Novel Closed-Loop Bronchoscopy Barrier Sheath: Valuable Addition for One-Lung Ventilation During the Coronavirus Disease 2019 Pandemic

To the Editor:

CORONAVIRUS disease 2019 (COVID-19) is a rapidly evolving pandemic, with serious implications for both patients and healthcare professionals.¹ One-lung anesthesia and ventilation constitute a high-risk procedure because they entail the use of repeated flexible bronchoscopy for confirmation of lung isolation, and troubleshooting intraoperative hypoxemia and bronchial suctioning during various stages of surgery; and has the potential for aerosol generation and environmental contamination, thus endangering the safety of healthcare professionals and providers. Recommendations are in place for airway management of suspected or confirmed patients with COVID-19 undergoing thoracic surgery.^{2 , 3} However, we were unable to find a description of any specific strategy to prevent aerosol generation during bronchoscopy apart from recommendations for using personal protective equipment.^{2 , 3} Similarly, other reports described use of high- efficiency particulate filters during one-lung anesthesia but avoided bronchoscopy to prevent risk of aerosol contamination.⁴ We describe a novel and simple closed-loop method for prevention of aerosol contamination during flexible bronchoscopy and suctioning procedures during one-lung ventilation.

We use a sterile, nonallergenic, single-use plastic laparoscopic camera port cord cover as a barrier against aerosol generation for such purposes. The length of the cover is 200 cm, and the cover is open at both ends. The cover is cut according to the length of the bronchoscope, leaving sufficient extra length of about 30 cm for taping at the proximal and distal ends. The proximal end of the cover is taped at the bronchoscope handle, and the distal end is taped around the double-lumen endotracheal tube (DLT) just proximal to the cuff inflation line (Fig 1 , A). Positioning the tape proximal to the cuff inflation line allows for easy cuff inflation and deflation. The distal end also incorporates the bronchial and tracheal connectors and the Y-connector (see Fig 1, A). A small slit is made in the plastic sheath at the Y-connector adaptor to allow connection with the ventilator circuit (see Fig 1, A). The cut end of the plastic sheath then is secured on the Y-connector with tape once the ventilator circuit is connected. To secure the distal end, ventilation needs to be interrupted for a few seconds, and as such, patients may be ventilated with 100% oxygen for a few breaths. Once the distal end of the cover is securely taped, the protective cap at the proximal ventilating port is opened to introduce the bronchoscope into the lumen of the DLT. The scope can then be negotiated within the DLT lumen for confirming the tube position or for bronchial suctioning. The nonventilated tube connector can be clamped easily with the plastic sheath in place (see Fig 1, A).

Fig 1.

(A) The plastic cover is used to cover the full length of the bronchoscope, with the proximal end taped to the bronchoscope handle. The distal end is taped on the double-lumen endotracheal tube just proximal to the cuff inflation line (arrow) and encloses the tracheal and bronchial connectors and the circuit Y-connector. A small slit is made at the Y-connector to accommodate the ventilator circuit, and this part of the plastic cover also is taped to the Y-connector adaptor (arrow head) to maintain the integrity of the closed-loop system. (B) The closed-loop system is hung vertical on an intravenous stand near the head.

We suggest leaving the scope in situ throughout the procedure to prevent environmental contamination. The scope can be hung easily on an intravenous stand near the patient's head (Fig 1, B). If the scope needs to be removed, the proximal end of the cover can be snared or taped and closed to prevent environmental contamination with patient secretions. To reintroduce the bronchoscope or suction catheters, the proximal end is opened and the scope or catheter is introduced. The margin of safety against aerosol contamination during opening the proximal end for removal or introduction of the scope or suction catheters is slightly more than the length of the scope, 51.5 cm for neonatal scope and 65 cm for pediatric and adult scopes. In addition, the cover is kept vertical during the introduction or removal processes. This is more than the margin of safety provided by video laryngoscopes, which are widely recommended for use as a measure to increase the “mouth-to-mouth” distance between the patient and the laryngoscopist.⁵

To demonstrate the integrity of this closed-loop system, a simulation was performed. The first part of the simulation involved generating aerosols due to mechanisms such as cough. We intubated an airway mannequin with a 37- Fr left-sided DLT (Portex; Smiths Medical, Minneapolis, MN). The distal bronchial end of the DLT was connected to a manual adult resuscitator (Fig 2 , A). A few drops of methylene blue were aspirated into a syringe filled with saline, and this solution then was instilled into the bronchial lumen of the DLT. A white screen was placed approximately 90 cm away from the proximal end of the DLT. The manual resuscitator then was squeezed vigorously to simulate a cough. This led to the generation of forced aerosol spray, which stained the white screen (Fig 2, B). The procedure was repeated with the closed-loop system in place. However, despite coming out with force, the dye was contained effectively by the plastic sheath and failed to stain the white sheet in this instance (Fig 2, C and Video 1).

Fig 2.

(A) A mannequin is intubated with a 37- Fr double-lumen endotracheal tube, and the distal bronchial end is connected to an adult resuscitator. A small volume of diluted methylene blue solution (arrow) then is placed in the bronchial lumen to simulate an open system with secretions inside the tube. (B) A vigorous squeeze of the resuscitator leads to forced aerosol generation, which stains a white sheet (arrow) kept nearly 90 cm away from the mannequin. (C) With the closed-loop system in place, the aerosols are effectively retained in the plastic sheath.

We have since used the closed-loop sheath in 3 non-COVID-19 patients undergoing lung surgery. In two patients, 37 Fr- left-sided DLTs were used, and in 1 patient, a 35- Fr left-sided DLT was used. The scopes used were 4.0 mm ID and 3.0 mm for the 37- Fr and 35- Fr tubes, respectively. The ease of negotiating the scope through the sheath cover and the DLT was graded on a 3-point Likert scale of 1- to- 3 as follows: 1, scope negotiated easily without any difficulty; 2, moderate difficulty in negotiating the scope; and 3, scope negotiation very difficult. In all patients, the score was 1, with scope negotiation performed easily because the width of the cover is 18.5 cm, which allows for flexibility to maneuver the scope even after taping it at the respective ends.

The covers are inexpensive and commercially available. Similar protective barriers have been reported recently for use with transesophageal echocardiography probes.^{6 , 7} Considering the fact that 41.3% of COVID-19 cases were hospital acquired, of which >70% of infected cases were healthcare professionals,⁸ we suggest use of these closed-loop barriers as an additional protection against aerosol contamination in all patients undergoing one-lung anesthesia and ventilation for thoracic surgery. This will further help to save use of scarce personal protective equipment.

Video 1. The closed-loop bronchoscopy barrier sheath effectively contains the aerosols despite them being generated with force.