Infection prevention


enteric organisms – pathogens that constitute the majority of SSI isolates across clean and clean-contaminated procedure categories.6 Shed squames range from 5–20 µm in diameter, a particle size that enables prolonged suspension in room air, penetration of surgical draping, and deposition onto exposed tissues and implant surfaces. Seminal work by Lidwell and colleagues in a landmark multicentre randomised controlled trial demonstrated a significant inverse relationship between intraoperative airborne bacterial counts and the incidence of deep sepsis following total hip and knee arthroplasty.7 Rooms ventilated to achieve ultraclean air standards (fewer than 10 colony-forming units per cubic metre [CFU/m³]) were associated with infection rates approximately four times lower than those observed in conventionally ventilated theatres. This dose-response relationship has been replicated in subsequent observational studies across orthopaedic, cardiac, and vascular surgical contexts, consistently demonstrating that airborne microbial burden is an independent predictor of SSI risk.8 Beyond direct wound inoculation, airborne


particles contaminate instruments, implants, scrub personnel’s sterile gown surfaces, and irrigating fields. Ritter et al demonstrated that bacterial particle counts at the wound site correlated significantly with culture positivity of removed prosthetic components at revision arthroplasty, providing direct mechanistic evidence linking intraoperative air quality to clinically relevant contamination events.9 More recently, Zhiqing and colleagues confirmed that airborne particle concentrations in the operating room increase substantially during surgical procedures compared to pre- case baseline measurements, with personnel movement, door openings, and procedural complexity serving as the principal drivers of contamination episodes.10


Limitations of conventional ventilation systems The current standard for operating room ventilation in the United States is codified in ASHRAE Standard 170 and the Guidelines for Design and Construction of Hospitals published by the Facility Guidelines Institute, which mandate a minimum of 20 total air changes per hour (ACH), of which at least 4 ACH must be outdoor air, with positive pressure differential and high-efficiency particulate air (HEPA) filtration at the supply.11


Laminar airflow (LAF)


systems, which deliver a unidirectional, high- velocity column of filtered air over the surgical field, were developed with the intent of further reducing intraoperative airborne contamination


48 www.clinicalservicesjournal.com I July 2026


and are widely deployed in orthopaedic and cardiothoracic suites. However, the clinical efficacy of LAF


systems has been challenged by more recent epidemiological data. A large retrospective analysis by Brandt and colleagues involving more than 99,000 surgical procedures found no significant reduction in SSI rates attributable to LAF ventilation compared to conventional turbulent systems, and some subgroup analyses suggested a paradoxical increase in SSI risk in LAF rooms.12


Proposed mechanisms include flow


disruption caused by personnel, equipment, and thermal plumes generated by surgical lighting, creating turbulence zones within and around the sterile field that may redirect rather than eliminate airborne contaminants. These findings highlight a critical limitation


of supply-side ventilation strategies: they modulate air delivery but do not actively remove contaminated air from the occupied room volume. The zone immediately surrounding the sterile field – sometimes characterised as the ‘contamination envelope’ – remains subject to ongoing microbial input from operative personnel, and conventional ventilation systems cannot achieve sufficient exchange rates within this localised volume during active procedural phases.13


Continuous air decontamination: emerging evidence and technological approaches Recognition of these ventilation limitations has stimulated interest in supplemental air decontamination technologies that operate within the occupied surgical environment,


continuously processing room air to reduce viable airborne microbial burden independent of fixed HVAC infrastructure. Two primary inactivation modalities have accumulated peer- reviewed evidence in the perioperative context: germicidal ultraviolet-C (UV-C) irradiation and HEPA mechanical filtration, with emerging systems integrating both mechanisms within a single portable platform. UV-C irradiation at a wavelength of 254 nm


disrupts microbial DNA through the formation of cyclobutane pyrimidine dimers, rendering organisms nonviable without triggering lytic cell death.14


Importantly, continuous-flow UV-C


systems – in which air is drawn through a contained photolytic chamber – circumvent the direct occupant exposure concerns associated with traditional room-level UV-C fixtures, permitting safe operation in occupied spaces. Independent laboratory testing of such systems has documented complete inactivation of viral aerosols and greater than 4-log reduction of bacterial bioaerosols under controlled flow conditions.15 Clinical evidence for portable, continuous-


flow air decontamination systems in surgical settings has been generated through both controlled laboratory studies and observational perioperative research. Peer-reviewed investigations published in The Journal of Arthroplasty and the American Journal of Infection Control have documented 50–72% reductions in intraoperative airborne bacterial concentrations in operating rooms employing continuous HEPA/UV-C recirculation units as an adjunct to standard ventilation, without modification to the underlying HVAC system.16,17


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60