Endotracheal tube and tracheal intubation

23.4 Endotracheal tube and tracheal intubation



Michelle Lin



Background


Endotracheal intubation (TI) provides a definitive airway. Insertion of a tube between the vocal cords and into the trachea allows optimal management of the patient’s oxygenation and ventilation, while also protecting the airway from aspiration. Depending on the preparation and skill of the practitioner, this procedure can be either life saving or life compromising. TI is the standard rescue procedure when bag–mask (BM) ventilation is ineffective or insufficient.


The anatomy of the paediatric airway creates unique considerations during intubation as compared to adult intubation. Specifically, the differences are as follows:


A paediatric patient has a relatively larger tongue, making visualisation of the vocal cords more difficult. Hence, preintubation positioning of the patient plays a crucial role in TI success.

A paediatric patient has a wider and floppier epiglottis. Thus, in neonates and infants, use a straight laryngoscopic blade to achieve the best visualisation of the vocal cords. The blade moves the posteriorly-hanging epiglottis anteriorly, exposing the vocal cords.

A paediatric patient has more anterior and cephalad vocal cords. A straight laryngoscopic blade provides the best direct line-of-sight to the anteriorly-positioned cords.

The cricoid ring is the narrowest part of the airway in patients less than eight years old. This anatomical narrowing naturally secures the endotracheal tube in place at the cricoid ring level without an air leak. Endotracheal tubes therefore do not need to be cuffed. In contrast, adolescents and adults have a cylindrical-shaped rather than a funnel-shaped airway, and they do require cuffed tracheal tubes to help secure the tube and prevent an air leak.

A paediatric patient has large adenoidal tissue and relatively small nares. Consequently, nasotracheal intubation in the paediatric population is technically difficult and has a high complication rate from traumatic bleeding, aspiration, and oesophageal intubation. These intubations also generally take a longer time to perform and require a patient who is awake and cooperative. The orotracheal route is the preferred approach.

In addition to proper positioning and equipment selection, successful emergent intubation often requires the administration of rapid sequence induction (RSI) medications. These medications provide transient sedation and neuromuscular relaxation during the procedure. Induction agents include ketamine, fentanyl, and midazolam, and neuromuscular paralysing agents include succinylcholine, rocuronium, and vecuronium. The advantages of RSI are twofold. First, the patient will not instinctually struggle against noxious stimuli, such as the laryngoscopic blade and tracheal tube insertion. This optimises the chances of visualising the vocal cords. Second, the induction agents affect the following autonomic responses.


Bradycardia – patients less than 5 years old have a higher risk for bradyarrhythmias with direct laryngoscopy because of vagal nerve stimulation. Consequently they may require atropine prophylactically in their RSI drug regimen.

Tachycardia and hypertension – induction medications attenuate this catecholamine response to laryngoscopy and intubation.

Gag reflex – patients requiring emergency intubation benefit from RSI medications because patients are assumed to have a full stomach, the contents of which may regurgitate during intubation. By blunting the gag reflex using RSI, the risk of oesophageal reflux and pulmonary aspiration decreases. The process of RSI includes cricoid pressure, which also limits regurgitation and aspiration.

The advantages of RSI agents, however, must be balanced against the primary disadvantage of persistent apnoea after a failed intubation. The practitioner must be aware that when patients receive these drugs, unsuccessful intubations may cause the patient to drop their oxygen saturation precipitously.



Indications



• Cardiopulmonary arrest.

• Respiratory failure or obstruction.

• Excessive work of breathing refractory to BM ventilation.

• Loss of the gag reflex.

• Need for prolonged ventilation or hyperventilation.


Contraindications



• Adequate response to bag mask (BM) ventilation with anticipated short requirement for assisted ventilation.

• Structural abnormalities, such as a large tongue haematoma, or massive facial injuries that require a tracheostomy or cricothyrotomy.

• Functioning tracheostomy.


Equipment



Cardiopulmonary and oxygen saturation monitor.

Rigid-tip suction catheter.

BM and self-inflating bag.

Laryngoscope (Figs 23.4.1, 23.4.2).

Endotracheal tube (Fig. 23.4.3).

Endotracheal tube stylet.

Syringe for cuffed endotracheal tube.

Device for confirmation of intubation (Chapter 23.5).

Strong adhesive tape for securing the endotracheal tube.

Bite block or oropharyngeal (OP) airway.

image

Fig. 23.4.1 Curved (top) versus straight (bottom) laryngoscopic blades.


image

Fig. 23.4.2 Insertion of laryngoscopic blades.


Laryngoscopes are available with either a straight blade end (A) or a curved blade end (B). The straight laryngoscopic blade should slide just ‘under’ or posterior to the epiglottis and elevate the tongue and epiglottis as a unit to visualise the vocal cords. Because of their floppy and large epiglottis, neonates and infants less than 5 years old require this straight blade for better visualisation of the cords. For older patients, both straight and curved blades are acceptable. When the curved laryngoscopic blade is used, the blade should rest in the vallecular space just anterior to the epiglottis and posterior to the base of the tongue. Lifting the laryngoscope up towards the ceiling elevates the vallecular space and the tongue as a unit, which indirectly lifts the epiglottis anteriorly to allow visualisation of the vocal cords.

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Sep 7, 2016 | Posted by in EMERGENCY MEDICINE | Comments Off on Endotracheal tube and tracheal intubation

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