Last reviewed: October 25, 2026
In this article
Warm, damp skin over the sacrum is a sign of heat and moisture where the body meets the support surface: the skin’s microclimate. The 2026 International Guideline’s support-surface chapter opens by describing what full-body support surfaces are for: they are “designed to redistribute pressure, reduce friction and shear, and aid microclimate management, all factors that play a role in pressure injury development.” [1] This article looks at when the guideline points to a low-air-loss surface. It picks up where Who Should Be Considered for a Powered Support Surface leaves off.
A 30-second read
Clinical takeaways
SS11 / SS15: Guideline recommendations
Heat and moisture contributing to pressure-injury risk?
Consider a low-air-loss surface within the individualized care plan. This is a situation specifically identified in SS11. [1]
An existing Stage 2–4 or unstageable pressure injury?
Reassess the current surface. SS15 suggests low air loss for these injuries; selection follows the resident’s assessment. [1]
For Directors of Care and purchasers: does your equipment assessment consider both pressure redistribution and microclimate management?
When to consider a powered surface
Seven signs to consider a powered surface in long-term care
Any one of these signs is a reason to assess whether a powered surface could better meet the resident’s needs.
Thinking of a resident? Tap the signs they show.
Also consider changing the surface when a resident with an existing pressure injury is uncomfortable or bottoming out on it (Guideline SS12).
PRESSURE 2 signs are the trial authors’ advice. The guideline suggests low air loss for Stage 2–4 or unstageable injuries (SS15), and that it could be used for people at risk, “especially when moisture and heat at the skin-surface interface are contributing factors” (SS11).
Sauvage et al., 2017 · Nixon et al., PRESSURE 2, 2019 · International Guideline (EPUAP/NPIAP/PPPIA), 2026 · BC PISWC mattress algorithm, 2026 · PRESSURE 2↗ · Sauvage 2017↗ · Guideline↗ · BC algorithm↗
Section 1 · The skin’s microclimate
What is the skin’s microclimate?
- NPIAP S3I 2024 · Terms and definitions
- Mifsud 2022 · Systematic review
The NPIAP Support Surface Standards Initiative defines microclimate as “the temperature and humidity/moisture in a specified location at the body interface” [4] — where skin meets the mattress. In a 2022 paper, the authors of the International Guideline’s chapter on how pressure injuries develop summed up the mechanism: “with an increase in temperature and humidity, the skin becomes more vulnerable to damage.” [5]
Mechanism 01
Heat
A 2022 systematic review reports that a rise in skin temperature increases water loss through the skin and damages its outer barrier. [6] NPIAP standards guidance adds that a higher interface temperature “may lead to an increase in risk for pressure injury.” [7]
Mechanism 02
Moisture
Prolonged moisture over-hydrates the skin, which “is then at further risk of damage caused by friction or shear forces from objects such as bedsheets or incontinence pads.” [8]
Section 2 · Who is exposed
Which residents are most exposed?
- SS4 · Good practice statement
- BC provincial algorithm · 2026
Incontinence is an everyday source of moisture: in a 2016 survey of US and Canadian facilities, 63% of 3,035 long-term-care residents were incontinent. [10] Moisture from incontinence “can be a risk factor for pressure injury development,” and continence care addresses it at the source. [2] Perspiration and fever also add moisture and heat; Wounds Canada lists “fever, air flow restriction” among the causative factors for incontinence-associated dermatitis. [8]
Alongside that care, the 2026 guideline makes it good practice to consider the resident’s “need for microclimate management and shear reduction features” when selecting or changing a mattress, together with overall risk, skin response, mobility, posture, preferences and care goals (SS4). [1]
Canadian selection tool
BC’s provincial algorithm points to microclimate management, such as low air loss, for damp skin
British Columbia
The June 2026 provincial mattress algorithm splits each surface category by the Braden Moisture subscale, marking a subscale score of 1 or 2 as “moisture is a concern.” Its appendix advises: “If skin is damp due to moisture (e.g. incontinence or perspiration), use a microclimate coverlet or a surface with microclimate management such as low air loss. Address wound exudate or incontinence with separate interventions.” [11]
The assessment question
Does this resident need support with microclimate management as well as pressure redistribution? Cochrane’s overview describes low-air-loss features as “designed to improve the skin microclimate with the aim of maintaining skin and tissue integrity, particularly in people with incontinence.” [12]
Section 3 · The function
What does a low-air-loss surface actually do?
- NPIAP S3I 2024 · Position statement
- NPIAP S3I 2020 · Microclimate working group
“a support surface construction that uses a flow of air to assist in pressure redistribution and may assist in managing the heat and humidity (microclimate) of the skin.”
NPIAP S3I · Low Air Loss Terminology Position Statement · 2024 [13]
Wounds Canada’s selection tool says the role of low air loss is to help evaporate moisture and that it can be considered where full-body moisture is an issue. [14] NPIAP’s microclimate working group states the aim plainly: keeping skin cooler and drier “can be an effective strategy to maintain homeostasis, lower frictional forces and thereby maintain skin integrity.” [15]
Foam is a reactive surface: by definition it changes its pressure-redistribution properties only in response to the load placed on it. [4] Conventional foam alone does not provide powered airflow for microclimate management. [1] For residents who also can’t reposition themselves, foam’s limits show in pressure-injury rates: in a randomized trial in nine French medium- and long-stay facilities, 13 of 37 residents on viscoelastic foam developed a new pressure injury within 30 days, versus 2 of 39 on an alternating-pressure air mattress. [16]
Section 4 · The 2026 guideline
When does the 2026 guideline suggest low air loss?
- SS11 / SS15 · Guideline recommendations
- SS4 · SS12 · Good practice
2026 International Guideline · SS11 · SS15
Two clinical pictures that point to low air loss
Picture 1 · SS11
Heat or moisture at the skin–surface interface
The guideline suggests a low-air-loss surface “could be used for individuals at risk of pressure injuries, especially when moisture and heat at the skin-surface interface are contributing factors,” and adds that such surfaces “[…] may be more appropriate for individuals at very high risk of PIs and may be indicated for moisture management in individuals with exposure to excess moisture” (SS11). [1] The NPIAP definition, Cochrane’s overview and BC’s provincial selection tool all describe low air loss as a way to manage heat and moisture at the skin. [11][12][13]
Picture 2 · SS15
An existing Stage 2–4 or unstageable pressure injury
After an immobility-related injury, the guideline asks teams to re-evaluate the surface (SS12). The surface the injury developed on “usually does not provide an appropriate environment for healing,” and a different one will usually be needed for better pressure redistribution, friction and shear management, and “modification of the microclimate.” [1] Stage 2 injuries, the NPIAP notes, “commonly result from adverse microclimate and shear in the skin over the pelvis.” [17] The guideline then suggests “using low air loss full body support surfaces for individuals with Category/Stage II–IV and unstageable pressure injuries” (SS15). [1] Repositioning remains essential to healing. [3] For stalled wounds, see When the Wound Isn’t Healing.
In either picture, selection follows the individual assessment (SS4). Stage 1 is not included in SS15; for an immobility-related Stage 1 injury, SS12 makes it good practice to re-evaluate the existing support surface. [1]
Hypothetical teaching scenario · for discussion
Example: damp, warm sacral skin on a foam surface
A long-term-care resident with limited mobility is on a foam mattress and is incontinent of urine overnight. Night notes mention damp linen. The day nurse documents new moisture-associated skin change over the sacrum, but no pressure injury. His individualized repositioning plan is being followed.
The team addresses the moisture source with a continence assessment and toileting plan, prompt changes of soiled products, a barrier preparation and breathable absorbent products, [8][2][18] and assesses the support surface alongside it. Working through the selection factors (SS4), the team confirms that this mattress has no powered airflow feature for microclimate management. [1] Between checks, the skin stays damp and warm even with continence care in place: heat and moisture at the interface remain contributing factors — the SS11 picture. [1] The team considers a low-air-loss surface, continues skin care, continence care and repositioning, [1][3] and agrees what it will review afterwards. [1][9]
Takeaway. Equipment follows assessment: the resident’s assessed needs make the case.
Section 5 · Existing injuries
What did a nursing-home trial find about healing rates?
- Ferrell 1993 · Randomized trial, US nursing homes
- Cochrane 2021 · Treatment review
The trial below is included in Cochrane’s 2021 review of beds, overlays and mattresses for treating pressure ulcers. [19]
Randomized trial in three Los Angeles nursing homes · JAMA 1993
9.0 vs 2.5
Median wound-area healing rate (mm²/day), low-air-loss bed vs 10-cm foam
Low-air-loss bed 9.0 mm² per day; 10-cm foam 2.5 mm² per day.
- Population
- 84 nursing-home residents with Stage 2 or worse pressure injuries on the trunk or hip (trochanter)
- Design
- Randomized trial — low-air-loss bed vs 10-cm foam mattress
- Finding
- The median rate of wound-area healing was more than three times higher on low air loss (P = .0002).
- Healing
- Accounting for fecal continence, residents on low-air-loss beds were 2.5 times more likely to heal in a given length of time than those on foam mattresses.
- Cost
- A companion economic analysis by the same team put the cost at about US$26 (in 1992 dollars) per added day free of pressure injuries for a typical resident, and found that for residents with milder injuries and good healing potential this is “comparable to other accepted health treatments.” [20]
Bruce A. Ferrell, MD, Dan Osterweil, MD, and Peter Christenson, PhD (UCLA) · JAMA 1993 [21]; also in Cochrane CD013624 [19] and Ontario’s 2009 health technology assessment [22]
Low-air-loss beds provide substantial improvement compared with foam mattresses despite other factors in pressure ulcer healing.
Bruce A. Ferrell, MD, Dan Osterweil, MD, and Peter Christenson, PhD (UCLA) · JAMA, 1993 [21]
Section 6 · The care plan
Using low air loss within the care plan.
- Repositioning R1 · Good practice statement
- SS11 implementation · Skin moisture and hydration
Alongside the surface
Three things that get the most from low air loss
Repositioning
The guideline states that “no support surface can entirely replace repositioning,” [3] and RNAO notes that people on advanced pressure-redistribution surfaces, including those with low air loss, still require it. [9]
Skin care and continence care
Controlling the moisture is the first step in treating any moisture-associated skin damage. [8] Barrier products “to protect skin from excessive moisture” and an “individualized continence (bladder and bowel) program” continue. [2]
Function and fit
Make sure the resident can move in and get out of the bed, and that devices, incontinence aids and bed linen don’t interfere with the surface’s function. [1]
One clear action
When heat and moisture are part of a resident’s care needs, consider whether the support surface provides suitable microclimate management. [1] Repositioning, skin care and continence care continue, and the team reviews the skin after any change. [1][2][3]
Questions teams ask
Education for your team
Bring the microclimate conversation to your team.
Request an in-service on the skin’s microclimate — heat and moisture at the skin–surface interface, what low air loss does, and practical setup and use. Bring your team’s questions and anonymized resident examples.
Or ask about a dealer-coordinated demonstration.
About Evergreen. An Evergreen educational summary of published studies and guidelines. Practical examples illustrate application. The sources do not endorse Evergreen or its products. Support surfaces do not replace repositioning. Selection and use should be based on individual clinical assessment and the product instructions for use.
Explore Evergreen’s powered surfaces.
These links describe Evergreen’s range. They are not study endorsements or product-specific evidence.
References
- National Pressure Injury Advisory Panel, European Pressure Ulcer Advisory Panel, Pan Pacific Pressure Injury Alliance. Full Body Support Surfaces. In: Haesler E, ed. Prevention and Treatment of Pressure Ulcers/Injuries: Clinical Practice Guideline. The International Guideline. 4th ed. 2026. Version date 20 May 2026 (site updated 25 August 2026). SS3, SS4, SS7, SS11, SS12, SS15; pp. 1, 5–7, 9–10, 13–14, 16. https://www.internationalguideline.com/surfaces
- Norton L, Parslow N, Ho C, O’Sullivan-Drombolis D, Rogers A, Parsons A, Moss L. Best practice recommendations for the prevention and management of pressure injuries. In: Best Practice Recommendations for Skin Health and Wound Management 2025. Toronto: Wounds Canada; 2025. doi:10.56885/GRYI5585. https://www.woundscanada.ca/health-care-professional/publications/bpr-new
- National Pressure Injury Advisory Panel, European Pressure Ulcer Advisory Panel, Pan Pacific Pressure Injury Alliance. Repositioning and Mobilization. In: The International Guideline. 4th ed. 2026. Version date 14 May 2026. R1; p. 1. https://www.internationalguideline.com/repositioning
- National Pressure Injury Advisory Panel, Support Surface Standards Initiative. Terms and Definitions Related to Support Surfaces. Rev. 18 April 2024 (PDF unpaginated; cited by PDF page). https://npiap.com/page/S3I
- Gefen A, Brienza DM, Cuddigan J, Haesler E, Kottner J. Our contemporary understanding of the aetiology of pressure ulcers/pressure injuries. Int Wound J. 2022;19(3):692–704. doi:10.1111/iwj.13667. https://pmc.ncbi.nlm.nih.gov/articles/PMC8874092/
- Mifsud T, Modestini C, Mizzi A, Falzon O, Cassar K, Mizzi S. The effects of skin temperature changes on the integrity of skin tissue: a systematic review. Adv Skin Wound Care. 2022;35(10):555–565. doi:10.1097/01.ASW.0000833612.84272.da. https://pmc.ncbi.nlm.nih.gov/articles/PMC9508978/
- National Pressure Injury Advisory Panel, Support Surface Standards Initiative. Guidance on Interpretation of Performance Standards for Support Surfaces, version 2.0. n.d. (PDF unpaginated; cited by PDF page). https://npiap.com/page/S3I
- Forest-Lalande L, Parsons L, McPhee S, Kuhnke JL, Hoover J, Lillington T, Dann LJ. Best practice recommendations for the prevention and management of moisture-associated skin damage. In: Best Practice Recommendations for Skin Health and Wound Management 2025. Toronto: Wounds Canada; 2025. doi:10.56885/JWRY3671. https://www.woundscanada.ca/health-care-professional/publications/bpr-new
- Registered Nurses’ Association of Ontario. Pressure Injury Management: Risk Assessment, Prevention and Treatment. Clinical Best Practice Guideline, 4th ed. Toronto: RNAO; 2024 (web version June 2025). pp. 39, 51, 54. https://rnao.ca/bpg
- Kayser SA, Phipps L, VanGilder CA, Lachenbruch C. Examining prevalence and risk factors of incontinence-associated dermatitis using the International Pressure Ulcer Prevalence survey. J Wound Ostomy Continence Nurs. 2019;46(4):285–290. doi:10.1097/WON.0000000000000548. https://pmc.ncbi.nlm.nih.gov/articles/PMC6716554/
- BC Provincial Interprofessional Skin & Wound Committee. BC Provincial Support Surface Mattress Algorithm (Adult Populations). June 2026. pp. 1–2 (flowchart and Appendix A) and p. 4 (placement notes). https://www.clwk.ca/get-resource/bc-provincial-support-surface-selection-qrg/
- Shi C, Dumville JC, Cullum N, Rhodes S, McInnes E, Goh EL, Norman G. Beds, overlays and mattresses for preventing and treating pressure ulcers: an overview of Cochrane Reviews and network meta-analysis. Cochrane Database Syst Rev. 2021;(8):CD013761. doi:10.1002/14651858.CD013761.pub2. https://pmc.ncbi.nlm.nih.gov/articles/PMC8407250/
- National Pressure Injury Advisory Panel, Support Surface Standards Initiative. Low Air Loss Terminology Position Statement. NPIAP; 2024 (PDF unpaginated; cited by PDF page). https://npiap.com/page/S3I
- Wounds Canada. Product Picker: Integrated Therapeutic Support Surface Selection for Pressure Injury Prevention and Management. Toronto: Wounds Canada; 2023. p. 4, Note above Table 2. https://www.woundscanada.ca/docman/public/3092-wc-product-picker-surfaces-fillable-1/file
- Lafleche P, Brienza D, Newton D; Microclimate Management Small Working Group, Support Surface Standards Initiative, National Pressure Injury Advisory Panel. Support Surface Standards Tests for Microclimate Management [poster]. NPIAP; 2020. Single-page poster, unpaginated; Background panel. Posted with the S3I documents at https://npiap.com/page/S3I
- Sauvage P, Touflet M, Pradere C, et al. Pressure ulcers prevention efficacy of an alternating pressure air mattress in elderly patients: E²MAO a randomised study. J Wound Care. 2017;26(6):304–312. doi:10.12968/jowc.2017.26.6.304. Turning frequency, Table 3 (p. 309); authors’ conclusion, p. 312.
- National Pressure Injury Advisory Panel. NPIAP Pressure Injury Stages. NPIAP; 2016. https://cdn.ymaws.com/npiap.com/resource/resmgr/online_store/npiap_pressure_injury_stages.pdf
- National Institute for Health and Care Excellence. Pressure ulcers: prevention and management. Clinical guideline CG179. 2014 (updated 2019). Recommendation 1.1.18. https://www.nice.org.uk/guidance/cg179
- Shi C, Dumville JC, Cullum N, Rhodes S, Jammali-Blasi A, Ramsden V, McInnes E. Beds, overlays and mattresses for treating pressure ulcers. Cochrane Database Syst Rev. 2021;(5):CD013624. doi:10.1002/14651858.CD013624.pub2. https://doi.org/10.1002/14651858.CD013624.pub2 — “Characteristics of included studies: Ferrell 1993” (in the full Cochrane record). Narrative also at https://pmc.ncbi.nlm.nih.gov/articles/PMC8108042/
- Ferrell BA, Keeler E, Siu AL, Ahn SH, Osterweil D. Cost-effectiveness of low-air-loss beds for treatment of pressure ulcers. J Gerontol A Biol Sci Med Sci. 1995;50(3):M141–M146. doi:10.1093/gerona/50a.3.m141. PMID: 7743399. Abstract: https://pubmed.ncbi.nlm.nih.gov/7743399/
- Ferrell BA, Osterweil D, Christenson P. A randomized trial of low-air-loss beds for treatment of pressure ulcers. JAMA. 1993;269(4):494–497. doi:10.1001/jama.1993.03500040060037. Abstract: https://jamanetwork.com/journals/jama/article-abstract/403027 — study characteristics and results are also reported in Cochrane CD013624 (reference 18).
- Medical Advisory Secretariat. Management of chronic pressure ulcers: an evidence-based analysis. Ontario Health Technology Assessment Series. 2009;9(3):1–203. Low-air-loss beds, pp. 91–92. PMID: 23074533. https://pmc.ncbi.nlm.nih.gov/articles/PMC3377577/
Continue the clinical pathway
This article is an educational resource for healthcare professionals and reflects Evergreen’s interpretation of the cited studies and guidelines; read the original sources for full methods and results. It is not intended to replace clinical judgment, individualized resident assessment, facility policy, or product instructions for use.