key: cord-0802697-yyzb3wne
authors: Bai, Johnny-Wei; Ravi, Ananth; Notario, Lowyl; Choi, Mabel
title: Opening the discussion on a closed intubation box
date: 2020-06-04
journal: nan
DOI: 10.1016/j.tacc.2020.06.004
sha: d2c636462af4ad04ad84d30249851db78a12a04c
doc_id: 802697
cord_uid: yyzb3wne

Abstract Background Airway management for patients with COVID-19 poses a significant infection risk to clinicians. As such, some providers have adopted the "COVID intubation box", a cuboid barrier which which separates the clinician from the airway. While this device has limitations, there is promising evidence on its effectiveness. Aim To summarize the history, evidence, and limitations of the popular intubation box design. Furthermore, we share our modified design and experiences from airway simulations. Methods Using our prototyping and validation facilities, our team designed and iteratively improved our device to arrive at a final design. The expert panel, consisting of anesthesiologists, infection control staff, and emergency clinicians, trialed the device using airway simulation mannequins and provided feedback. Results Our final device features a dome shape, increased height, wider arm port diameter, additional side port for assistants, and drapes to reduce viral escape. Feedback from simulations was overall positive, especially noting that the height and arm port diameter facilitated arm motion within the box. The infection control team preferred the unique dome shape for safe disinfection. Conclusion Our intubation box overcomes several challenges and criticisms of the popular intubation box. This device is an important harm reduction tool for clinicians during this COVID-19 pandemic.

The management of coronavirus disease 2019 (COVID-19) poses unique challenges and risks to 52 healthcare workers around the world. Troubling data from China and Europe estimates that up to 5-53 10% of cases are healthcare workers who constitute frontline efforts against this virus. 1 Viral 54 transmission is especially high during aerosol generating manoeuvres of airway management, such as 55 preoxygenation, tracheal intubation, suctioning, bag-mask ventilation, extubation. 2 As such, anesthesia, 56 intensive care, and emergency department providers who perform tracheal intubation face significant 57 risk of transmission which warrants special attention and effective solutions. Furthermore, prolonged 58 aerosol stability of viral particles, global personal protective equipment (PPE) shortage, and correlation 59 between disease and exposure to high viral load exacerbate the risk of transmission related to airway 60 management. 3,4,5 61 62

One creative solution to mitigate these risks was first published by Dr. Lai and his medical team 64 in Taiwan. 6 Their original "aerosol box" involves a clear 40x50x25cm plastic box placed over the 65 patient's head, with two 10cm holes for arms to access the airway. During intubation and extubation, 66 aerosolized viral particles may be contained within this semi-closed box, thereby reducing risk to the 67 intubator, assistants, and aerosolization to the patient's environment. In fact, a study simulating 68 laryngoscopy of a mannequin and expelled fluorescent dye showed that this type of barrier greatly 69 reduced exposure to the laryngoscopist. 7 Therefore, this tool -combined with simulation training and 70

appropriate PPE -affords an extra layer of protection for healthcare workers and has been 71 recommended by authors and guidelines as a form of engineering control. 8 72

Since the original design, the device has gained popularity with several groups developing their 73 own variations featuring similar cuboid shape, two arm holes, and clear plastic material. 9,10 However, difficulty intubating with a raised head-of-bed, and lack of access for assistants. Depending on the 76 height of the intubator, the cuboid design could even impair their line of sight or present glare from 77 overhead lighting. If heavier materials are used for stability, the box can be cumbersome to remove in a 78 difficult airway scenario or may even fall off the table and injure the patient. Furthermore, the box's 79 perpendicular edges and corners are more difficult to clean which renders the device a possible fomite 80 for transmission. Designs that were meant to be flat-packed for shipping may have exposed crevices at 81 the joints that can also be difficult to clean. 10 These challenges may limit the practicality and adoption 82 of this tool. However, we believe that this device is an important harm-reduction tool and with 83 adequate training, can greatly reduce viral load exposure for intubator. 84

To address the above challenges, our team has re-designed the COVID intubation box in 87 collaboration with our hospital's Department of Radiation Oncology, Anesthesia, Emergency Services 88 Department and Infection Prevention and Control (IPAC) Team. We created several designs in-hospital 89 with input from the radiation oncology team with experience in custom moulds, and the final 90 prototypes were manufactured with industry assistance. As we had access to clinical areas to perform 91 clinical validation and simulation, we were able to iteratively improve the design through a prototyping 92 and evaluation strategy. The expert panel, consisting of anesthesiologists, infection control staff, and 93 emergency clinicians, conducted full end-to-end dry-runs using airway simulation mannequins to 94 mimic the clinical use of the device. 10 With each iteration, clinician feedback was captured in order to 95 achieve a final design. We present here the details of our design, rationale for modifications, and our 96 local simulation and patient experiences. 97

Design 100

The final design aimed to address the main concern associated with the cuboid shape, which is 101 that seams, edges, and joints are more difficult to disinfect and present a transmission risk (Figure 1) . 102

As such, a single sheet of polyethylene terephthalate glycol (PET-G) was thermoformed into a curved 103 dome shape without abrupt corners. In this process, the sheet is heated, shaped over a custom designed 104 mould, and then cooled to its final form. This allowed us to create the curved shape, which was 105 approved by our IPAC team for ease of disinfection and reuse of the device. Furthermore, a single 106 curved sheet of 0.47cm thick PET-G dramatically reduces the mass of the dome, thereby limiting the 107 risk of the unit tipping. Line of sight and glare issues were also resolved with the curved shape. 108

In order to improve the restricted arm movement-another key criticism-we increased the 109 device height from our initial 48.3cm to 55.9cm, the width to 50.8cm (standard operating room table  110 has 55.9cm width), and depth to 38.1cm. These dimensions provide more room to maneuver arms and 111 airway equipment without colliding with the internal walls. Also, the arm ports were upsized from 112 10.2cm in Dr. Lai's original prototype to 12.7cm, to accommodate for greater arm movement and 113 varying body habitus of the intubator. Granted, while this theoretically increases the risk of viral 114 particles escaping the intubation box, clear adhesive can be easily used to cover any redundant hole 115 while preserving flexibility of movement (see Figure 2) . Finally, the broader base compared to the 116 narrower dome lowers the center of gravity, thereby increasing stability and preventing the lightweight 117 device from being knocked over. In the operating room where a narrow table may increase fall risk, 118 attaching standard armboards to the table provides further stability. 119

Finally, a unique feature of our design is the addition of a third arm port to accommodate an 120 airway assistant (e.g., handling a stylet or passing equipment). If not used, this port can be easily sealed 121 off with a disposable cover such as adhesive dressing or plastic wrap to further reduce the risk of dye shows minimal contamination beyond the barrier, akin to previous data on the effectiveness of such 161 an intubation box. 7 Ultimately, we believe this device has potential to decrease infection risk to the 162 intubator in conjunction with PPE, reduce cumulative viral exposure to nearby personnel and surfaces, 163 provide some protection in resource-limited settings without proper PPE capacity, and limit viral 164 spread during extubation. 165

While there is convincing evidence that this device provides a physical barrier for droplet 167 transmission-thereby reducing viral load to the operator-it may not fully protect from aerosols 168 generated from airway management, which is one of the main concerns in tracheal intubation. 2,7 169 Therefore, airway operators must continue to wear appropriate PPE. Nonetheless, the intubation box personnel which may otherwise be exposed to viral particles many metres away. 14 Another area for 172 careful consideration is that all intubation barriers may contain a high viral concentration in a relatively 173 enclosed space, which necessitates careful removal of the device to prevent inadvertent spread of 174 fomites. Finally, while our design improves flexibility, this device still imposes some restriction to the 175 operator's arm motion, which could impair successful airway management. Our study did not directly 176 compare time and outcomes with and without the device. Therefore, if intubation is expected to be 177 difficult, the patient has poor respiratory reserve, or initial attempts with the intubation box are 178 unsuccessful, operators must be prepared to abandon the device. Nonetheless, we believe the intubation 179 box still has value in protecting airway clinicians, especially in straightforward intubations or elective 180 settings (e.g., perioperative). 181 182

Airway management presents significant risk to healthcare workers during this viral pandemic. 184

In addition to proper PPE, other harm reduction tools must be considered to protect clinicians during 185 airway management. We believe this intubation box has great potential to decrease the risk of 186 transmission and should be part of the clinician's armamentarium for airway management. By sharing 187 our designs and experiences, we aim to advance the discussion on how anesthesia, ICU, and emergency 188 care providers can better protect themselves while providing safe patient care. 

• Does this intubation box improve clinical outcomes by reducing infection rates amongst healthcare workers? • Does this intubation box reduce quantitative viral load on clinicians' personal protective equipment and skin? • Are there differences in time-to-intubation and rates of succesful intubation between using the intubation box, other physical barriers (e.g., clear drape over airway only), or no additional barrier devices? 205

• Aerosol generating procedure: Medical procedures (e.g., intubation, suctioning, bag-mask ventilation) that induce microscopic airborne particles ('aerosol') that can remain in the air or even travel short distances. If inhaled, aerosols containing viruses can lead to infection. 

World Health Organization Europe, Coronavirus disease (COVID-10) outbreak

Aerosol generating procedures and risk of transmission of acute respiratory infections 219 to healthcare workers: a systematic review

Personal protective equipment for preventing highly infectious diseases due to exposure to 223 contaminated body fluids in healthcare staff

Aerosol and Surface 227 Stability of SARS-CoV-2 as Compared with SARS-CoV-1

Anaesthesia and COVID-19: infection control

Endotracheal Intubation

COVID-19 and Risks Posed to Personnel During 235

Epub ahead of print

Current concepts in the management of the difficult airway

Airborne transmission of SARS-CoV-2: The world should face the reality

246 247 Highlights: • Airway management for patients with COVID-19 is a high-risk period for providers • Closed intubation barriers may reduce transmission risk, despite their limitations • Our novel design overcomes many challenges associated with the current "box" design • Airway providers may consider adopting these types of devices in addition to

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