Barrier enclosure use during aerosol-generating medical procedures: A scoping review

An Individual Barrier Enclosure Actively Removing Aerosols for Airborne Isolation: A Vacuum Tent

BACKGROUND

Aerosol barrier enclosure systems have been designed to prevent airborne contamination, but their safety has been questioned. A vacuum tent was designed with active continuous suctioning to minimize risks of aerosol dispersion. We tested its efficacy, risk of rebreathing, and usability on a bench, in healthy volunteers, and in an ergonomic clinical assessment study.

METHODS

First, a manikin with airway connected to a breathing simulator was placed inside the vacuum tent to generate active breathing, cough, and CO2 production; high-flow nasal cannula (HFNC) was applied in the manikin's nares. Negative pressure was applied in the vacuum tent's apex port using wall suction. Fluorescent microparticles were aerosolized in the vacuum tent for qualitative assessment. To quantify particles inside and around vacuum tent (aerosol retention), an airtight aerosol chamber with aerosolized latex microparticles was used. The vacuum tent was tested on healthy volunteers breathing with and without HFNC. Last, its usability was assessed in 5 subjects by 5 different anesthesiologists for delivery of full anesthesia, including intubation and extubation.

RESULTS

The vacuum tent was adjusted until no leak was visualized using fluorescent particles. The efficacy in retaining microparticles was confirmed quantitatively. CO2 accumulation inside the vacuum tent showed an inverse correlation with the suction flow in all conditions (normal breathing and HFNC 30 or 60 L/min) in bench and healthy volunteers. Particle removal efficacy and safe breathing conditions (CO2, temperature) were reached when suctioning was at least 60 L/min or 20 L/min > HFNC flow. Five subjects were successfully intubated and anesthetized without ergonomic difficulties and with minimal interference with workflow and an excellent overall assessment by the anesthesiologists.

CONCLUSIONS

The vacuum tent effectively minimized aerosol dispersion. Its continuous suction system set at a high suction flow was crucial to avoid the spread of aerosol particles and CO2 rebreathing.

Development and demonstration of the protective efficacy of a convertible respiratory barrier enclosure: a simulation study

OBJECTIVE

The efficacy of previously developed respiratory barrier enclosures to limit healthcare workers' exposure to aerosols from COVID-19 patients remains unclear; in addition, the design of these devices is unsuitable for transportation or other emergency procedures. Therefore, we developed a novel negative pressure respiratory isolator to improve protection from patient-generated aerosols and evaluated its protective effect in conversion to systemic isolator.

METHODS

This in vitro study simulated droplets by nebulizing 1% glycerol + 99% ethanol solution. We performed cardiopulmonary resuscitation (CPR) and converted a respiratory barrier enclosure into a systemic isolator with a respiratory barrier as well as a respiratory barrier with negative pressure generator (NPG), which were compared with control and room air. During the procedure, particles were counted for 30 seconds and the count was repeated 10 times.

RESULTS

During CPR, the total number of particles in the respiratory barrier with NPG (280,529; interquartile range [IQR], 205,263-359,195; P=0.970) was similar to that in the control (308,789; IQR, 175,056-473,276). Using NPG with a respiratory barrier reduced the number of particles to 27,524 (IQR, 26,703- 28,905; P=0.001). Particle number during conversion of the respiratory barrier into a systemic isolator was also lower than in the control (25,845; IQR, 19,391- 29,772; P=0.001).

CONCLUSION

The novel isolator was converted to a systemic isolator without air leakage. The aerosol-blocking effect of the isolator was quantified using a particle counter during CPR. Further studies comparing the barrier effect of isolators within various pressure differentials are warranted.

Design and quantitative evaluation of 'Aerosol Bio-Containment Device (ABCD)' for reducing aerosol exposure during infectious aerosol-generating events

The Coronavirus Disease 2019 (COVID-19) pandemic renewed interest in infectious aerosols and reducing risk of airborne respiratory pathogen transmission, prompting development of devices to protect healthcare workers during airway procedures. However, there are no standard methods for assessing the efficacy of particle containment with these protective devices. We designed and built an aerosol bio-containment device (ABCD) to contain and remove aerosol via an external suction system and tested the aerosol containment of the device in an environmental chamber using a novel, quantitative assessment method. The ABCD exhibited a strong ability to control aerosol exposure in experimental and computational fluid dynamic (CFD) simulated scenarios with appropriate suction use and maintenance of device seals. Using a log-risk-reduction framework, we assessed device containment efficacy and showed that, when combined with other protective equipment, the ABCD can significantly reduce airborne clinical exposure. We propose this type of quantitative analysis serves as a basis for rating efficacy of aerosol protective enclosures.

Pulmonary function testing during SARS-CoV-2: An ANZSRS/TSANZ position statement

The Thoracic Society of Australia and New Zealand (TSANZ) and the Australian and New Zealand Society of Respiratory Science (ANZSRS) commissioned a joint position paper on pulmonary function testing during coronavirus disease 2019 (COVID-19) in July 2021. A working group was formed via an expression of interest to members of both organizations and commenced work in September 2021. A rapid review of the literature was undertaken, with a 'best evidence synthesis' approach taken to answer the research questions formed. This allowed the working group to accept findings of prior relevant reviews or societal document where appropriate. The advice provided is for providers of pulmonary function tests across all settings. The advice is intended to supplement local infection prevention and state, territory or national directives. The working group's key messages reflect a precautionary approach to protect the safety of both healthcare workers (HCWs) and patients in a rapidly changing environment. The decision on strategies employed may vary depending on local transmission and practice environment. The advice is likely to require review as evidence grows and the COVID-19 pandemic evolves. While this position statement was contextualized specifically to the COVID-19 pandemic, the working group strongly advocates that any changes to clinical/laboratory practice, made in the interest of optimizing the safety and well-being of HCWs and patients involved in pulmonary function testing, are carefully considered in light of their potential for ongoing use to reduce transmission of other droplet and/or aerosol borne diseases.

An overview of COVID-19 aerosol box for preventing droplet and aerosol contaminations in healthcare providers performing airway intubation

The COVID-19 is caused by the SARS-CoV-2, which is extremely infectious. Numerous virologist suggestions and guidelines advised using P2/N95 masks, gloves, goggles, face-shields, and frocks or gowns as routine specific protective tools during airway management to protect healthcare personnel from infection (PPE). However, numerous imitation research has indicated that conventional PPE cannot adequately protect healthcare personnel. Since then, numerous firms and healthcare professionals have created their personal reformed devices "aerosol containment devices" (ACD). Their usage has expanded throughout the world without being properly evaluated for usefulness, efficacy, or safety. The practice of "ACD" has been shown to make tracheal intubation (TI) more problematic in several simulated tests. Furthermore, the device should limit the transmission of droplets from a patient; however, it might put healthcare personnel at danger of being exposed to greater levels of viral aerosols. Consequently, the existing state of information suggests that "ACD" deprived of a vacuum mechanism can simply protect healthcare personnel against viral transmission to a limited extent. We search various databases for the literatures with keywords "COVID-19", "aerosol box", "aerosol contaminations" and "droplet contaminations. The current review focused on the aerosol box from various perspectives, including their mechanism, optimum time of use, the spread of aerosol control, current gaps and future perspective for bridging those gaps.

Effectiveness of a novel semi-closed barrier device with a personalized exhaust in cough aerosol simulation according to particle counts and visualization of particles

Oxygen therapy is an essential treatment for patients with coronavirus disease 2019, although there is a risk of aerosolization of additional viral droplets occurring during this treatment that poses a danger to healthcare professionals. High-flow oxygen through nasal cannula (HFNC) is a vital treatment bridging low-flow oxygen therapy with tracheal intubation. Although many barrier devices (including devices without negative pressure in the barrier) have been reported in the literature, few barrier devices are suitable for HFNC and aerosol infection control procedures during HFNC have not yet been established. Hence, we built a single cough simulator model to examine the effectiveness of three protective measures (a semi-closed barrier device, a personalized exhaust, and surgical masks) administered in isolation as well as in combination using particle counter measurements and laser sheet visualization. We found that the addition of a personalized exhaust to a semi-closed barrier device reduced aerosol leakage during HFNC without negative pressure. This novel combination may thus reduce aerosol exposure during oxygen therapy, enhance the protection of healthcare workers, and likely reduce nosocomial infection risk.

Effectiveness of “Resuscitation Cover All” in minimizing COVID-19 transmission to health-care workers during cardiopulmonary resuscitation: A simulation-based study

Introduction:

Coronavirus disease 2019 (COVID-19) is a highly contagious disease transmitted by contact, droplets, and aerosols. Front line health-care workers (HCWs), particularly emergency physicians and acute care providers, are vulnerable to being exposed while treating their sick patients. Despite appropriate personal protective equipment use, HCW gets infected, suggesting the need for multiple layers of protection such as barrier devices.

Methods:

We aimed to determine the effectiveness of our novel “Resuscitation Cover All”(RCA) in reducing the exposure of HCW to simulated respiratory particles and its feasibility during cardio pulmonary resuscitation (CPR). This was a pilot simulation-based study. Five CPR simulation sessions were performed in Standard and RCA protocols, individually. Exposures through contact, droplets, and aerosols were simulated using a standardized volume of liquid detergent. Under Wood's lamp illumination, exposures of participants were compared between the protocols. Rate and depth of chest compressions, time taken to intubate, interruptions in CPR, and first-pass success were analyzed.

Results:

Overall mean exposure in standard protocol was 4950.4 ± 1461.6 (95%confidence interval [CI]:3135.7–6765.2) sq.pixels and RCA protocol was 2203.6 ± 1499.0 (95%CI: 342.4–4064.9) sq.pixels (P = 0.019). In standard, chest compressor had the highest exposure of 3066.6 ± 1419.2 (95%CI: 2051.3–4081.9) sq.pixels followed by defibrillator assistant 1166.4 ± 767.4 (95%CI: 617.4–1715.4) sq.pixels. Chest compressor of RCA had reduced exposure compared to that of standard (P < 0.001). Hands were the most frequently exposed body part. Airway manager of RCA had no exposure over head and neck in any session. No significant difference in CPR performance metrics was observed.

Conclusion:

This pilot simulation-based study shows that the novel RCA device could minimize the exposure of HCW to simulated respiratory particles during CPR. Also, it might not alter the high-quality CPR performance metrics. We need more real-life evidence.

Simulation and evaluation of the protective barrier enclosure for cardiopulmonary resuscitation

INTRODUCTION

The COVID-19 pandemic has presented a significant challenge for infection prevention and control during airway management in anaesthesia and critical care. The protective barrier enclosure has been described and studied particularly for perioperative anaesthesia use. The potential use of the protective barrier enclosure during cardiopulmonary resuscitation has been poorly explored in the current literature. This work aims to demonstrate the potential of protective barrier enclosure in limiting aerosol dispersion during cardiopulmonary resuscitation delivery.

METHODS

A proof-of-concept simulation study was conducted to evaluate the protective properties of the protective barrier enclosure during cardiopulmonary resuscitation. Aerosol was simulated using a fluorescent dye trapped within the manikin. Three different methods of cardiopulmonary resuscitation delivery with a protective barrier enclosure applied over the manikin's head were conducted. The first method simulated a chest compression only cardiopulmonary resuscitation, the second method also used chest compressions only, with a face mask fitted on the victim, while the third method, the victim was given chest compression and bag-valve-mask ventilation by two rescuers.

RESULTS

In the first method, release of aerosol from the manikin's mouth was observed during chest compression, while in second method, most of the aerosol was trapped within the face mask, with only minor leaking. However, when bag-valve-mask ventilation was delivered, the aerosol leaked out at high speed around the bag-valve-mask seal. No aerosol condensation was found outside of the protective barrier enclosure in all scenes.

CONCLUSION

Protective barrier enclosure may reduce aerosol exposure to the rescuers during out-of-hospital cardiac arrest.

Comparison of the Efficiency and Usability of Aerosol Box and Intubation Tent on Intubation of a Manikin Using Personal Protective Equipment: A Randomized Crossover Study

Background

The aerosol box and intubation tent are improvised barrier-enclosure devices developed during the novel coronavirus pandemic to protect health care workers from aerosol transmission.

Objective

Using time to intubation as a crude proxy, we aimed to compare the efficiency and usability of the aerosol box and intubation tent in a simulated manikin.

Methods

This was a single-center, randomized, crossover manikin study involving 28 participants (9 anesthetists, 16 emergency physicians, and 3 intensivists). Each participant performed rapid sequence intubations in a random sequence of three different scenarios: 1) no device use; 2) aerosol box; 3) intubation tent. We compared the time to intubation between different scenarios.

Results

The median total intubation time with no device use, aerosol box, and intubation tent were 23.7 s (interquartile range [IQR] 19.4–28.4 s), 30.9 s (IQR 24.1–52.5 s), and 26.0 s (IQR 22.1–30.8 s), respectively. Post hoc analysis showed a significantly longer intubation time using the aerosol box compared with no device use (p < 0.001) and compared with the intubation tent (p < 0.001). The difference between the intubation tent and no device use was not significant. The first-pass intubation success rate did not differ between the groups. Only aerosol box use had resulted in breaches of personal protective equipment. Participants considered intubation with the intubation tent more favorable than the aerosol box.

Conclusions

The intubation tent seems to have a better barrier-enclosure design than the aerosol box, with a reasonable balance between efficiency and usability. Further evaluation of its efficacy in preventing aerosol dispersal and in human studies are warranted prior to recommendation of widespread adoption.

The barrier techniques for airway management in covid-19 patients - review of literature

The coronavirus disease 2019 (COVID-19) has emerged as a pandemic and shall prevail for some time around the globe. The disease can manifest from asymptomatic to severe respiratory compromise requiring airway intervention. Transmission of COVID-19 has been reported to be by droplets, fomites, and aerosols, and airway management is an aerosol-generating procedure. The high viral load in the patient's airway puts the clinician performing intubation at a very high risk of viral load exposure. So, the need for barrier devices was considered and led to reporting of various such devices. All these devices have been reported individually and have not been compared. We present a review of all the information on these devices based on the reported literature.