Dr. Guillermo A. Castorena-Arellano graduated from Universidad Nacional Autónoma de México, and completed his residency in Internal Medicine, Anesthesia, and Critical Care at Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, México City. He is a research fellow in Anesthesia at the Massachusetts General Hospital, Harvard Medical School, Boston. Currently, he is Professor of Anesthesiology at the Fundación Clínica Médica Sur-UNAM. Dr. Castorena-Arellano has many publications on anesthesia, pain, internal medicine, and critical care to his credit. He has edited a book on perioperative medicine and has given numerous conferences at congresses and meetings around the world. He is the past president of the Mexican Society of Anesthesia and the Mexican Society of Intensive Care Medicine.