Magill first developed a tracheal tube in response to the need to deliver anesthetic gases to patients in the United Kingdom who incurred facial injuries in World War I. The original tubes, subsequently manufactured and sold by Portex, were cut from a roll of red rubber tubing, resulting in a natural curve. Because these devices were not cuffed, swabs of cotton were placed at the side of the tube once the tube was in place in the patient’s trachea.

Contemporary tracheal tubes have circular walls, which help prevent kinking. The proximal portion (the machine end) attaches through a standardized connector to the anesthetic circuit. The distal portion (the patient end) typically includes a slanted portion, called the bevel, and a Murphy eye (Figure 10-1), which provides an alternative conduit for gas flow should the tip of the tube obstruct if pressed against the carina or wall of the trachea. Tracheal tubes also commonly have a radiopaque marker that runs the length of the tube and can be used radiographically to determine tube position within the trachea.

Most adults are intubated with cuffed tubes, whereas the practice of using cuffed versus uncuffed tubes varies in children (Figure 10-2). The cuff acts as a seal between the tube and the trachea, the purpose of which is threefold: to prevent aspiration of pharyngeal, gastric, or foreign objects into the trachea; to prevent gas leak; and to center the tube in the trachea. If the tracheal tube includes a cuff, it will also have an inflation valve, a pilot balloon, and an inflation tube at the proximal end. Several different cuff systems are in use (Table 10-1).

Because a variety of factors may lead to changes in cuff pressure, some authorities recommend that cuff pressures be measured at end expiration in operations that last longer than 4 to 6 hours (Box 10-1). Pressure measurements can be obtained by connecting the inflation tube to a manometer or to the pressure channel of a monitor by using an air-filled transducer. Using the “feel” of the pilot balloon as a measurement of intracuff pressure has not been shown to be reliable. Pressures should be maintained between 25 and 34 cm H₂O (18-25 mm Hg) in normotensive adults. N₂O can diffuse into the cuff, leading to increased intracuff volume and pressure if the cuff is filled with air. When N₂O use is discontinued, the intracuff pressure decreases rapidly; therefore, if the tracheal tube is to be left in postoperatively, the cuff should be deflated and reinflated with air to prevent a leak.

Tracheal tubes contribute to airway resistance and increase the work of breathing. The internal diameter (ID) correlates with the tube size and is the main determinant of the resistance to flow. The length of the tube also contributes to resistance. The smaller and longer the tracheal tube, the greater the resistance. There is no dedicated method for determining the appropriate tube size for a given patient. A 7.0-mm ID tube is adequate for most women and an 8.0-mm ID tube is appropriate for most men. Age is the most reliable indicator of tube size for children. A tracheal tube should be inserted until the cuff is 2.25 to 2.5 cm past the vocal cords. Typically, this correlates with an insertion distance of 23 cm at the incisors for a man and 21 cm for a woman.

Tracheal tubes have many desirable features, such as providing a secure protected airway; decreasing pollution in the operating room by inhibiting escape of anesthetic gases; and allowing for accurate monitoring of end-tidal gases, tidal volume, and pulmonary compliance. However, their use is associated with a variety of complications (Box 10-2