In Reply: Thank you for your interest in our manuscript entitled, “Demonstration and mitigation of aerosol and particle dispersion during mastoidectomy relevant to the COVID-19” (1). We are pleased to hear that you have used a variant of the OtoTent during otologic surgery, and found a way to improve its functionality. Thank you for sharing your experience, particularly with regard to the use of thicker plastic, which improves the structural integrity of the barrier drape and keeps it away from the surgical field.
We agree that reducing biomaterial spray and large droplet splatter is prudent during the COVID-19 era, although exact risks to the operating room staff depend on local community prevalence of COVID-19 as well as the availability and reliability of testing. This study and our subsequent follow-up study (2) have revealed to us that large amounts of droplet and particulate splatter and airborne aerosolization routinely occur with mastoidectomy. Therefore, many of us personally envision continuing to use a source control drape to prevent biomaterial aerosol dispersion even when the current coronavirus is no longer an immediate threat.
Since this publication, we now routinely employ the OtoTent and have gained further experience. We agree that the drape as described in the manuscript poses some challenges. Firstly, the drape can sag and touch the end of the drill. Secondly, the opaque nature of the 1,060 drape used in the manuscript makes changing instruments with the scrub nurse or technician more challenging (and even poses a potential safety risk if sharp instruments are handed). Thirdly, there is a potential need to replace the drape if your operative plan requires that you alternate between drilling and microsurgical dissection (e.g., for cholesteatoma surgery). In addition, while our initial study demonstrated that the OtoTent mitigated large droplet (>100 um) spray very effectively, our second study revealed that it does not successfully mitigate small aerosolized droplets and particulates (<10 um) which are small enough to remain airborne (2). We hypothesized that this is due to the open bottom area of the drape, and lack of seal around the surgeon's arm entry points. We also found that taping a second suction tubing with the open end near the surgical site (Fig. 1) reduces aerosol dispersion when used with the OtoTent (though with some variability), but not when used in an open surgical field without any barrier drape.
In order to address some of the challenges described above and to better mitigate small aerosolized droplets and particulates, we are developing and testing a custom drape for otologic surgery to be manufactured for use with any microscope and some exoscopes (Fig. 2). We have found that using internal scaffolding to add structure, clear medium-weight plastic, and materials that allow us to remove/reattach the drape to the microscope are helpful. Further, it can provide improved aerosol management through a semienclosed design with an attachment site for a second suction tubing, as shown with recent testing of one prototype (2).
In summary, while the risk of transmission of COVID-19 to the operating room staff during otologic cases is unknown, many of us continue to use a barrier drape to decrease biomaterial dispersion. Given the now-evident aerosolized and splattered biomaterials, we may continue to use a drape for mastoidectomy even after COVID-19 transmission is no longer an immediate concern.
Thank you again for your letter and sharing your insights. We hope our colleagues continue to refine the design to make it more safe and ergonomic.
1. Chen JX, Workman AD, Chari DA, et al. Demonstration and mitigation of aerosol and particle dispersion during mastoidectomy relevant to the COVID-19 era. Otol Neurotol
2020; Online ahead of print.
2. Chari DA, Workman AD, Chen JX, et al. Aerosol dispersion during mastoidectomy and custom mitigation strategies for otologic surgery during the COVID-19 era. Otolaryngol Head Neck Surg