Retrograde intubation : an old – new technique

Introduction In the last decade, a new boom of scientific articles about retrograde intubation has been published. Case reports, applications, technique variations and comparison with other techniques reintroduce the scientific discussion of the technique, its indications, contraindications, complications and technical advances. Despite the complications and contraindications linked to retrograde intubation, its utility is incontestable in specific situations. Although the success rate of retrograde intubation is variable, some authors affirm that in the hands of those who use the technique frequently, retrograde intubation appears to have a high success rate. We believe that training in retrograde intubation would definitely be an advance that could increase the success rate of the technique as well as decrease the complications associated with it. Conclusion Recent developments are happening to enhance the retrograde intubation technique, such as the combination with laryngeal nerve block, fibre optic bronchoscopy and ultrasound guidance. During the booming phase of advances in airway management technologies, anaesthesiologists should sometimes return to the basics and learn and practice simple techniques like retrograde intubation that can save patient lives. Introduction Retrograde endotracheal intubation was first described by Butler and Cirillo1 in 1960 as a way to remove the tracheostomy tube in neck surgery. In this procedure, a catheter is passed towards cephalad through the tracheostomy site and emerged in the mouth; then, the catheter is sutured to an endotracheal tube and it is pulled into the trachea. Waters2, in 1963, described passing a plastic tube through the cricothyroid membrane and then using it as a guide to intubate patients. Basically, retrograde intubation encompasses the introduction of a wire into the larynx through a Tuohy needle (Figure 1) in the cricothyroid membrane or membranous space between the cricoid cartilage and the first tracheal ring and blindly retrograde emerging in the mouth or nostril (Figure 2). Then, the technique proceeds with the antegrade guiding of a tracheal tube into the airway using the wire as a guide (Figure 3). Finally, with the orotracheal tube which is already present in the trachea, the wire is removed and the position of the tube is confirmed by capnography and auscultation. The technique evolved between the 60s and 80s, and underwent a lot of developments to improve its effectiveness. It has been used in conscious, sedated or apnoeic patients3–5. It has been performed in the supine, prone and sitting positions6 and has been used successfully in both adults7,8 and the paediatric population9–11 as young as 4 months old. There is also a report about the successful placement of a doublelumen endotracheal tube using the retrograde intubation technique to perform an approach to a lesion in the right lung12. Retrograde intubation can be performed using local anaesthesia with or without sedation, or under general anaesthesia with or without spontaneous ventilation, depending upon the patient, the operator, and the clinical situation13,14. One of the greatest enhancements in retrograde intubation has been the introduction of the Cook Retrograde Intubation Set®13. It made possible the use of the technique not only in urgent situations, but also in unpredictable situations in which there is no time to assemble all the components necessary for the procedure from different kits. The use of the retrograde wire technique to assist the management of difficult airway was first reported in 198115. Retrograde intubation is recognised as a useful technique in airway management, which is included in the difficult airway algorithm of the American Society of Anesthesiologists16 in 1993 and maintained in the review of this algorithm 10 years later in 200317. Owing to the emergence of new equipments for intubation such as laryngeal mask airway, fibre optic bronchoscope, airway bougie, lighted stylet, combitube and video laryngoscopy, the retrograde intubation was somehow put aside in the management of predictable and non–predictable difficult airways in the 90s. The evidence from a study conducted by Harris et al.13 suggests that the procedure is not widely taught and is felt by some to be an antiquated technique in a world of fibre optic visualisation tools. Regardless of the availability of more sophisticated tools, anaesthetists are occasionally faced with scenarios * Corresponding author Email: dianamsvieira@gmail.com 1 Resident Physician, Department of Anesthesiology, Centro Hospitalar Alto Ave, Guimarães 4835-044, Portugal 2 Specialist Registrar, Department of Anesthesiology, Centro Hospitalar Alto Ave, Guimarães 4835-044 Portugal 3 Consultant in Anesthesiology, Department of Anesthesiology, Centro Hospitalar Alto Ave, Guimarães 4835-044 Portugal


Introduction
Retrograde endotracheal intubation was first described by Butler and Cirillo 1 in 1960 as a way to remove the tracheostomy tube in neck surgery.In this procedure, a catheter is passed towards cephalad through the tracheostomy site and emerged in the mouth; then, the catheter is sutured to an endotracheal tube and it is pulled into the trachea.Waters 2 , in 1963, described passing a plastic tube through the cricothyroid membrane and then using it as a guide to intubate patients.
Basically, retrograde intubation encompasses the introduction of a wire into the larynx through a Tuohy needle (Figure 1) in the cricothyroid membrane or membranous space between the cricoid cartilage and the first tracheal ring and blindly retrograde emerging in the mouth or nostril (Figure 2).Then, the technique proceeds with the antegrade guiding of a tracheal tube into the airway using the wire as a guide (Figure 3).Finally, with the orotracheal tube which is already present in the trachea, the wire is removed and the position of the tube is confirmed by capnography and auscultation.
The technique evolved between the 60s and 80s, and underwent a lot of developments to improve its effectiveness.It has been used in conscious, sedated or apnoeic patients [3][4][5] .It has been performed in the supine, prone and sitting positions 6 and has been used successfully in both adults 7,8 and the paediatric population [9][10][11] as young as 4 months old.There is also a report about the successful placement of a doublelumen endotracheal tube using the retrograde intubation technique to perform an approach to a lesion in the right lung 12 .Retrograde intubation can be performed using local anaesthesia with or without sedation, or under general anaesthesia with or without spontaneous ventilation, depending upon the patient, the operator, and the clinical situation 13,14 .One of the greatest enhancements in retrograde intubation has been the introduction of the Cook Retrograde Intubation Set ®13 .It made possible the use of the technique not only in urgent situations, but also in unpredictable situations in which there is no time to assemble all the components necessary for the procedure from different kits.
The use of the retrograde wire technique to assist the management of difficult airway was first reported in 1981 15 .Retrograde intubation is recognised as a useful technique in airway management, which is included in the difficult airway algorithm of the American Society of Anesthesiologists 16 in 1993 and maintained in the review of this algorithm 10 years later in 2003 17 .
Owing to the emergence of new equipments for intubation such as laryngeal mask airway, fibre optic bronchoscope, airway bougie, lighted stylet, combitube and video laryngoscopy, the retrograde intubation was somehow put aside in the management of predictable and non-predictable difficult airways in the 90s.The evidence from a study conducted by Harris et al. 13 suggests that the procedure is not widely taught and is felt by some to be an antiquated technique in a world of fibre optic visualisation tools.Competing interests: none declared.Conflict of interests: none declared.

All authors contributed to conception and design, manuscript preparation, read and approved the final manuscript. All authors abide by the Association for Medical Ethics (AME) ethical rules of disclosure.
been used successfully in many clinical situations 14 .
In the last decade, a new boom of scientific articles about retrograde intubation has been published.Case reports, applications, technique variations and comparison with other techniques reintroduce the scientific discussion of the technique, its indications, contraindications, complications and technical advances.The aim of this review was to discuss retrograde intubation.

Discussion
The authors have referenced some of their own studies in this review.These referenced studies have been conducted in accordance with the Declaration of Helsinki (1964), and the protocols of these studies have been approved by the relevant ethics committees related to the institution in which they were performed.All human subjects, in these referenced studies, gave informed consent to participate in these studies.
Several problems have been reported with retrograde intubation, which is the most frequently failed intubation caused by the tracheal tube springing into the oesophagus after the guide is removed 18 .Most frequent complications are trauma to the larynx from the introduction of the needle or wire, bleeding, haematoma, inadvertent puncture of oesophagus, the wire may pass distally into the trachea rather than into the mouth, oral or nasal trauma from the wire or passage of the endotracheal tube 19 , subcutaneous emphysema, pneumomediastinum, and infection 18 .
Retrograde intubation is contraindicated in the presence of unfavourable anatomy in the area of the cricothyroid (non-palpable landmarks, pre-tracheal mass, severe flexion deformity of the neck), some laryngotracheal pathologic conditions, significant coagulopathy, and infection 20 .
Despite the complications and contraindications described, the utility of an extremely useful tool in the anaesthesiologist's armamentarium for managing difficult airways, and it has where they are unable to ventilate or intubate.Although infrequently used, retrograde intubation can be  who use the technique frequently, retrograde intubation appears to have a high success rate 19 .A Canadian National Survey demonstrated that older anaesthesiologists had more experience with the retrograde technique and were more comfortable using it 30 .Limited teaching of retrograde intubation is due to two factors: the misperceived, exaggerated invasive nature of the procedure 26,31 and the proximity of the cricothyroid puncture site to the vocal cords 32 .We believe that training in retrograde intubation would definitely be an advance that could increase the success rate of the technique as well as decrease the complications associated with it.This belief was expressed by Harris et al. 13 also who mentioned that retrograde intubation should be included in any thorough anaesthesiology curriculum.
Recent developments are happening to enhance the retrograde intubation technique.The success of retrograde intubation and other intubation techniques when performed with the patient who is awake depends on the patient's collaboration.Thereby, there are several ways to make the procedure less aggressive to the patient.Superior laryngeal nerve block, ultrasound guided or not, is frequently used to facilitate endotracheal intubation in patients who are awake 33,34 .In a case report made by the authors of this review 22 , they have described the use of ultrasound-guided superior laryngeal nerve block (Figure 4) and transcricothyroid membrane block ( Figure 5) to suppress reflexes from the larynx, vocal cords and trachea above to smooth a retrograde intubation procedure in a patient who is awake.
Some authors bring out the combination of retrograde intubation and fibre optic bronchoscopy 31 .Fibre optic-aided retrograde intubation uses a long guide wire that emerges in the nostril; then the wire is inserted at the distal end of the working channel objective of oxygen delivery to the trachea 26 .
Unfortunately, the success rate of retrograde intubation is variable 27 .Nevertheless, Barriot and Riou 28 have reported that physicians trained in retrograde intubation can perform it in <5 minutes and in the same article, they concluded that retrograde intubation is a technique that is easy to learn and that should be developed for pre-hospital care of trauma patients.van Stralen et al. 29 reported that after training in retrograde intubation by modelling, every subject successfully completed intubation at the first time.The mean time to perform the technique was 71 seconds (95% confidence interval ±4 seconds), with a range of 42-129 seconds.They concluded that retrograde intubation can be taught easily with a mannequin.Tüfek et al. 8 stated that retrograde intubation is a simple quick procedure when performed by experienced practitioners.Some authors affirm that in the hands of those retrograde intubation is incontestable in specific situations such as blood and secretions in the airway 13,21,22 , trismus 9,23 , congenital anomalies [9][10][11] , limited mouth opening 8 , and bone and joint disorders such as rheumatoid arthritis, ankylosing spondylitis 7 , airway tumours 21,22 or failed intubation with the direct laryngoscopic technique 22,24 .
One advantage of the retrograde technique is that unlike most intubation techniques, it can be accomplished without requiring visible airway landmarks 14 .The advantages of retrograde intubation over fibre optic bronchoscope-guided intubation include its applicability when blood and secretions are present in the upper airway 8 , shorter procedural duration and a lower risk of subglottic oedema and stenosis 25 .Retrograde intubation is less invasive than needle cricothyrotomy and surgical cricothyrotomy, and if the intubation or ventilation scenarios are not possible, it can achieve the primary Competing interests: none declared.Conflict of interests: none declared.
All authors contributed to conception and design, manuscript preparation, read and approved the final manuscript.
All authors abide by the Association for Medical Ethics (AME) ethical rules of disclosure.
to come out through the proximal end of the working channel.The fibre optic bronchoscope with a preloaded tracheal tube is then rail-roaded through the nostril to the trachea, with direct visualisation of the tube with the fibre optic bronchoscope.This combination of techniques probably enhances the success rate of intubation.A case report published by the authors of this review 22 describes the use of ultrasound guidance in retrograde intubation in a patient with ulcer-vegetating neoformation of the oropharynx and hypopharynx that required tracheostomy.In this case, ultrasound visualisation of the trachea and surrounding structures secure the location of the needle ( Figure 6 and Figure 7) in the tracheal lumen, possibly to allow to reducing some of the complications that arise when retrograde intubation is "blindly" performed, like injury to blood vessels, subcutaneous emphysema or caudal migration of the guide wire.In a study conducted about the use of ultrasound in placing the cannula for tracheostomy, it was confirmed that the ultrasound had increased the success rate (43-83%) and decreased the time (110 s to 57 s) required for successful placement 35 .By performing the ultrasound guided in the retrograde intubation, authors have concluded that ultrasound guidance may be an upgrade in the retrograde intubation technique and may decrease the likelihood of complications and increase the success rate when compared with 'blind' retrograde intubation 22 .
As the Anaesthesiology Scientific Society is interested in the resurgence of retrograde tracheal intubation, more developments are expected in the near future which will possibly decrease the complications and increase the efficiency of the procedure.
While retrograde intubation may never have the popularity of other airway management techniques, we believe that it is a useful alternative in some difficult intubation    Retrograde intubation has a high level of skill retention 36 and is a simple and useful technique, with commonly available equipment or Regardless of the availability of more sophisticated tools, anaesthetists are occasionally faced with scenarios Licensee OA Publishing London 2013.Creative Commons Attribution License (CC-BY) For citation purposes: Vieira D, Lages N, Dias J, Maria L, Correia C. Retrograde intubation: an old new technique.OA Anaesthetics 2013 Nov 01;1(2):18.

Figure 1 :
Figure 1: Placement of Touhy needle in airway and introduction of a wire into the larynx through the Tuohy needle.

Figure 2 :
Figure 2: Emerging of the wire in the mouth.

Figure 3 :
Figure 3: Antegrade guiding of a tracheal tube into the airway using the wire as a guide.

Figure 4 :
Figure 4: Performance of superior laryngeal nerve block with ultrasound guidance.

Figure 5 :
Figure 5: Performance of transcricothyroid membrane block with ultrasound guidance.

Figure 6 :
Figure 6: Performance placement of Touhy needle in airway -Positioning ultrasound probe in cricothyroid membrane.

Figure 7 :
Figure 7: Performance placement of Touhy needle in airway-ultrasound image showing Touhy needle inside airway.