On occasion the question arises, "What is the best way to manage an open pressure sore for someone that must continue to sit"? The resulting answers vary considerably. Some responses take issue with the shape and density of the support surface. Others focus on elements of posture and weight shift. But invariably, most conversations turn to recommendations for a specific product or stories of a one-time, successful outcome. Unfortunately, once the conversation arrives to this point, the question of "Best Practice" is quickly forgotten.

If we look at just the general complexity of managing skin trauma we can find a significant amount of information regarding the formation and treatment of pressure sores but very little as it relates to seated posture that exhibits multiple anomalies; including abnormal tone, structural asymmetry or previously compromised skin tissue. The reality is that protocol for managing a soft tissue wound should take into consideration factors outside the cushion environment which also influence the outcome.

From my experiences, skin trauma to the buttocks region alone can initiate: as a direct flaw in the cushion's initial shape or structure; deterioration or fatigue of the support medium; incorrect placement and orientation of the client within the seating system; sudden loss or change in tissue mass; surgical interventions intended to correct an unrelated issue but leaving the skin at risk to breakdown; or trauma initiated outside the cushion environment but later exacerbated by the cushion; etc. In order to prescribe a future plan or determine a corrective action, the first rule of order is to decipher which of a number of variables is the likely cause. From there, we can easily determine whether to modify, repair, replace, re-educate or rescind the sitting regimen altogether.

In the following discussion we'll take a look at a list of typical recommendations then determine whether we can define reasonable plans of action and best practice for wound management; within the context of wheelchair seated posture.

Don't let 'm sit. Period!
In the good old days, this was the only emphatic response. And for good reason! We now know that any pressure applied to compromised soft tissue can alter the flow of blood and other nutrients at that site. We also know that if we apply enough pressure to a given site the flow of these life sustaining nutrients will stop altogether. So, no pressure against a wound is in fact the best treatment for most types of wounds. But, this rule may be very difficult to observe for a large portion of the sitting dependent population.

Many sitting dependent professionals and high activity consumers insist on remaining productive (and employable) despite the presence of a pressure sore. To do so requires that they sit and perform a multitude of sitting dependent activities; beginning from the moment they rise from bed. Unfortunately, accidental bumps or skin wrenching against hard surfaces before or during transfers can initiate inflammation that, if not recognized, may become the precursor of deeper trauma. Consequently, any support surface that may have worked well previously may suddenly aggravate swollen tissues, thus setting the stage for repetitive insult and permanent damage.

For skin trauma that originates within a fairly-new foam seat cushion (and assuming that the cushion was shaped correctly to begin with) the culprits are often: feet bound to footplates or shoe holders that are installed too low or too far forward; a contoured seat with excessive seat depth; insufficient adaptation for pelvic obliquity or posterior pelvic tilt; legrests positioned too high relative to lower leg length; or legs (with knee flexion contractures) raised too high on elevating legs rests. All of these miscalculations eventually introduce excessive pressure at the ischial tuberosities, coccyx or unilateral trochanter, which over time set the stage for chronic, repetitive insult and eventual skin breakdown.

When it pertains to pressure wounds around the spine and rib cage, I find that they are easily managed with a simple recess (that also provides allowance for the bandage). As for backrests, I have seen skin trauma after a system has been dis-assembled and then re-assembled incorrectly. Another cause is insufficient adaptation for rib and spinal deformities combined with inappropriate alignment between body mass and gravity pressure. Trauma to the lateral aspect of the thorax is typically caused by excessive weight-bearing on lateral supports. This usually implies that weight-bearing equilibrium was incorrectly established or that not enough care was taken to ensure postural correctness after a transfer is completed.

Finally, because skin trauma has occurred, don't automatically assume that the shape or composition of the seating system is the likely point of origin. A pressure sore that becomes visible today may have initiated days before. It's important to establish a timeline for cause and effect and then correlate a plausible event to the time of visible onset. By doing so provides a means for explaining a corrective action to the daily regimen or living environment. This also creates a great opportunity to recommend increasing vigilance of skin inspections to assess whether the corrective actions are in fact producing the desired results.

Use air flotation only!
If you can't eliminate sitting pressure altogether then air flotation is, without a doubt, the best support medium for wound management. The principle behind air-flotation is that, as it envelopes the buttocks it increases the contact surface area. This in turn disperses the forces of body weight and gravity pressure over a larger area of support, thus reducing contact pressure to a lower, wound-friendly magnitude. However, not all air cushions can provide an appropriate wound healing environment. For example, a good air cushion must encapsulate enough air to suspend the body above the underlying (usually firm) support surface. A Google search will reveal a diverse selection of products that do not meet this requirement yet promote numerous claims for improving a consumers well being.

From an orthopedic perspective, the biggest drawback for air-only designs (even with multiple chambers) is that, as pressure is reduced at critical sites (or equalized overall), the support surface becomes universally more buoyant and less stable. The significance in turn is that the occupant must possess sufficient upper body strength, coordination and dexterity to counter the effects of buoyant instability. Furthermore, the instability is magnified when the wheelchair is set in motion and even more so while negotiating a downhill grade.

Another drawback to air-flotation seat cushions is that in some cases there is a conflict between the support requirements of the upper body versus that of the lower body. The most significant arises with the presence of pelvic obliquity and a fixed spinal deformity. If the postural goal includes neutralizing the head position to prevent a lateral flexion bias, then with air cushion it is not always possible to support the pelvis in an oblique orientation of more than 1.5". The net result is that the pelvis will tend to submerge too deeply and bottom-out, especially if the expanse of the pelvis is too narrow to begin with.

As a final note, an Ethafoam spacers (or contoured insert) can easily change the flow of pressure and stability the performance of an air cushion. For example; an insert can be shaped to mimic a hip flexion or hip extension contracture or a severely oblique pelvis so that any chance of bottoming out is minimized.

Use gel flotation only!
There are actually three types of gel mediums available to the custom seating market: fluidized gel constrained by an envelope; compartmentalized gel cushions; and formed gel slabs. The principle behind gel flotation is that as pressure is applied the gel is capable of migrating away from high pressure to an area of lower pressure. Fluidized gels are the most conforming of the three since they do not have a specified limitation of shape.

The drawback to fluidized gel is that like other fluids, they flow with gravity and away from pressure. Meaning that; there is a high likelihood that the ischial tuberosities (or other bony prominence) will protrude through the gel and into the underlying surface. This is an event commonly referred to as "bottoming out". Another noticeable shortcoming is the tendencies for fluidized gels to harden over time and lose its ability to flow away from pressure. Then again, since gels tend to be heavy, they also flow according to gravity. This may pose the problem of flowing downhill when it's not desired. This drawback is most evident with wheelchairs that have a "squeezed" or "dumped" orientation.

Foam cushions don't work!
There are three essential components needed to promote wound healing: a stable posture, selective pressure distribution and minimal wound contact. All three of these requirements are easily achieved with polyurethane (PU) foam cushions. On the other hand, if improperly executed, a PU foam cushion can be one of the most harmful mediums used for supporting both healthy or pressure sensitive skin tissue.

There are actually three types of foam used by the custom seating industry: conventional open cell polyurethane, open cell memory foam and closed cell polyethylene foam. The difference is that memory foam includes a viscosity additive that causes the cells to deform and recover more slowly and in turn reduce the effects of both internal and external vibrations.

Closed cell foams, such as Ethafoam (a Dow brand product), can be very lightweight and provide the longest life-cycle of use and is available in a number of strengths, densities, anti-static formulations and fire ratings. Unfortunately, the ones used for wheelchair seating are also very resistant to repeated impact; meaning that they do not change shape when pressure is applied. So, they work best to create structured, alignment shapes, but in general, are not used as a pressure relieving medium.

As for a polyurethane based cushion, the best manner to influence how sitting pressure is distributed is to create a shaped profile that either: accounts for vulnerable bony prominences; provides clearance for a pressure ulcer (and its protective dressing); or, selectively controls support pressure. Better yet, if we combine all three key principles into a single design, we can minimize or altogether eliminate pressure under a wound, the ischial tuberosities, posterior trochanters, coccyx or other area of the body. This can be achieved by laminating various densities of foam in selective areas of the support surface. The net composition is a very stable yet malleable structure that can be easily revised or repaired over time. Furthermore, if a foam cushion is contoured and structured correctly, there is no need to insert an air-sac or gel-pack to improve its performance.

Excise the foam and replace it with a gel or air packet!
For a client that already has a cushion, carving out the foam and then replacing it with a different material may not produce the desired results. Here's why: The more that foam is compressed, the more it will push back and attempt to recover to its original shape. So, reducing the thickness of the foam at a specific location will diminished that recovery force and thus the contact pressure at that location. However, replacing the void with an air or gel-pack will only serve to re-increase the contact pressure at that very location. In fact, if the air or gel-pack is too dense or too large for the indentation, point pressure can actually increase beyond previous recordings.

The best actions are simply to excise the foam and leave the recess as is. Or, reduce the surface tension of the foam by scoring it, as described below.

Score the foam to soften the area of contact!
Grid pattern scoring allows each resulting pylon to compress independent of the adjacent pylons, thus adding even more flexibility to the open cell structure which in turn reduces surface tension and skin pressure. If done correctly, scoring can in fact be much more effective than interjecting small gel-packs or air-cells. But first, make sure to draw your pattern and visualize the outcome before making that first cut.

Scoring is a quick fix but should be used only as a last resort since it tends to allow debris to infiltrate the cushion and hasten deterioration. Also, if you score too deeply or over too large an area, the entire region could collapse without producing the desired results. If you choose to employ this technique, be conservative because this is a one-way process. As a starting point, score no deeper than one-inch, with pylons no larger than one-inch square and no more than three pylons in either direction.

Silicon based mixtures tend to flex and elongate better than others. However, if the coating seems to be too unforgiving, you can reduce point pressure significantly by removing this moisture barrier at areas of concern. There is one more word of caution. If the trial fitting was performed prior to application of the waterproof coating, site specific pressure readings will no doubt increase after the coating is applied. To avoid complications, make sure that pressure relief recesses at bony prominences are carved extra deep.

A Word about Wound Dressings

Wound dressings applied while lying supine or prone can create a problem when seated. If applied while the body is extended the bandage will add pressure against the wound once the joints are flexed for sitting. Worse yet, the pressure will become even more amplified when the wound area is subjected to weight-bearing. Instruct clients and caretakers to apply wound dressings while side-lying and with the hips and spine flexed into a simulated sitting posture. Whenever possible, they should also allow a bit of play in the dressing. This is particularly true when using a layered gauze pad since it does not have elastic qualities. Also, keep in mind that too many layers of gauze will also increase pressure upon weight-bearing.

A Word about Foam-In-Place (FIP)

FIP kits are seldom used as a tool for wound management. In fact, with the exception of a few pediatric markets, it is rarely used to produce a seat cushion. However, FIP kits are used as quick-fix solutions for postural anomalies associated with the upper body. When applied correctly and detailed for growth or gravity influences, this product type can be a cost-effective custom alternative.

However, over the years, I've seen several clients that developed stage-1 through stage-3 pressure sores within months after receiving a FIP backrest. From these experiences I've noticed that neither the shape nor orientation of the backrests were designed to re-orient gravity pressure or provided additional allowance for protruding rib or spine deformities. In each case, no modifications were made after the pour. In essence, the shape of rib and spine deformities were simply captured and locked into chronic postural imbalance. Consequently, while pressure was diminished overall, it remained highest at the bony protrusions. This unforeseen consequence occurs most rapidly with individuals experiencing a growth spurt or rapid change in posture.

Please note that this is not to say that all FIP projects produce these results. For low-tone, semi-recumbent clients, excessive point pressure appeared to occur mostly when there was no evidence of post-pour, pressure attenuation or no attempt to re-direction postural imbalance. Nonetheless, my biggest reservation about poorly orchestrated FIP projects is that, with the multitude of production variables involved, the outcome can be a bit like that box of chocolates; "You never know what you're going to get".

A Word about Mix 'n Match Solutions

On occasion a clinician will retain a backrest but choose to replace the seat cushion with another of different material or profile. Their actions are often based on the belief that the seat initiated the skin trauma. In my experience, this approach may address concerns for pressure management at the buttocks but can also conflict with posture management goals for the upper body. This conflict implies that either the original product selection or the original goals were flawed to begin with. Always verify that vertical alignment of the backrest remains consistent with spinal/pelvic alignment on the new seat.

A Word about Tilt and Recline

Both, tilt and recline are very effective mechanisms for shifting gravity pressure away from the buttocks. However, most research data indicated that individuals with power control systems for tilt or recline do not employ either feature to a sufficient angle, duration or frequency to provide adequate unloading and rest benefit to healthy skin tissue. There is currently no data regarding angle, duration or frequency of use for individuals with wheelchairs equipped with manual tilt or recline systems. There is no available data referencing these wheelchair features for individuals with an existing (or history of) pressures sores.

From my perspective, we cannot rely upon caregiver diligence nor power or manual weight shifting mechanisms as primary wound prevention or management devices. This is particularly true for individuals with asensory skin or lacking the ability to intrinsically regulate posture.

Conclusions

There are many types of soft tissue wounds that a sitting dependent person may exhibit. For example: Third degree burns, infections, maceration, recent sutures, various stage pressure sores and wounds with a drainage pump. The purpose of this discussion is to shed light on the consequence of postural management choices relative to the presences of pressure sores; specifically within the context of the wheelchair seating environment. This discussion is also meant to demonstrate that intuitive actions do not always produce the desired results. More importantly, once a pressure sore develops, the entire posture management protocol may have to be altered from a once tolerable pressure plateau to a focused goal of zero contact and zero recurring insults.

Furthermore, because a client develops a pressure sore does not necessarily indicate that the seating system is at fault. Time taken to review the "typical day" catalog of activities will help to better understand not only how the initial insult occurred but may also reveal environmental factors that may contribute to repetitive insult and thus compromise or delay the healing process. As seating specialist, designing or modifying an appropriate seating environment is not enough. As part of our services we must include proactive (re)education for clients and caretakers regarding specific rules of wound management. Not only within the context of the wheelchair but relative to all other ADL surfaces as well.

Also keep in mind that the healing process for pressure sore is not strictly an external cause and effect scenario. The manner in which a wound is cleansed and dressed, as well as poor nutrition and unhealthy behaviors (such as smoking or ineffective pressure reliefs) will also impede or prolong the healing process. There is no doubt that a review of the basics for skin care will serve to strengthen everyone's winning strategy in the shortest span of time.

I can also tell you from experience that individuals I've spoken to (and whom present with a pressure wound years after SCI or onset of disability), say that when they received their first instructions on skin management their head was consumed by the trauma of a new reality and, training for skin care was the least of their focuses. Especially, since most of that initial task of rehab was done by proxy. So now, decades later combined with repetitive stress and age related atrophy, what once worked by chance, no longer does.

Obviously, prevention is the best tool in the arsenal for wound management. Regardless of diagnosis and no matter that sensation is fully normal, any person who is life dependent on sitting is susceptible to repetitive tissue trauma and pressure sores. All the materials and techniques we spoke of in this article serve to prevent trauma or aid the healing process. However, because of daily exposure to stressful demands, the quality and life-cycle of these materials may diminish much faster than typically perceived. Additionally, once the wound is healed, the architecture of a wound-healing support surface may not suffice for long-term post-therapy skin management.

As for believing that the composition, structure or shape of the seating system is at fault; knowing when to revise, repair, remake or replace a cushion will provide the strongest argument for best practices, given any scenario of wound management in seated posture.

A Final Word about Building from Scratch

Let's say you have a client with a pressure sore and you intend to design a foam cushion from scratch. If the sore is under the ischial tuberosities and the pelvis is relatively symmetrical and registers to the midline of the wheelchair then make sure to include a deep ischial cutout or ischial recess. If the sore is under the hips, then a recess below the trochanter would work but it must be coupled with a proximal femoral elevation and a elevated posting at the posterolateral flank of the buttocks. If the sore is at the sacrum or coccyx, then a simple recess will suffice at either location. However, if you think about it, these pressure redistribution and manipulation features should be standard topography for any custom cushion design.

And finally, if any of the above sores are also accompanied with pelvic obliquity, scoliosis or another pressure sore, then I'd have to suggest that pressure management must account for balance and stability of the entire body. If the resulting design renders functional sitting difficult to manage then resending the sitting regimen until at least one sore completely heals may be the best course to follow.

Richard Xavier Cushmaster
CUSHMAKER.com

©Copyright September, 2008

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