Lack of Association of High Backrest With Sacral Tissue Changes in Adults Receiving Mechanical Ventilation

Although higher backrest elevation may be a theoretical risk for integrity of sacral tissues, few data support use of high backrest elevation.

To describe the effect of backrest elevation on the integrity of sacral tissue in critically ill adults receiving mechanical ventilation.

Patients from 3 critical care units (surgical trauma, medical respiratory, and neuroscience) who were expected to have mechanical ventilation for at least 24 hours were intubated and mechanical ventilation was started. Participants were enrolled in the study within 24 hours of intubation. Backrest elevation was continuously measured by using mechanical system- based accelerometers. Integrity of sacral tissue was evaluated by using high-frequency sonography.

Data for 84 patients who had measurements of both backrest elevation and skin integrity were available for analysis. General linear models indicated no significant difference among the proportions of time spent at less than 20° (P values: .57 the first 24 hours, .17 the first 48 hours, .81 the first 72 hours), 20° to 30° (P values: .25 the first 24 hours, .08 the first 48 hours, .25 the first 72 hours), or greater than 30° (P values: .62 the first 24 hours, .28 the first 48 hours, .68 the first 72 hours) among participants with no injury, no change in injury, improvement in injury, or injury that worsened.

Level of backrest elevation is not associated with changes in tissue integrity. Body positioning in critically ill patients receiving mechanical ventilation may not be as important or as effective as once thought.