key: cord-0997633-aevc28gt
authors: Okada, Mali; Sousa, David C.; Fabinyi, David CA.; Hadoux, Xavier; Edwards, Thomas L.; Brown, Karl D.; Chiu, Daniel; Dawkins, Rosie CH.; Allen, Penelope J.; Yeoh, Jonathan; van Wijngaarden, Peter
title: Vitrectomy as an Aerosol generating Procedure in the time of COVID-19: The VAPOR Study
date: 2020-07-30
journal: Ophthalmol Retina
DOI: 10.1016/j.oret.2020.07.023
sha: 2e2862f630a473370a84380bfc6506983dc37cc3
doc_id: 997633
cord_uid: aevc28gt

Aerosolization during vitrectomy surgery was assessed by measuring fluorescein droplet spread in the surgical field and airborne particle counts. This study demonstrates that valved-port vitrectomy surgery under regional anesthesia is not likely to be an aerosol generating procedure.

Aerosolization during vitrectomy surgery was assessed by measuring fluorescein droplet 3 spread in the surgical field and airborne particle counts. This study demonstrates that valved-4 port vitrectomy surgery under regional anesthesia is not likely to be an aerosol generating 5 procedure. 6 7 Word count = 35 (limit 35) 8 9 10

Report 11 12

The COVID-19 pandemic has highlighted the risk to patients and healthcare staff of viral 13 transmissions arising from aerosol generating procedures (AGP). As the novel coronavirus 14 (SARS-CoV-2) has been isolated from human conjunctiva and tears, 1 aerosol generation 15 during surgery may carry risk of viral transmission. sheep's eye. The vitrectomy cutter (Alcon Accurus®) was inserted and turned on (cut-rate 34 vent) were performed. The Perspex box was removed for analysis of any fluorescein droplet 1 deposition using photographs captured with an iPhone 8 (Apple Inc.) and cobalt blue filter in 2 a 3D-printed custom housing unit (Supplemental Figure 1D ). (ii) A particle counter (3016-3 IAQ, Lighthouse) was used to quantify the number of aerosolized particles of specific sizes 4 (0.3µm, 0.5µm, 1.0µm, 2.5µm, 5.0µm, and 10µm) within the Perspex box during sheep eye 5 vitrectomy. Particle counting was also performed during "open-air" vitrectomy, with the 6 cutter tip submerged and turned on in a BSS-filled 40mm gallipot. (iii) The same particle 7 counter was used to measure aerosolized particles during standard vitrectomy surgery in 18 8 patients (25-gauge Alcon Constellation® valved vitrectomy system with cut-rate of 5000 9 cuts/min). The counter was positioned above the drape 30cm from the operated eye at a level 10 plane on a tray between the primary and assisting surgeons. Surgery was performed under 11 regional anesthesia and patients wore a Hudson facemask with low-flow oxygen (<2 L/min). 12

Particle recordings were taken at standardized time-points: pre-draping, post-draping, during 13 vitrectomy, FAX, gas-air exchange, after port removal and after drape removal. The ocular 14 surface was coated with HPMC-PAA gel (Alcon Inc.) mixed with BSS. An empty operating 15 theatre was used as a negative control; a water spray mist at 30cm and loud talking into the 16 particle counter were positive controls. Calibration was performed prior to each surgery. 17

Mean paired comparison and repeated-measures ANOVA were performed as appropriate. Particle counts during routine human vitrectomy surgeries were lower than pre-draping levels 30 for all particle sizes (p<0.05 for all particle sizes except for the 10µm particles) and repeated 31 measurements during the surgeries did not differ significantly with time or specific (10µm), which have been suggested to be potentially infective respiratory droplets, 6 were 1 24.1 ± 8.4 particles/m 3 after draping and 14.4 ± 7.1 particles/m 3 during vitrectomy, p < 2 0.0001. Interestingly, an increase in particle concentration was noted from the end of case to 3 after drape removal (p<0.05 for all particle sizes). At all stages during surgery, concentrations 4 of all particles were lower than the levels recorded for the positive controls of spray mist or 5 talking into the counter. 6 7 To our knowledge, this is the first study to quantify aerosols/droplets levels generated during 8 human vitrectomy surgery in real world conditions. The results of all three experiments are 9 consistent with previous ex-vivo vitrectomy and phacoemulsification studies, 4,5,7 10 demonstrating that although vitrectomy cutter is a high-speed device, surgery using valved 11 ports is unlikely to generate significant aerosolization. However, when used in "open-air 12

conditions" inside a gallipot, a vitrectomy cutter may cause a slight increase in particles. 13 14 Interestingly, "pre-drape" particle measurements, particularly the largest particle sizes, were 15 significantly higher than in an empty theatre (negative control) and during all stages of 16 surgery (p=0.02 for 10µm particles) (Figure 1 ). We hypothesize this may be due to the 17 movement of personnel in theatre before each surgery, which seems to increase particle 18 dispersion. Additionally, the use of a non-occlusive oxygen mask by the patient may be a 19 source of aerosol generation prior to draping and after drape removal. 20

The results of this study demonstrate that the vitrectomy component of vitrectomy surgery, 22

when performed under regional anesthesia with valved ports, does not significantly increase 23 aerosol or droplet counts around the surgical field. However, careful removal of the surgical 24 drape is advised as removal appears to increase particle dispersion. It is possible that 25 suctioning underneath the drape, or the use of a surgical mask for the patient and avoidance 26 of an oxygen mask, could reduce the accumulation of respiratory particles under the drape 27

and their dispersion at the time of drape removal. We did not test whether non-valved port 28 use is associated with aerosolization, though findings from open-air use of the cutter indicate 29 that there may be some particle generation. In addition, as we did not examine the 30 transmissibility of SARS-CoV-2 from aerosolized ocular fluids or test aerosol generation 31 under general anesthesia, definitive conclusions regarding the safety of vitrectomy surgery 32 cannot be made. However, on the basis of the evidence presented here, we consider the risk 1 to be very low. 

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