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\begin{document}

\title{Two-bronchoscope technique for cryoextraction: An alternative approach
for the removal of endobronchial thrombi in children}



\author[1]{Ryne Simpson}%
\author[1]{Isabel Virella-Lowell}%
\author[2]{Hitesh Batra}%
\author[1]{Guillermo Beltran Ale}%
\affil[1]{Division of Pediatric Pulmonary and Sleep Medicine University of Alabama at Birmingham Birmingham AL}%
\affil[2]{Division of Pulmonary Allergy and Critical Care Medicine University of Alabama at Birmingham Birmingham Alabama}%


\vspace{-1em}



  
  \date{June 18, 2024}


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\selectlanguage{english}
\begin{abstract}
This case illustrates another promising example of the recent advances
within pediatric interventional bronchoscopy. As innovative medical
therapies continue to make their way into the pediatric realm (e.g. a
1.1-mm flexible cryoprobe has been recently developed by Erbe),
opportunities for novel approaches and techniques will continue to
present themselves.%
\end{abstract}%



\sloppy


Two-bronchoscope technique for cryoextraction: An alternative approach
for the removal of endobronchial thrombi in children

\emph{To the Editor:}

Cryotherapy has become an important aspect of pediatric interventional
bronchoscopy. Through application of the Joule-Thompson effect,
cryotherapy utilizes freeze-thaw cycles via rapid expansion of
pressurized gas {[}1{]}. Bronchoscopic cryoextraction (i.e. using
cryotherapy to remove material \emph{en bloc} from the airway) has shown
promise for the removal of large mucus plugs, obstructive thrombi, and
foreign bodies in children {[}2, 3{]}. Although there are no reports of
serious complications related to cryoextraction in children, the risk of
hemorrhage is likely enhanced in coagulopathic patients, including those
receiving anticoagulation for extracorporeal membrane oxygenation (ECMO)
support. Because the bronchoscope and cryoprobe must be removed in
tandem to extricate foreign material, there is a period of time when
visualization of the airway is lost. As such, the ability to quickly
address complications is hampered.

Sriprasart et al. described a 2-bronchoscope approach in adults
undergoing cryobiopsy for undiagnosed interstitial lung disease (ILD)
{[}4{]}. By utilizing an additional bronchoscope with a patent
suction/instrumentation channel, this approach minimized time outside of
the patient's airway and facilitated prompt hemostasis following lung
tissue removal. In this report, which we believe to be the first of its
kind, we describe a similar technique performed in a pediatric patient
undergoing cryoextraction of a massive airway thrombus secondary to
prolonged ECMO support.

\textbf{Patient Case}

An 11-year-old female with a recent diagnosis of acute myeloid leukemia
developed respiratory failure following chemotherapy induction.
Progression of her respiratory failure led to initiation of
venous-venous ECMO (VV-ECMO) and concomitant anticoagulation. While on
VV-ECMO, the patient developed recurrent, consolidative opacifications
on chest imaging consistent with large airway obstruction. Over the
course of 3 weeks, the patient underwent 8 therapeutic bronchoscopies to
remove mucus plugs and large endobronchial thrombi. Several approaches
(including standard suctioning, saline lavage, and alligator forceps)
were trialed with decreasing benefit. Ultimately, radiography
demonstrated complete opacification of the thorax {[}Figure 1A{]}, and
flexible bronchoscopy revealed thrombus extending upwards into the ETT
{[}Figure 1C{]}. Otolaryngology was consulted, however, the patient's
tenuous status precluded endotracheal tube (ETT) removal and rigid
bronchoscopy. At that time, the decision was made to attempt thrombus
removal via cryoextraction.

\emph{The Endoscopic Technique}

Two pulmonologists and one respiratory therapist were present at the
time of cryoextraction. Two bronchoscopes (Olympus BF-P180, Olympus,
Tokyo, Japan) were utilized and each controlled by a separate
pulmonologist. A single Olympus endoscope video cart was used. An Erbe
(Tubingen, Germany) 1.9-mm multi-use cryoprobe was inserted through the
2.0 mm working channel of 1 bronchoscope and advanced into the center of
the thrombus. Freeze times of 5 - 15 seconds were utilized to adhere to
the proximal end of the thrombus, being mindful to avoid contact with
the ETT or tracheobronchial wall. The bronchoscope and cryoprobe (with
attached thrombus) were withdrawn en bloc. Immediately following
bronchoscope removal, the assisting respiratory therapist disconnected
the bronchoscope-cryoprobe from the video cart and connected the second
bronchoscope, already in the hands of the other pulmonologist. This
second bronchoscope, with a clean lens and patent suction channel, was
inserted into the ETT to assess the airway and control bleeding. Once
bleeding was controlled, any fresh blood obfuscating the remaining
thrombus was cleared in preparation for repeat cryoextraction. The
bronchoscopes were then disconnected-reconnected in the same fashion
until the entire thrombus extending from the distal trachea to the left
subsegmental bronchi was removed {[}Figures 1B and 1D{]}. Due to
increasing degrees of active bleeding at the proximal portion of the
right main bronchus, dilute epinephrine was instilled near the carina.
The procedure was then terminated with plans for cryoextraction of the
right side at a later date. The second procedure was performed 7 days
later in the same manner, and the entire tracheobronchial tree was
subsequently cleared of obstruction {[}Figure 2{]}. Roughly 1 week
following cryotherapy, the patient was taken off of ECMO and ultimately
extubated to non-invasive positive pressure ventilation.

\textbf{Discussion:}

Bronchoscopic cryotherapy has become increasingly prevalent within
pediatric pulmonary medicine. This has been largely due to the
development of smaller cryoprobes more suitable for use in children
{[}1, 2{]}. Nevertheless, cryotherapy does have potential for harm, and
adequate care must be taken to ensure the safety of the patient {[}5{]}.
This case highlights some of the drawbacks associated with
cryoextraction (namely loss of airway visualization and inoperative
suction channel) and offers a solution similar to what has been
described by a center performing cryobiopsy in adults with ILD.

The 2-bronchoscope approach described here does not, in theory, require
2 separate pulmonologists. The authors describing the initial technique
only utilized a bronchoscopist and an assistant. It is assumed that the
authors had separate modalities for viewing each bronchoscope which
would obviate the need for `disconnection-reconnection' mentioned in
this paper. Because our case occurred in the pediatric intensive care
unit, there was not enough physical space for 2 separate mobile carts
(in addition to the endoscopy cart, both ECMO and continuous renal
replacement therapy circuits were present). Although a single
proceduralist would have likely sufficed, we believe there was benefit
in having 2 physicians share the workload and discuss the case in
real-time. As an example, utilizing 2 providers allowed for intermittent
cleaning of the bronchoscope and cryoprobe (a potentially time-consuming
process due to friction associated with insertion/removal of the 1.9 mm
probe in a 2.0 mm channel) while preserving suction capabilities and
airway visualization. For these reasons, if qualified staff are
available, we would recommend having more than 1 bronchoscopist present
for this technique.

Although this report focuses primarily on the technical aspects of the
case, the overall performance of bronchoscopic cryotherapy should not go
unrecognized. As was previously mentioned, numerous time-consuming and
unsuccessful attempts at thrombus removal were made prior to
cryoextraction. This case illustrates another promising example of the
recent advances within pediatric interventional bronchoscopy. As
innovative medical therapies continue to make their way into the
pediatric realm (e.g. a 1.1-mm flexible cryoprobe has been recently
developed by Erbe), opportunities for novel approaches and techniques
will continue to present themselves.

\textbf{References:}

\begin{enumerate}
\tightlist
\item
  J. Piccione, EB. Hysinger, AG. Vicencio. Pediatric advanced diagnostic
  and interventional bronchoscopy. Seminars in Pediatric Surgery. Volume
  30, Issue 3 2021. ISSN 1055-8586.
  https://doi.org/10.1016/j.sempedsurg.2021.151065.
\item
  J.J.~Brewington,~\emph{et al.} Flexible bronchoscopic thrombus
  cryoextraction in a neonate on extra-corporeal membrane oxygenation.
  Am J Respir Crit Care Med~(2020).
\item
  K.~Engelhardt,~\emph{et al.} Successful use of pulmonary cryotherapy
  for tracheobronchial thrombus extraction and recanalization of the
  tracheobronchial tree during a pediatric venovenous extracorporeal
  membrane oxygenation run. Pediatr Allergy Immunol
  Pulmonol,~32~(1)~(2019), pp.~28-30.
\item
  Sriprasart T, Aragaki A, Baughman R, Wikenheiser-Brokamp K, Khanna G,
  Tanase D, Kirschner M, Benzaquen S. A Single US Center Experience of
  Transbronchial Lung Cryobiopsy for Diagnosing Interstitial Lung
  Disease With a 2-Scope Technique. J Bronchology Interv Pulmonol. 2017
  Apr;24(2):131-135. doi: 10.1097/LBR.0000000000000366. PMID: 28323726;
  PMCID: PMC5367496.
\item
  Hammer J, Trachsel D, Nicolai T, Weiss M, Eber E. Caution to use
  bronchoscopic CO2 cryotherapy for foreign body removal in children.
  Pediatr Pulmonol. 2016 Sep;51(9):889-91. doi: 10.1002/ppul.23450. Epub
  2016 Apr 29. PMID: 27128205.
\end{enumerate}

\textbf{Authors:}

Ryne Simpson MD\textsuperscript{1, 2}, Isabel Virella-Lowell
MD\textsuperscript{1, 2}, Hitesh Batra MD\textsuperscript{3, 4},
Guillermo Beltran Ale MD\textsuperscript{1, 2}

\textsuperscript{1}Division of Pediatric Pulmonary and Sleep Medicine,
University of Alabama at Birmingham, Birmingham, AL

\textsuperscript{2}Department of Pediatrics, University of Alabama at
Birmingham, Birmingham, AL

\textsuperscript{3}Division of Pulmonary, Allergy, and Critical Care
Medicine, University of Alabama at Birmingham, Birmingham, Alabama

\textsuperscript{4}Department of Medicine, University of Alabama at
Birmingham, Birmingham, AL

\textbf{Institution:}

University of Alabama -- Birmingham

Department of Pediatrics, Division of Pediatric Pulmonary and Sleep
Medicine

1600 7\textsuperscript{th} Avenue South

Birmingham, AL 35233

\textbf{Financial Disclosure:}

The authors declare they have no relevant financial interests.

\textbf{Conflicts of Interest:}

The authors declare they have no conflicts of interest.

\textbf{Correspondence to:}

Ryne Simpson, MD

University of Alabama -- Birmingham

Department of Pediatrics, Division of Pulmonary and Sleep Medicine

620 Jarman F. Lowder Building

1600 7\textsuperscript{th} Avenue South

Birmingham, AL 35233

Email: rcsimpson@uabmc.edu\selectlanguage{english}
\begin{figure}[H]
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\includegraphics[width=0.70\columnwidth]{figures/image4/image4}

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Figure 1. Chest radiograph before (A) and after (B) cryoextraction.
Thrombus extending upwards into the distal endotracheal tube (C) and
patent left main bronchus following cryoextraction (D).\selectlanguage{english}
\begin{figure}[H]
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\includegraphics[width=0.70\columnwidth]{figures/image5/image5}

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\includegraphics[width=0.70\columnwidth]{figures/image6/image6}

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Figure 2. Right main bronchial thrombus, before and after
cryoextraction.

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