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Awareness, Communication, EEG, fMRI, Heart rate variability, Unconscious patients



  1. Lawrence, Madelaine M. PhD, MSN, BSN
  2. Ramirez, Rebecca P. MD, MHCM, FACP, SFSHM
  3. Bauer, Paul J. RN, BA


Background: Nurses are told to speak to their unconscious patients because hearing is said to be the last sense to depart. There was little reliable evidence before the 1990s that patients in an unconscious state could hear and understand what was being said. That led to reluctance on the part of health professionals to communicate with these unresponsive patients.


Objective: This historical overview aims to present researched evidence from the 1990s to the present detailing awareness that occurs in unconscious patients, when that awareness increases, and how to detect that awareness. It also includes research about the benefits of communicating with unconscious patients and descriptions of how registered nurses and other health care professionals, from a postsurvey after a continuing education course on experiences of unconscious patients, plan to communicate with unconscious patients.


Methods: A literature search was conducted, which included more than 150 articles and books about experiences of unconscious patients in several electronic databases, including PubMed, CINAHL, and the British Nursing Index. In addition, an analysis of 105 postcourse responses by registered nurses (89%) and other health professionals (11%), licensed practical nurses, emergency medical technicians, and cardiac technicians after taking a continuing education course on experiences of previously unconscious patients were analyzed.


Results: The Glasgow Coma Scale and the Full Outline of Unresponsiveness scale are helpful behavioral tools to identify levels of coma but miss detecting awareness in patients who can hear and understand but cannot move. The estimates are that 25% to 40% (J Trauma. 1975;15:94-98; J Neurosci Nurs. 1988;20:223-228; J Neurosci Nurs. 1990;22(1):52-53; Am J Crit Care. 1995;3:227-232) of patients diagnosed with a disorder of consciousness can hear and understand what is being said in their environment. Substantial evidence supports that isolation and loneliness, such as experienced by some patients perceived to be unaware, can be physically and psychologically harmful.


Conclusions: Strong evidence shows that some patients diagnosed as being in a vegetative state can hear and understand what is being said in their environment. Interviews with previously unconscious patients and electrophysiological methods show that awareness can be detected in patients perceived to be unconscious. There is documented evidence that patients experience awareness when going into unconsciousness, even when they appear unaware and when moved. To our knowledge, these times have not been researched using electrophysiological devices but established from interviews.