title: A wireless lingual feedback device to reduce overpressures in seated posture: a feasibility study.
abstract: BACKGROUND
  Pressure sores are localized injuries to the skin and underlying tissues and are mainly resulting from overpressure. Paraplegic peoples are particularly subjects to pressure sores because of long-time seated postures and sensory deprivation at the lower limbs.
  
  
  RESULTS
  Here we report outcomes of a feasibility trial involving a biofeedback system aimed at reducing buttock overpressure whilst an individual is seated. The system consists of (1) pressure sensors, (2) a laptop coupling sensors and actuator (3) a wireless Tongue Display Unit (TDU) consisting of a circuit embedded in a dental retainer with electrodes put in contact with the tongue. The principle consists in (1) detecting overpressures in people who are seated over long periods of time, (2) estimating a postural change that could reduce these overpressures and (3) communicating this change through directional information transmitted by the TDU.Twenty-four healthy subjects voluntarily participated in this study. Twelve healthy subjects initially formed the experimental group (EG) and were seated on a chair with the wireless TDU inside their mouth. They were asked to follow TDU orders that were randomly spread throughout the session. They were evaluated during two experimental sessions during which 20 electro-stimulations were sent. Twelve other subjects, added retrospectively, formed the control group (CG). These subjects participated in one session of the same experiment without any biofeedback.Three dependent variables were computed: (1) the ability of subjects to reach target posture (EG versus CG), (2) high pressure reductions after a biofeedback (EG versus CG) and (3) the level of these reductions relative to their initial values (EG only). Results show (1) that EG reached target postures in 90.2% of the trials, against 5,3% in the CG, (2) a significant reduction in overpressures in the EG compared to the CG and (3), for the EG, that the higher the initial pressures were, the more they were decreased.
  
  
  CONCLUSIONS
  The findings suggest that, in this trial, subjects were able to use a tongue tactile feedback system to reduce buttock overpressure while seated. Further evaluation of this system on paraplegic subjects remains to be done.
authors.affiliation: Techniques for biomedical engineering and complexity management-informatics, mathematics and applications-Grenoble (TIMC-IMAG)-UMR UJF CNRS 5525-Domaine de la Merci, La Tronche, France. olivier.chenu@imag.fr
authors.forename: Olivier
authors.initials: O
authors.lastname: Chenu
authors.forename: Nicolas
authors.initials: N
authors.lastname: Vuillerme
authors.forename: Jacques
authors.initials: J
authors.lastname: Demongeot
authors.forename: Yohan
authors.initials: Y
authors.lastname: Payan
mesh_terms: D000328:Adult; D001676:Biofeedback, Psychology; D002138:Calibration; D016022:Case-Control Studies; D003201:Computers; D004867:Equipment Design; D005246:Feedback; D006801:Humans; D004856:Postural Balance; D011187:Posture; D011312:Pressure; D011434:Proprioception; D012189:Retrospective Studies; D014059:Tongue; D014110:Touch