key: cord-0726666-f4pf5hsu
authors: Chen, Darren A.; Lee, Mark; Lelli, Gary J.; Kacker, Ashutosh
title: Evaluation of the aerosol generating potential of endoscopic dacryocystorhinostomy
date: 2021-08-17
journal: Laryngoscope Investig Otolaryngol
DOI: 10.1002/lio2.639
sha: 177e64fd9bb6eaf982de832faf3c8b8410a12c7c
doc_id: 726666
cord_uid: f4pf5hsu

PURPOSE: The COVID‐19 pandemic gave rise to renewed concerns of the transmission risks posed by surgeries on sites of high viral colonization such as the nasopharynx. Endoscopic dacryocystorhinostomy (DCR) involves the creation of a new tear duct from the lacrimal sac to the nasal cavity. The purpose of this project is to determine if endoscopic DCR is an aerosol generating procedure (AGP). METHODS: An optical particle sizer (OPS) was used to intraoperatively quantify aerosol concentrations during four cases of endoscopic DCR. The OPS sampled the air once every 60 seconds throughout the operations. The time of important operative steps were documented and correlated with OPS readings. Particle concentrations during each major surgical step were compared to baseline readings by the Mann Whitney U Test. RESULTS: There were statistically significant increases in median particle concentrations during laryngeal mask airway intubations for both particles 0.3 to 5.0 μm and >5.0 μm (P < .001 and P = .023, respectively). Median particle concentrations during nasolacrimal duct probing, middle meatal debridement, drilling, balloon insertion, tube insertion, and Posisef insertion were not statistically different from baseline. CONCLUSIONS: Endoscopic DCR in itself does not appear to be an AGP. It is, however, associated with other aerosol generating events such as laryngeal mask intubation, and thus requires appropriate personal protective equipment. Cautious interpretation of the results is encouraged given the limitations of OPS. LEVEL OF EVIDENCE: 4.

The COVID-19 pandemic has highlighted the risk to health care workers posed by surgical procedures that are potentially aerosol generating. Endoscopic dacryocystorhinostomy (DCR) corrects nasolacrimal duct obstruction and involves the use of a surgical drill to remove bone from the lacrimal sac fossa. 1 The SARS-CoV-2 virus is a highly virulent pathogen that colonizes the nasopharynx and has been a common point of concern for endoscopic nasal procedures. 2, 3 Drilling within the nasopharynx in other procedures such as endoscopic sinus skull base surgery has been shown to generate high levels of aerosols, potentially putting those in the operating room at risk for infection. 4 Endoscopic DCR may pose a similar theoretical risk, but this conjecture has yet to be investigated.

In the context of the COVID-19 pandemic, guidelines have been issued for both otolaryngologists and oculoplastic surgeons for aerosol generating procedures (AGPs). 2, 5 As has been discussed in recent commentary, oculoplastic surgeons regularly probe and irrigate the nasolacrimal duct system. 5 There has been concern that probing could lead to aerosolization of viral particles from the nasal mucosa and a similar concern has been raised regarding drilling for osteotomies during orbital cases. There is still an open question of whether these procedures should be deferred during an active pandemic.

The purpose of this project is to determine whether or not endoscopic DCR is a high-risk AGP. Particular attention is paid to aerosolization risk during intubation, probing of nasolacrimal system, and drilling at the osteotomy site. We utilized an optical particle sizer (OPS) intraoperatively to quantify the changes in aerosol concentrations during endoscopic DCR. has been used to quantify aerosols during laryngoscopy procedures in the previous literature. 6 It takes in air through an isokinetic inlet at 2.84 L/min ± 5%; light scatter is then measured by an internal laser system to give an approximate count of air particles every 60 seconds.

All procedures were carried out in a standard operating room.

Baseline measurements from the OPS were taken prior to the patient coming into the room. The isokinetic inlet of the OPS was placed 18 in. away from the nose of the patient, maintaining sterility.

The OPS collected particle counts in one-minute intervals for the duration of the surgery. Specific operative steps of interest included laryngeal mask intubation, probing of the nasolacrimal system, middle meatal debridement, surgical drilling, balloon insertion, tube insertion, and Posisef insertion. The times of these steps were documented for later correlation to measured particle counts. Probing of nasolacrimal duct was done using a lacrimal metal probe. Debridement of nasal mucosa off the underlying bone was carried out. Drilling through the lacrimal sac fossa was done using a low speed Medtronic drill at 12 000 rpm with suction attached for approximately 1 and 2 minutes.

Rate of oscillation during microdebridement was 5 000 rpm with suction on medium setting at 60 to 105 mm Hg. Once an adequate osteotomy was created, a sickle blade was utilized to open the lacrimal sac widely into the nose. A 5 mm lacrimal balloon was placed through lacrimal sac and into the nose and inflated for 90 seconds in the osteotomy site at the middle meatus. Bicanalicular intubation was performed with Crawford tubes that were tied to themselves and allowed to retract into the nose. A 1 cm  1 cm segment of Posisef was placed at the site of the osteotomy and injected with local anesthesia (lidocaine 1% with 1:100,000 epinephrine). Particles were stratified according to size, 0.3 to 5.0 μm and >5 μm for data analysis.

The 5 μm cutoff was chosen due to the existing convention that particles less than this size are thought to represent aerosols and those larger than 5 μm are considered droplets; it is important to note that there is still existing controversy over these cutoffs. 6, 7 For statistical analysis, we first utilized Kruskall-Wallis testing to evaluate for differences in median particle counts between any intraoperative event including baseline. Where Kruskall-Wallis was significant, we utilized Mann-Whitney pairwise comparison between each event and baseline conditions. All statistical analysis was done using Microsoft Excel and Prism. All P-values calculated were two-tailed, evaluated at the .05 alpha level for significance.

There were statistically significant differences in median particle concentrations during the operations for both particles 0.3 to 5.0 μm and >5.0 μm (Figures 1 and 2) . Results of pairwise multiple comparisons is presented in Table 1 . A statistically significant increase in median 

With the rising number of COVID-19 cases, ophthalmologists are at continued risk for infection due to close contact with patients both in the outpatient setting and in operating room. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can be transmissible through fomites, droplets, and aerosols. 8 AGPs are traditionally defined as events that lead to significantly more air particles than baseline risks such as breathing, talking, coughing, and sneezing. 9 AGPs have been shown to produce particles <10 μm in size, 10 and other surgical procedures with an endoscopic nasal approach can generate significant aerosols in the immediate surgical field. 11, 12 Many of these studies in the past have utilized OPS technology due to its ease-of-use and accessibility. It is important to note, however, that OPS has limitations in its sensitivity, and there are more developed and complex methods of quantifying aerosols including microscopy, interferometric Mie imaging, aerodynamic particle sizing, and others that could complement OPS. 13 Our data suggest that endoscopic dacryocystorhinostomy in itself is not likely an aerosolizing generating procedure. Debridement, low- dacryocystorhinostomy is likely of lower risk and is comforting to know for surgeons. As described in the literature, further mitigation of any aerosol production during drilling can also be addressed with the use of additional suction or with the addition of a built-in suction to the low speed drill as was done in our cases. 18, 19 Surgical smoke evacuators have also been shown to be the most effective in reducing aerosols. 18 The results herein suggest that DCR is not aerosol generating; however, it is associated with an aerosol-generating event in laryngeal mask intubation.

There are limitations to this study that should be addressed. As Lastly, the definition of AGPs requires that the intervention lead to increased air particles compared to baseline risks including 

The COVID-19 pandemic has highlighted the risks of AGPs. We used an OPS in a small number of endoscopic dacryocystorhinostomies to evaluate for generation of aerosols; our results suggest that DCR does not appear to be an AGP but is associated with an aerosol generating event in laryngeal mask intubation. Surgeons should don standard personal protective equipment during these procedures and consider the use of an N95 if there is concern for virulent transmission.

Provisional patent EFS ID 39386708, Application #63021722 submitted by Cornell University on May 8, 2020. The authors report no conflicts of interest.

Darren A. Chen https://orcid.org/0000-0003-3096-7442

Mark Lee https://orcid.org/0000-0001-6643-4360 BIBLIOGRAPHY

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