key: cord-355177-62v1qhia
authors: Emery, Andrew Robert; Saniukovich, Olga; Lang, Angela Lu; Tannyhill, R. John; Wang, Jingping; Statement, AAOMS Disclosure
title: A Novel Approach to Fiberoptic Intubation in COVID-19 Patients
date: 2020-07-24
journal: J Oral Maxillofac Surg
DOI: 10.1016/j.joms.2020.07.027
sha: 
doc_id: 355177
cord_uid: 62v1qhia

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), has created a strain on the healthcare workforce and industrial supply chains of personal protective equipment (PPE). In response, efforts have shifted to alternative methods to protect patients and healthcare providers. Several patient isolation hood designs have been proposed to reduce the risk of aerosolization during endotracheal intubation. However, oral and maxillofacial surgery commonly involves in patients with difficult airways that require fiberoptic intubation (FOI), which is not well suited for current hood designs. In this manuscript, we describe a negative-pressure intubation hood (NPIH) designed for fiberoptic intubation, which contains aerosols of the patient and better protects healthcare workers who are present at the time of intubation and extubation on oral and maxillofacial surgery cases.

Coronavirus disease 2019 (COVID- 19) , which is caused by severe acute respiratory syndromecoronavirus-2 (SARS-CoV-2), rapidly overwhelmed hospitals and personal protective equipment (PPE) supply chains around the world during the first half of 2020. A significant concern with treating patients with COVID-19 in the operating room (OR) or intensive care unit (ICU) is the risk of aerosolizing viral particles. Securing the airway of these patients while limiting virus exposure to providers can be challenging. 1 One of the first barrier devices created to improve the safety of endotracheal intubation in patients with COVID-19 consisted of a rigid box with two circular working ports called the "aerosol box." 2 The effectiveness of the "aerosol box" was later demonstrated by Canelli et al. 1 Since then, other barrier hood designs with disposable clear plastic drapes have emerged, 3, 4 some of which are coupled with smoke evacuators to create an environment with negative pressure. 5, 6 In addition to direct laryngoscopy, there are many patients, particularly those undergoing surgery in the head and neck region, that require fiberoptic intubation (FOI). 7 FOI involves guiding a fiberoptic camera through the mouth or nose into the trachea before advancing the endotracheal tube. This technique for intubation is commonly employed in patients undergoing surgery in the head and neck region. 7 Given the need for the anesthesia providers to maintain the fiberoptic controller above the patient's head with one hand and guide the fiberoptic cable with the other, there is a need for a new barrier design and protocol to accommodate this unique procedure. To our knowledge, there have not been any prior publications addressing FOI with a negativepressure intubation hood (NPIH). Thus, the purpose of this study is to describe a novel approach to fiberoptic barrier (FOB) intubation in COVID-19 risk patients.

Equipment needed (see Figure 1 ):

• 2 large and 2 medium transparent medical dressings (Tegaderms TM ) • Equipment cover (aka: plastic bag)

• 6 IV pole clips Prior to beginning this protocol, the hood frame must be fabricated. To do so, ¾ inch polyvinyl chloride (PVC) pipe is cut into 2 segments that are 4 feet long, 2 segments that are 3 feet long, and 2 segments that are 1.5 feet long. Next, 2 segments of ¾ inch copper pipe of approximately 1 foot in length are inserted half-way into one end of each 4-foot PVC segments and secured with PVC cement. These copper pipe segments will allow the hood to fit into the Clark adaptors along the OR bed. On the opposite free ends of the 4-foot PVC segments, ¾ inch threaded male adaptors were cemented. These two pieces will be the vertical supports for the hood. Next, a 3way side outlet PVC elbow was threaded onto each of the male adaptors. Then, a 3-foot PVC segment was used to connect these elbows and unite the two vertical supports. Finally, 1.5-foot PVC segments were cemented into the unoccupied openings of the 3-way elbows in a parallel direction. The free ends of these segments were then cemented to the each other via 2-way PVC elbows and the last 3-foot PVC segment.

To construct the hood frame, first insert each copper pipe into a 4-foot PVC segment and secure with PVC cement. These copper pipe segments will allow the hood to fit into the Clark adaptors along the OR table. Next, attach ¾ inch threaded male adaptors to the free ends of the 4-foot PVC segments, and secure with cement. Attach 3-way elbows to the male adaptors, and connect the two elbows using a 3-foot PVC segment. Complete constructing the rectangular visor using the remaining PVC segments and elbows. Cement to secure at each connection.

With the hood frame assembled, our protocol then begins with setup of the hood. First, attach Clark adapters to both sides of the OR headboard and mount the PVC hood frame with the top rectangular visor projecting towards the foot of the bed (see Figure 2a) . Open and attach a plastic bag to the rectangular frame using 6 IV pole clips (2 per long end, 1 per short end).

Allow the bag to drape down and place 1 large transparent medical dressing (such as Tegaderm TM ) on the side facing the provider at elbow level and another transparent medical dressing on the ceiling of the hood. Cut a slit in the transparent medical dressing at elbow level for arm entry and a smaller opening in the transparent medical dressing over the patient's head for the fiberoptic bronchoscope and endotracheal tube to pass through. At this point, the hanging drapes can be maneuvered around the back of the frame to rest on top of it until the patient is laying on the OR table.

Before the patient is brought into the OR, the monitors such as ECG leads, blood pressure cuff and pulse oximeter should be placed. This reduces the need to work around the negative-pressure hood once inside the OR. Once the patient is brought to the OR, position them on the table as needed, which may vary from supine to sitting upright at 45 degrees (e.g. awake fiberoptic intubation). Next, place all necessary airway equipment for the procedure under the hood, put a mask on patient's face for preoxygenation of 10 L/min. After attaching the Buffalo TM smoke evacuator tube to the patient's pillow, turn on the evacuator. Lower the drapes after or prior to induction, such that the patient's chest and upper chest is enclosed in the hood. Tuck in the edges to create a sufficient seal to achieve negative pressure, which is noted when the drapes bow inward. This seal can be further improved by placing a blanket across the drape over the patient's chest. A small leak is tolerable given the smoke evacuators ability to suction at a robust 839L/minute at its maximum capacity 5 .

With the hood set up and holding negative pressure, the operator should don sleeve covers and double glove prior to entering the hood. The intubation process may begin with the operator standing at the head of the bed, and inserting one arm into the hood through the pre-made slide, and lowering the fiberoptic scope through the other opening from above (see Figure 2b and 2c, also see Video). A second provider at the side of the patient is positioned ready to provide assistance in order to facilitate intubation as needed.

Following intubation, place medium transparent medical dressings over the arm port and bronchoscope port to seal the hood. At this point, keep the hood over the patient for 5 minutes to allow for 98% air clearance under the hood. 5 When it is safe and appropriate to remove the hood, begin by rolling the plastic bag inward to avoid contamination and dispose of it. The frame can then be either tilted back or removed completely for the surgical procedure.

Prior to the end of the procedure, a second hood is made for extubation. However, instead of placing 1 large transparent medical dressing at elbow level and 1 large transparent medical dressing above the patient, 2 large transparent medical dressings are placed at elbow level on the provider side for standard endotracheal extubation. The remainder of the extubation procedure mirrors the steps described for intubation.

Should the provider need to intubate from in front of the patient instead of behind, the only modification would be to place the large transparent medical dressing at elbow level on the side of the hood in front of the patient instead of behind them. Also, in the case of an airway emergency, additional ports into the hood can be quickly created by taping large transparent medical dressings, creating a cut, and inserting one's arm. Should the hood interfere despite these efforts, it can be quickly removed by loosening the Clark adaptors and lifting up and away from the patient.

As healthcare providers continue to treat patients with COVID-19, they must modify existing high-risk procedures to make them safer. FOI has been categorized as a high-risk procedure due to the high probability of coughing and dissemination of viral particles. 8 Due to the frequency of FOI, especially in oral and maxillofacial surgery, 9, 10, 11, 12 we believe our revised protocol will protect the operating room team. To our knowledge, this is the first protocol described for FOI within a negative pressure hood designed to guide providers treating patients with COVID-19.

FOI is most often indicated, and considered by many to be the gold standard, 13, 7 for the intubation of patients with difficult airways, and is often done while the patient is awake before general anesthesia is administered. 14 There are many factors leading to a difficult airway, including: unique head and neck anatomy, trauma, cervical spine instability, difficulty with prior intubation, or anticipated difficulty with direct laryngoscopy based on physical exam. 7 A meta-analysis of over 50,000 patients with normal airway anatomy on preoperative exam found difficulty with intubation in 5.8% of cases. 15 However, in oral and maxillofacial surgery, where the surgical field is closer to the airway and mouth opening is commonly affected by the disease process, difficult intubations have been reported to comprise of 15.4-16.9% cases. 16 Although the oral and maxillofacial surgery literature lacks incidence data of overall FOI use, many individual studies of a specific procedure type have done so. One study of 264 trauma patients with facial fractures found FOI utilized in 55.21% of cases. 9 Another study of 26 patients with deep neck infection showed FOI was used for 25 patients with 1 patient receiving a tracheostomy. 10 In a report of 500 head and neck cancer patients undergoing surgery, 320 of them underwent FOI. 11 In another study of 36 patients undergoing surgery for with temporomandibular joint (TMJ) ankylosis, 22 (61.1%) had airways secured by FOI. 12 In addition, many of these studies involved nasal intubation over oral intubation. One report of 634 elective maxillofacial surgeries found that 579 patients were intubated nasally. 17 Given that many authors advocate for fiberoptic nasal intubation over conventional nasotracheal intubation, 18 there appears to be ample need for FOI in oral and maxillofacial surgery. Although our hood is especially beneficial for awake FOI due to expected coughing and aerosol generation, this protocol is equally as effective for both awake and sleep patients by either oral or nasal route of FOI.

Compared to direct laryngoscopy, FOI has several advantages including the ability to visualize the entire airway, the control to navigate around pathology, the versatility to be used for nasal or oral intubation, 7 and ability to reduce spinal manipulation. 19 Few studies have compared FOI directly against other devices. One report of FOI versus intubating laryngeal mask airway (ILMA) found similar success with securing the airway, but ILMA failed in patients with prior head and neck cancer treated with cervical radiotherapy, suggesting FOI was superior for these patients. 20 Another study comparing ILMA and oral FOI for awake intubation found success rates of 84 and 96%, respectively. 21 Overall, despite an absence of evidence of FOI's superiority in all scenarios, there is sufficient literature to indicate it is an effective method of intubating, and a favorable choice for the difficult airways of many oral and maxillofacial surgery patients.

There have been several barrier intubating hood designs created so far. 1, 3, 4 Our study proposes using a negative-pressure design, which is disposable and has been validated in two recent studies. Lang et al, 5 using a humidifier to replicate aerosol production, showed that the particle count at the clinician's head level decreased from 700 to 18 L -1 with the use of the negative pressure patient isolation hood (NPPIH). They also demonstrated a 63% decrease in the particle count inside the hood with a smoke evacuator suctioning at 230 L min -1 . Without the evacuator or humidifier turned on, it took 183 minutes for the particle count in the hood to clear by 98%, compared to 5 minutes with negative pressure applied. 5 This study informed our hood design for aerosol containment and provided guidance for the time course of how long the hood should remain in place after intubation or extubation in order to achieve a significant reduction in particle count. Additionally, Matava et al 3 also showed that the disposable plastic drapes of intubation hoods could be rolled up and disposed of without causing additional contamination to health care providers, 3 thus further validating the safety of disposable drape hoods and our design.

Shaw et al 5 found that high-risk aerosol-generating procedures such as high-flow nasal cannula (HFNC) can be safely used with an ICU tailored version of the hood design. Using a humidifier and HFNC at 70 L/min, particle counts decreased from 155 without the smoke evacuator on to 50 particles.L -1 when the evacuator was at maximum suction of 839 L.min -1 . The particle counts also decreased by more than half with the use of negative pressure. Finally, the time needed to filter out 99% of the particles decreased from 87 to 9 minutes at 60% evacuator capacity and 6 minutes at 80% evacuator capacity. 6 This study verified safe containment of aerosol generating procedures using this hood design. Importantly, our study chose to use the Buffalo TM suction device as opposed to other manufacturers because it is an institutional preference within our ORs, but more importantly because it utilizes an ultra-low particulate air (ULPA) filter which is rated at 99.9995% efficiency for particles 0.12 µm or larger. As compared to high-efficiency particular air (HEPA) filters, which are rated at 99.97% efficiency for particles 0.3 µm or larger, 22 the ULPA filter is more efficient, and the best choice for SARS-CoV-2, which has a viral particle size range of 0.065-0.125 µm. 23 Should patients need to use these hoods outside of the OR where the Buffalo TM system may not be available or need to be transported through the hospital within a negative pressure hood, mobile suction devices, such as the Neptune TM smoke evacuator system, 24 could be considered. Given the ubiquitous presence of COVID-19 patients throughout the hospital, a mobile suction system may allow even greater implementation of this protocol.

Overall, these studies suggest that our negative-pressure hood could effectively reduce aerosol particle exposure to the provider during aerosol generating procedures, similar to awake FOI.

With the use of this hood and appropriate donning of PPE, the provider performing FOI should be more protected exposure to viral particles, thus decreasing the risk of nosocomial SARS-CoV-2 infections.

An advantage of this design is that it is inexpensive and disposable, which keeps cost low.

Despite needing to create two hoods per OR case, this low-cost design utilizes available resources and helps reduce additional PPE utilization at a time when PPE is difficult to procure 3 and implicates its potential use throughout the hospital, including ICU's.

A concern with utilizing a hood for intubation is the ability to gain rapid access to the patient during an airway emergency. Depending on the urgency of the situation, additional transparent medical dressings and cuts can be made anywhere along the walls of the hood for quick patient access by one or more providers simultaneously. This feature has the advantage over other rigid plastic designs that restrict access to the plastic cut-outs incorporated into the hood designs. 2 Should an airway issue call for a more rapid response, the hood can be instantly removed altogether by loosening the two Clark adapters. In addition, the ability to create access ports anywhere on the hood walls also makes it more versatile during intubation. Although our protocol primarily focuses on accessing the patient from behind and above, some upright awake FOI may be easier with access from in front of the patient and above, which is made possible by the soft plastic drapes.

A limitation of this design is the extra OR time needed. Given that surgery around the head and neck likely necessitates removal of the hood, the breaking down and setting up of the hood for intubation and again for extubation is seemingly unavoidable. Our experience shows that once the hood is completed, the actual intubation process itself takes roughly as long as without barriers. However, additional OR time is needed for 5 minutes of waiting at the end of intubation and extubation for the smoke evacuator to remove viral particles prior to removing the hood. Therefore, the added case time is estimated to be around 10-12 minutes per patient.

Another disadvantage of our design includes the need to replace the ultra-low particulate air (ULPA)-grade filter of the smoke evacuator, which adds cost to use of the hood. 5

COVID-19 has provided an impetus for innovation. In the specialties of anesthesia and oral and maxillofacial surgery, it has led us to innovate and design a negative pressure patient intubation hood for FOI of patients with difficult airways. Our hood design has been informed by prior studies and this study shows how additional modifications can expand its use to FOI. Through implementation of our negative-pressure patient intubation hood, we have been able to more safely serve our patients and safeguard the wellbeing of our front-line healthcare providers. Video. Demonstration of fiberoptic intubation using the negative pressure hood for a supine patient with the anesthetist at the head of the operating table behind the patient.

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