So much about the art and the science of seating is about working effectively with factors that are unchangeable — the wheelchair rider’s diagnosis, progression of the condition, and past mobility equipment, just for starters.
Seating teams also need to account for inescapable factors such as pressure, which can be strategically managed, but never fully avoided.
That’s true as well for microclimate, whose management is critical for optimal seating outcomes.
What is microclimate?
Sunrise Medical’s clinical education team — Jessica Presperin Pedersen, OTD, MBA, OTR/L, ATP/SMS, director of clinical education, North America; Erica Walling, MPT, ATP/SMS, manager of clinical education, southeastern United States; Lindsey Veety, PT, DPT, ATP/SMS, manager of clinical education, northeastern United States; Karla Sonderland, MS, OTR/L, ATP, manager of clinical education, midwestern United States; and Christy Natale, DPT, ATP/SMS, CRTS, manager of clinical education, western United States — teamed up to talk about microclimate.
“The term microclimate was coined in the 1950s to describe any climatic condition in a relatively small area,” they said. “Historically, the term has been used in a geographical, meteorological or topographical context. But as of late, it has made its way into the Complex Rehab industry to describe the mini atmosphere at the area of contact between the seat cushion and client.
“The National Pressure Injury Advisory Panel (NPIAP) defines microclimate as ‘the impact of a support surface on the temperature and humidity/moisture in a specified location at the body interface,’” the Sunrise Medical team added. “So the skin microclimate would include airflow, temperature, and humidity between the body and the surface of support.”
Bart Van der Heyden, PT, a physical therapist in private practice and owner of SuperSeating, described microclimate as a “very complicated” issue.
“In a simple form, it refers to the interface that a client makes with a seat or a cushion or support surface, any type of material,” Van der Heyden said in describing microclimate. “We’re looking at temperature, humidity, and air flow, air movement.”
When considering pressure injury risk, microclimate is not, perhaps, as intuitive a concern as pressure or shear.
Nicole LaBerge, PT, ATP, is the commercial product manager for Permobil Americas.
“I think people are finally realizing that the causes of pressure injury are not just pressure, “ LaBerge said. She added that while it seemed logical that pressure wasn’t the only cause of pressure injuries, it’s taken research and astute investigation to determine that whether micro-climate is well managed or poorly managed can impact outcomes, including pressure injury risk.
The mechanics of microclimate
“We still don’t know exactly” what the optimal microclimate for wheelchair riders is, Van der Heyden said. “However, we know that increased temperature and humidity make skin more vulnerable. The European Pressure Ulcer Advisory Panel (EPUAP), National Pressure Injury Advisory Panel and Pan Pacific Pressure Injury Alliance in 2019 extended clinical guidelines said wetness of an interface plays an important role in this mechanical interaction between skin and a medical device. The more wet your skin becomes, the higher the friction component and tissue deformation resulting from any frictional sliding movement and shear force will become.
“So usually when skin is exposed to warm and moist conditions, it becomes weaker, less stiff and affects the load transfer from the skin to deep tissue. We know that body-core and skin-surface temperatures influence water loss or sweating. And then we’re talking about sweating and evaporation of this moisture. That depends on the local and ambient humidity. So the local humidity would be your climate, and the ambient would be the interface, and that will be microclimate. We know that will influence that friction property, and the magnitude of the friction component increases will actually also influence the amount of forces acting on the body and therefore the deformation of tissue.”
Van der Heyden referenced moisture-associated skin damage, “an umbrella term for all kinds of possibilities of having excessive moisture. It can be incontinence-associated dermatitis, for instance. We know mechanical, physical and chemical irritation of that skin might trigger inflammation and skin damage. I would call those microclimate issues to some degree. It’s not perspiration; it’s linked to incontinence, perhaps. But that’s then a physical and a chemical irritation of the stratum corneum,” i.e., the outermost layer of skin.
Who does microclimate impact?
What microclimate areas should be monitored?
“Any area in contact with a support surface,” the Sunrise Medical team said. “Increased interface pressure while sitting reduces blood flow to high-risk areas, especially the ITs [ischial tuberosities] and sacrum. Higher skin temperature increases tissue metabolism and demand for oxygen and nutrients (about 10% higher for 1°C raised). Increasing skin temperature seems to be associated with general decline of skin resistance to damage. Temperature and humidity affect the structure and function of the skin, lowering damage thresholds for the skin and underlying soft tissues.”
While all clients should be aware of microclimate, some are at greater risk.
“We know as we get older that our skin naturally gets more dehydrated,” LaBerge pointed out as one example. “You have less moisture in your own body, and you could also have a change in your ability to regulate temperature; as an example, you are all of a sudden warm in the middle of the day for no reason. That can have a huge impact on your skin integrity compared to what was occurring a couple years ago.”
“Yes, there needs to be awareness of microclimate management for all riders; however, some are at higher risk than others,” the Sunrise Medical team said. “Anyone with the inability to regulate temperature, has excessive sweating, or is prone to incontinence has the potential to create an unhealthy microclimate between the body and the support surface. Individuals with spinal cord injury may have a hard time regulating temperature or have dysreflexia. In these instances, where body temperature as a whole is increased or a person is sweating above the level of injury, methods to control this may be a goal through the body contact surfaces.
“For individuals with bariatric conditions, skin issues can arise due to folds in the skin that harbor moisture or have a higher body temperature. Increased sweating can lead to moist skin. People with multiple sclerosis potentially have impaired sweat glands, reducing the body’s ability to control body temperature.”
The Sunrise Medical team also listed generally reduced mobility — such as difficulty or inability to independently change positions, as well as spending more time seated compared to someone capable of independent ambulation — as factors that can make microclimate more difficult to manage.
Seating technology that addresses microclimate
As the industry’s understanding of microclimate has evolved, manufacturers have stepped up their microclimate focus as well.
Sam Hannah, CEO of Symmetric Designs, has also served as an Assistive Technology Professional (ATP). Among Symmetric Designs’ lines is the Free Form custom-molded seating solution.
“Looking at a wheelchair user’s seating system, the largest part of their body that’s making contact with the seating surface is typically their back,” Hannah said. “Their back typically has a lot of bony prominences with the spine, the scapulas. With wheelchair users that are not as active, not as mobile, that pressure is more constant; there’s less weight shifting. So, with a modular seating system, it’s really quite important to distribute pressure. You can’t eliminate pressure, but distributing pressure as much as you can throughout that surface is going to reduce overall pressure and support the person in the desired posture. With a system like Free Form, you have that added benefit of air flow right through the custom mold, which is going to dissipate heat, dissipate moisture, and lead to overall better skin integrity.”
Symmetric Designs also offers the Respira back support, available with both passive ventilation through its padding and cover, and an active fan system. The Sport version of Respira features Stimulite honeycomb padding, while the Respira Comfort has perforated cooling gel-foam with a stretch 3D air mesh cover.
“When we designed our Respira Sport line in particular, we wanted to take into account that people are going to be quite active using this, and as a result of that, there would be increased body temperatures, more perspiration,” Hannah said. “We wanted the ability to sanitize the system, to fully wash all the materials and have everything be durable.”
Hannah added that Symmetric Designs is in the application process to get a HCPCS code for Respira to improve funding opportunities in the United States. “I would love to see microclimate become a more prominent aspect of justification for funding of different types of products that enable better microclimate control,” he said. “The aspects [payers] look at typically for wheelchair back supports are the level of posture, the lateral depth, the weight capacity. But in our funding applications or our coding applications, microclimate really hasn’t come into play as an aspect that they would look at as potentially saving them costs in terms of better skin integrity down the road.”
For clients with incontinence issues, LaBerge suggested taking a closer look at cushion options while keeping microclimate in mind. Wheelchair riders wearing incontinence pads or briefs “still need to change those out [promptly]” to avoid having their skin be in contact with bodily fluids, bacteria, etc., for long periods of time.
As for cushion choices: “[Manufacturers] put incontinence liners on our products to protect the product, not the user,” she said. “[Clients] think, ‘I’ll just get an incontinence liner for my foam cushion.’ That’s great; that’ll help your foam last longer. But if you are incontinent, that moisture and wetness are still going to be touching you. So that’s not the complete solution. We still need to get you dry or in an offloading position so you’re not having trapped moisture.”
Another recommendation could be for funding sources to pay for a second seat cushion cover so a wheelchair rider could wash and dry one cover while using the second cover on the chair.
“How much could [payers] save with preventive equipment — in this case, an extra cover for a cushion or back support?” LaBerge asked. “How much could that save versus the cost of one pressure injury and all of the dressing changes and potential hospitalizations? Why don’t we allow for another cover to be included?”
Making microclimate part of the conversation
While health care’s understanding of pressure injuries has evolved, understanding microclimate and its outcomes is just gaining speed.
LaBerge gave the example of a patient with a wound who’s in a hospital bed and needs assistance with transfers. “They may have the necessary position changes and even a mattress that allows for air flow,” she said of the support surface. “But then what do people do? They put an incontinence pad on top of that sheet, and then the patient on top of that. They may also put a [patient lift] sling underneath the patient as well. Then they wonder why the wound is not healing. Because now you have the air mattress, sheet, incontinence pad, sling, clothing, dressing, and then the wound. That’s not going to work. There’s a lot of layers in there that are trapping that moisture and the heat and not helping with their microclimate.”
Ideally in such situations, having more caregivers on hand could mean the patient is changed quickly when accidents or leakage occurs, and that wound dressings are changed right on time (with no “rationing” of dressings needed). Perhaps the sling could also be used only during transfers.
But in addition to education, LaBerge said more research is needed to show “that in this scenario, microclimate was poor and skin was breaking down faster. Or their healing was slowed because they were sweating, something that external factors could possibly assist with. We have to show the things we’re suggesting are necessary. I think that’s hard because we know how long research takes, and we know how long it takes to change policies. Simply providing preventative equipment (e.g., at least two covers for cushions and back supports) or insurance funding the necessary number of dressings for the wound could have a huge impact on overall health-care savings.”
“It’s all about education,” Hannah said. “A lot of this research that Bart in particular has been doing is quite new and evolving as well.”
Van der Heyden agreed, but added that NPIAP and EPUAP guidelines do exist. “It’s not like there is no link between skin integrity and microclimate,” he noted. “It’s evidence based, and it’s researched. I think it just translated better into the nursing field, perhaps because they have this moisture-associated skin damage issue, and they have microclimate often linked to incontinence issues. I think there is a huge awareness of it.
“I also think that a lot of skin damage from microclimate is not always managed best with pressure redistribution surfaces. For instance, if you have skin damage from moisture-associated skin damage, then perhaps your answer could be a different [cushion] cover and not a new cushion. But of course, we know it’s an additional risk. It’s definitely documented. I think just for the seating world, it’s a relatively new thing to look at.”
“When we explain microclimate to people and why they should be looking at it, it’s a no-brainer, really,” Hannah said. “Just go for a drive in your car on a hot day. How is your lower back? People just naturally perspire, but then think about someone who is in a mobility device all day and they’re not able to get out of their seat and air out. Just look at it from a very simplified perspective and how that affects people that have limited mobility and don’t have the ability to weight shift.
“It comes down to education, clearly explaining or reminding people that heat is an issue.”
Editor’s note: This story was originally published in the June digital edition of Mobility Management.
