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Operating room sponges: a nonwoven product opportunity.

Laparotomy and x-ray sponge sales during 1991 in the U.S. were in the range of $65 million, representing more than 10% of total wound care sales and approximately 17% of the total wound care fabric demand. Laparotomy sponges utilized 100 million square yards of woven gauze in nominal sizes 12x12, 18x18, 18x4 and 36x8 inches of four ply gauze. X-ray sponges utilized 60 million square yards of gauze in sizes 4x4 and 4x8 inches in 12, 16 and 32 ply configurations. Currently, approximately 1% of these sponges are made of nonwoven fabric.

Specialized sponges are only used in operating rooms and are distinguished from other sponges by their sizes, plies of fabric and the incorporation of an x-ray detectable (radiopaque) element in the form of a flexible monofilament thread or flat tab that is either woven, sewn and/or heat sealed into the gauze in several thread counts and yarn sizes that comply with U.S. or European pharmacopoeia standards for construction and purity.

There is currently only one nonwoven operating room sponge in the market and although this laparotomy sponge has been sold by Johnson & Johnson for many years, it has not achieved significant marketshare. Perhaps these minimal sales are due to a lack of appropriate physical attributes, premium price and the difficulty in changing the operating room team's long term use of woven sponge products.

Surgeons and their nurses have developed procedures and techniques for using woven gauze, especially the sponge counting and handling techniques peculiar to the operating room, and tend to be reluctant to change if there are no perceived cost or performance advantages gained by using nonwovens. Product and fabrics for operating room sponges in comparison to general purpose sponges have more critical design requirements and this presents opportunities for nonwoven research, product development and marketing.

Operating room sponges are cost efficient products used almost exclusively for absorbing blood, body fluids and drainage, walling off the operative site, protection and cushioning of tissues and organs and blunt tissue dissection. Operating room personnel perceive x-ray detectable 4x4's and laparotomy gauze sponges as commodity products with only minor variations between brands.

This product commonality is probably due to the use of the same or similar woven gauze construction by all manufacturers. Surgeons and nurses consider operating room sponges to be important commodity items but, in general, are only concerned about them if they are functionally defective or do not meet their particular requirements.

The Optimum Sponge

The following product and fabric attributes describe those features needed in functional operating room sponges:

- ease of counting and visibility of radiopaque element

- ease of unfolding and folding

- functional dry and wet strength

- low lint and resistance to fraying

- rapid wicking and high absorbent capacity

- atraumatic surface for tissue contact

- optimum fluid retention for tissue hydration

- sterilizable by steam, gas or radiation

- suitable to high speed low cost converting

- meet safety and toxicological standards.

In most cases these attributes are generally met by woven cotton gauze sponges that have to be acceptable to most surgeons and O.R. nurses, but it is possible that nonwovens designed and configured specifically to meet the above attributes could provide a superior sponge that is cost effective and both user and patient performance friendly.

Woven gauze has been the operating room sponge standard for decades, however, and it is appropriate to review the physical and performance characteristics of this material as a basis for understanding what nonwovens must equal or preferably exceed in order to compete against the gauze standard. It is probable that the spunlaced or hydroentangled type of nonwoven is currently the best available technology to compete with gauze, if appropriate cost effective fabrics can be designed that lend themselves to suitable converting processes and offer operating room professionals performance and perhaps price advantages over gauze products.

The averaged data and information in Table 1 characterizes the gauze sponge products.
Table 1
CHARACTERISTICS OF GAUZE SPONGE PRODUCTS
Sponge 4x4", x-ray 18x18" laparotomy
Weight (gm) 3.8 31.0
Ply 16 4
Fabric USP Type VII USP Type IV
Grab Tensile (lbs.)
M.D. 4 Ply 20.0 44.0
C.D. 4 Ply 7.0 26.0
Sink Time (s) 1.0 3.0
Absorbency (gm) 25.0 121.0
Abs. Factor (gm/gm) 6.6 3.9
Fluidity (rhes) 3.5 3.5


Gauze product have traditionally conformed to U.S. or European pharmacopoeial standards for thread count, weight per unit area, purity and absorbency. Nonwoven products do not have to conform to these standards because they are not covered in official pharmacopoeia monographs. Therefore, after the purity and safety of the nonwoven is established, the physical characteristics of the fabric and functional sponge requirements need only reflect what will meet operating room performance standards and what is accepted by medical professionals.

The high machine direction sponge strengths are inherent in the gauze fabrics used but in general are not necessary for use in the operating room. The 4x4" x-ray and laparotomy sponges are not unfolded below four-ply. When sponges are unfolded, such as to 4x16" x four ply, stress by surgeons is usually applied in the sponge's long dimension, which is the gauze cross machine direction and thus its weaker direction. A 4x4" C.D. grab tensile at four ply is in the range of 7.0 lbs. dry and perhaps 10% higher when wet. Thus, the functional strengths of a nonwovens sponge need only equal the weakest gauze configuration as a functional initial target.

It should be possible to utilize a hydroentangled nonwoven fabric of various fiber types such as polyester, polyolefin, rayon and cotton in blend ratios of 50 / 50 to 80 / 20. A fabric weighing approximately 40 grams per square yard in a 3-4 ply configuration can be used to design a 4x4" sponge that is lighter in weight than its gauze counterpart, will absorb and retain more liquid, have low lint and be less traumatic to delicate tissue while providing adequate cushioning and strength. Reducing the sponge total plies to three or four should allow the use of high speed converting equipment significantly faster than current gauze sponge folding machines.

The product characteristics of the 4x4" sponges should also be obtainable for the larger laparotomy sponges with 2-3 ply of hydroentangled fabric. The lap sponge with its loop tape handle, x-ray detectable tab or monofilament element and sewing patterns that are used to stabilize the several plies of gauze and raw fabric edges should lend itself to creative designs with nonwovens that can be adhesively, thermally or ultrasonically converted to finished sponges.

This gauze product area is open to new sponge concepts and innovative designs that nonwovens are ideally suited to challenge.

Donald Patience is a consultant in the medical device field, based in Wilmington, NC. He has been an R&D director in the woven and nonwoven dressings market for more than 40 years.
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Title Annotation:Nonwovens Technology
Author:Patience, Donald
Publication:Nonwovens Industry
Date:Dec 1, 1992
Words:1149
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