Know Your Dressings: Calcium Alginates, CMC, and Gelling Fibers

Successful wound care involves selecting the appropriate dressing to optimize the wound healing environment. Dressing selection plays an important role in supporting autolytic debridement and promoting wound healing. 1 Wounds with heavy drainage require dressings that are absorptive, yet still maintain a moist wound environment to promote healing, such as calcium alginate or carboxymethylcellulose (CMC) gelling fiber dressings.

What is a calcium alginate dressing?
Calcium alginate dressings are made from sodium alginate extracted from brown seaweed and processed with calcium salts into nonwoven biodegradable dressings. 2 Alginate dressings can be found in sheet or rope form. The dressings uniquely gel as they come in contact with wound exudate to provide a moist wound environment that facilitates autolytic debridement. The dressings can fill wound dead space and absorb up to 20 times their weight in exudate depending on the manufacturer’s process. 3
What is a CMC gelling fiber dressing?
Carboxymethylcellulose (CMC) dressings are highly absorptive textile fiber dressings derived from natural cellulose sources and are commonly known as CMC gelling fiber dressings. 9 CMC dressings form a transparent moist gel as they bind wound exudate into the dressing. 9 The exudate cannot reenter the wound bed and inflammatory cells, especially neutrophils, are sequestered which helps to hasten wound healing. 4 CMC dressings are available in rope and sheet form and the fiber strength of these dressings makes them suitable for loosely packing sinus cavities. 4 CMC dressings do provide a moist wound environment, supporting autolytic debridement as the dressing gels and traps exudate.
Calcium alginate and CMC gelling fiber dressings:

  • Are designed for use in moderately to heavily draining wounds
  • Are non-adherent, conformable and can be cut and manipulated in the wound bed
  • May contain silver which can provide antimicrobial protection in the dressing
  • Should not be used for dry wounds since they can adhere to the dry wound bed
  • Expand in the wound due to the natural swelling of the dressing as it comes in contact with exudate, avoid overfilling the wound space
  • Can be left in place for several days depending on the condition of the wound
  • Require a secondary dressing
  • Are appropriate for use on partial and full thickness wounds, surgical incisions, pressure ulcers, infected wounds, donor sites, and in sinus tracts and tunnels. 8

What is a superabsorbent dressing?
Superabsorbent dressings also have the ability to manage exudate for moderately to heavily draining wounds. These dressings have multiple layers which include a nonadherent contact layer, a middle layer which contains fibers or gelling material to absorb exudate, as well as a water repelling outer layer. 7 Superabsorbent dressings may have an adhesive border. If an adhesive border is not present, these dressings will require a secondary bandage or adhesive to secure the product to the wound site. A superabsorbent dressing can be used on a variety of wounds including pressure ulcers, venous ulcers, diabetic foot ulcers, trauma wounds or arterial ulcers. 7
Select the correct dressing
Dressings should be selected based on the characteristics of the wound.
Calcium alginate and CMC dressings are primary dressings* designed for use on wounds with moderate to heavy drainage.
A superabsorbent dressing can be a primary or secondary dressing** which manages moderate to heavy wound exudate.
The longer wear time of these dressings minimizes the number of times the wound bed is disturbed which may improve healing outcomes. 6 Cost effectiveness should always be considered when selecting a dressing, however the least expensive dressing may not be the most cost effective. Longer wear time reduces clinician labor costs, a significant factor in overall wound care costs. 5 Dressing selection should be based on the needs of the wound to obtain the best outcomes for healing.
* Primary Dressing: The dressing that is in contact with the wound and may remain on the surface of the wound over an extended period of time and in some cases until the wound is completely healed.
** Secondary Dressing: A cover dressing contains an absorbent material which will absorb wound exudate and which can be changed without disturbing the position of the primary dressing on the surface of the wound.
AquaRite™ Extra CMC is a highly absorbent CMC fiber wound dressing that converts into a clear, soothing gel sheet when exposed to exudate or other liquids.

  • Highly absorbent
  • Traps debris & bacteria in the dressing
  • Maintains dressing integrity for one piece removal

Click here to learn more!
Plus, be sure to explore these other fiber / superabsorbent dressings from DermaRite:
HydraLock SA

  1. Murphy, Patrick S., and Gregory R.D. Evans. “Advances in Wound Healing: A Review of Current Wound Healing Products.” Plastic Surgery International, vol. 2012, Sept. 2012, pp.1-8, doi:10.1155/2012/190436.
  2. Qin, Yimin. “Gel swelling properties of alginate fibers.” Journal of Applied Polymer Science, vol. 91, no. 3, 2003, pp. 1641–1645., doi:10.1002/app.13317.
  3. Morgan, Nancy. “Calcium alginate.” Wound Care Advisor, vol.1, no.2, July/Aug.2012 pp. 26-27.
  4. Merry, A., “Absorbent Hydrofiber and Calcium Alginate Foam Dressings” Accessed 23 Sept. 2017.
  5. Making The Case For Cost-Effective Wound Management.
  6. “Challenging Wounds.” Accessed 27 Sept. 2017
  7. Wound Care Today-Product Pyramid-Superabsorbent Dressings. Accessed 26 Sept. 2017
  8. “Evidence Summary: Wound Management: Dressings –Alginate”, Wound Practice and Research, vol. 21, no. 2, pp 90-92., Accessed 23 Sept. 2017.
  9. Bahai, H S, et al. Carboxymethylcellulose wound dressings. 15 Mar. 2005. Accessed 23 Sept. 2017.

Deeper Dive

Want to learn more about this topic? In addition to the reference links above, here are some great articles and resources that you can explore.

  1. Qin12*, Yimin, et al. “Marine Bioactive Fibers: Alginate and Chitosan Fibers-A Critical Review.” Journal of Textile Engineering & Fashion Technology, MedCrave Online, 15 May 2017,
  2. “Alginates.” Alginate Dressings | Calcium Alginate Dressings for Wounds,
  3. “Practical Treatment of Wound Pain and Trauma: A Patient-Centered Approach. An Overview.” Practical Treatment of Wound Pain and Trauma: A Patient-Centered Approach. An Overview | Ostomy Wound Management,
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