For citation purposes: Thong SY, Goh SY. Reported complications associated with the use of GlideScope® video laryngoscope–How can they be prevented? OA Anaesthetics 2013 Mar 01;1(1):1.

Critical review

 
Equipment

Reported complications associated with the use of GlideScope® video laryngoscope-How can they be prevented?

SY Thong*, SY Goh
 

Authors affiliations

Department of Anaesthesia, Singapore General Hospital, Block 2, Level 2, Outram Road, Singapore 169608

* Corresponding author E-mail: thongszeying@gmail.com

Abstract

Introduction

The use of the GlideScope® video laryngoscope has increased tremendously since its release in 2001. Compared to the Macintosh laryngoscope, its unique design allows an improved view of the glottis. During intubation, it decreases the need to anteriorly displace the lower jaw or manipulate the cervical spine. As a result, there is lesser sympathetic response to intubation and possibly fewer traumas to the dentition. Intubation may be performed on an awake patient more easily. The GlideScope® video laryngoscope plays a significant role in the management of routine and difficult airways. Unfortunately, the same unique design also requires the use of a stylet and introduces blind spots in the oropharynx during intubation. As a result of this drawback, cases of airway trauma have been reported. We have aimed to write a critical review discussing the complications and precautions associated with the use of the GlideScope® video laryngoscope.

Conclusion

The GlideScope® video laryngoscope is an improvement over the Macintosh laryngoscope as it reduces airway manipulation, but further research must be conducted in order to increase our understanding of the potential pitfalls associated with it and to develop strategies to avoid them.

Introduction

GlideScope® was developed by the Canadian surgeon John Pacey and became commercially available in late 2001. It allows real-time viewing of the airway and tube placement, and it is one of the more widely used video laryngoscopes available, with more than 300 associated publications in Medline[1].

The purpose of this critical review is to provide a basic, concise overview of the GlideScope® video laryngoscope, with emphasis on the advantages and reported complications in literature, and to discuss strategies to optimise intubation technique.

Discussion

Types of GlideScope® video laryngoscopes

The reusable GlideScope® video laryngoscope has a 60-degree curve blade and comes in four blade sizes: 2, 3, 4 and 5, to facilitate intubations in infants weighing 1.8 kg to the morbidly obese. It uses a high resolution, anti-fog complementary metal-oxide semiconductor camera and a light emitting diode located near the distal tip of the blade, allowing a wide angle of view. The unit consists of a portable colour video monitor which has a colour image of 320 × 240 pixels. Device start-up is quick with a single button, and the image does not require any adjustment or white balance. It uses a 12V lithium rechargeable battery, which has an average battery life of 90 minutes and approximately 500 charge cycles.

Other GlideScope® models include the GlideScope® advanced video laryngoscope designed for difficult and unpredictable airways, and the GlideScope® Ranger, optimised for rugged conditions in pre-hospital settings. A summary of the GlideScope® product range is provided in Table 1.

Table 1

Range of GlideScope® products.

How GlideScope® works during intubation

In conventional laryngoscopy with the Macintosh laryngoscope, the patient’s head is positioned by flexing the lower cervical spine and extending the atlanto-occipital joint, known as ‘sniff the morning air’ position[2].

It is believed that direct laryngoscopy aligns the oral, pharyngeal and laryngeal axes to aid in the direct visualisation of the glottis, as shown in Figure 1[3]. In contrast, the camera is sited near the distal tip of the GlideScope® blade. When correctly positioned, the camera acts as the ‘eye’ of the operator and is situated in the pharynx of the patient. This enables the image of the glottis to be projected on the monitor, allowing the operator to see around the corner. The main advantage conferred by this technique includes an improved view of the glottis without the need to anteriorly displace the lower jaw and reduce cervical spine motion[4]. As a result, there is less sympathetic response to intubation and possibly less leverage force on the teeth[5]. Intubation may then be performed on an awake patient more easily[6]. Therefore, this technique has a significant role in the management of routine and difficult airways[7].

Oral-pharyngeal-laryngeal axes not aligned.

Its similarities to the Macintosh laryngoscope, as compared with other video laryngoscopes like the Pentax, may contribute to greater user acceptability for most operators experienced with the Macintosh. For both the novice and experienced anaesthetists, it is easier to achieve successful intubation with the GlideScope® as compared with the Macintosh[8,9]. Direct laryngoscopy generally requires a steeper learning curve and a longer duration to master the technique as compared with the GlideScope®[10,11].

Problems encountered during the use of GlideScope®

An interesting paradox is seen with the use of GlideScope®. Even though it provides an improved view when compared with direct laryngoscopy, that does not necessarily translate to better intubation success[12]. Due to the line of sight created by direct laryngoscopy, even in poor views, intubation may be possible with adjuncts like the bougie and stylet[13]. In contrast, even when a grade 1 or 2 Cormack and Lehane view is obtained with the GlideScope®, intubation may not be possible in the first attempt.

The manufacturer recommends a four-step technique when using the GlideScope®:

The GlideScope® is first introduced into the midline of the oral pharynx with the left hand.

The epiglottis is identified on the screen and the scope is manipulated to obtain the best glottic view.

The endotracheal tube is then guided into position near the tip of the laryngoscope by direct vision.

When the distal tip of the endotracheal tube disappears from direct view, it should be viewed on the monitor. Gently rotate or angle the tube to redirect as needed.

Clinical pearls for intubation success and injury avoidance are summarised in Table 2.

Table 2

Clinical pearls for intubation success and injury avoidance.

The common factor associated with intraoral injuries such as palatopharyngeal, anterior tonsillar pillar or soft palate perforations, is blind advancement of the endotracheal tube. Injuries have occurred despite apparent gentle technique and the lack of resistance encountered by the operator. When upward force is applied to the GlideScope® to achieve better laryngeal visualisation, the tonsillar pillars and related structures may be stretched taut and become susceptible to perforation[14].

This highlights the need for constant visual assessment of the tip of the endotracheal tube under direct vision during the initial oral-pharyngeal insertion, as well as during subsequent advancement of the tube on the GlideScope® monitor. In the interim, there may be a blind spot, depending on the patient’s oral anatomy[15]. A strategy to overcome such problems is to advance the endotracheal tube right next to the GlideScope® blade, near the midline. This provides maximal space for endotracheal tube advancement. The anatomy of the oral structures is demonstrated in Figure 2.

Picture of the oral cavity.

There was one report of a palate injury caused by the leading edge of the GlideScope® video laryngoscope[16]. At all times, the advancement of the blade should be midline, gentle and under vision if possible. After intubation, the oral airway should be examined during laryngoscope withdrawal. Details of reported complications associated with the use of GlideScope® are summarised in Table 3.

Table 3

Clinical reports of complications associated with the use of GlideScope®.

Conclusion

The GlideScope® video laryngoscope is a useful tool for intubation. It improves glottic view and reduces the need for airway manipulation. Despite its ease of use, thorough understanding of its unique characteristics is important in avoiding potential intubation injuries.

Author Contribution

All authors contributed to the conception, design, and preparation of the manuscript, as well as read and approved the final manuscript.

Competing interests

None declared.

Conflict of Interests

None declared.

A.M.E

All authors abide by the Association for Medical Ethics (AME) ethical rules of disclosure.

References

  • 1. . US National Library of Medicine, National Institutes of Health. USA. 31 Jan 2012.
  • 2. Brindley PG, Simmonds MR, Needham CJ. Teaching airway management to novices: a simulator manikin study comparing the ‘sniffing position’ and ‘win with the chin’ analogies. Br J Anaesth 2010 Apr;104(4):496-500.
  • 3. Adnet F, Borron SW, Lapostolle F, Lapandry C. The three axis alignment theory and the “sniffing position”: perpetuation of an anatomic myth?. Anesthesiology 1999 Dec;91(6):1964-5.
  • 4. Turkstra TP, Craen RA, Pelz DM, Gelb AW. Cervical spine motion: a fluoroscopic comparison during intubation with lighted stylet, GlideScope, and Macintosh laryngoscope. Anesth Analg 2005 Sep;101(3):910-5.
  • 5. Russell T, Khan S, Elman J, Katznelson R, Cooper RM. Measurement of forces applied during Macintosh direct laryngoscopy compared with GlideScope® videolaryngoscopy. Anaesthesia 2012 Jun;67(6):626-31.
  • 6. Jones PM, Harle CC. Avoiding awake intubation by performing awake GlideScope laryngoscopy in the preoperative holding area. Can J Anaesth 2006 Dec;53(12):1264-5.
  • 7. Thong SY, Lim Y. Video and optic laryngoscopy assisted tracheal intubation–the new era. Anaesth Intensive Care 2009 Mar;37(2):219-33.
  • 8. Lim TJ, Lim Y, Liu EH. Evaluation of ease of intubation with the GlideScope or Macintosh laryngoscope by anaesthetists in simulated easy and difficult laryngoscopy. Anaesthesia 2005 Feb;60(2):180-3.
  • 9. Cinar O, Cevik E, Yildirim AO, Yasar M, Kilic E, Comert B. Comparison of GlideScope video laryngoscope and intubating laryngeal mask airway with direct laryngoscopy for endotracheal intubation. Eur J Emerg Med 2011 Apr;18(2):117-20.
  • 10. Nouruzi-Sedeh P, Schumann M, Groeben H. Laryngoscopy via Macintosh blade versus GlideScope: success rate and time for endotracheal intubation in untrained medical personnel. Anesthesiology 2009 Jan;110(1):32-7.
  • 11. Latif RK, Akca O. Simulation based training of airway management with Macintosh blade and GlideScope video laryngoscope. Minerva Anestesiol 2011 Jan;77(1):1-3.
  • 12. Cooper RM, Pacey JA, Bishop MJ, McCluskey SA. Early clinical experience with a new videolaryngoscope (GlideScope) in 728 patients. Can J Anaesth 2005 Feb;52(2):191-8.
  • 13. Weisenberg M, Warters RD, Medalion B, Szmuk P, Roth Y, Ezri T. Endotracheal intubation with a gum-elastic bougie in unanticipated difficult direct laryngoscopy: comparison of a blind technique versus indirect laryngoscopy with a laryngeal mirror. Anesth Analg 2002 Oct;95(4):1090-3.
  • 14. Cooper RM . Complications associated with the use of the GlideScope® videolaryngoscope. Can J Anaesth 2007 Jan;54(1):54-7.
  • 15. Choo MK, Yeo VS, See JJ. Another complication associated with videolaryngoscopy. Can J Anaesth 2007 Apr;54(4):322-4.
  • 16. Shields OK, Srinivasogopalan R. A complication associated with the GlideScope® video laryngoscope. Br J Anaesth Array.
  • 17. Malik AM, Frogel JK. Anterior tonsillar pillar perforation during GlideScope® video laryngoscopy. Anesth Analg 2007 Jun;104(6):1610-1.
  • 18. Magboul MM, Joel S. The video laryngoscopes blind spots and possible lingual nerve injury by the Gliderite rigid stylet–case presentation and review of literature. Middle East J Anesthesiol 2010 Oct;20(6):857-60.
  • 19. Hsu WT, Hsu SC, Lee YL, Huang JS, Chen CL. Penetrating injury of the soft palate during GlideScope® intubation. Anesth Analg 2007 Jun;104(6):1609-10.
  • 20. Hsu WT, Tsao SL, Chen KY, Chou WK. Penetrating injury of the palatoglossal arch associated with use of the GlideScope® videolaryngoscope in a flame burn patient. Acta Anaesthesiol Taiwan 2008 Mar;46(1):39-41.
Licensee to OAPL (UK) 2013. Creative Commons Attribution License (CC-BY)

Range of GlideScope® products.

  GlideScope® video laryngoscope GlideScope® advanced video laryngoscope GlideScope® Ranger
Single use Preterm/small children Reusable Ranger Single use
Key features High resolution CMOS camera High resolution digital camera High resolution CMOS camera High resolution digital camera High resolution CMOS camera
Suitable for patient weight 1.8 kg to morbidly obese 500 g to morbidly obese 500 g to 28 kg 4 kg to morbidly obese 10 kg to morbidly obese 500 g to morbidly obese
Blade sizes (#) GVL® 2, 3, 4, 5 GVL® Stat 0, 1, 2, 2.5, 3, 4 GVL® Stat 0, 1, 2, 2.5 GVL® 2, 3, 4, 5 Ranger® GVL 3, 4 GVL® Stat 0, 1, 2, 2.5, 3, 4
Monitor type/ display pixels Video monitor 320×240 pixel TFT colour, VGA 640×480 pixel Video monitor 320×240 pixel
Unit size Height 167 mm Width 207 mm Depth 83 mm Weight 1.4 kg Height 190 mm Width 225 mm Depth 80 mm Weight 1 kg Height 168 mm Width 173 mm Depth 49 mm Weight 0.56 kg
Battery type 12 V Li ion rechargeable 7.2 V, 2200 mAh Li ion rechargeable 12 V Li ion rechargeable
Average battery life 90 minutes
Overall lifespan 2–3 years, approximately 500 charge cycles
Digital video recording availability Not applicable Maximum capacity SD card 2 GB Recording time on 1GB SD card approximates 1.5 h

CMOS, complementary metal-oxide semiconductor; GVL, GlideScope® reusable video laryngoscope; Li, lithium; SD, secure digital; TFT, thin film transistor; VGA, video graphics array.

Clinical pearls for intubation success and injury avoidance.

- Verathon recommends the insertion of the GlideScope® blade via the midline of the tongue to the epiglottis. This should be done under vision control14.
- The GlideScope® may be used like a Macintosh laryngoscope to indirectly lift the epiglottis or produce a Miller’s lift.
- The use of the ETT stylet is recommended. A malleable stylet with a 60–90 degree curvature may be used. GlideRite® Rigid Stylet produced by Verathon is also available.
- Introducing the ETT close to the side of the blade helps to avoid blind, traumatic insertions as the space created by the presence of the blade allows direct visualisation of the styletted ETT, until its tip is seen on the monitor14.
- To aid the passage of the ETT, once the tip is at the vocal cords, withdraw the stylet slightly, about 2–3 cm, before further ETT advancement. This avoids trauma to the vocal cords by the rigid stylet. Withdrawal of the laryngoscope or reduction of the lifting force allows the glottis to drop, which may also aid the passage of ETT.
- Always ensure that the tip of the ETT is observed during advancement– initially via direct vision, and then via the monitor when the tip disappears from direct view after further advancement. Avoid blind advancement of the ETT. This will reduce the risk of injury in the oral structures caused by the rigid stylet17.
- After intubation, as the GlideScope® is withdrawn, attention should be paid to the path of the ETT and possible injury to the oral cavity18.
- The use of soft-edge ETT (such as the Parker Flex-Tip™) may avoid trauma to the pharynx17.
- Insert the ETT with the bevelled tip facing against the blade of the GlideScope®15.

ETT, endotracheal tube.

Clinical reports of complications associated with the use of GlideScope®.

Journal Patient characteristics Complications Outcome Comments
Hsu WT et al.19Anesth Analg, 2007. 29-year-old ASA 1 male scheduled for rhinoplasty Intubated with #7.5 ETT angled to a 60-degree curvature with a stylet. ETT had pierced right soft palate. Surgeon diagnosed the injury during oral cavity examination intraoperatively. There was no bleeding at the palate and the ETT was removed uneventfully. Patient was discharged 3 days later without any untoward events. Authors stressed that during the advancement of the ETT from the mouth to the pharynx, the tip of the ETT that could have damaged the soft tissue could not be monitored on the monitor.
Malik AM et al.17Anesth Analg, 2007. 72-year-old male with congenital myotonia, previous Cormack-Lehane grade 3 laryngeal view and history of difficult intubation Intubated with #8 ETT, mounted on manufacturer recommended GlideRite® Rigid Stylet, was inserted under GlideScope® vision. It perforated the right anterior tonsillar pillar. Injury was indicated by blood in the retropharynx seen on the GlideScope® monitor. During the withdrawal of the GlideScope® blade, the injury was seen on the monitor. ETT was removed and the trachea was reintubated with a fiberoptic laryngoscope. No delay in extubation. Patient reported minimal throat soreness. Easy grade 1 view on GlideScope®. However, ETT was passed through the oropharynx blindly until it was seen on the GlideScope® screen. Patients with congenital myotonia can be resistant to the effects of non-depolarising muscle relaxants which may have contributed to the mishap.
Choo MK et al.15 Can J Anaesth, 2007. 65-year-old female who was scheduled for urological surgery #7.5 ETT, preformed with stylet, was used for intubation. At the end of the case, it was noticed that he ETT had perforated the right palatopharyngeal fold. Surgical consult was required for haemostasis with electrocautery. Patient was subsequently extubated after bleeding stopped. Patient required overnight hospitalisation for observation. Follow-up 6 weeks later showed good wound healing. No resistance was encountered while passing the ETT into the oropharynx, but slight resistance was encountered as the ETT passed the laryngeal inlet.
Cooper RM et al.14 Can J Anaesth, 2007. 57-year-old female with hemifacial microsomia presented for facial scar revision. She exhibited features of a difficult airway including a small mouth and limited cervical extension. Subsequent airway examination after intubation with direct laryngoscopy revealed Cormack-Lehane grade 4 view. The ETT was seen dissecting the right palatopharyngeal arch. Bleeding was minimal. The dissection was surgically repaired with two sutures. Patient was discharged the next day any without further problems. Good laryngeal view was obtained on the GlideScope®. There was difficulty in the introduction of the styletted ETT into the larynx by the first operator. The second operator completed the intubation with the GlideScope®. No resistance was felt by the experienced laryngoscopist during the advancement of the ETT as it dissected the palatopharyngeal arch.
72-year-old female presented for aortic valve replacement and coronary bypass grafting with severe aortic stenosis and coronary artery disease. She was edentulous. The ETT had perforated her right palatopharyngeal arch, causing significant bleeding. Upon the completion of cardiopulmonary bypass and surgery, blood was seen on the patient’s face. This prompted airway examination with direct laryngoscopy, which revealed the injury. There was persistent bleeding which required electrocautery for haemostasis. Patient remained intubated and mechanically ventilated for unrelated reasons. Novice operator performed the intubation, supervised by an experienced GlideScope® user. Grade 1 Cormack-Lehane view was obtained with the GlideScope® easily. To bring the ETT (preformed with a malleable stylet) into view on the monitor, two attempts were required. Subsequent ETT manipulation was not difficult.
Hsu WT et al.20 Acta Anaesthesiol Taiwan, 2008. 38-year-old female with 40% total body-surface-area burn injuries (face, neck and thorax), inhalational injury and respiratory distress, required an ETT exchange. She had a difficult airway, Cormack-Lehane grade 4 view was obtained due to her burn injuries After removal of the existing ETT, a #7.0 ETT with a stylet was inserted through the vocal cords under GlideScope® visualisation. Examination of the oropharynx with direct laryngoscopy showed that the ETT had perforated the right palatoglossal arch. The ETT was removed and reinserted under direct laryngoscopy after surgical consult. There was no active bleeding and the patient remained mechanically ventilated. An experienced operator performed the intubation. Cormack-Lehane grade 2 view of the vocal cords was obtained with the GlideScope®. A contributory factor to the injury was the small oral cavity which contained a nasogastric tube, duodenal tube and an existing ETT.
Magboul MM et al.18 Middle East J Anesthesiol, 2010. 80-year-old female with morbid obesity and difficult airway #7 ETT, mounted on GlideRite™ Rigid stylet, perforated the retromolar trigone. Injury was diagnosed by the surgeon during oral surgery. Repeat intubation with the same technique was uneventful. No delay in extubation or lingual nerve injury. View of vocal cords and epiglottis seen. One attempt intubation with easy introduction of ETT.
Shields OK et al.16 Br J Anaesth, 2012. 49-year-old male with rheumatoid arthritis, obesity and predicted difficult airway, presented for emergency laparoscopy. Modified, rapid sequence induction was performed. GlideScope® #4 blade inserted by trainee and observed by specialist. The posterior soft palate was traumatised and the pharynx was filled with blood, which obscured the view of the vocal cords. Pharyngeal suctioning, cricoid pressure release and mask ventilation, were required before the next attempt at intubation. Injury occurred despite proper gentle technique and the absence of bleeding diathesis. The blade appeared to have no defects although the leading edge might have been sharp or malformed.

ASA 1, American Society of Anaesthesiology patient classification status 1 (normal healthy patient); ETT, endotracheal tube.

Keywords