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The difference between hydrogel dressing and hydrocolloid

Let’s talk about hydrocolloid dressings. The most common component that absorbs water is carboxymethyl cellulose (CMC for short). The current hydrocolloid has a semi-permeable membrane on the outside, which can make the wound airtight, waterproof and bacteria-proof , But it can allow air and water vapor to penetrate. Its composition does not contain water. After absorbing wound exudate, it will form a gel-like substance to cover the wound to keep the wound environment moist, and the absorbed tissue fluid, Contains a large amount of enzymes, growth factors and collagen, so that granulation tissue can grow from clean wounds, and wounds with necrotic tissue can produce autologous debridement. This gel-like substance also allows the dressing to be removed without pain. The disadvantage is that when the hydrocolloid absorbs the exudate, it will dissolve into a white turbid jelly, and will have an unpleasant smell, which is often mistaken for an abscess and is afraid to use it (picture1). And its water absorption ability is not strong, only about the water absorption of a piece of gauze, so it is often used several times a day when it is used for a scratch or a deep wound. Some hydrocolloids are even designed as acne patches or Bondi patches to facilitate various occasions. Among them, J&J’s hydrocolloid hydrogel waterproof and breathable stretch is called hydrogel, but in English it is Band-Aid Hydro Seal hydrocolloid gel, so it is still classified as a hydrocolloid dressing. (picture1). After the hydrocolloid absorbs the exudate, it swells into a gel to achieve a moisturizing effect.

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Let’s talk about hydrogel, which is a kind of compound hydrophilic polymer (containing glycerin or water). The water percentage can be as high as 80%-90%. As the literal meaning, it is designed to moisten the wound and soften the eschar. , And can provide moisture to dry wounds to help the wound produce self-cleansing effect. The gel form can be indefinite gel (no picture), sheet(no picture), or impregnated gauze (such as IntraSite Conformable dressing), or impregnated gauze (such as IntraSite Conformable dressing). Indefinite gel can can easily replace wet gauze padding, and only needs to be replaced once a day. It has the effect of providing a moisturizing “moisture donor” to necrotic tissue. The softening and moistening of the crust can increase the production of collanginase to promote autodebridement effect. However, due to its high water content, care should be taken not to touch the skin to avoid infiltration. Sheet hydrogels are cross-linked to convert hydrogel hydrophilic polymers to solid state. The first commercially available sheet hydrogel dressing for wounds in history was made by Geistlich Pharma AG, a company called Geistlich Pharma AG. “Geely Bao Geliperm” was launched in 1977. It contains 96% water, 1% agar, and 3% polyacrylamide. The second generation of Geely Bao Geliperm adds 35% glycerol, in order to promote its water absorption capacity.  Therefore, gel and hydrogel dressings (sheet hydrogels) have similar compositions, except that sheet hydrogel dressings have less water content to facilitate the absorption of a small amount of exudate. Like artificial skin, they can only be used for exudation, and provide a moist environment for wounds. But when it absorbs water, it will not leak out due to squeezing, and the solid sheet-like hydrogel has a unique “cooling” and soothing effect on the skin, so it can be used for burns and painful wounds ( If necessary, under certain conditions, the flaky hydrogel dressing can also be refrigerated in the refrigerator first, and then taken out when used to play a cooling effect). In addition, it can also be used to treat chickenpox and shingles. , And because it is transparent, it is convenient to observe the wound. This kind of sheet dressing usually adds a layer of waterproof film on the outside to prevent water loss, prevent the gel from being squeezed out and increase its adhesive force to prevent it from falling off. This kind of dressing will not absorb water very well and cannot be used for wounds with too much fluid or infection, otherwise it is easy to produce skin infiltration around the wound, which will have a taste or thick blisters, or it will promote the proliferation of bacteria in the infected wound. . According to the textbook, this hydrogel dressing is actually suitable for any superficial wounds, such as second-degree burns, diabetic foot wounds, crush injuries, or bruises. If the main ingredient of the sheet-like hydrogel is water, when it is used in an open wound, it should be cut to fit the shape of the wound. Do not touch the skin next to the wound to avoid infiltration. However, if the main ingredient is glycerin, the sheet-like hydrogel can be applied to the skin next to the wound. There is little chance of infiltration, but this type of glycerin-based dressing is rare.

Since sheet hydrogel dressings have so many advantages, why are they still not commonly used in the wound industry until now? I think the most important thing is the price, and there are too many alternative products (such as seaweed cotton, hydrocolloid dressing, PU foam, etc.).


Post time: Jul-14-2021