How Do We Know If 30-Degree Lateral Turned Position Equals Effective Pressure Relief?

A Narrative Review of Positioning Accuracy, Anatomical Offloading, and Sustained Support in Pressure Injury Prevention?

A literature review of the evidence

Through years of clinical nursing practice and wound care, I observed considerable variability in the effectiveness of supported lateral positioning. These observations raised concerns about whether commonly used positioning devices consistently achieved and maintained adequate pressure relief. Ultimately, my observations and findings inspired my efforts to develop more effective positioning support solutions.

This narrative review examines published evidence addressing these concerns and provides the clinical and scientific rationale for the development and subsequent evaluation of improved lateral positioning support devices.

Background: Repositioning patients into a 30-degree lateral position is an established intervention in pressure injury prevention, intended to reduce sustained loading over vulnerable bony prominences, particularly the sacrum and coccyx.

However, achieving a prescribed turning angle does not necessarily establish that effective pressure redistribution has occurred. The actual position and resulting pressure distribution may vary according to support device design, placement, patient anatomy, and the stability of the supported position over time.

Three considerations emerged as particularly important:

1. Positioning accuracy: The degree of lateral tilt achieved may vary according to the design, dimensions, and placement of the support device. These variances effect the level of pressure exerted onto bony prominences of the sacrum/coccyx, greater trochanter, and acromia.

2. Anatomical alignment: A 30-degree angle, typically measured at the sternum, does not necessarily establish equivalent pelvic rotation or adequate offloading of the sacrum, coccyx, greater trochanters, scapulae, and acromia.

3. Sustained positioning: Patient movement due to natural shifting or discomfort, displacement of support devices, and compression or bottoming out of support device(s) may alter the intended position and compromise pressure redistribution before the next scheduled turn.

Abstract

Supporting patients in a 30-degree lateral position is an established intervention for pressure injury prevention. However, achieving the prescribed turning angle does not necessarily ensure effective or sustained pressure redistribution over vulnerable bony prominences.

Objective: To review published evidence examining the influence of support device design, positioning accuracy, anatomical alignment, and positional stability on pressure redistribution during supported lateral positioning.

Methods: A focused narrative review of five clinical and observational studies evaluating interface pressure distribution, anatomical positioning, and maintenance of supported lateral positions.

Findings: Studies demonstrated considerable variability in the angles achieved and maintained using different positioning devices. Interface pressure measurements revealed that lateral repositioning did not consistently eliminate elevated pressures over vulnerable anatomical sites. Hip rotation significantly influenced sacrum/coccyx and greater trochanteric pressures. Reductions in sacral pressure were sometimes accompanied by increased loading elsewhere.

Studies evaluating positional stability demonstrated that supported angles may change substantially over a two-hour period, with differences observed between support devices. Few studies simultaneously evaluated anatomical alignment, interface pressure distribution, and sustained positioning.

Conclusion: Achieving a prescribed lateral turning angle does not independently establish effective pressure redistribution or its maintenance over time. The findings support evaluating positioning devices based on their ability to achieve appropriate anatomical alignment, redistribute pressure across vulnerable bony prominences, and sustain effective offloading throughout the repositioning interval.

Review of Relevant Studies.

1. Lateral Repositioning Does Not Reliably Eliminate Elevated Interface Pressures

Peterson et al. (2010) ¹ Effects of turning on skin-bed interface pressures in healthy adults. This study investigated the effects of standard lateral repositioning on skin-support surface interface pressures in 15 healthy adults. Experienced intensive care nurses positioned participants using pillows and wedges while researchers measured pressure distribution over the sacral, trochanteric, and buttock regions.

The investigators found that repositioning did not consistently eliminate areas of elevated interface pressure. In 93% of participants, areas exposed to pressures of at least 32 mmHg persisted across all evaluated positions. These were described as triple jeopardy areas.

The extent of these persistently loaded areas differed significantly between the wedges and pillows evaluated. Elevation of the head of the bed to 30 degrees also increased peak interface pressures and the area exposed to elevated pressure.

Clinical significance: These findings demonstrate that performing a lateral turn does not necessarily achieve adequate pressure redistribution across all vulnerable areas. They also establish that the support materials used to maintain the position can influence the resulting interface pressure distribution.

The study was conducted in healthy adults, and its findings cannot be generalized to all wedge designs or used to establish comparative pressure injury prevention outcomes.

2. Anatomical Alignment Influences Pressure Redistribution

Yoshikawa, Y, et al (2015) ² A 2015 study, Positioning bedridden patients to reduce interface pressures over the sacrum and great trochanter, investigated the relationship between hip rotation and interface pressure in 17 bedridden patients.

Researchers measured pressures over the sacrum and greater trochanter in supine, 90-degree lateral, and 30- and 40-degree inclined positions. The latter positions were evaluated with both neutral and externally rotated hip alignment.

At both 30 and 40 degrees, neutral hip positioning produced significantly lower peak pressure indices over the greater trochanter than external hip rotation.

Clinical significance: These findings demonstrate that pressure redistribution is influenced by anatomical alignment, not simply the degree of lateral inclination.

Although this study did not directly compare thoracic and pelvic turning angles, it provides evidence that lower-body positioning affects loading over vulnerable bony prominences. Consequently, measurement of a single body angle may be insufficient to characterize the quality of a pressure-relieving position.

3. Pressure Reduction at One Anatomical Site May Increase Loading Elsewhere

Bush et al. (2015) ³ A comparison of pressure mapping between two pressure-reducing methods for the sacral region compared pillows with a commercially available wedge system for reducing sacral interface pressures in 21 healthy volunteers.

Pressure mapping was performed over the shoulder and sacral/buttock/thigh regions at head-of-bed elevations of 0, 20, and 30 degrees. Both positioning methods significantly reduced mean sacral pressures compared with the bed-alone condition, with the wedge system producing greater sacral pressure reduction than the pillows tested. However, both methods also increased pressures over the posterolateral buttock and thigh regions.

Clinical significance: This study demonstrates that successful offloading of one anatomical region may redistribute increased loading to other regions. The effectiveness of a positioning intervention therefore cannot be fully evaluated by measuring sacral pressure alone.

Assessment of pressure distribution across multiple anatomical sites is necessary to determine whether pressure has been redistributed appropriately without introducing excessive loading elsewhere. These findings also demonstrate that differences between specific positioning devices can be quantified through interface pressure measurement

4. The Supported Lateral Position May Deteriorate Over Time

Kapp et al. (2019) ⁴ An observational study of the maintenance of the 30° side-lying lateral tilt position among aged care residents at risk of developing pressure injuries when using the standard care pillow and a purpose-designed positioning device. Researchers conducted an observational study involving 12 aged-care residents to evaluate the maintenance of a 30-degree lateral position using standard pillows compared with a purpose-designed fluidized positioner.

Body angles were measured immediately after positioning and again at one and two hours.

The mean supported angles were:

The fluidized positioner maintained the intended lateral angle more consistently than the pillows, with statistically significant differences in angle maintenance over time.

Clinical significance: This study provides direct evidence that the initially achieved position may not be maintained throughout the repositioning interval.

It also demonstrates that support device characteristics can influence positional stability. Although the investigators measured changes in lateral angle, they did not establish corresponding changes in interface pressure at individual bony prominences. Therefore, maintenance of the prescribed angle should not be interpreted as confirmation of sustained anatomical offloading.

5. Positioning Devices Differ in Their Ability to Achieve and Maintain the Intended Angle

Sousa et al. (2020)⁵ Positioning immobile critically ill patients who are at risk of pressure injuries using a purpose-designed positioning device and usual care equipment: Investigators conducted an observational feasibility study involving eight immobile, critically ill patients, comparing a fluidized positioner with standard design foam wedges and pillows.

The investigators recorded body angles immediately following positioning and at one and two-hour intervals.

Mean lateral angles at baseline and two hours were:

All three methods demonstrated relatively small changes in mean angle over the two-hour period. However, the achieved angles varied.

An interesting finding was that individual angle measurements with a foam wedge included a wide range of initial and final angles. Suggesting the angle of the support wedge varies widely.

Mean lateral and range angles of foam wedge are:

Clinical significance: These findings illustrate two important considerations: the achieved angle may differ according to the support method, and a group mean near 30 degrees does not necessarily indicate that individual patients are positioned at the intended angle.

Unlike the findings reported by Kapp et al., this small feasibility study did not demonstrate substantial deterioration in mean lateral angle over two hours for any device. Together, the studies suggest that positioning stability may depend on the clinical population, equipment, and conditions of use. Neither study established the corresponding degree or duration of interface pressure relief.

Discussion

Observational studies demonstrate variability in the angles achieved with different support devices and in the maintenance of those angles over time.

Collectively, these studies demonstrate that the effectiveness of supported lateral positioning involves more than achieving a prescribed turning angle. Interface pressure investigations have established that standard repositioning does not reliably eliminate elevated pressures at all anatomical sites. Furthermore, reducing pressure over the sacrum may increase loading elsewhere, and anatomical alignment can significantly influence pressure distribution.

These findings highlight an important distinction between three measures of positioning effectiveness.

• Position achieved: Whether the patient has been placed at the intended lateral angle.
• Pressure redistribution achieved: Whether the position effectively reduces loading over vulnerable bony prominences without creating excessive pressure elsewhere.
• Position and offloading maintained: Whether the intended anatomical alignment and resulting pressure redistribution are sustained throughout the repositioning interval.

These measures are related but not interchangeable. Studies measuring pressure injury incidence provide important evidence of clinical outcomes, while studies measuring interface pressure and body position provide information about the performance and mechanisms of positioning interventions. Both approaches are valuable, but neither independently answers every question about device effectiveness.

The studies reviewed here also have limitations. Several involved small samples of healthy volunteers, evaluated specific commercially available devices, or measured body angle without simultaneously measuring interface pressures. The findings therefore should not be generalized to all positioning wedges or interpreted as evidence that any one device design is universally superior.

Implications for Clinical Practice and Future Research

The evidence supports a more comprehensive approach to evaluating lateral positioning interventions.

Future investigations would benefit from simultaneous measurement of chest and pelvic positioning angles, interface pressures over multiple vulnerable bony prominences, and changes in these measurements throughout the intended repositioning interval.

Research should also examine how device geometry, placement, patient movement, support displacement, and material compression influence interface pressures and body angle, both the initially and over time.

Such measurements could help distinguish a device’s ability to achieve the desired position from its ability to provide and sustain effective pressure redistribution.

Conclusion

Published research demonstrates that supported lateral positioning is subject to variability in anatomical alignment, interface pressure distribution, and maintenance of the intended position.

Achieving a prescribed lateral turning angle does not, by itself, establish that vulnerable bony prominences have been adequately offloaded or that effective pressure redistribution will be maintained until the next repositioning event.

These findings support the need to evaluate positioning devices not only by the angle they achieve or their association with pressure injury outcomes, but also by their ability to establish and sustain effective pressure redistribution across vulnerable anatomical sites

Study citations.

1. Peterson, M. J., Schwab, W., van Oostrom, J. H., Gravenstein, N., & Caruso, L. J. (2010). Effects of turning on skin-bed interface pressures in healthy adults. Journal of Advanced Nursing, 66(7), 1556–1564.

https://doi.org/10.1111/j.1365-2648.2010.05292.x

2. Yoshikawa, Y, Maeshige, N., Sugimoto, M, Uemura, M, Noguchi, M, Terashi, H (2015) Positioning bedridden patients to reduce interface pressures over the sacrum and great trochanter.

J Wound Care, Jul;24(7):319-25.

https://pubmed.ncbi.nlm.nih.gov/26198554/

3. Bush, T. R., Leitkam, S., Aurino, M., Cooper, A., & Basson, M. D. (2015). A comparison of pressure mapping between two pressure-reducing methods for the sacral region. Journal of Wound, Ostomy and Continence Nursing, 42(4), 338–345.

https://doi.org/10.1097/WON.0000000000000144

4. Kapp, S., Gerdtz, M., Gefen, A., Prematunga, R., & Santamaria, N. (2019). An observational study of the maintenance of the 30° side-lying lateral tilt position among aged care residents at risk of developing pressure injuries when using the standard care pillow and a purpose-designed positioning device. International Wound Journal, 16(5), 1080–1086.

https://doi.org/10.1111/iwj.13142

5. Sousa, I., Kapp, S., & Santamaria, N. (2020). Positioning immobile critically ill patients who are at risk of pressure injuries using a purpose-designed positioning device and usual care equipment: An observational feasibility study. International Wound Journal, 17(4), 1028–1038.

https://doi.org/10.1111/iwj.13365