case study
By Sue Barnes, RN, CIC, FAPIC
Contaminated Air and Surgical Infection
Associated With Implant Procedures
Surgical Site Infection (SSI) Risk for Patients Who
Have Implant Procedures
Patients undergoing surgical procedures which involve
an implant such as prosthetic joint replacement, are at risk
of post-operative infection caused by the very smallest
bacterial inoculum. 1 This is due to the surface of the implant
on which biofilm can expediently develop, and also due to
the patient’s immune system focusing initially on the implant
versus any bacteria that might have adhered to its surface.
Consequently, the number of organisms required to cause
an infection when an implant is involved is reduced by a
factor of 100,000. 2
The Impact of Implant-Associated SSI
A common implant procedure in the United States is
total hip replacement, of which there are approximately
300,000 performed annually. The average SSI rate for these
procedures is 2.18 percent. 3 While this is a low rate it still
represents 8,400 patients, each experiencing pain, suffering
and for some lost wages and impact on family and quality
of life. 4 For each patient the range of cost for treatment of
the infection is between $389,307 and $474,004, and is
associated with a mortality rate of between 2 percent and 7
percent. 5,6 In addition to prosthetic joint replacement, many
other types of surgical procedures now involve implants
including, breast, plastics, orthopedic, spine, general (hernia
mesh), gynecology (pelvic floor mesh), cardiac (pacemaker,
stent, valve, internal atrial defibrillator).
Air Contamination and SSI
The direct correlation of bacteria laden particulates
in operating room air to surgical infection risk has been
reported for decades in peer reviewed studies. 7-9 These
particulates can become transiently airborne during a case,
settle in the open incision and adhere to the implant. 10 These
may originate from any one of several sources, including
respiratory aerosols of the surgical team which can escape
from the surgical mask, especially in the presence of an upper
respiratory tract viral infection. 11,12 Another potential source
of transiently airborne pathogens in operating rooms is the
skin of surgical team members and/or patient. Skin scales
are constantly shed from the human body, to which bacteria
are often attached. 13 Illustrating this risk, is a documented
outbreak involving eight SSI reported after modified radical
mastectomy in a tertiary-care hospital, caused by Group A
streptococci (GAS). The source was found to be a surgeon
colonized (skin) with GAS. 14
A third potential source of transient airborne contami-
nation in operating rooms is equipment which includes a
water reservoir. The outbreak of Mycobacterium chimaera
SSI after cardiac surgical procedures demonstrates this risk. In
this outbreak, the water tanks on the heater-cooler devices
24
used in open heart surgery were found to be the source for
the airborne transmission of M. chimaera resulting in more
than 100 SSI cases since 2013 in Europe and the U.S. 15,16
Current State of Air Quality in US Operating Rooms
(OR) versus Compounding Pharmacies
In the OR, surgical procedures involve an incision (sterile
space), which remains open to the OR air. In compounding
pharmacies sterile solutions are prepared to be introduced
into the sterile vascular system. Regulations governing
these two spaces are not equivalently protective. On the
one hand, U.S. compounding pharmacies must comply with
International Standards Organization (ISO) class 5 standards
for air quality. 17 However, there is no requirement for air
quality testing in US operating rooms, where it is assumed to
be sufficient as a result of the engineering controls (positive
air pressure, increased air changes, temp and humidity control
and high efficiency particulate air filter or HEPA). 18 However,
it has been demonstrated that those controls can be defeated
by door openings and room traffic during cases. 19-21
Adjunctive Air Decontamination Technology
Technologies designed to improve air quality in operating
rooms fall into three primary categories – air filtration,
air disinfection and combined filtration plus disinfection.
This adjunctive technology is arguably most crucial in the
outer area of the OR beyond the OR table, which is not
protected with directional air flow and HEPA air filtration.
In this outer area of the OR, there is typically less effective
air flow, increased human activity, door openings and floor
contamination. Consequently, the air in this surrounding
area can potentially contaminate instrumentation, implants,
gloves, surgical team members, surgical drapes, and tables
which are in direct communication with the patient.
Employing an adjunctive technology for the outer area of
operating rooms, which provides air disinfection plus filtration
of particulates, would seem prudent. Innovative portable
devices which combine ultraviolet (UV) technology and HEPA
filtration to eliminate particulates and microorganisms are
in use in increasing numbers of ORs. These devices have
been reported in peer reviewed studies to reduce transiently
airborne bacteria in operating rooms by 50 percent to 60
percent and reduce overall rates of prosthetic joint infection
(p<0.042). 22-29
Conclusions
Current standard methods for ensuring adequate OR air
quality are limited to positive air pressure, 20 air changes per
hour, surgical attire, traffic control (and HEPA filtration in some
ORs). These methods alone have been proven insufficient
to prevent contaminated air associated SSI as demonstrated
by multiple outbreaks including the M. chimera outbreak in
february 2020 • www.healthcarehygienemagazine.com