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.

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%.