No abstract available.
Autoradiography*

BACKGROUND: Several different patterns of wavebreak have been described by mapping of the tissue surface during fibrillation. However, it is not clear whether these surface patterns are caused by multiple distinct mechanisms or by a single mechanism. METHODS: To determine the mechanism by which wavebreaks are generated during ventricular fibrillation, we conducted optical mapping studies and single cell transmembrane potential recording in 6 isolated swine right ventricles. RESULTS: Among 763 episodes of wavebreak (0.75 times/sec/cm2), optical maps showed 3 patterns: 80% due to a wavefront encountering the refractory waveback of another wave, 11.5% due to wavefronts passing perpendicularly each other and 8.5% due to a new (target) wave arising just beyond the refractory tail of a previous wave. Computer simulations of scroll waves in 3-D tissue showed that these surface patterns could be attributed to two fundamental mechanisms: head-to-tail interactions and filament break. CONCLUSION: We conclude that during sustained ventricular fibrillation in swine RV, surface patterns of wavebreak are produced by two fundamental mechanisms: head-to-tail interaction between waves and filament break.
Computer Simulation ; Heart Ventricles* ; Membrane Potentials ; Swine* ; Ventricular Fibrillation*

Postoperative epidural hematoma (EDH) usually present with neurological deficit. Massive EDH presenting with only severe pain without neurological deficit are rare. Atypical presentations of postoperative EDHs may lead to delayed diagnosis and treatment. We present three such cases after posterior cervical spine surgery. Three patients presented with severe neck pain and spasms without motor deficits several days after posterior cervical decompressive procedures. Imaging studies identified compressive EDHs at the surgical site with severe compression of the spinal cord. All were treated with emergent decompression, with resulting improvement of symptoms and pain relief without further neurological sequelae. In conclusion, postoperative EDHs after posterior cervical spine surgery may result in minimal neurological deficit. Our report reminds surgeons to keep this possibility in mind when patients complain of unusually severe neck pain and spasms after posterior cervical spine surgery.
Decompression ; Delayed Diagnosis ; Hematoma* ; Humans ; Neck Pain* ; Neck* ; Postoperative Complications ; Spasm ; Spinal Cord ; Spine*

A dichotomous (2-category) outcome variable is often encountered in biomedical research, and Multiple Logistic Regression is often deployed for the analysis of such data. As Logistic Regression estimates the Odds Ratio (OR) as an effect measure, it is only suitable for case-control studies. For cross-sectional and time-to-event studies, the Prevalence Ratio and Cumulative Incidence Ratio can be estimated and easily interpreted. The logistic regression will produce the OR which is difficult to interpret in these studies. In this report, we reviewed 3 alternative multivariate statistical models to replace Logistic Regression for the analysis of data from cross-sectional and time-to-event studies, viz, Modified Cox Proportional Hazard Regression Model, Log-Binomial Regression Model and Poisson Regression Model incorporating the Robust Sandwich Variance. Although none of the models is without flaws, we conclude the last model is the most viable. A numeric example is given to compare the statistical results obtained from all 4 models.
Cross-Sectional Studies ; Humans ; Incidence ; Models, Statistical ; Multivariate Analysis ; Odds Ratio ; Outcome Assessment (Health Care) ; methods ; Poisson Distribution ; Prevalence ; Proportional Hazards Models ; Risk ; Risk Assessment

Education, Medical ; History of Medicine ; Humans ; Medicine ; Precision Medicine ; Singapore ; Teaching ; Terminal Care

Thyroid nodules are very common and found in up to 68% of the general U.S. population on ultrasound. Although thyroidectomy has long been the mainstay of treatment for malignant and symptomatic benign thyroid nodules, various interventional ablative techniques have emerged in the last couple of decades as alternative non-surgical treatment options. Globally, the most widely adopted technique has been ultrasound-guided radiofrequency ablation (RFA). RFA of thyroid nodules was first performed in 2002, and there has been an expanding body of evidence since 2006 showing that RFA and other interventional ablative techniques are effective treatments for benign solid thyroid nodules, toxic adenomas, and thyroid cysts. More recently, evidence has emerged that these techniques may be effective treatment for low-risk thyroid cancer and recurrent disease. Despite these findings, the United States has been slow to adopt these techniques, with only a single publication on RFA more than a decade after the first series was published. EM Rogers’ Diffusion of Innovation Theory provides us the appropriate lens to carefully analyze the process of adoption of RFA for thyroid nodules-to understand where we are currently, as well as, the important next steps that must be accomplished in order for RFA and other ablative techniques to be successfully adopted into the management algorithm of thyroid nodules in the United States.

BACKGROUND: Air-purifying, tight-fitting facepieces are examples of respiratory protective equipment and are worn to protect workers from potentially harmful particulate and vapors. Research shows that the presence of facial hair on users' face significantly reduces the efficacy of these devices. This article sets out to establish if an acceptable seal could be achieved between facial hair and the facepiece. The team also created and investigated a low-cost “pressure testing” method for assessing the efficacy of a seal to be used during the early design process for a facepiece designed to overcome the facial hair issue. METHODS: Nine new designs for face mask seals were prototyped as flat samples. A researcher developed a test rig, and a test protocol was used to evaluate the efficacy of the new seal designs against facial hair. Six of the seal designs were also tested using a version of the conventional fit test. The results were compared with those of the researcher-developed test to look for a correlation between the two test methods. RESULTS: None of the seals performed any better against facial hair than a typical, commercially available facepiece. The pressure testing method devised by the researchers performed well but was not as robust as the fit factor testing. CONCLUSION: The results show that sealing against facial hair is extremely problematic unless an excessive force is applied to the facepiece's seal area pushing it against the face. The means of pressure testing devised by the researchers could be seen as a low-cost technique to be used at the early stages of a the design process, before fit testing is viable.
Hair ; Masks ; Methods

Fournier’s gangrene is a severe life-threatening infection involving the perianal area, perineum, and external genitalia. It demands prompt recognition, critical care therapy, surgical therapy, and a combination of antibiotics. The infection commonly spreads via the fascial planes and causes superficial vascular thrombosis within the Colles’ fascia around the external genitalia. It can extend cephalad to involve the Scarpa’s fascia and Camper’s fascia in the abdominal wall. The treatment would include multiple debridements, which would result in disfiguring scars of the perineum and might lead to significant physical and psychological complications. We describe a case of a 58-years-old man presenting with Fournier’s gangrene resulting from an infection of an impacted urethral stone. The patient previously had obstructive voiding symptoms for 1 month but chose to neglect them. The resultant infection was severe and caused penile and right testicular gangrene. He underwent multiple wound debridements, which included a total penectomy and right orchiectomy. Psychological and rehabilitative support was necessary for him to overcome his loss and disfigurement.