The New Standard for Barrier Surgical Gowns and Drapes
What It Means to the Infection Control Practitioner
By Nathan L. Belkin, PhD
How it All Began
From the time that an operating room gown first became a part of the surgeons armamentarium, its primary purpose was to protect the patient from the members of the surgical team. In that capacity, the garment was made of a relatively loosely woven, readily permeable, all carded cotton type 140 (thread count) material generically known as muslin. The material fulfilled the essential requirement of the application, in that it was considered effective in terms of providing what was believed to be a satisfactory aseptic barrier, was readily available, and was economical to use.
Then in 1952, the surgical community was alerted to the fact that although the muslin material may have been considered an effective bacterialogical barrier when it was dry, it lost its barrier capabilities once it became wet even when multiple layers were used.1
The Need for a Liquid Barrier
This disclosure encouraged the textile industry to develop more satisfactory materials for this unique application. In responding to the challenge, both segments of the industry the nonwoven disposable and woven reusable introduced a new generation of fabrics. Whereas both made claims about their performance capabilities, there was no similarity to the tests upon which those claims were predicated.
In the meantime, the American College of Surgeons (ACS) Committee on the Operating Room Environment (CORE) charged the entire textile industry with the responsibility to develop a test method that had the capability to simulate the stresses that they astutely described as usual conditions of use.2
Not being able to either correlate the results of the tests being used by industry or consider them as simulating usual conditions of use, a distinguished surgical researcher not only developed a test method but introduced the term for the phenomena of liquid penetration that has been commonly used ever since: strikethrough. The published results of his study indicated that some of the nonwoven materials that had passed their Mason jar test proved to be totally ineffective, and that some were moderately effective. However, included with the number that performed quite well was one woven reusable.3 Be that as it may, it was these findings that supported the researchers appeal to the Surgical Device Classification Panel of the Food and Drug Administration (FDA)s Bureau of Medical Devices for classification of aseptic barrier materials for surgical gowns and drapes as Class II medical devices: high priority, that is, those in need of performance standards.4
One response to the FDA classification process has been the development of voluntary standards, user guidelines, and recommended practices by cooperative working groups comprised of representatives from the clinical community, other healthcare professionals, and industry. Thus it was that representatives from the three groups formed an ad hoc committee to address the issue.
Subsequently, the group was formally organized under the auspices of the Association for the Advancement of Medical Instrumentation (AAMI) and identified as the Committee on Aseptic Barriers. Unfortunately, because of a lack of consensus among its members, the Committee was disbanded and the task abandoned in May 1983.6
The Emergence of HIV
With the emergence of the era of the hazards associated with the transmission of bloodborne pathogens, the primary purpose of the surgical gown suddenly changed from third person to first person to protect the surgeon from the patient. This also meant that whatever degree of strikethrough may have been tolerated in the past was no longer acceptable.
It was during this period that two clinical researchers,7-8 working independently of one another, reported on the barrier effectiveness of a variety of products that were on the market. What exemplified the need for a standard test method was the fact that some of the materials that had been found to be satisfactory under the conditions of one of the tests would have failed when subjected to the challenge of the other test that had been especially designed for this purpose. What is particularly noteworthy is that the results of the less challenging test reported detecting penetration of human immunodeficiency virus (HIV) through plastic-reinforced materials in which strikethrough was not visible.
Nevertheless, the results of these studies exemplified the need for a meaningful test method that could be adopted by both the clinical community and industry for use in assessing a materials barrier capability. It was also reasonable to assume that whatever test method would be developed would measure a materials ability to resist liquid penetration at various levels.9 Rating the materials in this manner would be in accord with the results of a comprehensive in vivo study specifically designed for that purpose. 10 More importantly, it would facilitate the selection process mandated by the Occupational Safety and Health Administration (OSHA)s final rule that the garments be appropriate for the task and degree of exposure anticipated. 11
The Development of New Tests
With the pressing need for a test method, an industry-driven committee of the American Society for Testing Materials (ASTM) released a modification of one of its existing mechanical devices that had originally been developed for determining the effectiveness of protective clothing worn by chemical workers. The group incorporated the methodology in two tests; one for liquid penetration and one for viral penetration. Both methods were first adopted as emergency standards and subsequently adopted as regular standards in 1995.
However, rather than the results of either of the tests being reported on a comparative basis, they were identified as pass/fail, with a pass predicated on the materials ability to resist penetration at a level of 2 pounds per square inch (psi). In responding to how that level of resistance was selected, the tests developer and chairman of the ASIMs committee advised that it had a high correlation to the manual elbow-lean test (simple and manually executed) that had been used by one of its member manufacturers to demonstrate its materials effectiveness).14
It should be noted that prior to the ASTMs adoption of the test methods, several reports had been published in the clinical literature that indicated that the pressure exerted on surgical gowns and drapes in both in vivo and in vitro circumstances had been found to be far in excess of 2 psi.15-17 As observed by one of the researchers, Because conditions of use are known to vary greatly by type of procedure and task, all materials do not need to have the same level of resistance, yet the ASTM tests subject all to a single method.18
Notwithstanding the ASTMs noble mission to help reduce the risk of occupational exposure to bloodborne pathogens, the fact of the matter is that the healthcare delivery system is financially strained at an unprecedented level and is being pressured to not only contain costs, but reduce them. Under these circumstances, to indiscriminately provide all healthcare workers with what the industry group believes to be the maximum level of protection would be neither prudent nor fiscally responsible. All things considered, it appears that the ASTMs tests may have been developed for the benefit of its industry committee rather than for the benefit of the surgical community and can only be viewed as being blatantly self-serving and morally irresponsible.
The New Standard
The American National Standards Institute (ANSI) has recently published a document which is said to provide a solution to this half-century need.19 Titled Liquid Barrier Performance and Classification of Protective Apparel and Drapes Intended for Use in Healthcare Facilities,20 it has been adopted by the FDA and is considered to satisfy the agencys need for performance requirements for those Class II medical devices
The standard establishes the use of four different test methods and two different liquids to classify the differences in the levels of a materials barrier performance.
To accommodate the need for determining a materials barrier performance for the duration and level of anticipated exposure, AAMIs Protective Barrier Committee selected two other tests, the American Association of Textile Chemists and Colorists (AATCC) #42-2000 water impact penetration test and their #127 hydrostatic test for that purpose. (It should be noted that this same AAMI group had several years earlier maintained that neither of the two tests were suitable for use for this purpose.21
Thus the new standard establishes four levels of barrier effectiveness. For Level 1, the lowest of the four, the AATCCs 42-2000 water impact penetration test is used. (See Figure 1.) The materials capability to resist penetration is determined by being challenged by a fixed amount of water sprayed on it while being held at a 45-degree angle. An absorbent blotter affixed under the fabric is then weighed to ascertain its weight gain. According to the standard, the blotter should not have gained more than 45 grams to be considered a Level 1 fabric.
For Level 2 fabrics, there are two tests that can be used. One is the same test used for Level I except that the weight gain of the blotter can be no more than 1 gram. An alternate test is the AATCCs 127-1996 hydrostatic head test. (See Figure 2.) A sample of the fabric is clamped horizontally on the bottom of a metered glass cylinder. The hydrostatic pressure is steadily increased as the height of the water in the cylinder is raised. To be acceptable for a Level 2 barrier, it must resist penetration of water when it reaches a height of 20 centimeters.
For Level 3 fabrics, both of the AATCC tests may be used. However, for the impact penetration test, the weight gain of the blotter is again 1 gram. For the hydrostatic head test, the water level in the cylinder must be at least 50 centimeters. For level 4 fabrics, the ASTMs mechanical device is used for both. For surgical gowns, the material must pass their F-1671 test for viral penetration; surgical drapes need only pass the F-1670 for resistance to penetration to synthetic blood. The test sample is mounted in a vertical position onto a cell that separates the challenge and a viewing port. The time and pressure protocols specify atmospheric pressure for five minutes, 2 pounds of pressure psi for one minute, and atmospheric pressure for 54 minutes. The test is terminated if visible penetration occurs before or after 60 minutes.
(It should be noted that the standard makes no mention of the level of protection that a pass provides, i.e., 2 psi.)
Interpreting the Results
For Levels 1, 2, and 3, the results of the water impact penetration test must stand on their own merit since there is no known method of correlating the weight of the blotter to the level of pressure exerted on it.
For the hydrostatic pressure test used for Levels 2 and 3, the correlation between the height (in centimeters) of water and the level of pressure is known. For Level 2, the equivalent of pounds psi at 20 cm is 0.20; when the level of water is raised to 50 cm, the psi is 0.73.
The question that logically arises is how the barrier effectiveness of a material that is awarded a pass (at 2 psi) when tested with the ASTMs device can reasonably be compared to the psi of the Levels 2 and 3? Unfortunately, they cannot be. The culprit? Surface tension.
The Role of Surface Tension
As defined in the document, surface tension is the intermolecular forces acting on the molecules at the free surface of a liquid. Surface tension affects the degree to which a liquid can wet a material (i.e., the lower surface tension, the more easily the liquid wets a materials surface). Surface tension is measured by a unit of dynes per centimeter.
Whereas water used in both of the AATCC tests measures around 72 dynes/cm, blood is around 42 dynes/cm. (It is viscosity that makes blood thicker than water.) This means that liquids, such as blood, which have a low surface tension, can penetrate fabrics more readily than those with a higher surface tension such as water. Thus, in terms of interpreting the results of the tests for Levels 1, 2, and 3, they do not mean that under actual conditions of use, they would not permit the penetration of blood.
Leakage in the Critical Zone
The ANSI/AAMI standard defines the critical zone as an area of protective apparel or surgical drape where direct contact with blood, body fluids, and otherwise potentially infectious material (OPIM) is most likely to occur.23
One of those areas of the surgical gown, in which leakage at the gown/glove interface was first reported in 1975.24 Some 20 years later, in a multi-center study of blood contacts in 8,502 surgical procedures, it was found that of the total of 1,043 contacts, 60 percent were experienced by surgeons, and that 53 percent of those involved the fingers, hands, and arms.25 (It is interesting to note that only 2 percent were on the body.) A recent report on this danger zone included a proposed solution to this problem area that has yet to be pursued commercially in a wide fashion.26-27 Nevertheless, it now appears in the list of exclusions as one of the items that the standard does not cover.
In response to an inquiry of the FDA about the exclusion, the agency advised that AAMIs Barrier Committee excluded this subject because the standard is for the barrier properties of the gowns and drapes, especially the critical zone, and it is not possible to determine how an individual would select a gown that assured there would no be a potential problem with this interface.29
In the interim, until such time as some changes in the design and construction of this area, the protective capability of the surgeon gown, regardless of the material of which it is made, will continue to be compromised.
It is to be noted that the standard classifies the patient drape as an item of protective clothing. In so doing, it calls for the inclusion of a barrier-quality material in the critical zone. As recently stated, the influence of a barrier material on the incidence of surgical site infections has not been assessed by scientific studies.30 This confirms the statement made on their use more than 20 years ago. In a commentary on the factors that must be considered that can influence post-operative wound infection, the author stated that there is no convincing evidence for all of them; one of which was barrier materials. Thus, he concluded that their use was predicated on anecdotal experience and commercial interests rather than scientific studies.31
Not to be overlooked is the fact that the authors of the standard failed to consider the widespread use of incise drapes and the advent of minimally invasive surgical procedures that preclude the need of the protective capability of a costly barrier material.
Nathan L. Belkin, PhD, retired in 1991 following a 40-year career in the healthcare industry. He is the author of more than 100 articles and consulted with a variety of healthcare organizations including APIC and AORN.
1. Beck, W.C. and Collette, T.A. False faith in the surgeons gown and surgical drape. Ann Surg. 85:125-126. 1952.
2. Bernard, H.R. and Beck, H.C. Operating room barriers: idealism, practicality, and the future. Bulletin of the American College of Surgeons. 60(9):16.1975.
3. Laufman, H.A., Eudy, W.W., and Vandervoot, A.M. Strikethrough of moist contamination by woven arid nonwoven surgical materials. Ann Surgery. 181:857- 862. 1978.
4. Laufman, H. Breach of truth in advertising regulations. Read before the Surgical Device Classification Panel of the Device Agency, Food and Drug Administration. 1978.
5. Belkin N.L. Textiles as aseptic barriers: the past, present and future. Medical Instrumentation. 14:233-8. 1980.
6. Beck, W.C. and Meeker, M.H. Demise of aseptic barrier committee: success and failure. AORN Journal. 38:384-8. 1983.
7. Shadduck, P.D., Tyler, D.S., Lyerly, H.X., et al. Commercially available surgical gowns do not prevent penetration of HIV-1. Surgical Forum. 41:77-80. 1990.
8. Smith, J.C. and Nichols, R.J. Barrier efficacy of surgical gowns. Arch Sur. 26:756-761. 1991.
9. Belkin, N.L. Gowns: selection on a procedure- driven basis. Infection Control Hosp Epidemiology. 15(11):713-716. 1994.
10. Quebbemen, E.J. and Telford G.L., et al. In-use evaluation of surgical gowns. Surgery Gynecology and Obstetrics. 174:369-375. 1992.
11. Occupational Exposure to bloodborne pathogens: final rule. Federal Register 56. Dec. 6, 1991. 64040-64182.
12. ASTM. Standard test method for resistance of materials used in protective clothing to penetration of synthetic blood. F1670-95.
13. ASTM. Standard test method for resistance of materials used in protective clothing to penetration by bloodborne pathogens using Phi-X174 bacteriophage penetration as a test system. F1671-97b.
14. Stull, O.J. Response. OR Reports 2. July/August 1993.
15. Altman, K.W., et al. Transmural surgical gown pressure measurements in the operating theatre. Am J Infection Control 19. June 1991. 147-155.
16. Smith, J.W., et al. Determination of surgeon-generated gown pressures during various surgical procedures in the operating room. Am J Infection Control 23. August 1993. 237-246.
17. Telford, G.L. and Quebbeman, E.J. Assessing the risk of blood exposure in the operating room. Am J Infection Control 2. December 1993. 351-356.
18. Nichols, R.L. The operating Room. Hospital Infections, fourth edition. Chapter 27. Lippincott-Raven Publishers. Philadelphia. 1998.
19. Koch, F. Perspectives on barrier material standards for operating rooms. Am J Infection Control. April 2004. 115-117.
20. ANSI/AAMI PB 70:2003. Liquid barrier performance and classification of protective apparel and drapes intended for use in healthcare facilities. 2003.
21. AAMI. Technical Information Report. Selection of surgical gowns and drapes in healthcare facilities. AAMI TIR 11. 1994.
22. Ibid. 20. Page 4 (3.2B).
23. Ibid. 20. Page 2 (3.9).
24. Ibid. 3.
25. White, M.C. and Lynch, P. Blood contact and exposure among operating room personnel, a multi-center study. Am J Infection Control. 1993. 21:243-248.
26. Meyer, K.K. and Beck, W.C. Gown/glove interfaces: a possible solution to the danger zone. ICHE 16. August 1995. 488-490.
27. Ibid. 20. Page 1.
28. Ibid. 3.
29. Personal communication with C.S. Lin, Office of Device Evaluation, FDA. Oct. 5, 2004.
30. Rutala, W.A. and Weber, D.J. A review of single-use and reusable gowns and drapes in healthcare. ICHE 2001. 22:248-257.
31. Nichols, R.L. Postoperative wound infection. New England Journal of Medicine. 1982. 307:21:1701-2.