Aneurysmal Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is a devastating neurological syndrome, which occurs at a rate of 3–25 per 100,000 population. Smoking and hypertension are the most important risk factors of subarachnoid hemorrhage. Rupture of cerebral aneurysm leads to rapid spread of blood into cerebrospinal fluid and subsequently leads to sudden increase of intracranial pressure and severe headache. Subarachnoid hemorrhage is associated with neurological (such as re‐bleeding and vasospasm) and systemic (such as myocardial injury and hyponatremia) complications that are causes of high mortality and morbidity. Although patients with poor‐grade subarachnoid hemorrhage are at higher risk of neurological and systemic complications, the early and aggressive management of this group of patient has decreased overall mortality by 17% in last 40 years. Early aneurysm repair, close monitoring in dedicated neurological intensive care unit, prevention, and aggressive management of medical and neurological complications are the most important strategies to improve outcome

Perioperative Considerations for Revascularization and Non-Revascularization Surgeries in Moyamoya Disease

Moyamoya disease is a rare, progressive cerebrovascular occlusive disease; characterized by narrowing of the distal internal carotid arteries and their branches. The incidence is high in East Asians and most commonly presents in the first and fourth decade of life. Its symptoms are headaches, seizures, transient neurological deficits, and cognitive decline. Medical management is based on treating the symptoms and includes antiplatelet and anti-seizure medications. Surgical revascularization is the mainstay of treatment. Unique pathophysiology of moyamoya disease necessitates neuro-anesthesiologists to formulate an individualized plan perioperatively. The overriding goal of perioperative anesthetic management of moyamoya disease is to ensure optimal cerebral perfusion and protection. Maintenance of normotension, normocarbia, normo-oxygenation, normothermia, and euvolemia is the cornerstone during the perioperative period. Perioperative adequate analgesia is crucial to prevent cerebral ischemia and allows close neurological monitoring. This chapter reviews perioperative anesthetic management of patients with moyamoya disease

Urosepsis: Flow is Life

Urosepsis is one of the important etiological factors for community as well as hospital-acquired infections. Accordingly, urosepsis is divided into community-acquired and hospital-acquired urosepsis. Obstruction to the flow of urine is a common risk factor for community-acquired urosepsis, whereas the indwelling urinary catheter is the risk for the hospital-acquired urosepsis. E. coli remained the most common bacteria-causing urosepsis. If not treated early and appropriately, urosepsis can complicate into septic shock and multiple organ dysfunction. The cornerstone for the improved outcome of these patients is initial resuscitation and proper antibiotic therapy and restoring the flow of urine or removing the infected urinary catheter. Community-acquired urosepsis can be prevented by removing the obstruction to flow of urine permanently. The hospital-acquired urosepsis can be prevented by strictly following catheter-associated urinary tract infection prevention bundle and removing the catheter as early as possible

Cerebral Arteriovenous Malformation from Classification to the Management

Cerebral arteriovenous malformations (cAVMs) are the rare neurosurgical emergency. cAVM is an abnormal vascular web, composed of nidus, feeding artery and draining veins. It commonly occurs in the supratentorial area of the brain. The common grading system used in cAVM is Spetzler-Martin grading, which takes into consideration the size of nidus, the location of cAVM and the venous drainage. The cAVMs may develop flow and pressure-related aneurysms, which will increase the morbidity and mortality in these patients. cAVMs vary in size and undergo growth, remodeling and rarely regression. Most of the cAVMs are asymptomatic, but the common presentation are headache, seizure, intracerebral hemorrhage or focal neurological deficit. The cerebral angiography remains the gold standard for the diagnosis of cAVM. Management of the cAVM includes medical therapy, surgical excision, radiosurgery and embolization

Peripartum Pulmonary Embolism

Pregnancy and peripartum increase the risk of venous thromboembolism (VTE) by many folds. Interestingly, the VTE is more common during the pregnancy, whereas the pulmonary embolism is more frequent in postpartum period. There are various risk factors for the VTE and pulmonary embolism in these patients. The important risks are improper thromboprophylaxis, obesity, and multigravida. The clinical parameters and the d-dimer are not used for diagnosis of thromboembolism during pregnancy and in the postpartum period. The compression ultrasonography (CUSG) is commonly used for VTE diagnosis; for the pulmonary embolism diagnosis, one has to consider the radiation hazard to the fetus as well as to the mothers. Ventilation/perfusion scan is the imaging of choice for patient who has respiratory signs with normal chest radiograph. If chest X-ray is abnormal with suspicion of peripartum pulmonary embolism (PPE), the choice should be computed tomographic angiography. Heparin and its derivatives remained the anticoagulation of choice for the treatment of VTE as well as the PPE, as it is a shorter acting, easy to reverse with protamine sulfate. Proper thromboprophylaxis is the key for prevention of VTE and peripartum pulmonary embolism

Principles of Anesthesia and Airway Management in Head and Neck Surgery

This topic aims to discuss key aspects of anesthetic and airway management for head and neck surgery. Airway management is a central part of patient care and management in Head and Neck Surgery. Common challenges in Head and Neck surgery are shared airway, distorted airway anatomy due to existing pathology; risk of airway obstruction, disconnection or loss of airway intra-operatively; risk of soiling of the airway due to bleeding and surgical debris; and the potential for airway compromise post-operatively. The option for airway management technique is influenced by patient’s factors, anesthetic needs, and surgical requirements. Intubation technique necessitating either a small or large cuffed tracheal tube with a throat pack provides the highest level of airway protection Non-intubation or open airway techniques involve mask ventilation, apneic techniques, and insufflation techniques, or the use of a laryngeal mask airway. Lastly, jet ventilation techniques may be conducted via a supraglottic, subglottic or transtracheal routes. It is essential to have clear airway management plans including rescue airway strategies that should be communicated with the surgeons and patients at the earliest opportunity

Pulmonary Embolism in COVID-19 Patients: Facts and Figures

COVID-19 infection affects many systems in the body including the coagulation mechanisms. Imbalance between pro-coagulant and anticoagulant activities causes a roughly nine times higher risk for pulmonary embolism (PE) in COVID-19 patients. The reported incidence of PE in COVID-19 patients ranges from 3 to 26%. There is an increased risk of PE in hospitalized patients with lower mobility and patients requiring intensive care therapy. Obesity, atrial fibrillation, raised pro-inflammatory markers, and convalescent plasma therapy increases the risk of PE in COVID-19 patients. Endothelial injury in COVID-19 patients causes loss of vasodilatory, anti-adhesion and fibrinolytic properties. Viral penetration and load leads to the release of cytokines and von Willebrand factor, which induces thrombosis in small and medium vessels. D-dimers elevation gives strong suspicion of PE in COVID-19 patients, and normal D-dimer levels effectively rule it out. Point of care echocardiogram may show right heart dilatation, thrombus in heart or pulmonary arteries. DVT increases the risk of developing PE. The gold standard test for the diagnosis of PE is CTPA (computerized tomographic pulmonary angiography) which also gives alternative diagnosis in the absence of PE. Therapeutic anticoagulation is the corner stone in the management of PE and commonly used anticoagulants are LMWH (low molecular weight heparin) and UFH (unfractionated heparin). Mortality in COVID-19 patients with PE is up to 43% compared to COVID patients without PE being around 3%

Experimental and numerical investigation of composite tension absorber joints for improved aircraft crashworthiness

This thesis investigates the use of specially-designed “tension absorber” joints in composite vehicular structures for the absorption of energy in a crash situation through a process referred to here as “extended bearing failure”. The specific targeted application is future narrow-body composite aircraft fuselages which require an innovative energy absorption strategy due to the limited height available below the cargo floor for traditional crush beams. However, tension absorbers could be applied in any structure requiring energy-absorption capability in a crash or overload situation. Through a combined experimental-numerical approach, the work aims to provide fundamental information on the effects of geometric and material parameters such as stacking sequence, pin diameter, laminate thickness and loading rate, and an assessment of whether state-of-the-art numerical simulation is capable of providing genuinely predictive capability for such a complex problem. To make the results as useful as possible the chosen material is IM7/8552 carbon/epoxy, one of the most widely-characterised materials in the literature. Thus the results can be used by other researchers to test out modelling approaches without the need for further material testing. Besides the results in the published papers, videos provided as supplementary information contain complete three-dimensional (3D) maps of internal specimen damage, obtained from computed tomography (CT). The chosen performance parameters are ultimate bearing strength (UBS), mean crushing stress (MCS) and mass-specific energy absorption (SEA). Diameter-to-thickness (D/t) ratio is found to be an excellent predictor of UBS and SEA for both quasi-static and dynamic loading rates, with small D/t values giving best results, provided the thickness is sufficient to avoid global bending of the specimen. Concerning the effects of stacking sequence, it is found that the most important factor in maximising SEA is having small changes in orientation at ply interfaces. This is even more important than 0° content. Laminates with a high SEA tend to have a low UBS. Highest UBS was for quasi-isotropic laminates. Increased loading rate results in increased UBS but decreased SEA. The implemented model is a physically-based, three-dimensional damage model which uses in-situ ply strengths, stress-based fibre failure criteria, Puck’s criteria for matrix damage, a non-linear law for in-plane shear, a cohesive zone model for delamination, a crack-band model to mitigate mesh sensitivity, and frictional contact between the pin and the laminate, and between plies once they delaminate. The developed model is found to accurately predict the global response in terms of strength and energy absorption and can forecast the effects of changing geometry and material parameters. Critically, comparison with CT scans shows that it also captures the key mesoscale damage mechanisms