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\begin{document}

\title{Endoscopic Skull Base and Transoral Surgery During the COVID-19
Pandemic: Minimizing Droplet Spread with a Negative-Pressure
Otolaryngology Viral Isolation Drape (NOVID)}



\author[1]{Ivan H. El-Sayed, MD}%
\affil[1]{University of California, San Francisco}%


\vspace{-1em}



  
  \date{June 17, 2024}


\begingroup
\let\center\flushleft
\let\endcenter\endflushleft
\maketitle
\endgroup





\selectlanguage{english}
\begin{abstract}
Background:~ The COVID-19 pandemic has raised concern of transmission of
infectious organisms through aerosols formation in endonasal and
transoral surgery.

Methods: Retrospective review. We introduce the Negative-Pressure
Otolaryngology Viral Isolation Drape (NOVID) system to reduce the risk
of aerosol. NOVID consists of a plastic drape suspended above the
patient's head and surgical field with a smoke evacuator suction placed
inside the chamber.

Results:~ Four patients underwent endonasal (4) and endo-oral surgery
(1). Fluorescein was applied to the surgical field. Black light
examination of fluorescein treated operative fields revealed minimal
contamination distant to the surgical field. In two prolonged cases with
high-speed drilling, droplets were identified under the barrier and on
the tip of the smoke evacuator. Instruments and cottonoids appeared to
be a greater contributor to field contamination.

Conclusions: Negative-pressure aspiration of air under a chamber barrier
which appears to successfully keep aerosol and droplet contamination to
a minimum.%
\end{abstract}%



\sloppy


\subsection*{\texorpdfstring{Abel P. David, MD\textsuperscript{1}; Nicole
T. Jiam, MD\textsuperscript{1}; Joshua M. Reither,
CST\textsuperscript{2,3}; Jose G. Gurrola II, MD\textsuperscript{1,2};
Manish Aghi, MD PhD\textsuperscript{2,4}; Ivan H. El-Sayed,
MD\textsuperscript{1,2}{}}{Abel P. David, MD1; Nicole T. Jiam, MD1; Joshua M. Reither, CST2,3; Jose G. Gurrola II, MD1,2; Manish Aghi, MD PhD2,4; Ivan H. El-Sayed, MD1,2}}

{\label{794559}}

\textsuperscript{1}Department of Otolaryngology-Head \& Neck Surgery,
University of California, San Francisco (San Francisco, CA){}

\textsuperscript{2}Center for Minimally Invasive Skull Base Surgery,
University of California, San Francisco (San Francisco, CA){}

\textsuperscript{3}University of California, San Francisco Medical
Center (San Francisco, CA)

\textsuperscript{4}Department of Neurological Surgery, University of
California, San Francisco (San Francisco, CA){}

\textbf{Corresponding Author:}{}

Ivan H. El-Sayed, MD{}

Department of Otolaryngology-Head and Neck Surgery, University of
California, San Francisco{}

2233 Post Street, UCSF Box 349, San Francisco, California 94115{}

Phone: 415-353-2757{}

E-mail: Ivan.El-Sayed@ucsf.edu{}

\textbf{Disclosure of Funding:} None{}

\textbf{Short Running Head:} Preventing Droplet Spread During Skull Base
Surgery{}

\textbf{Keywords:} COVID-19; aerosolization; skull base; endoscopic
surgery; negative-pressure{}

\textbf{}

\textbf{~}

\textbf{Abstract}{}

\textbf{Background:}~ The COVID-19 pandemic has raised concern of
transmission of infectious organisms through aerosols formation in
endonasal and transoral surgery.

\textbf{Methods:} Retrospective review. We introduce the
Negative-Pressure Otolaryngology Viral Isolation Drape (NOVID) system to
reduce the risk of aerosol. NOVID consists of a plastic drape suspended
above the patient's head and surgical field with a smoke evacuator
suction placed inside the chamber.

\textbf{Results}:~ Four patients underwent endonasal (4) and endo-oral
surgery (1). Fluorescein was applied to the surgical field. Black light
examination of fluorescein treated operative fields revealed minimal
contamination distant to the surgical field. In two prolonged cases with
high-speed drilling, droplets were identified under the barrier and on
the tip of the smoke evacuator. Instruments and cottonoids appeared to
be a greater contributor to field contamination.

\textbf{Conclusions}: Negative-pressure aspiration of air under a
chamber barrier which appears to successfully keep aerosol and droplet
contamination to a minimum. {}



\textbf{Introduction}

The novel coronavirus (SARS-CoV-2) is a highly-transmissible zoonotic
respiratory virus with an astonishing global
impact.\textsuperscript{1}In December 2019, the first cases emerged in
Wuhan, China\textsuperscript{2}, and on March 11, 2020 the novel
coronavirus disease (COVID-19) was declared a worldwide pandemic by the
World Health Organization (WHO). During this pandemic, patients continue
to present with urgent head and neck, and skull base conditions
requiring timely surgery. Strategies to reduce risk of spread of
infection during surgery are needed to protect the surgical team and
patients.

While many infected with SARS-CoV2 will be asymptomatic, there are those
with COVID-19 who will develop an advanced form of the disease
presenting as an atypical pneumonia requiring ventilatory support and
associated with significant morbidity and
mortality.\textsuperscript{1}It is known that there is a high viral load
in the nasal cavity, nasopharynx, and oropharynx; the only higher
subsite being the lower respiratory tract.\textsuperscript{3} What is
more worrisome, is that infected asymptomatic carriers carry the same
high viral load in these anatomic sites as those with
symptoms.\textsuperscript{4,5} Among healthcare workers, certain
personal protective precautions are taken, particularly during aerosol
generating procedures, but these are not guaranteed to work.
\textsuperscript{6}

At the onset of the pandemic, anecdotal international reports suggested
otolaryngologists are also placed at great risk during
surgery.\textsuperscript{7} Intuitively, surgery of the aerodigestive
tract can expose workers to infected fluids and the use of high-speed
drills in these anatomic sites can be a contributing factor. Workman et
al. demonstrated in a simulated skull base surgery scenario that
high-speed drills generated aerosols and droplet contamination up to 36
cm away from the patient.\textsuperscript{8} Coronaviruses are well
studied, and measure approximately 0.125 microns and are transported in
respiratory droplets.\textsuperscript{9} Coronaviruses can remain
aerosolized for up to 3 hours, and are stable on surfaces like plastic
and stainless steel.\textsuperscript{10} ~Improved methods for
preventing droplet and aerosol spread are needed especially during
high-risk procedures. Here we describe our experience developing the
Negative-Pressure Otolaryngology Viral Isolation Drape (NOVID) to reduce
aerosol and droplet spread in and around the surgical field.

\textbf{Methods}

This is a retrospective descriptive review of our technique used in four
patients who underwent endonasal and/or endo-oral surgery during the
COVID-19 pandemic, in which a negative-pressure chamber barrier was
installed around the surgical field.

\emph{Protective Barrier and Negative Pressure Chamber}

We constructed a chamber around the patients head which consisted of a
transparent plastic film used to cover a patient's head.~ The plastic
film was a 112 cm x 112 cm fluid warmer drape (Ecolab; St. Paul, MN)
placed over a Lone Star disposable ring retractor (Cooper Surgical;
Product \#3308; Trumbull, CT) that was suspended by a Bookwalter
Retractor Laparoscopic Support Set (Symmetry Surgical; Product
\#50-5730; Nashville, TN) (Figure 1A). A space between the patients head
and the barrier was created to prevent the drape from being pulled into
the suction port (Figure 1B). Non-penetrating towel clamps were used to
secure the plastic film to the Lone Star and the bed to keep the drape
taught over the surgical field. Fenestrations were created in the
plastic barrier drape to allow passage of instruments for either an
endonasal or endo-oral procedure (Figure 1C). These materials were
readily available at our institution and are likely used by most general
surgeons performing laparoscopic abdominal surgery.

\emph{Negative Pressure Aerosol Chamber}

Smoke evacuator suction tubing (Stryker Corporation; Product\#
0700-026-000; Kalamazoo, MI) was placed under the drape and connected to
a Neptune 3 Waste Management System (Stryker Corporation; Kalamazoo, MI)
to create a negative pressure chamber for the aerosol housing system.
The Neptune 3 Waste Management System is a surgical suction system
designed to provide both hazardous fluid and smoke evacuation during
surgery. It contains both a smoke evacuator filter compartment with an
ultra-low penetrating air (ULPA) efficiency rating and a fluid suction
high-efficiency particulate air (HEPA) filter compartment.~The tubing is
connected to the smoke evacuator manifold port on the Neptune suction
system to provide a minimum negative pressure of 0.5 inches of water
gauge. These metrics are consistent with the minimum ventilation
requirements for Class III biological safety cabinets in California. In
addition to the suspension apparatus, we created one or more ventilation
ports, located near head of the bed, to allow airflow into the
negative-pressure chamber. We were not able to measure the pressure
under the drape but did verify the suction was active, and when these
openings for air intake were occluded the drape tended to collapse.

In the first case and NOVID design, a polyethylene film drape (3M Steri
Drape 1010) was supported only by a straight Bookwalter bar.
Unfortunately, the single bar did not provide enough structural support,
and the drape collapsed and occlude the smoke evacuator under vacuum
limiting aerosol clearance. In the final iteration of the negative
pressure housing system, we used the Lone Star ring retractor attached
to a laparoscopic Bookwalter retractor holder to suspend the drape above
the patient's face without collapse when the negative pressure
environment was created. Gauze was also placed near the tip of the smoke
evacuator to prevent the drape from occluding the smoke evacuator tip
during the surgery.

\emph{Fluorescein Markers for Droplet Spread}

We used fluorescein dye and ultraviolet (UV) light to assess the
efficacy of the negative pressure housing system in minimizing aerosol
dispersion. Droplet formation and patient secretion spread was evaluated
with the application of fluorescein into the nasal cavity.~ We diluted
fluorescein (Fluorescite, fluorescein injection USP, 10\% at 100mg/ml;
Alcon Laboratories; Fort Worth, TX) to a concentration of 1\%
fluorescein in 10ml of normal saline solution and topically applied
dropwise to the nasal cavity and nasopharynx at the beginning of the
case. This was further diluted with saline during the case. The
fluorescein solution washes away easily with saline irrigation, so
regular reapplication of fluorescein dye was performed the nasal cavity
prior to use of instruments like the microdebrider, bipolar and
monopolar cautery and high-speed drilling. At the conclusion of the
surgery, an evaluation of the surgical drapes and gowns was performed
using an ultraviolet Wood's lamp.

We did not have a control group because routine preoperative SARS-CoV-2
testing is not being performed at our institution at this time. As such,
a universal personal protective equipment (PPE) policy was applied for
all aerosol generating surgeries, including endoscopic endonasal and
endo-oral surgery, consisting of an N95 mask or powered air-purifying
respirator (PAPR), eye protection, and fluid resistant gown.

\emph{Additional Surgical Set-Up Considerations}

A stereotactic navigation system (Brainlab; Munich, Germany) was during
each endoscopic endonasal surgery. The protective barrier was placed
over the reference array without interfering with the infrared tracking.
Should it be needed, the reference array can be brought outside the
drape through holes in the barrier drape.

\textbf{Results}

\emph{Surgical Cases}

Four patients underwent endoscopic endonasal surgery for osteomyelitis,
sinonasal malignancies, nasopharyngeal malignancy, and a pituitary
adenoma threatening vision. Two patients required concurrent endoscopic
sinus surgery as well. Power instruments with aerosol generating
potential were used in these surgeries and are summarized in Table 1.
These instruments include a microdebrider (used in 3 cases),
electrocautery (used in 3 cases), and a high-speed drill (used in 2
cases).

\emph{Black Light Examination}

Our cases demonstrated there is minimal spread of fluorescein beyond the
immediate surgical field. We examined the surgical field and adjacent
area prior to and after the case with a UV emitting black light (Figure
2). We marked the areas of contamination. In general, we found very
little contamination of droplets on the patient. In all cases, we found
fluorescent dye at sites round the nares, on the wipe placed on the
patient's chest, and on the surgical instrument table.~ In the first
NOVID design, without the Lone Star ring retractor, we found one single
droplet on the vertical drape ``wall'' placed by the anesthesiologist at
the foot of the patient. This was about 4 feet from the surgeon. In the
two functional endoscopic sinus surgery cases, we did not find droplets
under the barrier beyond the nares or near the smoke evacuator. In the
transsphenoidal pituitary case, we did identify fluid under the barrier
several centimeters away from the nares. In both skull base cases, we
identified dye on the gauze placed over the tip of the smoke evacuator
(Figure 1D).

Examination of the surgeon revealed a few droplets along the abdomen
region and in one case (Table 1, Case 3) a single droplet on the
surgeon's arm. Also, during this case, the scrub nurse had large
droplets \textgreater{}5mm on the abdomen region. However, the nurse was
also handling fluorescein stained epinephrine cottonoids and caused
self-contamination had self-contaminated. It is noted that instruments
from the case are used to pick up cottonoids, such as Bayonet forceps,
should be considered contaminated as well.

\textbf{Discussion}

We present our experience after the introduction of a technique using
negative pressure in a housing barrier (NOVID) to reduce the spread of
droplets and aerosol during endonasal skull base and transoral surgery.~
We have used this technique both in the sinonasal region for
ethmoidectomy, maxillary antrostomy, transpterygoid nasopharyngectomy,
and transsphenoidal sellar skull base surgery, as well as for endo-oral
palate surgery. This technique is still in evolution, but we found a
minimum of contamination of the surgical field with dye or visible
fluid. While the fluorescein is only a surrogate marker, since it is
applied only intermittently during the case. Notably, we identified dye
at the inlet of the smoke evacuator after the skull base procedures,
indicating it is capturing fluid in the form of droplets or aerosol
under NOVID.

A surgeon routinely places suction in the patient's nasal cavity.
However, the routine suction is attached to the HEPA filter in the
Neptune suction machine which captures particles down to 0.3 microns.
The smoke evacuator ULPA filter attachment on the side of the Neptune
captures particles down to 0.1 microns.\textsuperscript{11} The COVID-19
virus is 0.125 microns and in theory should be captured by an ULPA
filter but not the standard suction.\textsuperscript{9}~ Viral particles
could theoretically escape from the Neptune system with the standard
filter. We did examine the Neptune machine at the end of the surgery and
found the fluid in the container to brightly fluoresce, and no dye
visible outside the machine.

In general, we found droplet spread where the instruments or cottonoids
were placed. We did find droplets on the surgeon's abdomen and on the
surgeon's arm. One droplet was found at the foot of the bed. In the two
cases that generated aerosol we found the droplets under the drape away
from the nares. Whether this occurred due to aerosol from drilling or
due to irrigation and instrument passing over a prolonged time period,
we cannot determine at this time. However, in general we found very
little droplet contamination away from the surgical field.~ Large
droplets were found at expected locations: the patient's chest where the
gauze wipe is located, the instrument table, around the epinephrine
cottonoids, and in one case on the nurse's abdomen. This suggest that
surgical fomites including the instruments, cottonoids and tissue
specimens are a major source of spread of fluid to the surgical field.
We suspect the droplet at the patient's foot occurred during removal of
an instrument or cottonoid as it was in a linear trajectory and no other
droplets identified outside the surgical field. This suggests that
methods to reduce contamination caused by surgical instruments and
cottonoids may be useful. We suggest, gentle withdrawal of instruments
from the nasal cavity and passage of cottonoids and biopsy specimens off
the field onto a plastic tray similar to the plastic safe sharps passing
tray used for the hands-free transfer or sharps in many operating
rooms.\textsuperscript{12}

There is wide concern within the skull base field regarding aerosol
generation and droplets spread during endoscopic endonasal and upper
aerodigestive tract surgery. The NOVID system combines a fluid resistant
barrier and a negative pressure environment to reduce the spread of
aerosols and droplets. One alternate option is to place a suction into
the nasal cavity to create negative pressure
environment.\textsuperscript{8} However, this may obstruct access to the
surgical field or become clogged. Surgeons commonly use suctions while
operating and drilling, but they can also become clogged, or be too deep
in the field to catch the aerosol generated anteriorly. NOVID also
allowed for repetitive entry and removal of instruments into and out of
the surgical field and allows the surgeon to operate unencumbered. There
are potential improvements in the instrument port design. We envision
that the ideal surgical port would create a better seal around the
instrument and could wipe off any fluid or droplet contamination from
the scope and instruments as it is removed from the barrier.

NOVID also~appears to reduce splash back during irrigation, and the
negative pressure may capture aerosol created by cauterization or
high-speed drilling. Identification of fluorescence at the smoke
evacuator tip suggests it was able to draw aerosolized droplets. It is a
limitation of this study that due to the urgent concerns created during
this pandemic, we do not have control group to compare droplet spread.
Nevertheless, it is encouraging to find in the skull base cases, no
droplets or fluorescence on the outside of the drape or around the
patient's head other than where the instruments were direct contact.
Also, fluorescein is routinely used on the epinephrine soaked
cottonoids, which could cause false positive findings. However, the
cottonoids after being removed from the patient should be considered
contaminated.

We also found the nursing staff and anesthesia team to be extremely
appreciative of the monitoring of spread of patient's fluids into the
operating room environment and with the use of a barrier. This
assessment seemed to provide the team some peace of mind to see how,
where, and the minimal amount of contamination that occurred.~ We now
routinely use the fluorescein during each case as a marker of fluid
spread for quality assurance for all the operating room staff.

\textbf{Conclusion}

Reducing fluid spread during surgery involving the upper aerodigestive
tract in the COVID-19 era is important for the positive or indeterminate
patient. We introduce the use of a negative pressure system which may be
more efficacious than a simple barrier in minimizing droplet
contamination. Our preliminary findings indicate regional containment of
the fluorescein dye within the housing system and at the smoke evacuator
port. We also identified other potential sources of field contamination
from surgical fomites suggests gentle instrument movements and isolation
of materials removed from the nasal cavity are important.

\textbf{References}

1. Zhou F, Yu T, Du R, et al. Clinical course and risk factors for
mortality of adult inpatients with COVID-19 in Wuhan, China: a
retrospective cohort study. \emph{Lancet.} 2020;395(10229):1054-1062.

2. Huang C, Wang Y, Li X, et al. Clinical features of patients infected
with 2019 novel coronavirus in Wuhan, China.
\emph{Lancet.}2020;395(10223):497-506.

3. Wang W, Xu Y, Gao R, et al. Detection of SARS-CoV-2 in Different
Types of Clinical Specimens. \emph{JAMA.} 2020.

4. Rothe C, Schunk M, Sothmann P, et al. Transmission of 2019-nCoV
Infection from an Asymptomatic Contact in Germany. \emph{N Engl J
Med.}2020;382(10):970-971.

5. Zou L, Ruan F, Huang M, et al. SARS-CoV-2 Viral Load in Upper
Respiratory Specimens of Infected Patients. \emph{N Engl J
Med.}2020;382(12):1177-1179.

6. Tran K, Cimon K, Severn M, Pessoa-Silva CL, Conly J. Aerosol
generating procedures and risk of transmission of acute respiratory
infections to healthcare workers: a systematic review. \emph{PLoS
One.}2012;7(4):e35797.

7. Vukkadala N, Qian ZJ, Holsinger FC, Patel ZM, Rosenthal E. COVID-19
and the otolaryngologist - preliminary evidence-based
review.\emph{Laryngoscope.} 2020.

8. Workman AD, Welling DB, Carter BS, et al. Endonasal instrumentation
and aerosolization risk in the era of COVID-19: simulation, literature
review, and proposed mitigation strategies. \emph{Int Forum Allergy
Rhinol.} 2020.

9. Fehr AR, Perlman S. Coronaviruses: an overview of their replication
and pathogenesis. \emph{Methods Mol Biol.} 2015;1282:1-23.

10. van Doremalen N, Bushmaker T, Morris DH, et al. Aerosol and Surface
Stability of SARS-CoV-2 as Compared with SARS-CoV-1. \emph{N Engl J
Med.} 2020.

11. Neptune 3: Waste Management System Smoke Evacuator.
https://www.neptunewastemanagement.com/neptune-smoke-evacuator/.
Accessed April 20, 2020.

12. DeGirolamo KM, Courtemanche DJ, Hill WD, Kennedy A, Skarsgard ED.
Use of safety scalpels and other safety practices to reduce sharps
injury in the operating room: what is the evidence? \emph{Can J
Surg.}2013;56(4):263-269.



\textbf{Tables:}

\textbf{Table 1:} Surgical case details and aerosol generating
instrument use.\selectlanguage{english}
\begin{longtable}[]{@{}llllllll@{}}
\toprule
\textbf{Case} & \textbf{Diagnosis} & \textbf{Surgery} &
\textbf{Microdebrider} & \textbf{Bone Drilling} & \textbf{Cautery} &
\textbf{Findings} & \textbf{Droplets on Surgeon}\tabularnewline
\midrule
\endhead
1 & Osteomyelitis and sinusitis & ESS & No & No & Yes & One droplet on
anesthesia wall & Microdroplets on abdomen\tabularnewline
2 & Adenoid Cystic Carcinoma & Transpterygoid nasopharyngectomy & Yes &
Yes & Yes & Gross dye on smoke evacuator & None\tabularnewline
3 & NK T-cell Lymphoma & ESS and transoral resection & No & No & No &
Large droplets on nurse's abdomen & Microdroplets on
abdomen\tabularnewline
4 & Pituitary Adenoma & ESS, Transphenoidal pituitary resection & Yes &
Yes & Yes & Droplets on smoke evacuator & None, for both
co-surgeons\tabularnewline
\bottomrule
\end{longtable}

ESS --~endoscopic sinus surgery; NK --~natural killer

\textbf{Figure Legends}

\textbf{}\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/HED-20-0615-Figure-1-(1)/HED-20-0615-Figure-1-(1)}
\caption{{This is a caption
{\label{480049}}%
}}
\end{center}
\end{figure}

\textbf{Figure 1:} The negative-pressure otolaryngology viral isolation
drape (NOVID) setup. \textbf{(A)} The apparatus consists of a
laparoscopic Bookwalter holder (arrow) and a lone star ring retractor
(arrow-head), with a close up view of the attachment point (square
inset); \textbf{(B)} HEPA filter (arrow) connected to suction beneath
the drape; \textbf{(C)} endoscope and instrument insertion through
fenestrations in the drape; \textbf{(D)} fluorescein-laden droplets at
the mouth of the suction device (square) and gauze used to clean the
scope (circle), the patient's nose (arrow) for reference.

\par\null\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/HED-20-0615-Figure-2/HED-20-0615-Figure-2}
\caption{{This is a caption
{\label{862304}}%
}}
\end{center}
\end{figure}

\textbf{Figure 2:} Postoperative black light exams. Panel A and B from
Case 2. (A) Demonstration of gross contamination of the nurse's gown on
the abdomen, after directly handling epinephrine-soaked cottonoids. (B)
Multiple \textgreater{}5mm droplets on the instrument table. Panels C-F
from Case 4. (C) Multiple small droplets \textless{}1mm on the surgical
field at chest level. (D) Instrument table with large drops
\textgreater{}5mm.

\selectlanguage{english}
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\end{document}

