Containment of procedure-associated aerosols by an extractor tent: effect on nebulized drug particle dispersal

Guidance on Mitigating the Risk of Transmitting Respiratory Infections During Nebulization by the COPD Foundation Nebulizer Consortium

BACKGROUND

Nebulizers are used commonly for inhaled drug delivery. Because they deliver medication through aerosol generation, clarification is needed on what constitutes safe aerosol delivery in infectious respiratory disease settings. The COVID-19 pandemic highlighted the importance of understanding the safety and potential risks of aerosol-generating procedures. However, evidence supporting the increased risk of disease transmission with nebulized treatments is inconclusive, and inconsistent guidelines and differing opinions have left uncertainty regarding their use. Many clinicians opt for alternative devices, but this practice could impact outcomes negatively, especially for patients who may not derive full treatment benefit from handheld inhalers. Therefore, it is prudent to develop strategies that can be used during nebulized treatment to minimize the emission of fugitive aerosols, these comprising bioaerosols exhaled by infected individuals and medical aerosols generated by the device that also may be contaminated. This is particularly relevant for patient care in the context of a highly transmissible virus.

RESEARCH QUESTION

How can potential risks of infections during nebulization be mitigated?

STUDY DESIGN AND METHODS

The COPD Foundation Nebulizer Consortium (CNC) was formed in 2020 to address uncertainties surrounding administration of nebulized medication. The CNC is an international, multidisciplinary collaboration of patient advocates, pulmonary physicians, critical care physicians, respiratory therapists, clinical scientists, and pharmacists from research centers, medical centers, professional societies, industry, and government agencies. The CNC developed this expert guidance to inform the safe use of nebulized therapies for patients and providers and to answer key questions surrounding medication delivery with nebulizers during pandemics or when exposure to common respiratory pathogens is anticipated.

RESULTS

CNC members reviewed literature and guidelines regarding nebulization and developed two sets of guidance statements: one for the health care setting and one for the home environment.

INTERPRETATION

Future studies need to explore the risk of disease transmission with fugitive aerosols associated with different nebulizer types in real patient care situations and to evaluate the effectiveness of mitigation strategies.

Characterization of Volatile and Particulate Emissions from Desktop 3D Printers

The rapid expansion of 3D printing technologies has led to increased utilization in various industries and has also become pervasive in the home environment. Although the benefits are well acknowledged, concerns have arisen regarding potential health and safety hazards associated with emissions of volatile organic compounds (VOCs) and particulates during the 3D printing process. The home environment is particularly hazardous given the lack of health and safety awareness of the typical home user. This study aims to assess the safety aspects of 3D printing of PLA and ABS filaments by investigating emissions of VOCs and particulates, characterizing their chemical and physical profiles, and evaluating potential health risks. Gas chromatography-mass spectrometry (GC-MS) was employed to profile VOC emissions, while a particle analyzer (WIBS) was used to quantify and characterize particulate emissions. Our research highlights that 3D printing processes release a wide range of VOCs, including straight and branched alkanes, benzenes, and aldehydes. Emission profiles depend on filament type but also, importantly, the brand of filament. The size, shape, and fluorescent characteristics of particle emissions were characterized for PLA-based printing emissions and found to vary depending on the filament employed. This is the first 3D printing study employing WIBS for particulate characterization, and distinct sizes and shape profiles that differ from other ambient WIBS studies were observed. The findings emphasize the importance of implementing safety measures in all 3D printing environments, including the home, such as improved ventilation, thermoplastic material, and brand selection. Additionally, our research highlights the need for further regulatory guidelines to ensure the safe use of 3D printing technologies, particularly in the home setting.

Aerosol containment device design considerations and performance evaluation metrics

BACKGROUND

Spurred by the Coronavirus infectious disease 2019 pandemic, aerosol containment devices (ACDs) were developed to capture infectious respiratory aerosols generated by patients at their source. Prior reviews indicated that such devices had low evidence of effectiveness, but did not address how ACDs should be evaluated, how well they should perform, nor have clearly defined performance standards. Towards developing design criteria for ACDs, two questions were posed: 1) What characteristics have guided the design of ACDs? 2) How have these characteristics been evaluated?

METHODS

A scoping review was performed consistent with PRISMA guidelines. Data were extracted with respect to general study information, intended use of the device, device design characteristics and evaluation.

RESULTS

Fifty-four articles were included. Evaluation was most commonly performed with respect to device aerosol containment (n = 31, 61%), with only 5 (9%), 3 (6%) and 8 (15%) formally assessing providing experience, patient experience and procedure impact, respectively. Nearly all of the studies that explored provider experience and procedure impact studied intubation. Few studies provided a priori performance criteria for any evaluation metric, or referenced any external guidelines by which to bench mark performance.

CONCLUSION

With respect to aerosol containment, ACDs should reduce exposure among HCP with the device compared with the absence of the device, and provide ≥90% reduction in respirable aerosols, equivalent in performance to N95 filtering facepiece respirators, if the goal is to reduce reliance on personal protective equipment. The ACD should not increase awkward or uncomfortable postures, or adversely impact biomechanics of the procedure itself as this could have implications for procedure outcomes. A variety of standardized instruments exist to assess the experience of patients and healthcare personnel. Integration of ACDs into routine clinical practice requires rigorous studies of aerosol containment and the user experience.

Portable HEPA filtration successfully augments natural-ventilation-mediated airborne particle clearance in a legacy design hospital ward

As the severe acute respiratory syndrome coronavirus-2 pandemic has proceeded, ventilation has been recognized increasingly as an important tool in infection control. Many hospitals in Ireland and the UK do not have mechanical ventilation and depend on natural ventilation. The effectiveness of natural ventilation varies with atmospheric conditions and building design. In a challenge test of a legacy design ward, this study showed that portable air filtration significantly increased the clearance of pollutant aerosols of respirable size compared with natural ventilation, and reduced spatial variation in particle persistence. A combination of natural ventilation and portable air filtration is significantly more effective for particle clearance than either intervention alone.

Real-time Monitoring of Aerosol Generating Dental Procedures

OBJECTIVE

We aimed to quantify aerosol concentrations produced during different dental procedures under different mitigation processes.

METHOD

Aerosol concentrations were measured by the Optical Particle Sensor (OPS) and Wideband Integrated Bioaerosol Sensor (WIBS) during routine, time-recorded dental procedures on a manikin head in a partitioned enclosure. Four different, standardised dental procedures were repeated in triplicate for three different mitigation measures.

RESULT

Both high-volume evacuation (HVE) and HVE plus extra-oral suction (LEV) eradicated all procedure-related aerosols, and the enclosure stopped procedure-related aerosols escaping. Aerosols recorded by the OPS and WIBS were 84 and 16-fold higher than background levels during tooth 16 FDI notation (UR6) drilling, and 11 and 24-fold higher during tooth 46 FDI notation (LR6) drilling, respectively. Ultrasonic scaling around the full lower arch (CL) or the full upper arch (CU) did not generate detectable aerosols with mitigation applied. Without mitigation the largest concentration of inhalable particles during procedures observed by the WIBS and OPS was during LR6 (139/cm³) and UR6 (28/cm³) drilling, respectively. Brief aerosol bursts were recorded during drilling procedures with HVE, these did not occur with LEV, suggesting LEV provides protection against operator errors. Variation was observed in necessary fallow times (49 - 280 minutes) without mitigation, while no particles remained airborne when mitigation was utilised.

CONCLUSION

This data demonstrates that correctly positioned HVE or LEV is effective in preventing airborne spread and persistence of inhalable particles originating from dental AGPs. Additionally, a simple enclosure restricts the spread of aerosols outside of the operating area.

CLINICAL SIGNIFICANCE

Employing correctly positioned HVE and LEV in non-mechanically ventilated clinics can prevent the dispersal and persistence of inhalable airborne particles during dental AGPs. Moreover, using enclosures have the additive effect of restricting aerosol spread outside of an operating area.

Airborne Fungal Spore Review, New Advances and Automatisation

Fungal spores make up a significant portion of Primary Biological Aerosol Particles (PBAPs) with large quantities of such particles noted in the air. Fungal particles are of interest because of their potential to affect the health of both plants and humans. They are omnipresent in the atmosphere year-round, with concentrations varying due to meteorological parameters and location. Equally, differences between indoor and outdoor fungal spore concentrations and dispersal play an important role in occupational health. This review attempts to summarise the different spore sampling methods, identify the most important spore types in terms of negative effects on crops and the public, the factors affecting their growth/dispersal, and different methods of predicting fungal spore concentrations currently in use.

Aerosol drug delivery to tracheotomized patients with COVID-19: Pragmatic suggestions for clinicians

Because of the wide and rapid spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the number of hospitalized patients with coronavirus disease 2019 (COVID-19) has rapidly increased medically complex and resource-intensive treatment requirements in health care settings. Although tracheostomy is frequently needed for critically ill patients requiring extended mechanical ventilation, it has been described as an aerosol-generating procedure that puts health care professionals at an increased risk of viral transmission. In addition, the delivery of aerosolized medications to this patient population has become controversial because of concerns on the transmission of SARS-CoV-2 via droplets. Although aerosol therapy in spontaneously breathing patients with COVID-19 was described in recent publications, innovations in aerosol drug delivery to COVID-19 patients with tracheostomy have not been presented. Therefore, empirically based guidance on how to deliver aerosols safely and effectively to tracheotomized patients with COVID-19 is still lacking. This paper provides recommendations and rationales for device selection, interface selection, delivery techniques, and infection control based on the evolving body of literature.