Pressure ulcer prevention in medullary wounded subjects

Context

A pressure ulcer is an ischemic skin lesion stemming from a persistent compression of the soft tissues between a hard surface and bony prominences. This complication is particularly harmful for the medullary wounded subjects due to sensitive and motor deficiencies but also to the associated vegetative paralysis.


Unlike an able-bodied subject, the medullary wounded person seated in his or her wheelchair does not automatically change position when overpressures occur. Pressure ulcer prevention is essential to avoid the functional, psychological and social consequences, as well as important economical repercussions (heavy and costly medical treatments).


The TexiSense pressure ulcer prevention device

TexiSense, in collaboration with the TIMC-IMAG and AGIM laboratories, develops an ulcer prevention prototype based on a 100% textile pressure sensing fabric able to measure the pressures at the interface between the wheelchair cushion and the buttocks.


The flexibility of the fabric makes it possible to integrate the pressure sensor between the cushion and its cover. The prototype comprises:

  1. A textile pressure sensor covering the cushion and placed on the wheelchair seat;
  2. A control unit connected to the sensor and wirelessly linked to tactile and visual actuators;
  3. Tactile and visual actuators such as a vibrating watch (and eventually a smartphone) used to raise an alert in case of overpressure.

The pressures are measured in real time and a signal processing algorithm implemented in the control unit warns the subject when atypical overpressure patterns (in magnitude and/or duration) are identified.


This algorithm relies on a biomechanical model of the subject’s buttocks to estimate the internal stresses within the soft tissues and at the vicinity of bony prominences from the external pressures measured at the skin surface. It has been acknowledged that the most serious deep ulcerations are triggered by these internal stresses.


Bénéfices escomptés

The prevention technique presented here makes it possible to continuously monitor the evolution of skin pressures in a way compatible with the daytime activities of the subject. The computation of internal stresses within the soft tissues is carried out through biomechanical modeling in accordance with each considered person’s morphology.


The TexiSense pressure ulcer prevention device sends a warning when a risk of ulceration is detected and helps the user find a new position on the seat that minimizes the pressures applied on the tissues.





Biomedical model of a pelvis



Example of intern deformations of the buttock