Special Techniques

Awake Tracheal Intubation

Preparation
* Monitoring
* Augment FiO2
* Anticholinergic drying agent- glycopyrrolate
* Topical anaesthesia
* Nerve blocks
* Sedation
* The natural airway is better maintained in awake patients and muscle tone is retained, keeping the upper airway structures and posterior pharyngeal separated from each other.
* With the induction of anaesthesia and paralysis, the larynx moves anteriorly making conventional intubation more difficult.

Topical Anaesthesia
* 4 ml 4% lignocaine ( nonviscous) nebulized directly via the mouth x2 ­ NB must allow sufficient time.
* If nasotracheal intubation is planned, both topical vasoconstrictors (cocaine), and local anaesthetic should be applied to the nose
Nerve Blocks
* Glossopharyngeal nerve
The lingual branch of the glossopharyngeal nerve usually needs to be blocked to ablate the gag reflex when awake direct laryngoscopy is planned.
* Superior laryngeal nerve
Supplies lower pharynx. When this nerve is blocked in conjunction with the above, awake direct laryngoscopy is possible.

Sedation
* Degree of sedation required depends primarily on how well the airway is prepared topically
* Must maintain meaningful contact with the patient.
* Remifentanil 0.05-0.15 mcg/kg/min reduces anxiety and increases the pain threshold. This should be started at the lowest rate and cautiously increased as the need arises.

Choice of Intubation Technique
* Direct laryngoscopy
* Blind intubation
* Flexible fibreoptic intubation

Flexible Fibreoptic Intubation
* Can be performed via the nasal or oral route, with or without a stiff conduit designed to bring the scope close to the laryngeal aperture without any manipulation on the part of the operator.
* Nasal ­ nasal tube ( presoftened in hot H2O)
* Oral ­ Berman, Ovassapian or Laryngeal mask
* Before insertion, the FOB should be lubricated and an appropriately sized ETT threaded over its proximal end. O2 can be insufflated down the FOB to augment FiO2 and blow away secretions.
* Once the FOB is above the cords it may be necessary to spray the cords with lignocaine via the side-port.
* After the FOB has been passed into the trachea the ETT can be threaded over it and the FOB withdrawn.The ETT adaptor is inserted and the tube connected to the circuit, position of the ETT is confirmed with capnography.

CRICOTHYROIDOTOMY

CRICOTHYROIDOTOMY

* Oxygenation can be achieved with:
IPPV using standard anaesthetic circuit
High pressure jet ventilation
* Continuous surveillance of airway access is vital as surgical emphysema will render any other emergency procedure (eg tracheostomy) more difficult if not impossible.
* IPPV with anaesthetic circuit via cricothyroidotomy
* Specific cricothyroidotomy kit with 15mm tapered connector allowing connection to anaesthetic circuit
* 14 or 16G cannula with size 7.5 ETT connector connected to 3ml plungerless syringe can be put together to use with breathing circuit
* Others……
* Be familiar with a system that uses equipment that is readily available in theatre

Transtracheal jet ventilation

* Percutaneous TTJV using a large bore ( 14G) intravenous catheter through the cricothryoid membrane is relatively quick and simple.
* Require a high pressure O2 source ( 50 psi)
* Formal minitrach kits which can be attached directly to a normal circuit provide a more stable airway which is almost as quick
* 14G needle midline through cricothyroid membrane
* 3 way tap to cannula which allows exhalation port if glottis closed.
* Means of connecting to anaesthetic machine
e.g. 1): 2ml syringe with plunger removed attached to 3 way tap. 7.5mm ETT connector removed and inserted into barrel of the 2ml syringe. This then allows connection to anaesthetic circuit.
e.g. 2): Pump set connected to 3 way tap. Hand pump section cut obliquely and placed over common gas outlet.
* Pushing flush valve then allows oxygenation of patient. Ventilation may not be adequate but oxygenation will give time for formal airway.
* Alternatively a jet injector may be connected to 3 way tap which will provide adequate oxygenation and ventilation

AFTER CRICOTHYROIDOTOMY?

Successful oxygenation via cricothyroidotomy should be followed by a definitive airway:

* Tracheostomy
* Tracheal intubation
* Restoration of spontaneous ventilation by patient

Retrograde Intubation

Retrograde Intubation

* 18G intravenous cannula through cricothyroid (confirm with air drawn through syringe with saline)
* Feed epidural catheter out through mouth/ nose
* ETT over epidural catheter (best ETT is Fastrach blunt tipped ETT)
* Advance ETT through to glottis
* FOB through ETT which should be on or just beyond vocal cords
* Pass FOB through to carina
* Remove epidural catheter
* Pass ETT over FOB
* Confirm with EtCO2

TRACHEOSTOMY

TRACHEOSTOMY

* Ideally, should be performed by a skilled ENT surgeon
* In an emergency: Cricothyroidotomy performed with surgical blade & incision spreaded with a Kelly clamp to allow passage of small ETT

Laryngeal mask airway

Laryngeal mask airway

* Routine airway
* Emergency and nonemergency situation
* Use of LMA as a conduit for tracheal intubation
* Fastrach intubating laryngeal mask
* Release of cricoid pressure may be required to insert & to allow correct placement of LMA.
* The standard LMA is easier to use than the intubating LMA, it also provides a conduit for intubating the trachea.
* A size 6 ETT can be loaded onto a fibreoptic bronchoscope & passed into trachea via the LMA
* Portex has recently put out a disposable LMA without laryngeal slits & a wider shaft. These features should facilitate the passage of an ETT into the trachea

Intubation via FOB through LMA

Intubation via FOB through LMA

* A 6 .0 ETT fits through a 3 or 4 LMA and a 7.0 fits through a size 5 LMA-remove LMA adaptor first.
* Once the FOB is in the trachea, the ETT can be passed through the LMA and into the trachea. If the LMA is left in situ, it will have to be sacrificed to avoid extubating the patient. Alternatively, the ETT can be passed through the LMA outside the patient while the FOB remains in the trachea as a guide for later passage of the tube.
* A 90°anticlockwise turn may be necessary to pass the ETT into the trachea if it catches on the right arytenoid cartilage

Intubating Laryngeal Mask

Intubating Laryngeal Mask

* Neutral head position
* Choose correct size:
30-50kg= ILM 3, 50-70kg=ILM 4, 70-100kg=ILM 5
* lubricate posterior surface of ILM
* Lubricated ETT passed through ILM and removed before patient insertion
* Once ILM positioned in patient connect to circuit
* commence IPPV with tidal volume < 8 ml/kg
* manipulate ILM to produce best capnography trace ie long straight expiratory curve
* Gently pass well lubricated ETT through LM do not force
* Once positioned connect to circuit and confirm position with capnography

Unsuccessful Passage of Intubating Laryngeal Mask

Unsuccessful Passage of Intubating Laryngeal Mask

* Note distance beyond transverse mark on ETT where obstruction occurs
* immediate resistance: ILM may be too large
* resistance at 2 cm: may be downfolded epiglottis
withdraw ILM 6 cm and reinsert
* resistance at 3 cm: ILM may be too small
* resistance at 4 cm: ILM may be too large
* Alternatively use FOB through ILM
ETT will need to be passed 1.5cm beyond transverse mark
this allows FOB to travel forward unimpeded by the epiglottic elevating bar of the ILM

Combitube

Combitube

* An airway device with two lumens and two cuffs
* Tracheal lumen (blue, labeled 1)
* Oesophageal lumen (clear, labeled 2)
* 2 syringes 140ml & 12ml
* Gently insert the Combitube into the mouth and continue to depth marker. The distal oesophageal lumen will then be either in the trachea or oesphagus
* Inflate blue oropharyngeal cuff with 85ml of air and the distal white cuff with 10-15ml of air
* Attempt ventilation through clear oesophageal lumen and confirm ventilation with capnography. If this lumen is in oesphagus attempt ventilation through blue tracheal lumen and confirm with capnography.