The muscle is more sensible to the effect of the isquemia. In the skin sanguineous suppliments of the cutaneous vascular net arrive and from the armor-piercing vases, it receives more blood of what its metabolic necessities. The muscles are irrigated by the armor-piercing ones, the occlusion of the same ones results in a muscular damage of more significant ratios and happens with bigger brevity of that one observed in the skin. The pathological effect of the external pressure in soft fabrics are dependents: Of the Intensity of the Pressure; Of the Duration of the Pressure; Of the Tecidual Tolerance. Beyond the intensity, the duration of the pressure is another parameter that will influence the appearance of the tecidual damage. An inverse relation between duration and intensity of pressure exists: pressures of low intensity for a long one period of time can cause teciduais damages, as much how much pressures of high intensity for short periods of time.
The normal hair pressures, in healthy adults, have approach values de30 a40mmHg for the arterial capillaries e10 a14mmHg for the venosos capillaries. A external pressure of 70mmHg for 2 hours, without relief, provokes the appearance of located isquemia. External Causal factors: Beyond the pressure we must consider other facilitadores for the appearance of the UPs: Shear: It is caused by two forces: of the gravity that pushes the body for low the contrary resistance of the proper body on the surface support (bed, chair), that it results in involuntary friction. A practical example is, when the headboard of the bed is raised more than 30 and the force of the gravity pushes the trunk of the patient for low. The result is angulao of the capillaries of soft fabrics of the region supplies-sacral, causing the reduction or elimination of it arrives in port sanguineous place, being able to result in tecidual death.