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\begin{document}

\title{Suspension Laryngoscopy Experiences in a Tertiary Airway Service: a
Prospective Study of 150 Procedures}



\author[1]{Elizabeth Maughan}%
\author[1]{Anthony Rotman}%
\author[1]{Maral Rouhani}%
\author[1]{Gerard Thong}%
\author[1]{James Poncia}%
\author[1]{John Myatt}%
\author[2]{Chadwan Al Yaghchi}%
\author[2]{Gurpreet Sandhu}%
\affil[1]{Charing Cross Hospital}%
\affil[2]{Imperial College Healthcare NHS Trust}%


\vspace{-1em}



  
  \date{May 17, 2024}


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





\selectlanguage{english}
\begin{abstract}
Abstract Objectives: In most cases, suspension laryngoscopy (SL) is
efficient, bloodless and with minimal post-procedure discomfort. We
aimed to identify predictive patient factors for acceptable surgical
views at SL as well as quantify our tertiary airway unit's complication
rates. Design: Prospective cohort study of 150 consecutive
microlaryngoscopy procedures involving SL over an 8-month period between
November 2019 and July 2020. Patients were assessed pre-operatively for
pre-existing oral, temporomandibular, dental, pharyngeal or laryngeal
pathology, interincisor distance and qualitative gross limitations to
neck extension and forward head posture. Intraoperatively, the
laryngoscopic view was graded by anesthetic and surgical teams, and
complications were recorded on patient interview in recovery. Setting:
Tertiary adult airway service for predominantly benign pathology.
Results: Adequate surgical views were obtained in 149/150 procedures.
BMI and limitations to chin and neck movement had mild positive
correlations with more difficult views in their own rights, but did not
correlate with a statistically significant increase in complications.
There was a negative correlation between age and interincisor gap
(p=0.014), and wider mouth opening correlated with a lower incidence of
sore throat (p=0.023). Macroglossia showed a statistically significant
positive correlation with tongue symptoms (p=1.611x10-8). Conclusion: In
the context of an experienced airway unit with a high caseload of
predominantly benign pathology, SL is very effective and safe with low
associated morbidity and no mortality. Patient-reported neck and chin
movement were found to correlate well with the surgical view obtained.
The most common complication of SL is temporary sore throat and there
remain recognized risks of temporary tongue and dental symptoms.%
\end{abstract}%



\sloppy


\textbf{Abstract}

Objectives: In most cases, suspension laryngoscopy (SL) is efficient,
bloodless and with minimal post-procedure discomfort. We aimed to
identify predictive patient factors for acceptable surgical views at SL
as well as quantify our tertiary airway unit's complication rates.

Design: Prospective cohort study of 150 consecutive microlaryngoscopy
procedures involving SL over an 8-month period between November 2019 and
July 2020. Patients were assessed pre-operatively for pre-existing oral,
temporomandibular, dental, pharyngeal or laryngeal pathology,
interincisor distance and qualitative gross limitations to neck
extension and forward head posture. Intraoperatively, the laryngoscopic
view was graded by anesthetic and surgical teams, and complications were
recorded on patient interview in recovery.

Setting: Tertiary adult airway service for predominantly benign
pathology.

Results: Adequate surgical views were obtained in 149/150 procedures.
BMI and limitations to chin and neck movement had mild positive
correlations with more difficult views in their own rights, but did not
correlate with a statistically significant increase in complications.
There was a negative correlation between age and interincisor gap
(p=0.014), and wider mouth opening correlated with a lower incidence of
sore throat (p=0.023). Macroglossia showed a statistically significant
positive correlation with tongue symptoms
(p=1.611x10\textsuperscript{-8}).

Conclusion: In the context of an experienced airway unit with a high
caseload of predominantly benign pathology, SL is very effective and
safe with low associated morbidity and no mortality. Patient-reported
neck and chin movement were found to correlate well with the surgical
view obtained. The most common complication of SL is temporary sore
throat and there remain recognized risks of temporary tongue and dental
symptoms.

\textbf{Keywords} : Suspension laryngoscopy; direct laryngoscopy;
surgical complications; laryngeal exposure

\textbf{Key Points}

\begin{enumerate}
\tightlist
\item
  With a careful and standardized multidisciplinary approach, suspension
  laryngoscopy for benign pathology is usually efficient and bloodless
  with minimal post-procedure discomfort.
\item
  In 150 consecutive suspension laryngoscopy procedures undertaken by
  our specialist airway service, we were able to obtain a view adequate
  for successful surgery in all but one case, and saw no major or
  permanent complications.
\item
  The most common complication was temporary sore throat (66\%), which
  significantly negatively correlated with interincisor gap.
\item
  Temporary alteration of tongue sensation (6.7\%), mucosal abrasions
  (2.7\%), and exacerbation of preexisting dental/temporomandibular
  joint pain (1.3\%) were also seen at rates favourable in comparison to
  the global literature.
\item
  Our centre advocates the exclusive use of the Dedo-Pilling\selectlanguage{ngerman}®
  laryngoscope in most cases, apart from in isolated supraglottic
  pathology where the Lindholm laryngoscope may be of additional value.
\end{enumerate}

\textbf{Introduction}

Suspension laryngoscopy (SL) is a staple procedure in otolaryngology
which facilitates bimanual laryngeal instrumentation under direct
vision, thus permitting microlaryngeal surgery using a wide variety of
surgical techniques including cold steel excision, laser and
radiofrequency ablation. With a careful and standardized approach, SL is
usually efficient and bloodless with minimal post-procedure discomfort
following reversal of general anesthesia (1). As with every procedure,
there are recognized complications, the rates of which vary widely in
the global literature. A distinction can be made between minor or
temporary complications, which are generally localized to the oropharynx
(such as pain, mucosal abrasions or bruising, dental pain or temporary
tongue symptoms), and much rarer serious or permanent complications
(such as airway swelling, major cardiovascular instability, dental loss
or permanent tongue symptoms).

Multiple preoperative scoring systems have been proposed to predict the
acceptability of the view obtained at SL (2-7); however it is our view
that these often involve measuring excessive numbers of additional
variables outside of our routine clinical care, increasing time burdens
on staff without demonstrable gains in management-changing data. We
aimed to elucidate SL complication rates from our tertiary airway
population with comparison to the global literature, in order to:

\begin{itemize}
\tightlist
\item
  identify easy-to-measure factors which might predict acceptable
  anesthetic and surgical views at SL;
\item
  establish baselines against which to introduce measures to decrease
  complications;
\item
  identify potential at-risk subgroups who could benefit from additional
  pre-operative planning to avoid injury; and
\item
  increase the robustness of our consenting process.
\end{itemize}

\textbf{Methods}

\textbf{Ethical considerations}

This project received Institutional Board Approval as a Quality Audit
(ID: ENT\_025) from Imperial Healthcare NHS Trust in accordance with
Good Clinical Practice guidelines. The STROBE reporting guidelines for
cohort studies were followed.

\textbf{Study Design}

We performed a prospective observational study, amongst a cohort of 150
consecutive SL procedures for suspected benign laryngeal pathology, in
our tertiary adult airway service. We recorded the grade of surgical
view obtainable by SL according to our current practice (Figure 1), as
well as the minor and major complication incidences, over an 8-month
period between November 2019 and July 2020.

\textbf{Inclusion and Exclusion Criteria}

All patients undergoing SL to enable their surgical procedure were
recruited unless they were unable to self-report complications (i.e.
patients who remained intubated post-procedure or with persistently
reduced conscious levels). Patients provided additional verbal consent
to be included in the study at the time of written documentation of
procedural consent.

\textbf{Data Collection}

Age, gender at birth, height, weight, dentition, gross macroglossia and
Mallampati score were pre-operatively recorded. On the day of surgery,
patients were assessed by both surgical and anesthetic teams for the
presence of pre-existing oral, temporomandibular, dental, pharyngeal or
laryngeal pathology. The maximum inter-incisor gap achievable by the
conscious patient was also quantitively measured, as well as any gross
limitations to comfortable neck extension and forward head posture -
reasons for limitations included high muscle mass/body mass index (BMI)
or cervical spine immobilization (Figure 2).

Intraoperatively, laryngoscopic view was independently graded with
reference to the Modified Cormack-Lehane System (MCLS, Table 1) by both
anesthetist and surgeon using their usual laryngoscopes. The duration of
time spent in suspension and the occurrence of major adverse events were
also recorded (e.g. major cardiovascular instability, deep prolonged
desaturations or airway fires). As far as practicable, surgical
assessment of view was blinded with respect to preoperative measurements
and anesthetic view.

Post-operatively, patients were specifically asked about symptoms
relating to SL complications by a surgical team member. Any
patient-reported symptoms were monitored by telephone follow-up on the
first postoperative day and subsequently monthly until resolution.

\textbf{Statistical Analysis}

Interpretation of data was performed using Prism 8 software (Graphpad,
CA, USA). Parametric or nonparametric tests were used as appropriate
following normality testing. Patient factors were assessed for
correlation with grade of view and complications using Spearman's
correlation of multivariables.

Missing data relating to preoperatively determined patient factors was
retrospectively addressed using the Hospital electronic documentation
system where possible. Patients who were not questioned about their
symptoms in recovery (usually due to exceptionally efficient delivery
back to the postoperative ward for same day discharge) were telephoned
on the first postoperative day and asked about their symptoms
retrospectively -- although this potentially introduced recall bias of
symptoms, this resulting in no patients being lost to follow-up.

\textbf{Results}

\emph{Patient Demographics}

150 consecutive microlaryngoscopy procedures (141 adult patients)
involving SL were prospectively recorded. Patient characteristics are
shown in Table 2. Pathologies were generally benign although 2 patients
with endoscopically-managed slow-growing airway tumors were also
included. No patients reported pre-existing dental or tongue symptoms at
the preoperative stage. The median procedure time was 16 minutes (range
2-61min).

\emph{Grade of View}

The Dedo-Pilling® laryngoscope was used exclusively in 90.7\%
procedures. The median anesthetic view was grade 2a (IQR 1-2b), whilst
median surgical view was grade 1 (IQR 1-2, p\textless{}0.0001). There
was no significant correlation between the seniority of surgeon and the
view eventually obtained, although this may have been confounded by more
senior surgeons needing to take over in difficult cases. BMI and
patient-demonstrated limitations to chin and neck movement were all
significantly positively correlated with each other, and each also had
mild significantly positive correlations with higher grade (i.e. more
difficult) views (Figure 2). Neck extension was also negatively
correlated with interincisor gap (r=-0.268, p=0.001).

\emph{Complication Rates}

There were no episodes of major cardiorespiratory instability related to
SL itself, although one patient suffered a short but major drop in
oxygen saturations in response to the apneic period during subglottic
balloon dilatation. 4 further patients required temporary intraoperative
intubation to allow positive pressure ventilation and recruitment
maneuvers as SJV alone was insufficient to maintain oxygen saturations;
all patients were successfully extubated post-procedure. No other major
complications were encountered over this data collection period.

The rates of minor complications associated with SL are shown in Table
3. The most common complication was that of a temporary sore throat
without significant dysphagia (66\%), which universally resolved by the
third postoperative day. On multivariate analysis, the incidence of sore
throat was negatively correlated with interincisor gap (r=-0.186,
p=0.023) -- although interincisor gap was also negatively correlated
with age (r=-0.2, p=0.014), no significant direct correlation was found
between age and sore throat. Tongue symptoms occurred in 10 cases
(6.7\%), all of which were mild and temporary sensory disturbances.
These positively correlated with macroglossia on multivariate analysis
(r=0.452, p=1.611x10\textsuperscript{-8}). No incidences of tongue
weakness occurred in our cohort. Oropharyngeal trauma occurred in 4
patients (2.7\%) -- these were mild in all cases. Dental and
temporomandibular joint pain were reported in a further 2 cases, both of
which were exacerbations of pre-existing symptoms on further
questioning. There were no incidences of dental loosening or injury.
Despite correlations with poor grades of view, the chosen markers for
unfavorable patient body habitus did not significantly correlate with
increases in complications. No other statistically significant
correlations between patient or procedural factors and complications
were identified.

\textbf{Discussion}

Over an 8-month period of 150 airway procedures, we were able to obtain
views by SL adequate for the procedure (grade S1-3) in all but one case
(in which failure had been predicted preoperatively and planned flexible
bronchoscopy back-up was successful) (8). This high success rate,
together with our low complication rates, compares well with series from
other centers specializing in laryngeal surgeries (Table 4), and is
likely multifactorial in nature. We are the UK referral service for
tertiary airway surgery - as such we have a high turnover of cases,
including many patients undergoing regular repeated procedures under our
care (albeit fewer in this time period due to COVID-19), and we have an
experienced surgical, anesthetic and nursing team who regularly work
together (1). Other factors which we feel contribute to this high
success rate include correct patient positioning (no shoulder roll and
head forward position), routine use of supraglottic jet ventilation,
infrequent endotracheal intubation and our predilection for the
Dedo-Pilling laryngoscope (although it must be stated that use of the
Lindholm laryngoscope was not correlated with increased complications)
(Figure 1).

Many other documented `laryngoscores', whilst useful in research
contexts, are limited in their potential for widespread clinical
adoption by the need for multiple time-costly measurements of specific
head and neck movements (2-7). We suggest, given that we found
patient-demonstrated gross limitations to neck or chin movement to
correlate with the surgical view, that the absence of problems with
patients pre-operatively demonstrating the appropriate surgical position
(i.e. a forward head posture with or without neck extension) is
generally sufficiently predictive of procedural success without the need
to measure (3, 4, 7). A `Mini-Laryngoscore` predicting glottic exposure
was recently proposed by Incandela \emph{et al} based solely on
thyromental distance, interincisor gap and upper jaw dentition (3).
However, interincisor distance and upper jaw dentition did not correlate
significantly with our grade of view in this series. The anesthetic
literature generally holds that BMI alone is not usually a strong
independent predictor of difficult intubation unless extremely high (9)
- although BMI and neck and head movement limitations were all
significantly correlated with higher grade view in our series,
intercorrelation of these variables could represent a confounding effect
(10).

Comparing anesthetic and surgical views can provide useful
management-changing information in the pre- to intra-procedure
transition, such as predicting the likelihood of requiring a senior
surgeon to perform the procedure, or to guide appropriate ventilatory
choices. We therefore adapted the widely-used MCLS anesthetic grading
system for our purposes to make the surgical score more relevant. The
anesthetic goal at laryngoscopy is somewhat different as the goal is
topicalization rather than to try and achieve the best view possible for
intubation; in cases where intubation is considered as first-line, a
video laryngoscope would usually be employed as a first choice in these
patients. The use of the straight-bladed Dedo, in contrast to the curved
anesthetic Mackintosh blade, may further explain the improved view of
the surgical team. If faced with a potentially difficult airway, the
anesthesia regimen would usually include higher doses of induction
agents and muscle relaxant to improve the view for the first attempt.

In this data collection period, we had no incidences of major
complications such as severe cardiovascular instability, esophageal
perforation or permanent tongue sequelae, incurring only mild temporary
complications (Table 3). Reassuringly, most large reported series also
report an absence of severe complications (1, 8, 11-19) and the
literature on these subjects is limited to isolated case reports (20).
The main complication experienced by our patients, in line with other
studies (18), was that of temporary sore throat (66\% of patients). It
can be difficult to unpick complications associated with SL itself
versus the procedures that it enables (for example, ablative surgery is
likely to cause throat pain in its own right irrespective of SL). Our
results showed those patients with wider mouth opening had a
significantly lower correlation with sore throat, although age, which
also positively correlated with an increased interincisor gap, did not
have a significant association with sore throat. This leads us to
suggest that interincisor gap may be a useful independent clinical
indicator for sore throat, although it must be acknowledged that the
Spearman coefficient indicates a very modest effect only (21).

In this time period, 6.7\% of patients experienced tongue symptoms, all
of which were followed up and seen to resolve by the end of the second
postoperative week. This is a relatively low incidence compared to other
reported series (8, 12, 13, 15, 17, 19, 22, 23). There was no
significant correlation between tongue symptoms and SL duration, however
as might be expected, there was a moderate significant positive
correlation with macroglossia (r=0.452, p=1.611x10\textsuperscript{-8}).
Anecdotally, one patient reported that `they always get tongue numbness,
and it always resolves'. Given this patient was young with a low BMI, no
gross limitations to movement, an average interincisor gap and no
macroglossia, this leads us to hypothesize that some patients may be
more at risk of developing lingual nerve compression, perhaps due to
internal jaw anatomy as others have suggested (24). As with most other
reported studies, we saw non-significant associations with gender,
although others have suggested a female preponderance (11, 19). Detailed
further studies to investigate this could form the basis for future
cohort research. In this data collection period, we had no serious
dental complications, although there were two cases of temporary
exacerbation of existing dental/temporomandibular joint pain. Our team
are extremely careful not to lever the laryngoscope on the teeth, but
additional care is taken in patients who self-report painful teeth,
given this is a potential sign of underlying instability requiring
additional vigilance and care (12).

Reassuringly, there was no significant correlation between any
investigated complication rate and more difficult views or longer
procedural duration, both of which would imply greater cumulative
oropharyngeal tissue compression (11, 25). However, other series report
associations of longer procedural duration with increased complications
(8, 17, 19). Our airway unit treats predominantly benign pathologies and
is separate from the Head \& Neck unit which manages malignant cases.
Our cases therefore tend to have shorter procedural times, and the
absence of adjuvant radiotherapy renders our patients' oropharyngeal
tissues less stiff, and dentition more stable, than that seen by the
Head \& Neck team. This makes comparison with other reported series
difficult (1, 8, 12, 15) as most report a mix of benign and malignant
cases and have much longer average procedural durations. Our findings of
common and uncommon procedural complications therefore pertain
specifically to benign laryngology and are not generalizable to mixed or
Head \& Neck patient populations. In addition, rarer risks (i.e., those
with a \textless{}0.7\% incidence) may not have occurred in our sample
size of 150 cases and the consent process should still contain mention
of more serious or long-lasting risks reported in the literature, such
as tongue weakness.

The major limitation of our work is that this is an unblinded snapshot
study, albeit one representative of our practice. Anesthesia regimes
also varied throughout the study by anesthetic consultant, and the
administered muscle relaxant dose was often incomplete on the electronic
documentation system - this factor was therefore subsequently excluded
from multivariate analysis. The relationships between relaxant dosage
and timing between administration and visualization, and between
relaxant type or dose and complication rates, are also important avenues
for further study.

\textbf{Conclusion}

In the context of an experienced airway unit with high caseloads of
predominantly benign pathology, SL with the Dedo-Pilling laryngoscope is
effective and safe with low associated morbidity and no mortality.
Patient-demonstrated neck and chin movement correlate well with the
grade of surgical view obtained. The most common complications of SL are
temporary sore throat, occurring in 66\% of patients, and temporary
tongue and dental discomfort.

\textbf{Funding}

None declared.

\textbf{Conflicts of Interest}

None declared

\textbf{Data availability}

The data that support the findings of this study are available from the
corresponding author upon reasonable request.



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3. Incandela F, Paderno A, Missale F, Laborai A, Filauro M, Mora F, et
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15. Ozdamar OI, Uzun L, Acar GO, Tekin M, Kokten N, Celik S. Risk
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\textbf{Tables}

\emph{Table 1:} The widely used Modified Cormack-Lehane anaesthetic
grading system for ease of laryngoscopic view was adapted for the
surgical team. Anaesthetic teams carried out assessments using curved
Mackintosh blades, whereas surgeons used the Dedo laryngoscope and
therefore the situation of not being able to pass past the supraglottic
structures including epiglottis was less relevant to include as a
surgical grading point.\selectlanguage{english}
\begin{longtable}[]{@{}lll@{}}
\toprule
\textbf{Grade of view (Anaesthetic)} & \textbf{Description} &
\textbf{Grade of view (Surgical)}\tabularnewline
\midrule
\endhead
A1 & Full view of cords including anterior commissure &
S1\tabularnewline
A2 a & Partial view of cords, full view of anterior commissure &
S2\tabularnewline
b & Partial view of posterior glottis/arytenoids & S3\tabularnewline
A3 & Only epiglottis visible & -\tabularnewline
A4 & No view & S4\tabularnewline
\bottomrule
\end{longtable}

\emph{Table 2:} Demographic characteristics of adult patients undergoing
benign airway procedures (n=141).\selectlanguage{english}
\begin{longtable}[]{@{}lllllll@{}}
\toprule
\begin{minipage}[b]{0.12\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[b]{0.12\columnwidth}\raggedright\strut
\textbf{Average}\strut
\end{minipage} & \begin{minipage}[b]{0.12\columnwidth}\raggedright\strut
\textbf{Range}\strut
\end{minipage} & \begin{minipage}[b]{0.12\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[b]{0.12\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[b]{0.12\columnwidth}\raggedright\strut
\textbf{No}\strut
\end{minipage} & \begin{minipage}[b]{0.12\columnwidth}\raggedright\strut
\textbf{Yes}\strut
\end{minipage}\tabularnewline
\midrule
\endhead
\begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
\textbf{Age (median)}\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
48 yrs\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
18-86 yrs\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
\textbf{Limitation to neck extension}\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
127 (90\%)\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
14 (10\%)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
\textbf{Gender at birth}\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
87F : 55M\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
87F : 55M\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
\textbf{Limitation to chin forward}\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
132 (94\%)\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
9 (6\%)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.14\columnwidth}\raggedright\strut
\textbf{BMI (median)}\strut
\end{minipage} & \begin{minipage}[t]{0.14\columnwidth}\raggedright\strut
27.6\strut
\end{minipage} & \begin{minipage}[t]{0.14\columnwidth}\raggedright\strut
17.4-59.2\strut
\end{minipage} & \begin{minipage}[t]{0.14\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[t]{0.14\columnwidth}\raggedright\strut
\textbf{Pre-existing loose} \textbf{teeth/caps/crowns}\strut
\end{minipage} & \begin{minipage}[t]{0.14\columnwidth}\raggedright\strut
137 (97\%)\strut
\end{minipage} & \begin{minipage}[t]{0.14\columnwidth}\raggedright\strut
4 (3\%)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
\textbf{Interincisor gap (mean)}\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
4.5 cm\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
2.8-6.9 cm\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
\textbf{Macroglossia}\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
138 (98\%)\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
3 (2\%)\strut
\end{minipage}\tabularnewline
\bottomrule
\end{longtable}

\emph{Table 3:} Incidences of minor complications in patients undergoing
SL by our team over the data collection period.\selectlanguage{english}
\begin{longtable}[]{@{}lll@{}}
\toprule
\textbf{Complication} & \textbf{Number (\%)} &
\textbf{Notes}\tabularnewline
\midrule
\endhead
\textbf{Sore throat} & \textbf{99 (66\%)} & Maximum duration 3 days, all
were discharged as planned able to eat and drink.\tabularnewline
\textbf{Tongue symptoms} & \textbf{10 (6.7\%)} &\tabularnewline
\textbf{Numbness/ paraesthesia} & 7 (4.7\%) & All resolved by end of
second postoperative week. One patient reported similar experiences with
both previous SL procedures.\tabularnewline
\textbf{Pain} & 3 (2\%) & Mild in all cases with resolution by third
postoperative day\tabularnewline
\textbf{Dysgeusia (metallic/bitter)} & 0 &\tabularnewline
\textbf{Weakness} & 0 &\tabularnewline
\textbf{Oral abrasion/bruise/haematoma} & \textbf{4 (2.7\%)} &
Resolution in all cases by end of second postoperative
week\tabularnewline
\textbf{Tongue} & 0 &\tabularnewline
\textbf{Gum} & 0 &\tabularnewline
\textbf{Lip} & 2 (1.3\%) & 1 crack in dry lip, 1 haematoma from LMA
insertion\tabularnewline
\textbf{Palate} & 0 &\tabularnewline
\textbf{Pharynx} & 2 (1.3\%) & 1 abrasion, 1 haematoma from LMA
insertion\tabularnewline
\textbf{Dental problems} & \textbf{2 (1.3\%)} &\tabularnewline
\textbf{Dental pain} & 1 (0.7\%) & Multiple loose tender teeth
preoperatively\tabularnewline
\textbf{Loose/chipped tooth - own} & 0 &\tabularnewline
\textbf{Loose/chipped tooth - cap/crown/implant} & 0 &\tabularnewline
\textbf{TMJ pain} & 1 (0.7\%) & Pre-existing TMJ pain - exacerbated by
procedure, settled to pre-procedure levels by end of second
postoperative week.\tabularnewline
\bottomrule
\end{longtable}

\emph{Table 4:} Comparison of our complication rates in this series with
relevant series in the global literature. Yr- year; No.- number;
Avg-average; Lscope-laryngoscope; Sx- symptom; Anesth.-anesthetic;
Comp.- complication; SL- suspension laryngoscopy; MLS-
microlaryngoscopy; VC- vocal cord; min- minutes; d- day; w- week; m-
month; POD -- post-operative day; POW -- post-operative week; f/u-
follow-up; Max- maximum;\selectlanguage{english}
\begin{longtable}[]{@{}lllllllllllllll@{}}
\toprule
\begin{minipage}[b]{0.04\columnwidth}\raggedright\strut
\textbf{Author (First, Last), Yr}\strut
\end{minipage} & \begin{minipage}[b]{0.04\columnwidth}\raggedright\strut
\textbf{Study Type}\strut
\end{minipage} & \begin{minipage}[b]{0.04\columnwidth}\raggedright\strut
\textbf{No. patients/ procedures}\strut
\end{minipage} & \begin{minipage}[b]{0.04\columnwidth}\raggedright\strut
\textbf{Avg age (yr, range)}\strut
\end{minipage} & \begin{minipage}[b]{0.04\columnwidth}\raggedright\strut
\textbf{Procedure type}\strut
\end{minipage} & \begin{minipage}[b]{0.04\columnwidth}\raggedright\strut
\textbf{Lscope}\strut
\end{minipage} & \begin{minipage}[b]{0.04\columnwidth}\raggedright\strut
\textbf{Avg procedure duration}\strut
\end{minipage} & \begin{minipage}[b]{0.04\columnwidth}\raggedright\strut
\textbf{Sore throat}\strut
\end{minipage} & \begin{minipage}[b]{0.04\columnwidth}\raggedright\strut
\textbf{Tongue Sx rate}\strut
\end{minipage} & \begin{minipage}[b]{0.04\columnwidth}\raggedright\strut
\textbf{Mucosal trauma rate}\strut
\end{minipage} & \begin{minipage}[b]{0.04\columnwidth}\raggedright\strut
\textbf{Dental Sx rate}\strut
\end{minipage} & \begin{minipage}[b]{0.04\columnwidth}\raggedright\strut
\textbf{Anaesth. Comp.}\strut
\end{minipage} & \begin{minipage}[b]{0.04\columnwidth}\raggedright\strut
\textbf{Other}\strut
\end{minipage} & \begin{minipage}[b]{0.04\columnwidth}\raggedright\strut
\textbf{Resolution course}\strut
\end{minipage} & \begin{minipage}[b]{0.04\columnwidth}\raggedright\strut
\textbf{NOTES}\strut
\end{minipage}\tabularnewline
\midrule
\endhead
\begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\textbf{Maughan, Sandhu 2020}\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Departmental series Prospective\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
141/150\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
48 (18-86)\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
All SL benign cases\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Dedo-Pilling (+/- Lindholm)\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
16min (range 2-61min)\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
66\%\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
6.7\%\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
3\%\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
1.3\%\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
All by end of second POW\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\textbf{Okui, Watanabe 2019}\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Departmental record review Retrospective\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
550/-\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
43.9 (28-60)\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
All MLS benign cases\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Nagashima (small or very small)\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
11min (+/-14mins)\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
40\%\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
22.8\%\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
12\%\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
4.9\%\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
1 anaphylactic shock to Suggamadex\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
1 VC oedema, 1 bleeding, 13.4\% cough, 2\% neck pain\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
All resolved, most in 4 days, 16.7\% tongue Sx took \textgreater{}POW3
to resolve.\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\textbf{Larner, Griffith 2019}\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Departmental series Retrospective\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
174/213\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
58.5 (24-89)\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Benign \& malignant SL cases\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Ossoff-Pilling, Dedo-Pilling, Zeitelsf \#4\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Not reported (but 2/213 \textgreater{}30mins)\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
43\%\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
1.2\%\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
0.2\%\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
0.5\%\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
1 gum ulceration, 1 nasal tip laser burn\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Not reported\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
3min breaks between 30min continuous SL periods. All tongue Sx occurred
with Lewy system\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\textbf{Ozdamar, Celik 2019}\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Single surgeon series Prospective Blinded f/u\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
56/56\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
47.7 (19-84)\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
All benign \& malignant SL cases\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Kleinsasser (small, medium or large)\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
26mins (range 20-45min)\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Not reported\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
8.9\%\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
-\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
-\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
3 Sx (2 mild numbness,1 ?what) resolved in POW1, 2 ?what resolved in
POM1\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\textbf{Feng, Song 2018}\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Experimental cohort Prospective Blinded\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
56/-\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
58 (19-83)\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
SL cases recruited in clinic, majority benign\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Size 6 universal modular glottiscope\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
34min (SD 7-18mins)\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Not reported\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
53.5\%\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
-\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
-\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Not reported\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Max force/Avg force/total impulse correlated with tongue Sx \&
odynophagia. Women 30\% more tongue Sx\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\textbf{Tessema, Sessions 2016}\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Single surgeon series Retrospective\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
122/100\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
46 (14-83)\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
All SL therapeutic cases\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Dedo-Pilling (+/- Lindholm)\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
43.6min. 19\% \textgreater{}60mins duration\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Not reported\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
18\%\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
-\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
4.0\%\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
14 resolved at POM1, 3 resolved at POM3, 1 residual dysguesia\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Lewy suspension system used\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\textbf{Dos Anjos Corvo, Campos Duprat 2007}\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Departmental series Prospective\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
36/37\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
48 (18-80)\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
All SL benign or malignant suspicion cases\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Holinger or Kleinsasser\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
14 \textless{}30min, 16 30-60mins, 7 \textgreater{}60mins\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Not reported\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
13.5\%\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
130\%\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
2.7\%\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
All tongues 'improved' by end of POM2\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Oral cavity exam pre-op incl teeth, taste \& sensation grossly
tested\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\textbf{Rosen, Buckmire 2005}\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Departmental series Prospective\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
53/56\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
50\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
All SL benign cases\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Size 4,5 or 6 universal modular glottiscope\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
52mins (range 5-142mins)\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Not reported\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
17.9\%\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
-\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
12.5\%\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
3 dry mouths\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Avg POD11, longest POD34\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Boston suspension system used. 9 patients had \textgreater{}1 symptom.
Largest scope UMG-6 caused 86\% complications \& of longer
duration\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\textbf{Klussman, Eckel 2002}\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Departmental series Prospective\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
339/-\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
59 (29-86)\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
All planned SL benign \& malignant cases, 82\% intubated\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Not specified\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Not reported\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Not reported\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
3.8\%\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
105\%\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
6.5\%\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Lingual POW1-60 (median 4), hypoglossal POW6-16 (median 8)\strut
\end{minipage} & \begin{minipage}[t]{0.06\columnwidth}\raggedright\strut
Mucosal lesions 20\% higher in intubated patients. 40\% dental injuries
were lower jaw. Vast majority had pre-op peridontal disease\strut
\end{minipage}\tabularnewline
\bottomrule
\end{longtable}

\textbf{Figure Legends}

\emph{Figure 1:} Summary of our current clinical practice for Suspension
Laryngoscopy, including specific points of care from both anesthetic and
surgical perspectives. Clinical photographs of our suspension
laryngoscopy setup in the operating theatre. Of specific note is the
placement of the patient's neck on the break in the operating table
(\textbf{A} ), which allows for easy single-handed manipulation by the
operating surgeon, and the use of the Dedo-Pilling laryngoscope
(\textbf{B} ).

\emph{Figure 2:} Heatmap of Spearman correlation of multivariables.
Those associations with p values \textless{}0.05 and with confidence
intervals not including 1 are highlighted in yellow on the lower cross.
Blank squares represent Spearman coefficients \textless{}0.001.

\emph{Supplementary Figure 1:} Data collection form used by staff to
record pre-, intra- and post-operative details.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/Figure-1-BandW/Figure-1-BandW}

\end{center}
\end{figure}\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/Figure-2-updated/Figure-2-updated}

\end{center}
\end{figure}

\selectlanguage{english}
\FloatBarrier
\end{document}

