The results from this study supported our primary hypothesis that a novel Trunk Release Maneuver (TRM) to reposition the torso in HF lead to a reduction in interface pressure at the sacral and gluteal regions. The TRM group showed statistically significant reductions in PPI from baseline to post-intervention compared to the control group who had a statistically significant increase in PPI.
Interface pressure mapping is commonly used as a clinical tool to monitor potentially concerning areas of high pressure when sitting on various support surfaces, such as mattresses and wheelchair cushions. In combination with additional considerations, including skin condition, anatomical location, age, hydration, and metabolism of the individual, pressure mapping can help identify areas at risk for pressure ulcers.
While there is an association between interface pressure and risk of pressure ulcers
, there is no solid evidence of a clinically significant pressure threshold. Current clinical practice guidelines suggest that efforts be made to reduce the duration and magnitude of pressure on areas of the skin that are in contact with a support surface
. Although we are not certain of a clinically significant pressure threshold, it is promising that participants in the intervention group had statistically significant reduction of 15 mmHg in mean PPI the sacral and gluteal regions after receiving the TRM compared to the control group who had a statistically significant increase in mean PPI. Since bony locations on the body are more prone to pressure ulcers
, even slight reductions in pressure at the sacrum and ischial tuberosities may have clinical implications. Furthermore, relieving pressure magnitude at areas where shear force is present is even more important to reducing risk of pressure ulcers because pressure magnitudes that increase risk of pressure ulcers are almost half of that when little to no shear is present
[31, 32]. More research is needed to establish pressure thresholds and to determine clinically significant pressure reductions.
Previous studies provide support for interventions that reposition the body while lying in bed to reduce pressure magnitude
[13, 33, 34]. A recent Cochrane Review stated that repositioning of the body is internationally recognized and promoted as an integral component of effective pressure ulcer management
, especially for individuals who are unable to move themselves. Despite clinical recommendations and research findings that support the use of repositioning for the prevention of pressure ulcers, the optimal technique has not been determined
[13, 36]. The limited documentations on optimal repositioning techniques combined with clinical concern for the development of pressure ulcers in older adults who are not capable of independent repositioning lead to the development of the TRM. However, the exact mechanism behind the TRM and pressure reduction at the sacral and gluteal regions is not clear. It is thought to be a combination of the simple repositioning in the bed to redistribute pressure from the sacral and gluteal area to the entire torso, in addition to a release of the trunk from the frictional forces that occur where the skin over the sacral area contacts the support surface.
The notion of a release of the trunk from the friction that occurs where the sacrum and low back contact the support surface was supported by our findings that participants in the TRM group had negative trunk displacement after the intervention compared to participants in the control group who showed positive trunk displacement. It was thought that if the TRM was successful in resetting the frictional relationship at the point where the skin and mattress were in contact at the sacral region, the trunk would be released from the frictional forces and the individual would be sitting higher in the bed. Although we did not have a direct measure of shear, there is reason to believe that a positive trunk displacement would indicate more risk of shear at the point where the skin contacts mattress as a result of friction and opposing forces between the elevation of the bed and gravity acting on the body. If this is true and shear occurs at the specific point of contact, the resultant forces are 10 times more destructive to the skin than pressure alone
. Recognizing the limitations to our crude proxy measure for shear, shearing forces pose a major risk factor for pressure ulcers and have not been quantified in a clinical setting in the literature to date.
Surprisingly, there were no differences between the TRM and control groups for level of perceived discomfort. While some participants in the intervention group reported an improvement in discomfort after the TRM, other participants did not. This finding was similar for the control group. Participants in this study were generally healthy with a good BMI and healthy muscle mass. It is possible that a healthy muscle mass may contribute to the decreases sensation of discomfort overtime. Another possible reason for the lack of difference in perceived discomfort between the TRM and control groups was the use of a generic pain scale to quantify discomfort. Interestingly, although asked specifically about discomfort, many participants used the term pain when asked to rate their discomfort. Discomfort and pain are different constructs and pain measures may not have captured the more diffuse symptoms of discomfort that our participants experienced. It is possible that perceived comfort may have been a more suitable and responsive measure for this study. More research in this area is needed to differentiate these constructs.
The limitations of our study include the generalizability of our findings from a healthy population who did not have the complex care needs and health disparities that are often present in older adults in long-term care. However, we still observed a difference in PPI between the TRM and control groups. Given that our participants likely had a healthier muscle mass than what would be observed in residents of long-term care facilities, it is plausible that even greater differences in PPI would be observed in a more vulnerable population. The challenge in determining the location of PPI should also be noted. Due to measurement of PPI on an FSA torso mat, the location of PPI could be located anywhere over the area of contact. Moreover, the location of PPI may change between laying supine and being positioned in HF, or after performing TRM. Future studies on the TRM should consider palpation or other techniques to determine location of PPI.
The measurement limitations in our study included a crude indicator of trunk entrapment to capture displacement of the trunk. Although our measurement device was fitted with a square-gauge and level to level to increases consistency, the reliability and validity of this measure was not determined. The premise for measuring trunk entrapment came about as a proxy measure for shear. However, a precise measure of shear is needed to make any conclusion about the effect of TRM on the reduction of shearing forces. Other limitations arose from our inability to ensure our participants remained completely still. Although participants were coached not to move, they were often observed making small movements of the limbs which may have influenced pressure and trunk entrapment measurements. Finally, we did not continue to measure pressure readings over several hours. It is unknown if prolonged sitting time in HF will negate the benefits of performing the TRM. However, it is known that prolonged sitting in an upright position is not advisable from a pressure ulcer prevention point of view. Therefore, it is suspected that frequent repositioning according to the TRM protocol would be necessary to reduce the risk of pressure ulcers.