emergency department vs trauma centre

emergency department

noun
  • A department of a hospital where seriously ill or injured patients, often with life-threatening conditions that require urgent or immediate treatment, are brought in, usually by ambulance. 

trauma centre

noun
  • A specialized section of a hospital intended to treat suddenly occurring life-threatening injuries and medical conditions. 

  • A type of hospital with a highly capable trauma department. 

How often have the words emergency department and trauma centre occurred in a corpus of books? (source: Google Ngram Viewer )