Hydrate for Healing

The concept of moist wound healing is not new; I recall the paradigm of moist versus dry as far back as the late 1970s. As a young nurse, I grew up in the antacid and heat lamp days. We did wet to dry dressings as a standard of care. As the work of George Winter¹ and others began to be disseminated, educating that wounds maintained with an optimal moisture level closed faster and were less painful, we began to see the emergence of products into the wound care space to help us treat based on our assessment of the wound and the perceived exudate level. Last month’s “Back to Basics” explored options for exudate management. This month, I discuss options for hydrating the wound that is dry or possibly unintentionally getting dry between dressing changes.

Most dressings are designed to absorb or maintain the ambient level of wound exudate. Few are able to actually donate moisture to a wound that is dry, which is probably less of a problem than wounds that are draining. One obstacle we frequently face is ensuring we adequately teach patients the need to keep their wounds moist. We often must overcome what our mothers taught us — that is, “Don’t pick your scabs” (we pick most scabs) and “Let that get some air…it needs to breathe” (and we know the answer to that).

Hydrogels were one of the first dressings that offered the opportunity to add moisture to the wound. Water- or glycerin-based, hydrogels are available in 3 forms: amorphous (ie, free flowing), impregnated gauze, and sheets. Hydrogels as a class are indicated for all wound types; they provide moisture and facilitate autolytic debridement. Care should be taken to confine them to the wound bed to prevent maceration of the periwound skin; in addition, some patients may experience stinging on application depending on the ingredients. The only contraindication is use with heavily exuding wounds.

Amorphous gels. Amorphous gels are likely the most commonly used. Indicated for all types of wounds, they should be applied to the surface of the wound and then covered with a dressing that prevents drying out. Although generally amorphous gels are changed daily, the frequency can be reduced if the secondary dressing does not allow for air flow and subsequent evaporation. A simple border gauze or oil emulsion dressing covered with gauze usually will do the trick. Amorphous gels are mostly used for superficial wounds. In deeper wounds, the clinician may want to consider an impregnated gauze or use a coating of hydrogel and loosely pack moistened gauze to fill the space. Hydrogels are available with various additives such as silver, honey, collagen, and particles that may allow for minimal amounts of absorption.

Impregnated gauze. Gauze with hydrogel is available commercially pre-impregnated or you can impregnate your own gauze; however, commercially available products are supersaturated and likely to be more effective.

Sheets. Hydrogel sheets are hydrogels that have been cross-linked to form a solid. This form does not deliver as much moisture initially; rather, it provides moisture as it warms. Patients find these very soothing in the presence of inflammation.

Additional more unique dressings adjust to the wound bed depending on the need. As a result, where the wound is dry, they donate moisture and where it is wet they absorb. One product is described as having “smart polymers” that sense the underlying tissue's physical conditions and adapt local function to provide optimal treatment for all different wound zones simultaneously.²

The use of moist gauze packing is a source of continued discussion and should not be confused with “wet to dry,” “moist to dry,” or “wet to moist.” Gauze is rarely placed into a wound “wet” — clinicians wring out most of the dripping solution before placing it into the wound. Appropriate uses for moist gauze packing into open wounds include but are not limited to:

• As a source of moisture and to fill space over other products or drugs such as hydrogels, collagenase, or becaplermin;
• For palliative care as long as removal is not painful; and
• For delivery of solutions for short-term reduction of odor; to reduce bacterial growth in infected, necrotic wounds; or as a temporizing procedure for a short period of time.

Using a layer of gauze, dried and adhered to a wound surface, to mechanically lift off necrotic tissue is an archaic method of wound debridement that most of the time is inappropriate. Facts that support this inappropriateness include:

• Clinicians often hide behind the concept of “moistened gauze” or “wet to moist” to feel better about packing a wound with gauze as the primary dressing. Woven gauze is made of cotton fibers that are made into strands and twisted to make threads. The threads are then woven to make cotton gauze. As the single layer of gauze rests down onto the base of the wound, exudates are pulled up and around the twists of the threads, embedding even moist gauze into the tissues and causing trauma upon removal.3
• Gauze is a poor barrier to outside contamination. Bacteria have been found to have the ability to penetrate 64 layers of gauze.⁴
• If someone has sensation, wet-to-dry dressings are painful.
• Most guidelines recommend avoidance of wet-to-dry dressings and describe it as substandard care.^5-7
• Wet-to-dry dressings are mistakenly considered to be cost saving. When one considers costs of nursing time as well as increased time to healing, these dressings are more costly to the patient and to the system.
• Even though normal saline is isotonic, as water evaporates from a saline dressing it becomes hypertonic. Wound fluid then is pulled into the dressing in an attempt to re-establish isotonicity, but it is not water and further dries out the wound surface⁸
• Regulatory agencies may consider extended use of wet-to-dry dressings substandard care with some exceptions, If these dressings are used, this should be well documented, particularly in long-term care.

A few more thoughts on use of gauze in wounds:

• Any time moist gauze is used for wound packing, it should be fluffed and loosely packed into the space. Do not overfill; this can cause trauma if used on a weight-bearing area or area under compression.
• For large and/or tunneling or undermining wounds, it is best to use cotton roll gauze as a continuous packing with an adequate amount outside of the wound to avoid loss or retention of the dressing in the wound.

The following analogy sums up the importance of ensuring a moist environment for wound healing. We have a 5-month-old puppy named Maggie (pictures available on request!). When we first brought her home, we worried she wasn’t drinking enough water. Now I often guiltily realize her water bowl is empty. What does this have to do with wound management? Little Maggie depends on our attention to detail to make sure she has what she needs to stay hydrated. You see where I’m going with this — we must make good decisions for the wounds we care for to confirm they have the optimal moisture level for cellular health.