title: Dyspnea prevalence, trajectories, and measurement in critical care and at life's end.
abstract: OBJECTIVE
  Dyspnea is a multidimensional response to an asphyxial threat that heralds respiratory failure. A clinician's ability to treat dyspnea warrants understanding the prevalence, burden, trajectories, and measurement across chronic conditions and exacerbations. This review focuses on two contexts: the intensive care unit and the near death stage of illness.
  
  
  RESULTS
  Dyspnea is the most distressing symptom experienced by critically ill patients at risk for dying. New longitudinal studies reveal varying dyspnea trajectories over time and by diagnosis. Patients with noncancer diagnoses, particularly chronic obstructive pulmonary disease, experience severe dyspnea for months before death, whereas patients with cancer even without apparent cardiorespiratory disease have an escalation of dyspnea near death. The sickest patients and those who are cognitively impaired or unconscious are not represented because self-report measures are used. Thus, dyspnea is underrepresented in most end-of-life cohorts. In most data, the Numeric Rating Scale for the intensity of breathlessness, while unidimensional, is the most valid measure for palliative care because of its simplicity. Use of the Respiratory Distress Observation Scale in future studies will permit the inclusion of patients who are unable to self-report dyspnea.
  
  
  CONCLUSIONS
  In summary, new evidence is demonstrating the high prevalence and distress associated with dyspnea among critically ill patients and patients near death.
authors.affiliation: Office of Health Research, College of Nursing, Wayne State University, Detroit, Michigan, USA. m.campbell@wayne.edu
authors.forename: Margaret L
authors.initials: ML
authors.lastname: Campbell
mesh_terms: D003422:Critical Care; D004417:Dyspnea / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology* / Q000523:psychology; D006801:Humans; D007362:Intensive Care Units; D015995:Prevalence; D013315:Stress, Psychological / Q000523:psychology; D013727:Terminal Care