These specialists have completed residency training in the field of Emergency and Critical Care, a competitive and rigorous program. (vcahospitals.com)
You can pursue a master's degree either during medical school or after completing residency training. (sciencemag.org)
Both fields require 4 years of residency training, during which time a typical MD / PhD student, at the right training program, can spend one and a half years doing research. (sciencemag.org)