PREN 13795 (PARTS 1,2,3) AND THE SELECTION OF SURGICAL GOWNS & DRAPES: MULTIPLE USE COTTON OR SINGLE USE NON WOVEN TISSUES?
Dr Med. Pedro Castillo
Medical Advisor Kimberly Clark Health Care
Spanish Clinical Expert in CEN / TC 205 / WG 14
Key words & abreviations:
Ø SGD (… surgical gowns and drapes)
Ø MU (… multiple use / reusable)
Ø SU (… single use / disposable)
Ø NWT (… non woven tissue)
Ø SMS (… Spundbond + Meltblown + Spundbond)
CONTENTS
The goal of this presentation is to try to answer a key question from the staff of the Central Supply Sterilization Department (CSSD) & the Operating Room (OR) in the Hospital: What is more cost / effective to use in my Department, the traditional reusable Cotton or the newer disposable Non Woven Tissue (NWT) ?.
The author structures his conference into 5 chapters:
1. Update on the prEN 13795 on Surgical Gowns & Drapes (SGD).
2. What are the characteristics to be evaluated for SGD?.
3. Different fabrics / materials used in medical dressings.
4. Cotton or NWT?: The testing evidence.
5. Price versus cos : Is cost-in-use the most valuable decision?.
1 ./ Update on the prEN 13795 ( parts 1,2,3 ).
The objective of this European Norm is to develop a “Standard” on SGD, with the essential requirements that comply with the Medical Devices Directive from 1993 (MDD 93 / 42 / EEC).
Surgical Gowns are used to prevent direct contact transfer of infective agents from the surgical team to the operating wound and vice-versa. They will prevent dispersal of skin scales, to the operating theatre air, only if they are made of a suitable material.
Surgical Drapes are used to provide a microbiologically clean working area around the wound.
Packaging materials (like the Sterilization Wraps,…) are not covered by EN 13795, but by a specific series of standards (EN 868), about which the author has just published an Article in “ El Autoclave ” (Abstracts of the XV International CEDEST Congress, May 2005; 17,1:31-36).
The scope of the EN 13795 is to give “general guidance on the characteristics of Single Use (SU) and Reusable - or Multiple Use (MU) – Surgical Gowns & Drapes, used as medical devices for patients, clinical staff and equipment ”.
It is well known that SGD are “used to minimize the spread of infective agents to and from patients’ operating wounds, thereby helping to prevent post-operative wound infections”.
Therefore, “it is intended to prevent the transmission of infective agents between the patients & clinical staff during surgical and other invasive procedures”. This is our challenging goal.
The EN 13795 consists of 3 Parts:
1. “General requirements for manufacturers, processors and products” (… approved as EN 13795 – 1, in Nov 2002).
2. “Tests methods” (… still in phase of discussion, mainly the “ Resistance to wet microbial penetration ” test: changes in ISO / DIS 22610 ?, etc.).
3. “Performance requirements and performance levels” (… still in phase of discussion, mainly the measurement parameter for the microbial penetration, expressed as “ Barrier Index ”, as well as the maximum acceptable level for “ Linting ” / particles release, etc).
These general requirements “are expected to be of help to (…) users when (…) processing (at CSSD),assessing and selecting products (at the OR) ”. So, you, the processors and end users of SGD, should know the main highlights of this EN and the differences in performance between the different fabrics or materials of which the Sterilization Wraps and the SGD are made.
2./ What are the characteristics to be evaluated for Surgical Gowns & Drapes ?.
They are listed in tables I and II of EN 13795 -1.
There are some common characteristics that must be requested, both for the Gowns and for the Drapes.
The author classifies them, according to the “feature ” to be evaluated.
When the “ Barrier ” is the feature to be evaluated, there are 3 measurable characteristics:
Ø Resistance to microbial penetration – Dry
Ø Resistance to microbial penetration – Wet
Ø Resistance to liquid penetration
When the “Mechanical Resistance ” is the feature to be evaluated, there are 4 measurable characteristics:
Ø Bursting strength –Dry (combination of air movement and mechanical action)
Ø Bursting strength – Wet (combination of wetness, pressure and rubbing)
Ø Tensile strength – Dry
Ø Tensile strength – Wet
When the “Freedom from contamination or unwanted foreign matter ” is the feature to be evaluated, there are 2 measurable characteristics:
Ø Cleanliness – Microbial (not viable micro-organisms)
Ø Cleanliness – Particulate matter (freedom from particles not generated by mechanical impact)
And when the “Release of fiber fragments or other particles, originally from the fabric itself ”, is the feature to be evaluated, there is 1 very important measurable characteristic:
Ø Linting
The only obvious characteristic that is exclusively requested for the Surgical Drapes (but not for the Surgical Gowns ) is:
Ø Adhesion for fixation for the purpose of wound isolation (for the drapes with tapes)
It is very important to know that EN 13795 – 3 classifies the SGD into 2 cathegories (depending on the risk of contamination ):
Ø Standard Performance (e.g. a Surgical Gown used during hand surgery)
Ø High Performance (e.g. a Surgical Gown used during hip replacement)
Additionally, within a specified Surgical Gown and a Drape, we may find 2 different areas (according to the risk of contamination):
Ø Critical product area (e.g. the front and sleeves of Surgical Gowns)
Ø Less critical product area (e.g. the back part)
3. / Different fabrics or materials used in Surgical Gowns & Drapes (as well as in Sterilization Wraps).
The term “fabric” means a “cloth made from yarn or fibers by weaving, knitting and/or other types of binding or manufacture”.
We, functionally, classify them into 2 cathegories:
Ø Reusable or Multiple-Use, MU (intended by the manufacturer to be reprocessed and reused).
Ø Disposable or Single-Use, SU (intended by the manufacturer to be used for only one surgical procedure before disposal).
Two usual representatives of the MU are:
Ø Cotton (linen)
Ø Polyester
As per the SU fabrics, we can mainly classify them into following categories:
Ø Crepe Paper (… only for the Wraps used in the CSSD)
Ø “Spunlace” (…combination of cellulose and polyester fibers, in different percentages from the different manufacturers). It is what we, traditionally, know as NWT, having a “sieve filtration ” type.
Ø “Polypropylene SMS” (…3-layered structure of polypropylene fibers, in the sequence Spunbond – Meltblown – Spundbond).It is the last generation of NWT, having a “ probability filtration ” type, with lower probability for the bacteria to pass through.
The author reminds that the Meltblown Polypropylene is currently the material of which the filter media layer of the face masks is made of.
The “Porosity” of every fabric is very important in their respective “Barrier effect”. Several ultra structural pictures are shown to visualize the porous size (in microns, µ) for every kind of material:
Ø Cotton … till 200 µ
Ø Spunlace … till 60 µ
Ø SMS Polypropylene… < 1 µ
In this respect, the Part 1 of EN 13795 states what follows in Annex C (Informative) “ Prevention of infection in the operating theatre ”:
“ … The airborne particles contaminate the wound directly by sedimentation or indirectly by first setting on instruments or other items that are then brought into contact with the wound. Fabrics with interstices larger than 80 µ do little to prevent the dispersal of skin scales… ”.
This is extremely important to be considered, as it is the intention of EN 13795 the ensure the same level of “ Safety ” (meaning “ Protection”, here) from SU and MU surgical clothing and drapes throughout their useful life cycle.
Does the traditional Cotton guarantees this “Protection Consistency” along the time of use ?.
The author shows several slides with Cotton deteriorated after washing and usage. That is why, according to Dr. J. Sommers: “In spite MU products can be adjusted to EN 13795, during their first utilization, their repeated usage might significantly deteriorate their barrier properties ” (Control, 2003).
It is, also, shown how Cotton loses its barrier properties, with the washing cycles, till going down below the “Minimum Acceptable Level ”, with:
Ø Progressive increase of the water penetration
Ø Progressive increase of the blood penetration
That is why, according to EN 13795 – 1, “if the device is intended by the manufacturer to be reused, information on the appropriate processes to allow reuse, including cleaning, disinfection, packing and, if appropriate, the methods of sterilization of the device to be resterilized, the number of reuses and any restriction to the reuse ”.
In fact, our WG 14 Convenor (Prof. Dr Med. Werner) has criticized Cotton as a fabric to be used in SGD:
Ø “The transfer of micro-organisms towards the incision is higher when Cotton drapes are used” ( Inside Hospitals, 2002, October:30-31 ).
Ø “The Cotton Gowns & Drapes will not meet the rigurous levels of performance requested in the new EN” ( European Journal of Surgery, 1998;9:324-329 ).
4./ Cotton or NWT ?: The testing evidence of the worse performance of Cotton/Reusable (MU) versus the Disposable (SU) clothing.
In the meanwhile we develop the final Testing Methods ( EN 13795 – 2), it is accepted to use alternative evaluation methods, with the condition that their results do correlate with those of the validated and homologated tests in this Standard.
The author shows the comparative results, when evaluating several key characteristics of Surgical Gowns, Standard version (unless differently specified, data are taken from Kimberly Clark Health Care documentation)
Ø Test 1 : “ Hydrostatic Head Repellency ” ( measures resistance to water penetration, expressed in cm of a column of water above the tissue sample):
o NWT of SMS … 60 cm ( … the highest hydro-repellency)
o NWT of Spunlace … 23 cm
o Washed Polyester … 1 cm.
According to EN 13795 – 3, when we assess the “Resistance to Liquid Penetration”, for a “ Standard Performance ” Surgical Gown, the proposed minimum accepted values are:
Critical Area / ≥ 20 cm H²OLess Critical Area / ≥ 10 cm H²O
When the assessed clothing is a Surgical Drape, the proposed minimum accepted values are:
Critical Area / ≥ 30 cm H²OLess Critical Area / ≥ 10 cm H²O
Ø Test 2: “ Blood Strike-Through ” (measures the percentage of blood that is retained by the material and does not pass through the test sample):
o NWT of SMS … 99 % ( … the highest resistance to blood penetration)
o NWT of Spunlace … around 25 %
o Washed Polyester … 60 %
Ø Test 3: “ Linting ” ( the Gelbo Lint Test, measures the number of > 3 µ particles released by the material ):
o NWT of SMS … 698 (… the minimum quatity)
o NWT of Spunlace … 2,133
o Washed Polyester … 2,519
There is scientific evidence that a NWT of Spunlace (wood pulp + polyester fabric) increases the release of fiber fragments (Linting), as per comparison to NWT made of SMS Polypropylene (The Clinical Services Journal, Aug. 2003).
There is also statistical evidence that the bacteria –carrying lint may settle in surgical sites and wounds, with a resultant increase in the probability of Surgical Site Infection (SSI) and other post-operative patient complications (AORN Journal, 2003;77.206-213).
According to a CEN Internal Document (Nº 480), an independent European Laboratory founded out that the Linting from Cotton is significantlly higher than the one from the newer & better performing NWTs, as follows:
Surgical clothing / Minimum Nº of particles released / Expressed in a base 10 logarithmic scale … Log ( 10 )NWT Gowns / 83 / 1.9
Cotton Drapes / 19,138 / 4.3
That is why, in the WG 14, we are discussing to accept a maximum Linting of around ≤ log (10) 4, and this would exclude traditional Cotton.
You, the Health Care Workers must request the maximum technical information (results of validated tests) about the Wraps & SGD that use in your Hospital.
The Hospital Administrators do also have a very important responsibility, because as stated by Dr. Jay Sommers: “ If a patient adquires an infection due to having used a defective gown and/or drape, the hospital authorities will be legally responsible of its consequences ” (Control, 2003).
5. / The most valuable decision in the selection of Surgical Gowns & Drapes : “Cost-in use” versus “Acquisition Price” ?
A quick review is made of the pros & cons of Cotton ( MU textile ):
Advantages / DisadvantagesØ Reusable
Ø Mechanical resistance
Ø Drapeability
Ø Comfort / Ø Lowest microbial barrier
Ø Highest liquid penetration
Ø Highest linting
Ø Washing costs ( laundry )
Ø Washing residua
Ø Re-sterilization costs
Ø Replacement costs ( rejections )
Ø Inspection & fixing costs
Ø Poor consistency in time
Ø How many usages ?
We also review the pros & cons of the SU Disposable Surgical Gowns & Drapes :
Advantages / DisadvantagesØ Higher microbial barrier
Ø Lower liquid penetration
Ø Lower linting
Ø Improved drapeability ( SMS )
Ø Improved resistance ( SMS )
Ø Non- Flammable ( SMS )
Ø Higher quality control & consistency
Ø Easiness of use
Ø Time reduction
Ø Less storage space
Ø Everything in one ( soft packs )
Ø Customization ( soft packs )
Ø More in line with EN 13795 / Ø Not reusable
Ø Disposal ( landing, incineration )
Finally, we come to the same conclusions that the many Operating Room Utilization Reviews Studies have founded out in the last decades:
Ø The modern SU Disposable Surgical Gowns & Drapes, made of NWTs, are more cost / effective, for the Hospital, than the traditional MU Reusable textiles made of Cotton.
Ø Additionally, there seems to be a significant contribution of the SU Disposable SGD, made of NWTs, to the reduction of the prevalence of the Surgical Site Infection.