Difficult Airway Rescue Techniques a course for Anaesthetists Course Handbook Welcome to the dart course!



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Course Handbook



Difficult Airway Rescue Techniques

A Course for Anaesthetists

Course Handbook



Welcome to the DART course!

The course is a hands-on, practical course covering difficult airway rescue techniques described in the Difficult Airway Society (DAS) guidelines for the unanticipated difficult intubation. These techniques also form part of the Royal College of Anaesthetists competencies for Speciality Trainees.

This handbook contains a brief outline of what you will learn on the course, with some useful facts, top tips and references, and most importantly, the DAS guidelines (see Appendix).

Please try to be familiar with the DAS guidelines before you attend the course.

We have had excellent feedback from all of our courses to date, and we hope that you find the course as valuable and enjoyable as other candidates have in the past.

Thanks for your participation in the DART course.



The Severn Airway Training Society

Contents

Introduction 4

Structure of the day 7

The skills stations:

1. The fibreoptic bronchoscope 8

2. The intubating LMA 14

3. Asleep fibreoptic intubation via a conduit 18

4. Can’t intubate, can’t ventilate 23

5. Alternative laryngoscopes and supraglottic airways 29

Appendix: DAS guidelines 37

Introduction – the origins of the DART course

Tracheal intubation is a core skill which we perfect during our training as anaesthetists. It may, however, take longer than in previous years to become a true expert in this skill due to increasing use of supraglottic airways and decreased training opportunities with consultants in theatre (1, 2). With this in mind, it would seem sensible for us to undergo concurrent training in techniques to be employed when things go wrong.

The Difficult Airway Society (DAS) has produced evidence-based, peer-reviewed guidelines for unanticipated failed intubation in both the elective setting and during rapid sequence induction (3). These guidelines outline relatively simple airway skills, several of which are listed as core competencies for Speciality Trainee (ST) years 3 and 4 by the Royal College of Anaesthetists (RCoA) (4).

In our region, we felt that training opportunities were inadequate in the area of difficult airway rescue techniques. This was substantiated by a survey of local trainees and consultants, who felt that training was average to poor for all the techniques concerned. Such skills are rarely used in everyday practice and consequently, the RCoA has recommended that they be taught in a simulator setting (4). Furthermore, the acquisition of simple airway skills does not require a full high-fidelity simulator: for example, there is good evidence that practice on a simple model bronchial tree helps trainees gain the manual dexterity required for fibreoptic bronchoscopy in real patients (5).

The Difficult Airway Rescue Techniques (DART) course is aimed at trainees in the first half of their Speciality Training. It covers simple airway rescue techniques but not awake fibreoptic intubation.

The introductory session covers the DAS guidelines. These place a heavy emphasis on planning: Plans B, C and D should be decided in advance so that they can be implemented quickly if Plan A (the primary technique) should fail. The guidelines stress that oxygenation takes precedence over everything else during the execution of each plan, and that the best available help should be sought early in cases of difficulty. Many hospitals have developed their own difficult airway algorithms and some have been adopted on a regional level (6). We believe that the DAS guidelines are the most comprehensive, so we teach them on this course.

The five skills stations that follow are very ‘hands-on’: to allow for repeated practice in order to memorise the skills.

Competency Handbooks

We do not sign trainee competency handbooks for the skills we cover, as we feel that this should be done by a local trainer after a more prolonged period of assessment than we can offer in one day. You should rehearse the DART course skills with a trainer as soon as possible in your workplace in order to demonstrate your competence.



Acknowledgements

We would like to thank the Bristol Medical Simulation Centre for their help in setting up the course, the Severn Deanery for financial support and Storz who provide us with fibreoptic bronchoscopes and teaching screens. Finally, we would like to thank the consultants for giving up their spare time to teach on the course.



References

1 Yarrow S, Hare J, Robinson KN. Recent trends in tracheal intubation: a retrospective analysis of 97 904 cases. Anaesthesia 2003; 58: 1003–7.

2 Underwood SM, MacIndoe AK. Influence of changing work patterns on training in anaesthesia: an analysis of activity in a UK teaching hospital from 1996 to 2004. British Journal of Anaesthesia 2005; 95: 616–21.

3 Henderson JJ, Popat MT, Latto IP, Pearce AC, Difficult Airway Society. Difficult Airway Society guidelines for management of the unanticipated difficult intubation. Anaesthesia 2004; 59: 675–94.

4 Royal College of Anaesthetists. CCT in Anaesthesia III: Competency Based Intermediate Level (Years 3 and 4) Training and Assessment. A manual for trainees and trainers (January 2007). http://www.rcoa.ac.uk/docs/CCTptiii.pdf (accessed April 2008).

5 Ovassapian A, Yelich SJ, Dykes MHM, Golman ME. Learning fibreoptic intubation: use of simulators v. traditional teaching. British Journal of Anaesthesia 1988; 61: 217–20.

6 Mulcahy AJ, Yentis SM. Management of the unexpected difficult airway. Anaesthesia 2005; 60: 1147-8.

Structure of the day

Introductory session (40 minutes)

Introduction, a clinical scenario and a run-through of the DAS guidelines



5 Skills stations (1 hour each)

1. The fibreoptic bronchoscope: assembly, manipulation, steering, aftercare

2. The intubating LMA: blind and fibreoptic techniques

3. Asleep fibreoptic intubation via a conduit:

  • via the Berman airway

  • via the LMA with and without the Aintree Intubating Catheter (AIC)

4. Can’t intubate, can’t ventilate: cannula and surgical cricothyroidotomy

5. Alternative laryngoscopes and supraglottic airways

  • Candidates rotate through in groups of four or five

  • Each station is run by a consultant and a senior trainee

The day is punctuated by a morning coffee break, lunch provided at a local restaurant and an afternoon tea break.

Skills station 1 – the fibreoptic bronchoscope

Background

Visually-guided techniques are always preferable to blind techniques, when appropriate equipment is available. The fibreoptic bronchoscope can be used as an adjunct for the unanticipated difficult airway in a “can’t intubate can ventilate” situation (Plan B of DAS guidelines). It can also be used electively in the patient with a known difficult airway to facilitate intubation using one of the following techniques:

  1. Fibreoptically guided intubating LMA technique (Station 2)

  2. Asleep fibreoptic intubation via the LMA or Berman airway (Station 3)

  3. Retrograde intubation in an elective setting

It has been suggested that a learning curve can be constructed to predict the number of fibreoptic intubations that are necessary to become competent (1). This study suggested that trainees can become “reasonably proficient” after 18 supervised intubations (two half lives) and expert after 45 intubations (five half lives). However, research suggests that preliminary practice on simple bronchial models allows trainees to gain the manual dexterity required to perform fibreoptic intubations, and improves performance when confronted with real patients (2). Various home-made models have been described, as well as the Dexter™ training model (3) and the more lifelike airway training manikins such as the Laerdal Airway Trainer™ and the Trucorp Airsim™, which have been found to be superior for teaching simple and advanced airway management skills (4). Video cameras are especially useful in the early stages of teaching and allow for feedback and guidance (5). You are encouraged to seek out and make use of any training bronchoscopes, bronchial models or training manikins in your own hospital. If there is no such equipment, you are encouraged to ask your department to provide it!

Learning objectives

You will receive practical instruction on the following:

  1. Assembly, manipulation and steering of the bronchoscope

  2. Aftercare of the bronchoscope

You will be given lots of time to practice on three different models: an anatomically realistic airway model, the ‘Oxford box’ and the ‘Viper pit’. This will be followed by a demonstration of the aftercare process. During the station the indications, contraindications and complications of fibreoptic techniques will be revised as follows:

Indications

  • Aid to intubation

    • Known / suspected difficult airway

    • Unstable C-spine

    • Confirm placement of tracheal tube (TT) / double lumen tube / bronchial blocker

    • High aspiration risk with potentially difficult airway

  • ITU uses

    • Percutaneous tracheostomy

    • Bronchoalveolar lavage (diagnostic or therapeutic)

  • Airway assessment (usually ENT)

    • Upper airway anatomy

    • Laryngeal / cord pathology

    • Infraglottic pathology – stenoses / masses / compression

  • Teaching and Training

Contraindications

  • Absolute

    • Patient refusal

  • Relative (depending on operator skill)

    • Patient cooperation

    • Bleeding

    • Extensive facial / neck trauma

    • Critical upper airway obstruction

    • Requirement to secure airway immediately

Complications

  • Malposition

  • False passage

  • Haemorrhage

  • Oesophageal perforation

  • Surgical emphysema

  • Barotrauma / pneumothorax

Techniques you will learn

Assembly, Manipulation and Steering of Scope

Description

  • Standard 60cm length (some are 55cm)

  • Commonly 4mm diameter. Available 1.8 - 6.4mm diameter

  • ↑ diameter = larger picture, better definition

  • ↓ diameter = easier manipulation, less trauma, fewer ports

Main components

  • Body

      • Eyepiece

      • Dioptre ring (focus)

      • Lever (steering)

      • Port

  • Flexible insertion cord

  • Light transmission cord and light source / battery

Using the fibreoptic bronchoscope

  1. Attach and turn on the light source.

  2. Attach suction or oxygen at 2l.min-1.

  3. Check focus and colour / white balance.

  4. Hold body with lever facing toward operator.

  5. Place thumb on lever, index finger on suction port.

  6. The other hand guides the distal insertion cord.

  7. Keep cord taut between hands so that the orientation of the tip remains the same as the body, and movements of the body are translated to the tip.

  8. There are only 3 movements:

  • Rotation – directed from the body of the bronchoscope

  • Flexion and extension – using the lever

  • Advancement / withdrawal

  1. Advance the bronchoscope through a manikin or Oxford box.

Tips

  • Preparation – local anaesthetic, antisialogoue

  • Assistant applies jaw thrust to increase space in posterior pharynx

  • Maintain straight scope at all times

  • Orientate yourself using the triangular 12 o’clock marker

  • Aim for black

  • Bring target (“black”) into flexion plane (i.e in line with marker, between 6 and 12 o’clock) by rotating, then advance towards it by flexing / extending.

  • Keep target in the centre of the field of vision

  • If you see red, withdraw until re-orientated, don’t push further

Common reasons for failure

  • Operator inexperience

  • Failure to negotiate nares  ensure good topical anaesthesia, check nostril patency beforehand

  • Advancing TT too early  advance bronchoscope to carina before advancing TT and take care when detaching TT

Care and Aftercare of the Scope

  • Avoid excessive bending

  • Avoid knocking insertion cord

  • Keep hanging up with insertion cord straight

  • Clean immediately after use

  • Don’t let secretions dry – difficult to remove

  • Brush through suction port

  • Suck 1L water through suction port

  • Clean outside with weak detergent / sterets

  • Steris treatment (takes about 30min)

Tip

Use of the fibreoptic bronchoscope may result in a significantly increased workload for the anaesthetic assistant. Helping them out as much as possible will make their lives easier and improve your chances of being able to use it on the next patient / list.



References

1 Smith JE, Jackson APF, Hurdley J, Clifton PJM. Learning curves for fibreoptic nasotracheal intubation when using the endoscopic video camera. Anaesthesia 1997; 52: 101-6.

2 Ovassapian A, Yelich SJ, Dykes MHM, Golman ME. Learning fibreoptic intubation: use of simulators v. traditional teaching. British Journal of Anaesthesia 1988; 61: 217–20.

3 Marsland CP, Robinson BJ, Chitty CH, Guy BJ. Acquisition and maintenance of endoscopic skills: developing an endoscopic dexterity training system for anesthesiologists. Journal of Clinical Anesthetics 2003; 14: 615–9.

4 Jordan GM, Silsby J, Bayley G, Cook TM. Evaluation of four manikins as simulators for teaching airway management procedures specified in the Difficult Airway Society guidelines, and other advanced airway skills. Anaesthesia 2007; 62: 708–12.

5 Smith JE, Fenner SG, King MJ. Teaching fibreoptic nasotracheal intubation with and without closed circuit television. British Journal of Anaesthesia 1991; 71: 206-11.

Skills station 2 – the Intubating LMA

Background

The ILMA is used in Plan B of the DAS guidelines (the “can’t intubate can ventilate” situation). Outside the DAS guidelines, they can also be useful in the elective management of the known difficult airway and in patients with C-spine injuries. Fibreoptic guidance is the gold standard, but when used correctly, blind techniques have a success rate of greater than 90%:

  • Blind insertion in patients without difficult airways: 95.7% (1).

  • Blind insertion in patients with known or anticipated difficult airways: 64% first pass, 92% overall, other 8% achieved with fibreoptic technique (2).

  • In unanticipated difficult airways: one study of 23 patients – 75% first pass blind insertion, 100% overall insertion (2).

  • Using the blind technique, oesophageal intubation may be up to 5% (3).

  • Fibreoptic technique improves first attempt success rate (2), overall insertion success rate (4), and nearly always succeeds when blind technique fails (5).

  • A learning curve of about 20 insertions has been described (6).

Learning objectives

You will receive practical instruction on the following:

1. Use of ILMA for blind intubation.

2. Use of ILMA using fibreoptic guidance.

During the station the indications, contraindications, and complications of the ILMA, and its role in the DAS guidelines will be revised as follows:



Indications

  • “Can’t intubate, can ventilate” i.e. DAS Plan B (recommends fibreoptic guided intubation via an ILMA or LMA).

  • “Can’t intubate, can ventilate” where no fibreoptic bronchoscope is available (recommends blind insertion of TT via ILMA).

Contraindications

  • No previous experience

  • High aspiration risk / rapid sequence induction (no plan B in RSI)

  • Upper airway abnormality

Complications

  • Failure

  • Oesophageal intubation

  • Trauma / bleeding

  • Dental damage

Techniques you will learn

ILMA for blind intubation

1. Ensure that the head and neck are supported in the neutral position.

2. Lubricate the TT and pass through the ILMA several times up to the black 15 cm marker. Fully deflate the ILMA cuff and lubricate the mask tip. Insert the ILMA by applying the tip to the palate and advancing using a circular movement along the curvature of the device.

3. Inflate the cuff, confirm adequate ventilation then administer a muscle relaxant.

4. Pass the lubricated TT as far as the transverse 15 cm black marker with the longitudinal black line facing the nose. This is the line point at which the TT reaches the epiglottic elevator bar.

5. Advance the TT cautiously through the larynx. If any resistance is felt, stop and reposition the ILMA before further attempt (see “Tips” below).

6. Confirm placement of the TT using auscultation and capnography.

7. Remove the connector and use the stabiliser to hold the TT in place whilst the ILMA cuff is deflated and the ILMA is removed. Reapply the TT connector and check ventilation.



Reasons for failure

  • Misalignment of ILMA

  • Inadequate depth of anaesthesia / relaxation

  • Incorrect size of ILMA

  • Wrong head and neck position

Tips

  • If using cricoid pressure, reduce or release this when inserting the ILMA

  • The Chandy manoeuvre: adjust ILMA position with sagittal rotation until optimal ventilation is obtained, then apply slight anterior lift with the ILMA handle before passing TT

  • Failure to pass TT commonly means:

a) ILMA too deep – try withdrawing device slightly / smaller size ILMA

b) Epiglottis folded over – try withdrawing ILMA 4 - 5cm then reinserting



  • ILMA can be reinserted (over TT left in place) for extubation to facilitate recovery and airway maintenance or enable deep extubation

ILMA for fibreoptic assisted intubation

1. Ensure the head is supported in the neutral position.

2. Lubricate the TT and pass through the ILMA several times up to the black 15 cm marker. Fully deflate the ILMA cuff and lubricate the mask tip. Insert the ILMA by applying the tip to the palate and advancing using a circular movement along the curvature of the device.

3. Inflate the cuff and confirm adequate ventilation, then administer a muscle relaxant.

4. Pass the lubricated TT as far as the transverse 15 cm black marker with the longitudinal black line facing the nose. Advance the TT a further 1.5cm to elevate the epiglottic elevator bar which lies at 16cm (the fibreoptic bronchoscope will not do this as it is too narrow) then pass fibreoptic bronchoscope. This also helps to prevent damage to the tip of the bronchoscope.

5. Guide the fibreoptic bronchoscope into trachea and railroad the TT into the trachea. Observe placement of the TT when withdrawing the bronchoscope.

6. Confirm placement of the TT using auscultation and capnography.

7. Remove the connector and use the stabiliser to hold the TT in place whilst the ILMA cuff is deflated and the ILMA is removed. Reapply the TT connector and confirm ventilation.



References

1 Caponas G. Intubating laryngeal mask airway. Anaesthesia and Intensive Care 2002; 30: 551–69.

2 Ferson DZ, Rosenblatt WH, Johansen MJ, Osborn I, Ovassapian A. Use of the intubating LMA-Fastrach in 254 patients with difficult-to-manage airways. Anesthesiology 2001; 95: 1175–81.

3 Dimitriou V, Voyagis GS. Blind intubation via the ILMA: what about accidental oesophageal intubation? British Journal of Anaesthesia 1999; 82: 478–9.

4 Pandit JJ, Maclachlan K, Dravid RM, Popat MT. Comparison of times to achieve tracheal intubation with three techniques using the laryngeal mask or intubating laryngeal mask airway. Anaesthesia 2002; 57: 128–32.

5 Joo HS, Kapoor S, Rose DK, Naik VN. The intubating laryngeal mask airway after induction of general anesthesia versus awake fiberoptic intubation in patients with difficult airways. Anesthesia and Analgesia 2001; 92: 1342–6.

6 Parr MJA, Gregory M, Baskett PJF. The intubating laryngeal mask. Use in failed and difficult intubation. Anaesthesia 1998; 53: 343–8.

Skills station 3 - Asleep fibreoptic intubation via a conduit

Background

Much like the ILMA, asleep fibreoptic techniques using the LMA or Berman airway as conduits can be employed in the unanticipated difficult airway (the “can’t intubate can ventilate” situation, Plan B). Outside the DAS guidelines, they can also be useful in elective management of the known difficult airway and in patients with C-spine injuries. However, unlike the ILMA, these techniques should always be carried out under fibreoptic guidance, as blind success rates are low (1, 2). With the aid of a fibreoptic bronchoscope, success rates of 90-100% can be achieved (3, 4). There is also evidence to suggest that the LMA facilitates asleep fibreoptic intubation as compared to the conventional technique (without a conduit) (4).

There are many examples in the literature of successful difficult airway management using the Aintree Intubating Catheter (AIC) in combination with the cLMA (5) and PLMA (6). A recent manikin study suggests that passage of the AIC via the PLMA is as easy and reliable as via the cLMA (7). The Supreme™ LMA (see Skills Station 5) does not seem to be suitable for this purpose as the angle of exit of the AIC from the device is unpredictable due to the epiglottic fins in its bowl (8).



Learning objectives

You will receive practical instruction on the following:

1. Asleep fibreoptic assisted intubation via the Berman airway

2. Asleep fibreoptic assisted intubation via the LMA

3.Asleep fibreoptic assisted intubation via the LMA using an AIC

During the station the indications, contraindications and complications of asleep fibreoptic techniques, and their role within the DAS guidelines will be revised as follows:

Indications


  • Unanticipated difficult intubation (Plan B)

  • Known straightforward bag-mask ventilation but difficult laryngoscopy (anticipated difficult intubation)

Contraindications

  • Any possible difficulty with bag and mask ventilation (i.e can’t ventilate)

  • High risk of aspiration

  • Upper airway abnormality

Complications

  • Failure

  • Oesophageal intubation

  • Desaturation

Techniques you will learn

Fibreoptic-assisted intubation via the Berman airway

1. The head and neck should be supported in the neutral position. Confirm adequate bag and mask ventilation then administer a muscle relaxant.

2. Insert the Berman airway as a conduit to aid ventilation and for the fibreoptic bronchoscope.

3. Preload the bronchoscope with a TT then manoeuvre through Berman airway into the larynx.

4. Jaw thrust and anterior displacement of tongue may help to increase space in the posterior pharynx.

5. Once the carina is visualised, remove the Berman airway laterally from the fibreoptic bronchoscope and railroad the TT over the bronchoscope.

6. Gentle rotation of the TT can help prevent its tip from getting caught in the piriform fossae (this is easier with a reinforced TT).

7. Confirm placement of the TT using auscultation and capnography.



Fibreoptic-assisted intubation via the LMA
LMA / TT COMPATIBILITIES

LMA sizes 3 and 4 have ID of 10mm, allowing passage of a cuffed TT size 6.0

LMA size 5 has ID of 11.5 mm, allowing passage of a cuffed TT size 7.0

1. Passage of the TT through classic LMA should always be fibreoptically guided as blind success rates are low.

2. The head and neck should be supported in the neutral position. Insert the LMA in the usual fashion. Inflate the cuff and confirm adequate ventilation, then administer a muscle relaxant.

3. Pass a heavily lubricated uncut TT through the LMA. Some resistance may be met at the grille of the cLMA.

4. Guide the bronchoscope into the trachea until the carina is visualised, then railroad the TT over the bronchoscope. Observe placement of the TT when withdrawing the bronchoscope.

5. Confirm placement of the TT using auscultation and capnography.

6. The LMA should stay in place due to the difficulty and potential failure of techniques to remove it (9). The Aintree Intubating Catheter can solve this problem (see below). This is especially useful if the LMA will interfere with surgical access.

Notes


  • A maximum of two LMA insertion attempts should be made before proceeding to PLAN C.

  • The length of standard Mallinckrodt size 6.0 TT (excluding the connector) is 26-27 cm. The average distance from the connector of correctly placed size 4 LMA to the vocal cords is approx 22 cm, therefore only 4-5 cm of TT protrudes beyond the LMA grille into the trachea using the above technique. The risk of the cuff sitting astride the vocal cords and accidental extubation is therefore high. This risk can be reduced by using specialised TTs such as the nasal (north-facing) RAE (which can be straightened), flexometallic / reinforced tubes or microlaryngoscopy tubes. Alternatively, other supraglottic airways can be used – such as the Proseal™ LMA (size 4 airway channel is 17cm long, though note that the internal diameter is only 9mm) or the i-gel (size 4 airway channel is 19 cm long).

  • The aperture bars of a classic LMA can obstruct the passage of the tracheal tube.

Fibreoptic-assisted intubation via the LMA using the Aintree Intubating Catheter (AIC)

1. The head and neck should be supported in the neutral position. Insert an LMA in the usual fashion. Inflate the cuff and confirm adequate ventilation, then administer a muscle relaxant.

2. Load the AIC over a well lubricated bronchoscope, then guide the assembly through the LMA grille and into the trachea, until the carina is visualised.

3. Remove the bronchoscope from the AIC. The “Rapi-fit” connector (which comes with the AIC) may be fitted to allow oxygenation using any anaesthetic circuit with a 15 mm connector.

4. Remove the LMA and railroad a lubricated TT size 7.0 or above.

5. Confirm placement of the TT using auscultation and capnography.


The Aintree Intubating Catheter has an external diameter of 6.5mm, so must be used with TT size 7.0 or above


Notes

  • Use of Aintree Intubating Catheter is preferable because:

  • It allows removal of the LMA

  • It reduces the likelihood of the TT getting caught in the LMA grille

  • It enables oxygenation via the “Rapi-fit” connector in case of difficulty passing TT

References

1 Lim SL, Tay DH, Thomas E. A comparison of three types of tracheal tube for use in laryngeal mask assisted blind orotracheal intubation. Anaesthesia 1994; 49: 255–7.

2 Asai T. Blind tracheal intubation through the laryngeal mask. Canadian Journal of Anaesthesia 1996; 43: 1275.

3 Pandit JJ, Maclachlan K, Dravid RM, Popat MT. Comparison of times to achieve tracheal intubation with three techniques using the laryngeal mask or intubating laryngeal mask airway. Anaesthesia 2002; 57: 128–32.

4 Koga K, Asai T, Latto IP, Vaughan RS. Effect of the size of a tracheal tube and the efficacy of the use of the laryngeal mask for fibrescope-aided tracheal intubation. Anaesthesia 1997; 52: 131–5.

5 Higgs A, Clark E, Premraj K. Low-skill fibreoptic intubation: use of the Aintree Catheter with the classic LMA. Anaesthesia 2005; 60: 915-20.

6 Cook TM, Seller C, Gupta K, Thornton M, O’Sullivan E. Non-conventional uses of the Aintree Intubating Catheter in management of the difficult airway. Anaesthesia 2007; 62: 169-74.

7 Blair EJ, Mihai R, Cook TM. Tracheal intubation via the Classic™ and Proseal™ laryngeal mask airways: a manikin study using the Aintree Intubating Catheter. Anaesthesia 2007; 62: 385-7.

8 Greenland KB, Tan H, Edwards M. Intubation via a laryngeal mask airway with an Aintree catheter – not all laryngeal masks are the same. Anaesthesia 2007; 62: 966-7.

9 Alexander R. Do not remove the laryngeal mask airway. Anesthesia and Analgesia 1999; 89: 536–7.

Skills station 4 – “Can’t intubate, can’t ventilate”: cannula and surgical cricothyroidotomy

Background

Cricothyroidotomy forms part of the DAS guidelines in the “can’t intubate, can’t ventilate” scenario once oxygen saturations have fallen below 90% on FiO2 of 1.0 (Plan D).

There are three basic methods to achieve trans-tracheal ventilation (1):

  • Small cannula techniques (2-3 mm) plus a high pressure gas source. These techniques rely on a patent airway for exhalation. However, inability to inflate the lungs with positive pressure ventilation via a facemask does not mean that there the airway will be obstructed in expiration, when positive intraluminal pressure tends to expand and open the upper airway. In one series, 86% of patients with CICV retained a patent expiratory route (2). Gas entrainment is also a feature of these techniques if the upper airway is not obstructed

  • Large cannula techniques (≥4 mm). These enable ventilation with a lower pressure gas source but require either a cuffed cannula or obstruction of the upper airway to achieve adequate driving pressure for ventilation

  • Surgical technique. This enables placement of a size 6,0 to 7.0 tube and conventional ventilation

A recent systematic review came to the conclusion that surgical cricothyroidotomy should replace needle techniques as the intervention of choice for the “can’t intubate, can’t ventilate” scenario (3). The authors maintain that the surgical technique is easily taught, allows for sustained, adequate ventilation and has relatively fewer complications than needle cricothyroidotomy.

There is general agreement that a small bore needle cricothyroidotomy must be coupled with a high pressure gas source (1, 3). However, when low pressure ventilation is to be utilised, different practitioners may opt for either a large bore cannula or a surgical technique. With the advent of cuffed Seldinger - based kits (such as the Melker™), practitioners (especially those familiar with percutaneous tracheostomy) may opt for this technique. Of note, the surgical technique has been found to be quicker to perform than Seldinger techniques in a manikin (4).

Learning objectives

You will receive practical instruction on the following:

1. Surgical cricothyroidotomy.

2. Cannula cricothyroidotomy.

During this session you will be taught how to carry out a surgical airway and a needle cricothyroidotomy. You will also be taught to use the Manujet™ / Sanders injector. During the station the indications, contraindications and complications of cricothyroidotomy, and its role within the DAS guidelines will be revised as follows:

Indications

  • “Can’t intubate, Can’t ventilate” situation (DAS guidelines Plan D)

  • Elective trans-tracheal ventilation in the anticipated difficult airway

  • Cricothyroid puncture for airway anaesthesia in awake fibreoptic intubation

Contraindications

  • In the emergency situation - none

  • In the elective situation: patient refusal, local trauma, surgical emphysema, infection, coagulopathy, goitre, aberrant vasculature

Complications

  • Malposition

  • False passage

  • Haemorrhage

  • Oesophageal perforation

  • Surgical emphysema

  • Barotrauma / pneumothorax

Techniques you will learn
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