Effectiveness of air purifiers in intensive care units: an interventional study

Society of Critical Care Medicine 2024 Guidelines on Adult ICU Design

RATIONALE

Advances in technology, infection control challenges-as with the COVID-19 pandemic-and evolutions in patient- and family-centered care highlight ideal aspects of ICU design and opportunities for enhancement.

OBJECTIVES

To provide evidence-based recommendations for clinicians, administrators, and healthcare architects to optimize design strategies in new or renovation projects.

PANEL DESIGN

A guidelines panel of 27 members with experience in ICU design met virtually from the panel's inception in 2019 to 2024. The panel represented clinical professionals, architects, engineers, and clinician methodologists with expertise in developing evidence-based clinical practice guidelines. A formal conflict of interest policy was followed throughout the guidelines-development process.

METHODS

Embase, Medline, CINAHL, Central, and Proquest were searched from database inception to September 2023. The Grading of Recommendations Assessment, Development, and Evaluation approach was used to determine certainty in the evidence and to formulate recommendations, suggestions, and practice statements for each Population, Intervention, Control, and Outcomes (PICO) question based on quality of evidence and panel consensus. Recommendations were provided when evidence was actionable; suggestions, when evidence was equivocal; and practice statements when the benefits of the intervention appeared to outweigh the risks, but direct evidence to support the intervention did not exist.

RESULTS

The ICU Guidelines panel issued 17 recommendations based on 15 PICO questions relating to ICU architecture and design. The panel strongly recommends high-visibility ICU layouts, windows and natural lighting in all patient rooms to enhance sleep and recovery. The panel suggests integrated staff break/respite spaces, advanced infection prevention features, and flexible surge capacity. Because of insufficient evidence, the panel could not make a recommendation around in-room supplies, decentralized charting, and advanced heating, ventilation, and air conditioning systems.

CONCLUSIONS

This ICU design guidelines is intended to provide expert guidance for clinicians, administrators, and healthcare architects considering erecting a new ICU or revising an existing structure.

Hospital-borne hazardous air pollutants and air cleaning strategies amid the surge of SARS-CoV-2 new variants

Indoor air pollutants and airborne contamination removal have been challenging in healthcare facilities. The airborne transmission control and HVAC system may collapse in hospitals due to the highly infectious respiratory disease-associated patient surge, like COVID-19. Common air filtration systems and HVAC systems enhance the patients' comfort and support indoor hygiene, hitherto insufficient to control highly infectious airborne pathogens and hospital-borne pollutants such as radon, PM2.5, patient droplets, VOC, high CO2, and anesthetic gases. This review summarized important air cleaning interventions to enhance HVAC efficiency and indoor safety. We discussed efficient air cleaning and ventilation strategies including air filtration, air ionization, passive removal materials (PRM), and UVGI to minimize cross-contamination in hospital wards.

Relative Health Risk Reduction from an Advanced Multi-Modal Air Purification System: Evaluation in a Post-Surgical Healthcare Setting

Advanced air treatment systems have the potential to reduce airborne infection risk, improve indoor air quality (IAQ) and reduce energy consumption, but few studies reported practical implementation and performance. PlasmaShield®, an advanced multi-modal HVAC-integrated system, was directly compared with a standard MERV-13 system in a post-surgical paediatric healthcare setting. The evaluation entailed monitoring of multi-size airborne particles, bioaerosols and key IAQ parameters. Measurements were taken for outside air, supply air and air in the occupied space for 3 days prior to, and after, the installation of the PlasmaShield system. Compared with the existing arrangement, very significant reductions in particle number concentrations were observed in the occupied space, especially with virus-like submicron particles. Significant reductions in airborne culturable bacteria and fungi were observed in the supply air, with more modest reductions in the occupied space. In the case of virus-like particles, there was an eight-fold improvement in equivalent clean air, suggesting a five-fold infection risk reduction for long-range exposure. The data suggest multiple benefits of airborne particle and bioaerosol reduction, with applications beyond healthcare. Long-term studies are recommended to confirm the combined IAQ, health and energy benefits.

A systematic review and meta-analysis of field studies of portable air cleaners: Performance, user behavior, and by-product emissions

Indoor air quality is important for the health of building occupants, and public interest in controlling indoor airborne pathogens increased dramatically with the COVID-19 pandemic. Pollutant concentrations can be controlled locally using portable air cleaners (sometimes called air purifiers), which allow occupants to apply air cleaning technology to meet their needs in the location and times that they find appropriate. This paper provides a systematic review of scientific literature that describes field studies of the effectiveness of portable air cleaners. Over 500 papers were considered, and 148 were reviewed in detail, to extract 35 specific research results (e.g., particulate removal performance) or characteristics (e.g., type of building). These were aggregated to provide an overview of results and approaches to this type of research, and to provide meta-analyses of the results. The review includes: descriptions of the geographical location of the research; rate of publications over time; types of buildings and occupants in the field study; types of air cleaner technology being tested; pollutants being measured; resulting pollutant removal effectiveness; patterns of usage and potential barriers to usage by occupants; and the potential for by-product emissions in some air cleaner technologies. An example result is that 83 of the 148 papers measured reductions in fine particulates (PM2.5) and found a mean reduction of 49 % with standard deviation of 20 %. The aggregated results were approximately normally distributed, ranging from finding no significant reduction up to a maximum above 90 % reduction. Sixteen of the 148 papers considered gaseous pollutants, such as volatile organic compounds, nitrogen dioxide, and ozone; 36 papers considered biological pollutants, such as bacteria, viruses, pollen, fungi, etc. An important challenge, common to several studies, is that occupants run the air cleaners for shorter periods and on low airflow rate settings, because of concerns about noise, drafts, and electricity cost, which significantly reduces air cleaning effectiveness.

The implementation of portable air-cleaning technologies in healthcare settings - a scoping review

The COVID-19 pandemic revealed opportunities to improve prevention practices in healthcare settings, mainly related to the spread of airborne microbes (also known as bioaerosols). This scoping review aimed to map methodologies used to assess the implementation of portable air cleaners in healthcare settings, identify gaps, and propose recommendations for future research. The protocol was registered in the Open Science Framework and reported following the checklist provided by the Preferred Reporting Items for Systematic Reviews and Meta-Analysis - an extension for Scoping Reviews (PRISMA-ScR) statement. The search strategy was performed in five databases and one grey literature source. At the last selection phase, 24 articles that fulfilled our inclusion criteria were summarized and disseminated. Of these, 17 studies were conducted between 2020 and 2022; one of them was a protocol of a multicentre randomized controlled trial. The outcomes measured among the studies include airborne microbe counts, airborne particle concentrations, and rate of infections/interventions. The leading healthcare settings assessed were dental clinics (28%), patient's wards (16%), operating rooms (16%), and intensive care units (12%). Most of the devices demonstrated a significant potential to mitigate the impact of bioaerosols. Although some indoor air quality parameters can influence the mechanics of aerosols, only a few studies controlled these parameters in their analyses. Future clinical research should assess the rate of infections through randomized controlled trials with long-term follow-up and large sample sizes to determine the clinical importance of the findings.

Evaluating the effect of air purifier Novarerus NV800 during orthopedic operations to reduce bioburden in the air

A locally installed air purifier Novaerus Protect 800 has recently been shown to reduce the air bioburden in an intensive care unit and the incidence of healthcare-associated infections (HAI). The aim of this study was to explore whether the same type of local air purifying unit could reduce bacterial concentrations in the air of an operating room (OR) during ongoing orthopedic operations, thereby reducing the risk of surgical site infections (SSI). Three air purifying units were installed in an OR in a Swedish hospital in 2018 in this prospective experimental study. The air was actively sampled during 11 operations by a slit-to-slit agar impactor with the air purifying units either in operation or switched off. Air movements were visualized with aid of smoke in mock-up studies. There was no statistically significant difference in the bacterial concentration in the air when the air purifying units were switched off and switched on (p=0,54). The air movements around and above the surgical wound were disordered and resembled that of dilution mixing air. In conclusion, the three air purifying units installed in the OR did not reduce the airborne bacterial levels in the critical zone during ongoing orthopedic operations in this study.