title: Infrared pupillometry. Basic principles and their application in the non-invasive monitoring of neurocritical patients.
abstract: BACKGROUND
  Pupil assessment is a fundamental part of the neurological examination. Size and reactivity to light of each pupil should be recorded periodically since changes in these parameters may represent the only detectable sign of neurological deterioration in some patients. However, there is great intraobserver and interobserver variability in pupil examination due to the influence of many factors, such as the difference in ambient lighting, the visual acuity and experience of the examiner, the intensity of the luminous stimulus, and the method used to direct this stimulus. In recent years, digital cameras have incorporated infrared devices allowing the development of user-friendly portable devices that permit repeated, non-invasive examinations of pupil size and its reactivity to light with an objective, accessible and inexpensive method.
  
  
  METHODS
  The purpose of this review is to describe the fundamentals of infrared pupillometry and discuss potential applications in the monitoring of neurocritical patients. We also present some recommendations in the routine assessment of pupils in neurocritical patients.
  
  
  CONCLUSIONS
  The possibility of evaluating the changes in pupil reactivity in an early, objective and almost continuous way provides a new non-invasive monitoring method. This method could improve the predictive factor of neurological deterioration and the bedside monitoring of the neurological state of the patient, avoiding unnecessary examinations and enabling early therapeutic intervention.
authors.affiliation: Servicio de Neurocirugía, Hospital Universitario Vall d'Hebrón, Universitat Autònoma de Barcelona, Barcelona, España.
authors.forename: F
authors.initials: F
authors.lastname: Martínez-Ricarte
authors.forename: A
authors.initials: A
authors.lastname: Castro
authors.forename: M A
authors.initials: MA
authors.lastname: Poca
authors.forename: J
authors.initials: J
authors.lastname: Sahuquillo
authors.forename: L
authors.initials: L
authors.lastname: Expósito
authors.forename: M
authors.initials: M
authors.lastname: Arribas
authors.forename: J
authors.initials: J
authors.lastname: Aparicio
mesh_terms: D000368:Aged; D000758:Anesthesia; D001930:Brain Injuries / Q000503:physiopathology; D003422:Critical Care / Q000379:methods*; D005128:Eye Diseases / Q000503:physiopathology; D015600:Glasgow Coma Scale; D016489:Head Injuries, Closed / Q000175:diagnosis / Q000503:physiopathology; D006801:Humans; D007035:Hypothermia / Q000503:physiopathology; D007259:Infrared Rays; D008297:Male; D008991:Monitoring, Physiologic; D009422:Nervous System Diseases / Q000503:physiopathology*; D009460:Neurologic Examination / Q000295:instrumentation / Q000379:methods*; D010783:Photometry; D011680:Pupil / Q000187:drug effects / Q000502:physiology*; D012025:Reflex, Pupillary / Q000187:drug effects / Q000502:physiology*; D014057:Tomography, X-Ray Computed