33.79 to 904.14 for s. The observed rollover in power laws presented in previous research matches the resolution of the data presented in this study. Our results show that this method of data capture is comparable to existing methods whilst offering significant benefits in field surveying time and cost.

Block shear failure mechanism of axially-loaded groups of screws

Self-tapping screws are fasteners that are versatilely applicable in timber engineering. For the design of such screw connections, preferential axial-loading, all possible failure mechanisms have to be considered. Recently, in compact groups of axially-loaded screws the block shear failure mechanism, which has not been investigated so far, turned out to fail rather brittle at load levels lower than currently allowed. This failure mechanism is defined as failure of (rolling) shear and/or tension perpendicular to grain planes encompassing the group of screws. This failure mechanism was observed in groups given a number of different parameter settings, i.e. thread-fibre angles of 90° and 45°, glulam, structural timber and cross laminated timber and various group designs. This paper focuses on groups of axially-loaded screws in glulam and solid timber of Norway spruce (Picea abies) and inserted at a thread-fibre angle of 90°. Varying group sizes, loading and supporting distances and group designs, i.e. various penetration lengths lef and spacing in and perpendicular to grain, a1 and a2, respectively, are analysed by two different “push-pull”-test setups. To predict the block shear capacity and failure characteristics of such groups of screws and to separate this failure mechanism from other failure mechanisms, a mechanical-based block shear model was established. This parallel acting spring model considers load sharing and redistribution between concerned failure planes and depends on a number of material, geometrical and stress distribution parameters. To ensure a reasonable parameter setting, background and potential influencing parameters on each model parameter are discussed. In validation, the model shows overall good predictions of capacities, failure mechanisms and failure sequence for all test series involved. It turned out that the current regulations, comprising the definition of minimum spacing together with minimum edge and end distances, are not sufficient for controlling this three-dimensional block shear failure. In addition, the consideration of the number of screws in the group as well as the penetration length is required.

Caudal Epidural Injection with a Catheter in Patients with Failure of Conventional Epidural Blocks

Caudal Epidural Injection with a Catheter in Patients with Failure of Conventional Epidural Blocks

Alternative techniques for failure of conventional inferior alveolar nerve block.

Successful local anesthesia in dental treatment is the most important prerequisite for pain control of patients. However, unlike that in the maxilla, it is difficult to administer local anesthesia in the mandible, and the success rate of conventional inferior alveolar nerve block (IANB) is only 80–85%. It is attributed to various causes such as anatomical variations, extreme anxiety, and technical errors; thus, various alternatives have been devised to improve this. We will analyze the causes of failure in conventional IANB and examine various alternatives that can be applied in these cases.

Slipping rib syndrome

Slipping rib syndrome (SRS) is an under-recognized cause of lower chest and upper abdominal pain. We described this rare condition in a 27-year-old female with chronic right hypochondrial pain. The condition was initially diagnosed as irritable bowel. Extensive imaging studies and laboratory investigations failed to determine the underlying cause of pain for 2 years. The diagnosis was made clinically by hooking maneuver and on ultrasound. After the failure of nonsteroidal anti-inflammatory drugs therapy and intercostal nerve block to improve symptoms, surgical resection of the anterior end of the free-floating right 10th rib was performed. Awareness of SRS can help rapid diagnosis and treatment of a benign cause of abdominal upper quadrant pain.

Anatomical variations in brachial plexus on ultrasound: Reason for failure of supraclavicular block - Nerve stimulator along with ultrasound can play a major role for success.

Anatomical variations in brachial plexus on ultrasound: Reason for failure of supraclavicular block - Nerve stimulator along with ultrasound can play a major role for success.