A Negative-Pressure Face-Mounted System Reduces Aerosol Spread during Endonasal Endoscopic Surgery

Abstract

Purpose Due to the potential risk of COVID-19 transmission during endonasal surgery, we studied methods to reduce droplet and aerosol generation during these procedures. Methods Droplet spread was assessed using ultraviolet light and a camera that detected fluorescence in the operative field and surgeon's personal protective equipment. Density of aerosols sized <10 µm was measured using a photometric particle counter. We designed a face-mounted negative-pressure mask placed on the patients' face during endoscopic endonasal surgery. Sixteen patients were recruited between October 2020 and March 2021 and randomly assigned to the mask and no-mask groups. We compared droplet spread and aerosols generated in both groups, with copious irrigation and continuous suction during drilling forming the mainstay of surgical technique in all cases. Results Droplet contamination due to direct spillage of fluorescein from the syringe was noted in two patients. Aerosol density rose during sphenoid drilling in both groups, with no significant difference when continuous suction and irrigation were employed (1.27 times vs. 1.07 times the baseline, p = 0 .248 ). Aerosol density rose significantly when suction and irrigation were interrupted in the no-mask group (44.9 times vs. 1.2 times, p = 0 .028) , which was not seen when the mask was used. Conclusion Aerosol generation increases during drilling in endonasal procedures and is a concern during this pandemic. The use of a rigid suction close to the drill along with copious irrigation is effective in reducing aerosol spread. The use of a negative pressure mask provides additional safety when inadvertent blockage of suction and inadequate irrigation occur.

Keywords: aerosol; droplet; endonasal surgery; generation; mask; suction.

Fig. 1

Photographs of the negative pressure suction face mask. (A) Front view of the mask with disposable nasal cover fitted in to the mask. (B) Lateral view of the mask demonstrating the straps of the mask that go around back of the patient's head. (C) Intraoperative anterior view with the face mask apply to show the position of endotracheal flexometallic tube far away from the surgical field. (D) Intraoperative view demonstrating the anterior nasal cover with longitudinal slits. (E) Intraoperative lateral view of the mask fitted on the patient's head after final draping connected to a suction to create negative pressure within the mask ( yellow arrow ). (F) Intraoperative lateral view demonstrating two vertical incisions being made through the tri-layered protection to introduce endoscopic instruments. (G) Intraoperative picture demonstrating binostril endoscopic four hand technique with drill, rigid suction, fluorescein irrigation ( white arrow ), suction port for collecting aerosols ( yellow arrow ).

Fig. 2

Intraoperative view demonstrating aerosol measurement using particle counting machine (DustTrak DRX Aerosol Monitor 8534–TSI Incorporated, UK). (A) Intraoperative lateral view showing measurement of airborne aerosol during drilling. (B) Measurements being recorded by the particle counting machine (DustTrak DRX Aerosol Monitor 8534–TSI Incorporated, UK).

Fig. 3

Photographs of droplet spread assessment using UV light and high-resolution camera. (A) Fluorescein droplets sprayed from an atomizer on a surface with each square grid measuring 1 cm × 1 cm. (B) Fluorescein droplets seen on the inner aspect of the mask on removing it after the surgery. (C) Fluorescein droplet seen on the right side of the nose depicted by the yellow arrow. (D) Fluorescein droplets due to accidental spillage by assistant surgeon over the patient drape ( yellow arrow ). (E) Fluorescein droplets due to cross contamination on the sleeve of main surgeon. (F) Fluorescein droplet on the surgeon's glove.

Fig. 4

Median increase in aerosol density from the baseline between the mask and no mask group during different stages of surgery.

Fig. 5

Change in aerosol density during drilling without continuous suctioning and with continuous suctioning.