It comprises a first strap (1), joined to a fastening band (2) that is secured to the bed, with a first section of eyelets (20), arranged successively, separated a certain distance from each other, and a second strap (3), joined to an abdominal belt (4) with two ends (15, 16) which when joined together wrap around and protect the patients body, with fastening band (2) and abdominal belt (4) also being joined together, characterized in that first strap (1) comprises a second section (5) of eyelets, double and unfolded, with at least three eyelets (9, 10, 12) near fastening band (2), with the distance between the first (9) and the second (10) eyelet being different to the distance between the second eyelet (10) and the third one (12).
