Perfusion, tissue oxygenation and peripheral temperature in the skin of heels of healthy participants exposed to pressure: a quasi‐experimental study.

Abstract

Aim: To evaluate the relationship between the pressure exerted on the heel of one footresting directly on a mattress, versus that exerted on the other heel, protected by a pillowbeneath the Achilles tendon area and the changes thus produced in perfusion, oxygena-tion and temperature in the skin of heels of healthy volunteers lying in a supine position.Design: Experimental study in a pre‐clinical phase, with healthy volunteer partici-pants and intrapeople control.Methods: The study was carried out from November 2017 – May 2018. A pressuremeasurement surface was placed between the participant and the constant low‐pressure support surface. Doppler laser devices were used to measure local tem-perature and perfusion. The degree of oxygenation was determined using an infraredbeam close to the pressure zone in each heel. Both feet rested immobile on the bed,in a natural position, for 2 hr. To ensure intrapeople control, in every case the left heelwas raised slightly, compared with the right.Results: Eighteen participants took part in this study. Analysis of the results obtainedshowed that capillary blood flow was significantly reduced in the heel subjected topressure, compared with the other heel, while no significant effects on oxygen satu-ration or temperature were observed. The variables associated with greater oxygensaturation were capillary blood flow, local temperature and pressure exerted. Fat‐free mass, fat mass and duration of exposure to pressure were all significantly associ-ated with reduced oxygen saturation.Conclusions: In healthy participants, when the heel is subjected to constant pressureagainst a constant low‐pressure support surface, there is a significant reduction inblood flow, compared with the heel where pressure is relieved. However, there areno significant differences in temperature or tissue oxygenation.