Endotracheal intubation involves target localization (direct laryngoscopy, an indirect method of imaging, or blind insertion with Fastrach LMA) combined with placement of the tube into the trachea. The design of a tracheal tube affects the procedure in several ways. Airway managers, especially those dealing with emergency airways, should understand these issues to ensure first-pass success and decrease the number of intubation attempts. Repetitive intubation attempts during cardiac arrest or following rapid sequence intubation are associated with hypoxia, regurgitation, aspiration, and death.
The tip of the tube interacts with the trachea rings and can cause different problems depending on the specific intubation technique. Tip design affects how the tube is delivered when it is slid off of a metal stylet, an optical stylet, a tube introducer (a.k.a., bougie), or a fiberscope. When using the nasal route of intubation, the tip of the tube (or nasal trumpet) interacts with the nasal turbinates and can cause trauma or bleeding if handled incorrectly. Standard tracheal tubes have an asymmetric left-facing bevel that frequently catches on the anterior tracheal rings, depending on how intubation is being performed and other factors (shape of stylet, etc.). Some standard left-facing bevel tubes have a straight cut, while others have a hooded tip design in which the leading edge of the tube is slightly rounded. Parker tracheal tubes have a symmetric ski-tip design made to minimize anterior tracheal ring trauma and mechanical issues. The custom tracheal tube on the Fastrach LMA has a soft symmetric tip that is ideal when passed blindly toward the larynx through a supraglottic airway.
Examples of tracheal tube tip designs (above, from left to right): Left-facing beveled tube with straight cut, left-facing bevel with rounded edge, Parker ski-tip, LMA Fastrach disposable tracheal tube tip.
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AIRWAY CAM distributes tracheal tubes from Parker Medical and SunMed.
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Most PVC tracheal tubes have an inherent arcuate shape that influences tube delivery and target visualization. Articulating tracheal tubes (distal tip flexes when pulling a proximal ring) are very helpful when using the nasal route. Tubes designed for oral surgery (oral or nasal RAE tubes) have preformed shapes to keep the tube out of the surgical field. Some tracheal tubes are packaged with preformed stylets that match the gentle arcuate shape of the tube. A straight-to-cuff stylet and tube shape has significant benefits for tube delivery during laryngoscopy, and arcuate shaped tube/stylet combinations are not recommended.
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Examples (above) of a pre-packacked tube and stylet (left), a standard tube with an inherent arcuate shape (middle), and an articulating tube with a ring to flex the distal tip (Parker EasyCurve).
Articulating tracheal tubes that are ideal for nasal intubation (Endotrol by Mallinckrodt, or articulating Parker EasyCurve tube) are made of a softer durometer (hardness) than standard tubes designed for oral intubation. Some practitioners thermosoften standard tubes to achieve the same effect because a softer tube minimizes nasal bleeding.
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In addition to tip design and shape, anther variable in tube design has to do with cuff shape. Standard tracheal cuffs have an oval shape, while others use a cuff that resembles a football and has a much small profile (even when deflated). A billowy or partially inflated tracheal tube cuff can obscure target visualization when performing direct laryngoscopy. A new design by Nellcor features a tapered cuff that decreases the incidence of ventilator associated pneumonia.
Different cuff designs (above) of Nellcor tube from left to right: Barrel (Hi-Lo), football (Lo-Pro), and tapered (TaperGuard).
Nellcor has also pioneered the development of tubes that allow suctioning of secretions that collect above the cuff, i.e. Evac tubes. These tubes have been shown to have a marked clinical benefit and many hospitals now recommend them in patients who likely to remain intubated for more than 72 hours. The added suction channel does increase the tube diameter, however, which can sometimes affect insertion.