REVIEW

ERCP: The Unresolved Question of Endotracheal Intubation

Basavana Goudra • Preet Mohinder Singh

Received: 14 September 2013 / Accepted: 18 October 2013 / Published online: 13 November 2013

� Springer Science+Business Media New York 2013

Abstract The anesthesia community is still divided as to the

appropriate airway management in patients undergoing endo-

scopic retrograde cholangiopancreatography. Increasingly,

gastroenterologists are comfortable with deep sedation (nor-

mally propofol) without endotracheal intubation. There are no

comprehensive reviews addressing the various pros and cons of

an un-intubated airway management. It is hoped that the present

review will benefit both anesthesia providers and gastroente-

rologists. The reasons to avoid routine endotracheal intubation

and the approaches for an un-intubated anesthetic management

are discussed. The special situations where endotracheal intu-

bation is the preferred approach are mentioned. Many special

techniques to manage airway are illustrated.

Keywords ERCP � Sedation � Airway � Endoscopic

retrograde cholangiopancreatography

Background

A 59-year-old American Society of Anesthesiologists (ASA)

physical status 2 male presented for an endoscopic retrograde

cholangiopancreatography (ERCP). Past medical history was

unremarkable apart from chronic atrial fibrillation. The ven-

tricular rate was well controlled with medications. After

providing an explanation of the MAC anesthesia and associated

risks, an informed consent was obtained. The gastroenterologist

explained in detail about the ERCP and the stone extraction. As

per the standard practice, a decision was made to proceed with

deep sedation without endotracheal intubation. During the

procedure, desaturation set in that could not be treated quickly.

This was followed by sudden onset of ventricular tachycardia.

The patient was turned supine, intubated and CPR instituted.

Although effective cardiac activity and circulation could be

reestablished, the patient died a few hours later.

Horrific experiences like this are bound to affect clinical

practice of all anesthesia providers. Irrational and many times

non-evidence based decisions can be made based on either

personal experience like this one or experiences of others.

However, as experienced and trained medical professionals, it

is important that crucial practice decisions like endotracheal

intubation are made based on the available evidence rather

than a rare clinical event, however disastrous it might be. To

highlight this statement consider another example.

A 66-year-old male presented for a diagnostic upper

gastrointestinal (GI) endoscopic procedure. History inclu-

ded severe aortic stenosis (valve orifice of 0.8 cm2). Again

as per the standard practice, sedation was administered

with propofol without endotracheal intubation. Hypoxemia

(as evidenced by desaturation) led to cardiac arrest. CPR

(cardio pulmonary resuscitation) was quickly instituted;

however, the patient sustained anoxic brain injury.

Although both of these unfortunate events were heralded

by hypoxemia and possibly could have been prevented by

elective endotracheal intubation (ETT), it is unlikely that

anesthesia providers will be inclined to intubate all patients

presenting for upper GI endoscopy, as much as they are

likely to intubate all patents presenting for ERCP. In spite

of adverse outcome in both situations, the prone position-

ing necessary for ERCP segregates this entity into a

B. Goudra (&)

Clinical Anesthesiology and Critical Care, Perelman School of

Medicine, Hospital of the University of Pennsylvania,

Philadelphia, PA, USA

e-mail: goudrab@uphs.upenn.edu

P. M. Singh

Department of Anesthesia, Post Graduate Institute of Medical

Education and Research (PGIMER), Chandigarh, India

e-mail: preetrajpal@gmail.com

123

Dig Dis Sci (2014) 59:513–519

DOI 10.1007/s10620-013-2931-3

separate category. It is partly due to our long-held belief

regarding the consequence of airway loss in an unintubated

patient undergoing procedure in prone position.

An important distinction has to be made regarding surgical

procedure versus endoscopic procedure conducted in prone

position. An intracranial procedure (with all its complexities in

terms of positioning) or a spine procedure is entirely different

than an ERCP, although both are conducted in prone position.

First, endoscopic procedures can be aborted at any notice to

facilitate airway management. The second difference, although

depth of sedation for an ERCP is similar to or even greater than

needed for a neurosurgical procedure, it is possible to titrate the

anesthetic depth to maintain spontaneous ventilation. The

intensity of stimulation for an ERCP is nowhere near a surgical

incision and, apart from the phase of gastroscope insertion, is

relatively constant. Further discussion on anesthetic approach

and airway management of patients presenting for an ERCP

will be based on these two factors.

The Intubation Dilemma

Endoscopic retrograde cholangopancreatography poses

unique challenges to both anesthesia provider and gastroen-

terologist. The last two decades have seen a phenomenal

increase in the number of ERCPS. With the expanding indi-

cations, the patient population presenting for these procedures

has also grown older and sicker. Some of the indications in our

own hospital (from a retrospective review of 653 patients) are

presented in Table 1 [1]. Although it is tempting to intubate all

ERCPS and such is the practice in many centers around the

world, the following considerations are to be borne in mind

before committing all or a majority of patients to ETT.

Why Routine ETT Anesthesia Should Be Discouraged?

How Safe is Laryngoscopy and Intubation?

Laryngoscopy and endotracheal intubation itself is not an

entirely innocuous procedure. Although the advent of video

laryngoscope is likely to change the landscape, intubation-

related injuries are common. Lip, dental and eye and other

soft tissue injuries happen with a degree of frequency [2–

4]. Although these injuries are not life threatening, they are

preventable and especially injuries to the eye can be dis-

abling. More serious injuries like bronchial rupture can

occur especially with the use of introducers [5].

Endotracheal intubation almost invariably requires

administration of skeletal muscle relaxants. Due to the

unexpected duration of this diagnostic and therapeutic

procedure, it is sensible to use succinylcholine for this

purpose. Apart from the well-known risks of muscle pain,

myoglobulinemia myoglobinuria, succinylcholine is

implicated in malignant hyperthermia [6, 7]. Depending

on the endoscopic findings, sometimes it becomes nec-

essary to administer a long acting relaxant along with the

need for reversal agents. Apart from a significant increase

in anesthesia times, use of muscle relaxants can increase

the incidence of postoperative pulmonary complications

[8, 9]. Use of reversal agents is associated with unwanted

anticholinergic effects. Use of glycopyrrolate is not uni-

versal. Use of atropine for this purpose can potentially

lead to central anticholinergic effects. Residual neuro-

muscular blockade is an important issue with nondepo-

larizing muscle relaxants [10, 11]. It can occur even 2 h

after reversal. Inadequate reversal is an additional risk

factor. It is hoped that advent of sugamedex [12] might

change the role of nondepolarizing muscle relaxants in

future.

Prone Positioning and ETT

Although all ERCP procedures involve prone positioning,

patients are asked to position themselves when ETT is not

involved. Turning prone after intubating in supine position

presents significant challenges. Endoscopy units are not as

well staffed as other surgical operating rooms. Injuries can

occur during positioning and while positioned. Accidental

extubation is risky, although can be managed either with

bag-mask or a laryngeal mask airway (LMA) [13].

Efficiency

Especially for very short procedures like change of stent,

the endotracheal anesthesia adds significant additional

time. In a retrospective study [14], we found that ‘‘anes-

thesia time’’ (total time minus procedural time) is a sig-

nificant factor contributing to overall time in ERCP

procedure. This time can be reduced by using dedicated

anesthesiologists, and decreased incidence of endotracheal

intubation is a contributing factor.

Table 1 Indications of endoscopic retrograde cholangiopancreatog-

raphy (ERCP) in an outpatient center

Indication Occurrence

Chronic pancreatitis 6.25 %

Post hepatic transplant 41.43 %

Hepatic cancer (including metastasis) 8.56 %

Cholangiocarcinoma 8.56 %

Primary sclerosing cholangitis 4.62 %

Pancreatic cancer 20.83 %

Others 9.72 %

514 Dig Dis Sci (2014) 59:513–519

123

Why Anesthesiologists Intubate the Trachea?

Fear of Losing Airway

Fear of losing airway during the procedure is probably the

most common reason for elective endotracheal intubation

among the anesthesia providers. However, those fears are

unfounded. Many publications during recent months have

affirmed the safety of unintubated ERCP. Goudra et al.

studied 653 consecutive patients undergoing elective

ERCP in their outpatient center. Their intubation rate was

\1 % and all the indications were fear of full stomach and

history of aspiration. There were no instances of procedure

interruption or emergency endotracheal intubation. Even

while anesthetizing far sicker patients in their inpatient

endoscopy center, the incidence of endotracheal intubation

was \10 %. In a recent study, non-obese patients who

underwent ERCP needed endotracheal intubation in about

10 % procedures [15].

Risk of Hypoxemia

Many investigators have closely studied the risk of hyp-

oxemia in patients undergoing advanced endoscopic pro-

cedures and ERCP [1, 14, 16]. In the study cited above

[15], although incidence of endotracheal intubation for

ERCP was \10 %, the incidence of oxygen desaturation

was worryingly high. It is well known that hypoxemia (as

evidenced by desaturation) is the most common precursor

of more serious adverse events like cardiac arrhythmias

and asystole. Part of the reasons for a striking difference in

the intubation and desaturation rates might be the airway

management technique. In one institution, airway man-

agement was geared towards preventing hypoxemia. By

extensive use of either a nasal trumpet or an oral trumpet

(both in turn connected to a mapelson breathing system,

Figs. 1a, b, 2), one center could reduce the incidence of

desaturation to negligible levels.

However, if an anesthesia provider decides to embark on

an unintubated approach while sedating these patients,

certain precautions need to be undertaken [1]. Preoxygen-

ation and timing of propofol administration along with the

timing of endoscope insertion are all crucial. As it is well

known, once the lungs are filled with 100 % oxygen by

elective preoxygenation, it can take up to 11 min for pulse

oximeter to register a desaturation to 90 %, in spite of no

ventilation. Although, both preoxygenation for 3 min or

four vital capacity breaths can provide at least 4 min of

‘‘safety time’’ before patients start desaturating, it is

advised to use the former technique as the time available to

deal with inadequate ventilation will be longer (up to

8 min) [17]. This is due to the nature of the oxygen

desaturation curve. The arterial partial pressure of oxygen

Fig. 1 a A nasal trumpet placed in the nose and connected to a

Mapelson C breathing system with an elective endotracheal intuba-

tion (ETT) adapter. b A nasal trumpet placed in the nose and

connected to a Mapelson C breathing system, bag squeezed to assist

Fig. 2 A nasal trumpet placed in the mouth and connected to a

Mapelson C breathing system with an ETT adapter

Dig Dis Sci (2014) 59:513–519 515

123

has to fall from an initial 660 to about 90 mmHg for a fall

in oxygen saturation. The patient needs to be either apneic

or hypopneic for prolonged periods (depending on FRC

and oxygen consumption) before the pulse oximeter can

register desaturation. This period is difficult to detect

without close observation. Although ASA has recom-

mended the use of ECO2 monitoring for all patients

undergoing GI endoscopic procedure under anesthesia-

provider provided sedation [18], its efficacy in the setting

of GI endoscopy is far from satisfactory [19]. Close

observation of the chest movement and alternative, more

reliable means of ventilation (like acoustic respiratory

monitor or impedance peumograpghy) are to be

considered.

The second issue is to have a means of assisting venti-

lation if (and when) hypoventilation is detected. Obviously,

any airway obstruction needs to be corrected by

appropriate airway manipulation. Assisting ventilation

using a Mapelson breathing system (while depth of seda-

tion is reduced appropriately) is useful [1, 14]. Many times,

nothing more is required until spontaneous ventilation is

established. However, the nature of the upper airway under

propofol sedation with the gastroscope in situ is unpre-

dictable and variable. As shown in the pictures, gastro-

scope might displace the tongue and help to establish the

patency of the airway in many cases; however, by no

means is it certain (Figs. 3 and 4).

Risk of Aspiration

The risk of aspiration in patients undergoing colonoscopy

under propofol mediated sedation was highlighted in a

recent large retrospective study [20]. Even in the absence

of gastric outlet obstruction, there is probably an increased

risk of aspiration in patients undergoing ERCP (although

no data are available). For procedures like drainage of

pancreatic pseudocyst, endotracheal intubation is the air-

way management of choice. Single stage drainage of these

cysts is common [21, 22] and the biochemical analysis has

shown high protein content [23]. Like in other endoscopic

procedures, silent aspiration of gastric contents cannot be

ruled out during ERCP [24].

Lack of Reliable Monitoring in an Unintubated Patient

ASA has recommended end tidal carbon dioxide monitor-

ing in all patients undergoing these procedures with mod-

erate to deep sedation [18]. However, practicalities of

implementation are a major problem. End tidal carbon

dioxide is not a reliable monitor in this setting [19]. There

is nothing inherently wrong with the monitor, however

practical obstacles prevent obtaining a reliable sample.

Various devices to obtain such a sample are proposed, their

reliability in the setting of upper GI endoscopy in general

and ERCP in particular is not studied. Acoustic respiratory

monitor and impedance pneumography are better respira-

tory monitoring alternatives. As impedance pneumography

cannot detect breathing against an obstructed upper airway,

acoustic respiratory monitoring may be preferable.

Cardiac Arrest in Patients Undergoing ERCP

and Upper GI Endoscopy

The incidence of cardiac arrest in patients undergoing GI

endoscpy is high compared to other forms of anesthesia.

Interestingly, the cardiac arrests were all heralded by

respiratory complications (much like pediatric anesthesia

practice). However both the incidence and severity of such

complications are no different between ERCP and other

forms of upper GI endoscopy (like endoscopic ultrasound

Fig. 3 A view from above taken from another fiber-optic broncho-

scope with gastroscope in place; airway classification Mallampatti

Fig. 4 A view from above taken from another fiber-optic broncho-

scope with gastroscope in place; airway classification Mallampatti

516 Dig Dis Sci (2014) 59:513–519

123

or therapeutic endoscopy). The incidence during colonos-

copy was zero during the same period.

Airway Management for Prone ERCP

As mentioned earlier, the oxygen dissociation curve is not

an anesthesia provider’s friend. Due to the steep portion of

the curve, it is very important (while anesthetizing any

unintubated, spontaneously ventilating patient) to have a

low threshold for endoscope withdrawal. Corrective airway

maneuvers need to be instituted in anticipation of hypox-

emia rather than as a response to hypoxemia. Waiting for

pulse oximeter to display a saturation of 90–95 to respond

might be too late. To facilitate such an approach, a

patient’s ventilatory efforts need to be observed very clo-

sely. If the attending anesthesiologist (supervising the case)

is doubtful of the abilities of his assistant, intubation might

be a safer option. These skills can be easily taught and

learnt. Especially in the initial stages of the procedure

(endoscope insertion and recommencement of effective

ventilation), documentation needs to be ignored and

attention paid to monitor the patient. Inadequate levels of

sedation can equally lead to severe cough and sometimes

laryngospasm. In the absence of effective preoxygenation,

hypoxemia can set in very quickly. As ERCP scopes have a

side camera (rather than at the tip) insertion difficulties can

lead to inadvertent stimulation of vocal cords triggering

violent cough. Immediate endoscope withdrawal and

deepening sedation is important. An anesthesia provider

should not hesitate to express his concerns and request for a

more experienced endoscopist to do the insertion. If the

difficulties continue, it is prudent to reevaluate the plan and

effect an endotracheal intubation after turning supine.

At times, after commencement of the procedure, airway

manipulations, insertion of nasal trumpet or bagging with

the oral/nasal trumpet are insufficient to prevent hypox-

emia. In such cases, withdrawal of the scope and bagging

with a face mask to reoxygente is required. In the absence

of any other difficulties, after appropriate adjustment of the

depth of sedation, endoscope reinsertion can be permitted.

There is increasing evidence as to the safety of LMA

both as a primary airway in prone position and as a rescue

method [13, 25, 26].

Although, a nasal trumpet connected to a Mapelson C

breathing system (Fig. 1a, b) has been used as a standard in

our hospital, it can also be used as a rescue measure.

Another way to administer oxygen is by use of a modified

nasal airway inserted into the mouth next to bite block and

connected to a Mapelson C breathing system (Fig. 2).

Both gastrolaryngeal tube (Fig. 5) and endoscopy mask

(Fig. 6) could be used as support and possible ventilation

during ERCP procedures [27]. However there is little

published literature with either of these airways during

these procedures. Absence of a suction port is an obvious

disadvantage with an endoscopy mask.

Studies documenting the use of LMA for ERCP are

lacking, but its use in prone position to administer anes-

thesia for other surgical procedures are plenty.

Who Should Provide Anesthesia for ERCP?

Another way to increase both the safety and efficiency in

ERCP sedation is to have a team of dedicated anesthesia

providers. This approach is known to decrease desatura-

tions and reduce the anesthesia time [14]. In this recently

published study, a comparison was made between two

naturally divided groups of anesthesia providers. Apart

from an incidence of desaturation, a comparison was also

made between the ‘‘anesthesia time’’ in the two groups. As

a group, non-dedicated anesthesia providers took more

time than dedicated providers. Moreover this amounted to

an increase in the cost of anesthesia by about 760,000 US$

Fig. 5 Gastrolaryngeal tube

Fig. 6 Endoscopy mask

Dig Dis Sci (2014) 59:513–519 517

123

in one hospital alone. Although no special fellowships and

certifications are currently necessary, out-of-OR anesthesia

might soon become frequent and complicated enough to

require additional training. At the hospital of the University

of Pennsylvania, dedicated out-of-operating-room resident

anesthesia rotations are already in place to address this

aspect of training. It is hoped that ASA and ABA will

notice this expanding field of anesthesia and make appro-

priate provisions in the residency training curriculum.

Frequently, the question arises about the nomenclature

of sedation technique used for these procedures. Gast-

roenterologists are always competing with anesthesia pro-

viders to administer propofol. As observed in our

institution, although the patients presenting for upper

endoscopy (including ERCP) are told (and consented) that

they will have moderate to deep sedation, 96 % of these

patients were under deep general anesthesia as measured

by brain function monitor (SEDLne). As a result, it is only

appropriate that ‘‘sedation’’ for these procedures is pro-

vided by anesthesia providers.

Having discussed the pros and cons of endotracheal

intubation for ERCP, a low threshold to intubate is advised

in the following subset of patients.

Obesity

As stated earlier, emergency expert help in turning the

patient supine to secure an airway may not be easy in an

endoscopic suite. In a morbidly obese patient, such heroics

could be fraught with dangers. With an already compro-

mised FRC and increased oxygen consumption, time

available to reestablish effective ventilation will be very

limited. ETT is the preferred method of airway manage-

ment, especially in the inexperienced.

Risk of Aspiration

Suspicion of gastric outlet obstruction, full stomach and

drainage of pseudocyst of pancreas are probably managed

better with an ETT.

Anticipated Difficult Ventilation

Although anticipated difficult intubation may not be an

indication for elective ETT, anticipated difficult ventilation

should be.

Additionally, other institution-specific factors like

availability of anesthesia provider with experience in

endoscopy anesthesia, location and size of the room, type

and extent of help are important in this decision making.

Conclusions

Patients presenting for an ERCP can be safely and effec-

tively sedated without the need for an elective endotracheal

intubation. Close respiratory monitoring, ready availability

of means of establishing ventilation and experience are

important. Various airway techniques and adjuncts

described can help in preventing and treating hypoxemia.

Conflict of interest None.

References

1. Goudra B, Singh P, Sinha A. Outpatient endoscopic retrograde

cholangiopancreatography: safety and efficacy of anesthetic

management with a natural airway in 653 consecutive proce-

dures. Saudi J Anaesth. 2013;7:259.

2. Newland MC, Ellis SJ, Peters KR, et al. Dental injury associated

with anesthesia: a report of 161,687 anesthetics given over

14 years. J Clin Anesth. 2007;19:339–345.

3. Vogel J, Stubinger S, Kaufmann M, Krastl G, Filippi A. Dental

injuries resulting from tracheal intubation—a retrospective study.

Dent Traumatol. 2009;25:73–77.

4. Yu H-D, Chou A-H, Yang M-W, Chang C-J. An analysis of

perioperative eye injuries after nonocular surgery. Acta Anaes-

thesiol Taiwanica Off J Taiwan Soc Anesth. 2010;48:122–129.

5. Sahin M, Anglade D, Buchberger M, Jankowski A, Albaladejo P,

Ferretti GR. Case reports: Iatrogenic bronchial rupture following

the use of endotracheal tube introducers. Can J Anaesth J Can

Anesth. 2012;59:963–967.

6. Dexter F, Epstein RH, Wachtel RE, Rosenberg H. Estimate of the

relative risk of succinylcholine for triggering malignant hyper-

thermia. Anesth Analg. 2013;116:118–122.

7. Hopkins PM. Malignant hyperthermia: pharmacology of trig-

gering. Br J Anaesth. 2011;107:48–56.

8. Tejada Artigas A, Bello Dronda S, Chacon Valles E, et al. Risk

factors for nosocomial pneumonia in critically ill trauma patients.

Crit Care Med. 2001;29:304–309.

9. Berg H, Roed J, Viby-Mogensen J, et al. Residual neuromuscular

block is a risk factor for postoperative pulmonary complications.

A prospective, randomised, and blinded study of postoperative

pulmonary complications after atracurium, vecuronium and

pancuronium. Acta Anaesthesiol Scand. 1997;41:1095–1103.

10. Debaene B, Plaud B, Dilly M-P, Donati F. Residual paralysis in

the PACU after a single intubating dose of nondepolarizing

muscle relaxant with an intermediate duration of action. Anes-

thesiology. 2003;98:1042–1048.

11. Varposhti MR, Heidari SM, Safavi M, Honarmand A, Raeesi S.

Postoperative residual block in postanesthesia care unit more than

two hours after the administration of a single intubating dose of

atracurium. J Res Med Sci Off J Isfahan Univ Med Sci.

2011;16:651–657.

12. Sokoł-Kobielska E. Sugammadex—indications and clinical use.

Anaesthesiol Intensive Ther. 2013;45:106–110.

13. Raphael J, Rosenthal-Ganon T, Gozal Y. Emergency airway

management with a laryngeal mask airway in a patient placed in

the prone position. J Clin Anesth. 2004;16:560–561.

14. Goudra BG, Singh PM, Sinha AC. Anesthesia for ERCP: impact

of anesthesiologist’s experience on outcome and cost. Anesth Res

Pract. 2013;2013:570518.

518 Dig Dis Sci (2014) 59:513–519

123

15. Barnett SR, Berzin T, Sanaka S, Pleskow D, Sawhney M,

Chuttani R. Deep sedation without intubation for ERCP is

appropriate in healthier, non-obese patients. Dig Dis Sci. (Epub

ahead of print). doi:10.1007/s10620-013-2783-x.

16. Berzin TM, Sanaka S, Barnett SR, et al. A prospective assessment

of sedation-related adverse events and patient and endoscopist

satisfaction in ERCP with anesthesiologist-administered sedation.

Gastrointest Endosc. 2011;73:710–717.

17. Gambee AM, Hertzka RE, Fisher DM. Preoxygenation tech-

niques: comparison of three minutes and four breaths. Anesth

Analg. 1987;66:468–470.

18. Weaver J. The latest ASA mandate: CO2 monitoring for moderate

and deep sedation. Anesth Prog. 2011;58:111–112.

19. Goudra BG. Comparison of acoustic respiration rate, impedance

pneumography and capnometry monitors for respiration rate

accuracy and apnea detection during GI endoscopy anesthesia.

Open J Anesth. 2013;03:74–79.

20. Cooper GS, Kou TD, Rex DK. Complications following colon-

oscopy with anesthesia assistance: a population-based analysis.

JAMA Intern Med. 2013;173:551–556.

21. Ahlawat SK, Charabaty-Pishvaian A, Jackson PG, Haddad NG.

Single-step EUS-guided pancreatic pseudocyst drainage using a

large channel linear array echoendoscope and cystotome: results

in 11 patients. JOP J Pancreas. 2006;7:616–624.

22. Ahn JY, Seo DW, Eum J, et al. Single-step EUS-guided trans-

mural drainage of pancreatic pseudocysts: analysis of technical

feasibility, efficacy, and safety. Gut Liver. 2010;4:524–529.

23. Monkemuller KE, Harewood GC, Curioso WH, et al. Biochem-

ical analysis of pancreatic fluid collections predicts bacterial

infection. J Gastroenterol Hepatol. 2005;20:1667–1673.

24. Raksakietisak M. Unrecognised aspiration pneumonitis during

enteroscopy: two cases report. J Med Assoc Thail Chotmaihet

Thangphaet. 2009;92:869–871.

25. Abrishami A, Zilberman P, Chung F. Brief review: airway rescue

with insertion of laryngeal mask airway devices with patients in

the prone position. Can J Anaesth J Can Anesth. 2010;57:

1014–1020.

26. Osborn IP, Cohen J, Soper RJ, Roth LA. Laryngeal mask air-

way—a novel method of airway protection during ERCP: com-

parison with endotracheal intubation. Gastrointest Endosc.

2002;56:122–128.

27. Fabbri C, Luigiano C, Cennamo V, et al. The gastro-laryngeal

tube for interventional endoscopic biliopancreatic procedures in

anesthetized patients. Endoscopy. 2012;44:1051–1054.

Dig Dis Sci (2014) 59:513–519 519

123