When the glottis is difficult to visualize via traditional direct laryngoscopy (DL), indirect line-of-sight devices have been used to facilitate endotracheal tube (ETT) placement. Two physical objects that can change the angle of reflected light are the mirror and the prism. These have been incorporated into laryngoscopic blades with varying success. The mirror blades enable a more “anterior” view of the larynx by reflecting the light. However, this reflection comes with the price of an inverted image, which can make initial use awkward. Two examples of blades that incorporate mirrors are the Siker blade¹ (Fig. 16-1) and the Neustein blade. The Neustein involves a mirrored attachment to the MacIntosh (Mac) blade that includes a guide channel for a stylet, over which the ETT is passed following blade removal.²

The prism can also be harnessed to obtain a better laryngoscopic view, and its utility has been understood since the early 20th century. It was not until the 1960s when Huffman described a prism made from Plexiglas that the concept came to fruition and became practical for use in airway management. Huffman’s prism was designed for attachment to the standard MacIntosh blade, and provided a generous 30° of light refraction (Figs. 16-2 and 16-3).³ A subsequent evolution of the prism blade is the Belscope. This is a derivation of the straight blade, with a 45° angulation at its midpoint as well as a design that incorporates an optional prism, and is available in three sizes.⁴ Although these devices may improve a grade 3 or grade 4 view of the larynx, they may also reduce the room needed for manipulation of the ETT in the mouth.

One of the limitations of using either prism or mirror blades is the potential for fogging. This challenge can be overcome by warming the devices before use, or the addition of a defogging solution. However, this preparatory work cannot be managed easily outside of the operating room (OR). In these settings, the Airtraq, another prism-based device, can be of great use. The Airtraq is essentially a self-contained single-use airway device with mirrors and a prism at its heart (Figs. 16-4 and 16-5). The device is constructed of plastic and is therefore more resistant to fogging. For routine OR use, inclusion of an antifog solution is advisable; however, the device is functional in an emergency without such accessories. It also has the advantage of being one integrated tool, and therefore it is impossible to misplace or scratch the integral prism, which is all too easy to do with the small Huffman devices. The Airtraq comes in several sizes, designed for oral, nasal, and double lumen endobronchial intubation. Indications for use include airway management in patients who are at risk for difficult intubation,⁵ morbidly obese,⁶ and/or in cervical spine immobilization.⁷ The Airtraq would therefore be uniquely suited to be included among equipment on ambulances and in difficult airway bags. In these situations, in which space is quite limited, inclusion of more technically advanced and significantly more expensive adjuncts (such as a rigid optical stylet or fiberoptic bronchoscope) is seldom practical. The Airtraq also has an optional wireless display screen with a reusable camera that can be attached. This screen view increases both field of view and discrimination of objects and can be useful when training airway novices.