Chapter 7. Advanced management of the airway and ventilation
The gold standard for airway control in prehospital care is endotracheal intubation using a cuffed tracheal tube, however basic airway management must be mastered before learning advanced techniques.
Accidental and unrecognised oesophageal intubation is likely to be fatal. Excessive movement of the head and neck during laryngoscopy and intubation may aggravate a cervical spine injury.
Tracheal intubation
The trachea can be intubated via the oropharynx or via the nasopharynx. Oropharyngeal endotracheal intubation requires a laryngoscope for successful placement.
Indications
• Airway obstruction or potential airway obstruction in the profoundly unconscious patient with no gag reflex
• Patient at risk of aspiration of foreign material (e.g. gastric contents, blood from maxillofacial trauma)
• Patient requiring positive pressure ventilation, e.g. in cardiorespiratory arrest
• To gain access to the lower respiratory tract to aspirate secretions or foreign material.
Contraindications
• Insufficient operator skill or experience
• Conscious or semiconscious patient
• Immobility of the head and neck (relative)
• Distorted anatomy (relative)
• In children:
• Croup
• Epiglottitis
• Gag reflex present.
On NO ACCOUNT should attempts be made to intubate children with croup or infections such as acute epiglottitis.
However, if the child loses their airway anyway, then cautious intubation or surgical airway may be life-saving.
Equipment for conventional endotracheal intubation
The following equipment is required:
• Appropriate sized laryngoscope in working order, different size blades
• Appropriate range of tubes cut to correct length with connections (15 mm) to fit the bag valve device
• Suction apparatus
• Lubricant on a gauze swab (only occasionally required in the prehospital setting)
• 20 mL syringe for cuff inflation
• Flexible bougie and stylet
• Magill’s forceps
• Tape or tie to secure tube in place
• Apparatus to inflate the lungs (bag valve device or ventilator)
• Pulse oximeter to monitor patient during and after intubation attempt
• End-tidal CO 2 apparatus to detect correct tube placement
• Rescue equipment including laryngeal mask airway and surgical airway.
Size of endotracheal tube
ET tubes of size 7–9 mm will fit most adults. ET tubes are made longer than is generally needed and should be cut to a length of 21–25 cm in order to reduce dead space. The length required in any individual will be twice the distance from the corner of the mouth to the angle of the jaw.
For children, the correct size can be calculated using the following formulae:
Once the correct diameter has been calculated, have the next biggest and the next smallest tube available to ensure a good fit.
In children it is important that the full range of ET tube sizes (including half sizes) are available. ET tubes <6.5 mm are not supplied with an inflatable cuff, in order to avoid pressure damage to the trachea.
Technique for endotracheal intubation using laryngoscopy
1. Ensure that all equipment functions correctly and that tubes and bougies are well lubricated if necessary
2. The patient should be supine with the head and neck aligned in the clear airway position (preferably with the head on a small pillow or rolled-up blanket). Apply cricoid pressure if possible
3. Holding the laryngoscope in the left hand, insert the curved blade into the right-hand corner of the patient’s mouth, ensuring that the lip is not caught between the blade and lower teeth
4. Advance the blade, aiming for the larynx in the midline, and displacing the tongue towards the left-hand side of the mouth to leave a clear view
5. When the tip of the blade reaches laryngeal level, lift the handle forwards and upwards. Slide the tip of the blade into the recess between the epiglottis and the base of the tongue
6. Maintain the backwards tilt of the head by pressing on the occiput with your other hand and against the tip of the blade to get the best view of the glottic opening. Cricoid pressure will generally improve the view and should be used in all patients in the field
7. Pass the tracheal tube from the right-hand side of the mouth through the glottic opening, rotating it 90° counter-clockwise if necessary, to ease entry between the vocal cords
8. If a full view of the glottis is not possible a bougie may be passed under direct vision through the cords and the tube introduced over the bougie into the trachea. The bougie is then withdrawn. Alternatively, a malleable stylet may be placed inside the lumen of the tube and bent to a curve suitable for introduction of the tube through the glottis
9. Once the tube has passed between the vocal cords it should be advanced so that the cuff lies below the larynx
10. The cuff should be inflated with air (or sterile water if the patient is to be transported at altitude or in a decompression chamber). Sufficient air should be introduced to eliminate any leak at the peak of positive pressure ventilation. Cuff inflation volumes requiring more than 15 mL should lead to a suspicion that the tube is misplaced in the oesophagus or that the cuff itself has developed a leak
11. Check that the tube is in the trachea by observing bilateral chest movement and listening for air entry over both upper lobes. Unilateral chest movement (generally on the right) may indicate that the tube has gone down too far and has entered the main bronchus. A check should also be made that air entry is not heard in the epigastric area. However end tidal CO 2 monitoring is the gold standard
12. Secure the tube in place with a tie or tape. Remove cricoid pressure.
The entire process of intubation should be accomplished in 30 seconds or less. If the attempt is taking longer, then it should be temporarily abandoned and the patient ventilated with oxygen via a face mask for 1–2 minutes before trying again. Note that ventilation via a mask between intubation attempts is pointless if the airway remains obstructed. No more than two attempts should be made before moving to other measures.
Complications of endotracheal intubation
• Trauma to lips, teeth, tongue and structures in the pharynx and larynx (a common problem is using the teeth as a fulcrum, causing damage to crowns particularly)
• Oesophageal intubation likely to guarantee patient death
• Intubation of a single bronchus will lead to hypoxia and collapse of the opposite lung
• Aspiration of foreign material such as stomach contents or blood during the intubation attempt
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