The Basics of Surgical Mask Selection
By Dianne Rawson, RN, MA
The issue of infection control in the hospital is an everyday concern for all members of the healthcare team and patients. In the surgical setting, surgeons, anesthetists, nurses, and infection control practitioners have informed opinions and subjective beliefs about causes and prevention of infection. What should be done to eliminate or at least reduce the causative agents of infection is a concern for all.
Historically, surgical attire and the ritual of gloving, gowning and donning of masks date back to the 1860s. It is known that live microorganisms are shed from the hair, exposed skin and mucus membranes. Based on studies done in Great Britain by Tuneval, it was concluded that the use of surgical masks during operations does not influence the number of potential pathogenic bacteria in the air close to the operative site and questioned the value of using surgical masks.1 Although there is no evidence to suggest that masks are not necessary to decrease wound infections, the use of surgical masks in protecting the surgical team from contaminated contacts is an important principle to consider. The protection of the health care professional, as well as the patient, has more recently become an issue of infection control and is becoming more complex. Some of the issues related to the real need to wear a surgical mask in the operating room (OR) are controlled by regulatory requirements.2
In the United States, standards and guidelines have been set by governing bodies such as:
- ANSI. The American National Standards Institute (ANSI) Practice for Occupational and Educational Eye and Face Protection ANSI Z87.1 1989 states: "These guidelines establish reasonable and adequate means, ways and methods for the testing, selection and safe use of face and eye protective equipment."
- AORN. The Association of periOperative Registered Nurses (AORN) AORN states that surgical masks should be worn at all times in the operating room and in environments where open sterile supplies or scrubbed personnel may be located. Masks should be secured in a manner to prevent venting. Recommendations include single use of surgical masks. It is also recommended that a surgical mask be used as a barrier to meet Centers for Disease Control and Prevention (CDC) Standard Precautions. (Note: AORN does not specify filtration levels of surgical masks. Individual practice settings should develop their policies based upon OSHA and state-mandated recommendations for wearing masks.)3
- ASTM. The American Society of Testing and Materials (ASTM) is a nonprofit organization that develops standard testing methods by the consensus of volunteers from manufacturers, users, and others. The ASTM uses the following test methods to determine specifications for performance of Materials used in medical face masks.
1. Bacterial Filtration Efficiency: Determines the bacterial filtration efficiency as directed in Test Method F 2101.
2. Differential Pressure: Determines breathing resistance or differential pressure as specified by a test method that provides a measurement of pressure per unit area of material specimen tested.
3. Sub-Micron Particulate Filtration: Determines particulate filtration efficiency as directed in Test method F 1215.
4. Resistance to Penetration by Synthetic Blood: Determines synthetic blood penetration resistance as specified in Test Method F 1862.
5. Flammability: Determines flammability as specified in 16 CFR Part 1610.4.4
- CDC. The CDC Guideline for Isolation Precaution in Hospitals was issued in 1995 and provides recommendations related to mask and respirator use by providing two tiers of precautions to help prevent transmissions of infections from both recognized and unrecognized sources in hospitals.
- Standard Precautions (formerly Universal Precautions). Applies to blood, all body fluids, secretions and excretions except sweat, regardless of whether or not they contain visible blood, non-intact skin and mucous membranes.
Healthcare professionals should wear a mask and eye protection or a face shield to protect mucous membranes of the eyes, nose and mouth during procedures and patient-care activities that are likely to generate splashes or sprays of blood, body fluids, secretions or excretions.
- Transmission-based precautions are recommended to be used in caring for patients documented or suspected to be infected with highly transmissible or epidemiologically important pathogens or when additional precautions beyond standard precautions are needed.
- Droplet precautions means a surgical mask generally is worn to provide protection against spread of infectious, large-particle droplets that are transmitted by close contact and generally travel only short distances (up to 3 feet) from infected patients who are coughing and sneezing. If susceptible persons must enter the rooms of patients known or suspected to have measles (rubeola) or varicella (chickenpox), they should wear respiratory protection.5
- FDA. The Food and Drug Administration (FDA) is responsible for regulating medical devices. A medical device is defined in section 201(h) of the Federal Food, Drug and Cosmetic Act. The definition includes: any article which is intended for use in the cure, mitigation, treatment or prevention of disease in man and which does not achieve any of its intended purposes through chemical action in the body or is dependent upon metabolism (i.e., a drug). A surgical mask is an example of an article regulated as a medical device.
- NIOSH. The National Institute for Occupational Safety and Health (NIOSH) is a federal agency and branch of the Department of Health and Human Services whose function is to identify substances that pose potential health problems and recommends exposure limits to OSHA. NIOSH does in-depth research on safety and health issues, provides technical assistance and recommends standards for adoption by OSHA. NIOSH also certifies respiratory protection equipment.
- BFE (Bacterial Filtration Efficiency) measures the percent efficiency at which the face mask filters bacteria passing through the mask.
- PFE (Particulate Filtration Efficiency) measures the percent efficiency at which the face mask filters particulate matter passing through the mask.
- Delta P (AP) (Breathability) is the pressure drop across a facemask, expressed in mm water/cm¾. The higher the Delta P, the more difficult the mask is to breathe through.
- Fluid resistance is defined as the ability of a facemask's material construction to minimize fluids from traveling through the material and potentially coming into contact with the user of the facemask. Fluid resistance helps reduce potential exposure to blood and body fluids caused from splashes, spray or spatter.
Masks are worn at all times in the restricted area of the OR where sterile supplies are opened, in clean cores and at scrub sinks. Masks with face shields or masks and protective eyewear are required whenever splash, spray or aerosol of blood or other potentially infectious materials may be generated.
A face mask is generally worn by healthcare personnel to provide protection against the spread of infectious, large-particle droplets that are transmitted by close contact and generally travel only short distances (up to 3 feet) from infected patients coughing or sneezing. The wearing of masks, eye protection and face shields in specified circumstances to reduce the risk of exposure to bloodborne pathogens is mandated by the OSHA Bloodborne Pathogen Standard (BBPS) (29 CFR 1910.1030). This regulation was issued in December 1991. The objective of the BBPS is to eliminate or reduce worker exposure to bloodborne pathogens such as hepatitis B (HBV) and human immunodeficiency virus (HIV). It includes requirements for written procedures, risk training, medical screening, vaccinations and treatment, engineering controls, work practices, labeling and employer-provided personal protective equipment. The BBPS:
- Requires a mask, used in combination with eye protection or a chin-length face shield, be used in situations where conditions for exposure to blood and other potentially infectious body fluids or materials exist.
- Requires a face mask be used that prevents blood and other infectious body fluids from passing through to reach employees' skin, eyes, mouth or other mucous membranes under normal use conditions of splashes, sprays and splatter.7
Masks can be found in various shapes with different features and are selected by personal protection need and personal preference of style and fit. Flat-fold tie-on, duck bill, cone shaped, flat-fold with shields, and duckbill with shields are the most common styles worn in the operating room. High fluid resistant earloop masks that can be worn by circulating nurses in the OR are also available.
Masks are effective only if worn properly. Masks reduce the passage of bacterial particles from the wearer into the environment and help protect the wearer from blood and body fluid splash or spatter. Masks should be comfortable and cover both the nose and mouth completely. A face shield or protective eyewear should be worn by staff within the sterile field. The fit should assure that there is no tenting at the sides of the mouth that would allow dispersion or entry of microbes. A small pliable strip at the nose area should promote a close fit. Masks should be changed frequently and anytime they become wet. When removing the mask, handle only by the strings and promptly discard it into a waste receptacle. It is not uncommon to see masks poorly fitted, placed below the nose, or wet with blood or body fluids. A mask should never be allowed to hang or dangle around the neck, nor should it be folded and placed in a pocket for later use; masks should be either on or off.8
Dianne Rawson, RN, MA, is a technical service specialist for 3M Health Care.