The length of a correctly sized nasopharyngeal airway is the same as the distance

Nasal and Oral Airways

Nasal and oral airways can sometimes be useful in pediatric patients to relieve airway obstruction, especially during face mask ventilation at the beginning or end of anesthesia. The nasal airway should be carefully placed through one of the nares after lubricating its exterior. The nasal airway must be long enough to pass through the nasopharynx, but short enough that it still remains above the glottis.

Oral airways relieve airway obstruction by displacing the tongue anteriorly. Too large an oral airway will either obstruct the glottis or may cause coughing, gagging, or laryngospasm in a patient who is not deeply anesthetized. Too small an oral airway will push the tongue posteriorly and make the airway obstruction worse. Oral airways should be placed with care to prevent trauma to the teeth and oropharynx.

Airway Adjuncts (Oral Airways, Nasopharyngeal Airways)

Oropharyngeal (OP) and nasopharyngeal (NP) airways can be used to maintain airway patency, particularly during BVM ventilation, but provide no airway protection. In general, a patient who requires a device to maintain airway patency may also require intubation for airway protection. Both devices exist in a range of sizes suitable for all pediatric ages. The correct size of an OP airway for a patient can be estimated by the distance from the patient's central incisors to the angle of the mandible; for NP airways, the correct size is estimated by the distance from the naris to the earlobe. OP airways, when properly positioned, tend to rest against the base of the tongue and, in conscious patients, can induce gagging and vomiting so they should be used only in the unconscious patient. An OP airway should always be used when an unconscious patient is undergoing bag-mask ventilation.

Oral and Nasal Airway Devices

Oral and nasal pharyngeal airway devices are used in pediatric anesthesia to improve the patency of the upper airway and to facilitate delivery of oxygen or anesthetic gases to the lungs. Minimum requirements for these devices are noted in ANSI/ISO5364-08 (ANSI/ISO 2008). The Guedel-type oral airway device is probably most commonly used in pediatric patients. It contains a central lumen for the passage of airflow and for suctioning of the posterior pharynx (Fig. 16-9,A). The oral airway device is primarily used to alleviate upper airway obstruction caused by tonsillar or adenoidal hypertrophy, or normal pharyngeal tissue obstruction, as often occurs in small infants. Oral airway devices may also be used to facilitate fiberoptic intubation attempts (Atlas 2004).

Oral airway devices are usually manufactured from plastic or polyethylene and are latex-free. They are sized according to the total length of the device (50 to 80 mm, flange to tip, for most children) or based on an arbitrary scale designated by the manufacturer. The appropriate size is determined by placing the airway device adjacent to the child's face to approximate its position in the oral cavity. An appropriately sized oropharyngeal airway device should extend from the corner of the mouth to the angle of the mandible (Fig. 16-9,B). When placed appropriately, its distal end snugly curves around the base of the tongue, without the proximal end protruding out of the mouth. Too small a device pushes the posterior portion of the tongue against the posterior pharyngeal wall, and too large a device may cause upper airway obstruction at the laryngeal inlet by compressing or distorting the epiglottis.

The oral airway device should be inserted in its normal orientation with the aid of a tongue depressor. In older children, insertion may be accomplished with the distal tip oriented cephalad and then turned 180 degrees when the tip has reached the posterior aspect of the palate. In younger children, this maneuver may push the tongue posteriorly and exacerbate airway obstruction.

Complications of using oral airway devices in children usually occur during emergence. Lip or tooth damage is possible; a loose tooth may become dislodged in the oral cavity and accidentally travel into the bronchopulmonary tree. Compression of oral structures by the oral airway device may result in transient postoperative numbness and a sore throat.

The nasal airway device is made from soft, latex-free rubber to allow easy insertion through the nasal passage and into the nasal or oropharynx. It can be bathed in warm or cold water to decrease or increase its stiffness, respectively. The proper diameter of the nasal airway device is determined by approximating the circular diameter of the nasal opening. The proper length of the nasal airway device is estimated by measuring the distance from the nares to the tragus of the ear. When appropriately placed, its distal tip should lie at the level of the angle of the mandible, between the posterior aspect of the tongue and above the tip of the epiglottis. To avoid trauma and bleeding of the delicate nasal mucosa, the nasal airway device should be lubricated and gently inserted in a posterocaudad direction along the floor of the nasal cavity.

Airway Adjuncts

Oropharyngeal airway devices should be available in the full range of sizes at each anesthetizing location. The required airway size can be estimated by a careful external examination of the child and by measuring the distance from the teeth to the base of the tongue. An oropharyngeal airway device that is too small can displace the base of the patient's tongue inferiorly toward the pharynx, thereby increasing the degree of obstruction, which may worsen with the application of CPAP in an effort to improve the airway obstruction. An airway that is too large may reach the laryngeal inlet and result in trauma or laryngeal hyperactivity and laryngospasm. It is common practice by some clinicians to insert an oropharyngeal airway device upside down, or convex to the natural curvature of the tongue and then to rotate the airway 180 degrees. However, this maneuver may abrade the hard palate and it is therefore not recommended. A less traumatic technique for the insertion of an oropharyngeal airway device is to use a tongue depressor to displace the tongue to the floor of the mouth and to insert the device concave to the tongue's surface.

Oropharyngeal airway devices are often used as “bite blocks” after a patient's trachea has been intubated, in order to prevent the clenching of the teeth on the endotracheal tube. This maneuver may, however, be hazardous in children between 5 and 10 years of age with loose deciduous teeth. Oropharyngeal airway devices are responsible for up to 55% of anesthesia-related dental complications (Clokie et al., 1989). Furthermore, when an oropharyngeal airway device is used as a bite block during long cases, it may cause necrosis of the tongue, uvular edema, or lip damage (Moore and Rauscher, 1977; Shulman, 1981). A gauze pad that has been rolled up and placed between the patient's upper and lower molar teeth is a better method of preventing the teeth from clenching on an endotracheal tube and minimizing dental trauma. Caution must be exercised, however, that the roll not slip and place undue pressure on the lateral aspect of the tongue (paraglossal sulcus), where the hypoglossal nerve runs.

Nasopharyngeal airway devices are generally constructed from red rubber or polyvinyl chloride and are available in various sizes. A nasal airway should be lubricated and gently inserted transnasally. Nasopharyngeal airway devices may traumatize the turbinates or adenoids of young children. Moreover, care must be exercised when using a nasopharyngeal airway device in children who have a bleeding diathesis or a congenital abnormality of the midface such as choanal atresia or frontonasal dysplasia. The proper length for the nasopharyngeal airway may be estimated by measuring the distance between the patient's auditory meatus and the tip of the nose. The insertion of a nasopharyngeal airway device that is too long may cause laryngospasm. Furthermore, if the airway is too short, the upper airway obstruction may not be relieved.

The LMA is used successfully for routine pediatric anesthetics and even for adenotonsillectomies (Webster et al., 1993; Williams and Bailey, 1993). LMAs are currently manufactured in several sizes, for patients ranging from neonates to large adults. With minimal inflation of the mask's cushion and thorough lubrication of the nonlaryngeal surface, an LMA should be seated at the laryngeal inlet and cause minimal discomfort to the patient postoperatively. Following its blind passage through the oral cavity, the proper seating of an LMA is generally heralded by a slight rise of the device when the mask's cushion is inflated with air. Care should be taken to use the minimal effective inflation pressure for the cuff, typically up to 60 cm H2O. The routine use of a manometer is advocated. In some patients, the cushion of the LMA overrides the proximal portion of the esophagus, thereby exposing the patient to the risk of the aspiration of gastric contents, with the LMA serving as a conduit to the lungs (Nanji and Maltby, 1992). Nevertheless, although ideal positioning of an LMA appears to be achieved in only 50% of cases, the vast majority of patients fare very well (Rowbottom et al., 1991; Goudsouzian et al., 1992; Mizushima et al., 1992).

Although it was originally thought that pediatric-sized LMAs might not function adequately because of differences in airway anatomy, this fear proved to be unfounded. The #1 LMA, a miniature version of the adult LMA, was designed to fit infants who weigh less than 6.5 kg. It has worked satisfactorily even in premature infants as small as 1 kg, in newborn resuscitation, and in airway maintenance for infants with upper-airway congenital anomalies (e.g., Pierre-Robin, Goldenhar's, Treacher-Collins, and Schwartz-Jampel syndromes). In difficult intubating conditions, it has been used throughout the whole procedure or as a conduit for endotracheal intubation. The endotracheal tube can often be easily directed through an LMA without fiberoptic laryngoscopy.

Flexible LMAs in sizes 2, 2.5, and 3 are also available for pediatric use. The cuff is similar to a standard LMA, but the airway tube is wire-reinforced, longer, and more flexible, allowing it to be positioned away from the surgical field. Although the flexibility of the tube is advantageous for positioning, it is more difficult to insert, it may dislodge more easily, and biting can occlude it. Moreover, the flexibility of this LMA does not allow the rotation technique for insertion. Adenoidectomy or even tonsillectomy can be performed with the flexible LMA, because the cuff prevents soiling of the glottis and the trachea by blood and secretions from the surgical site. If tracheal intubation is planned via LMA, a standard LMA is a more logical choice in children, because it is shorter and has a larger diameter; in adolescents or adults, the intubating LMA (Fastrach) can be used.

The more cephalad and anterior position of the larynx of a child as compared with an adult has prompted the use of an alternate insertion technique in children. In this case, the LMA is inserted with its cushion placed against the hard palate. The device is then rotated through 180 degrees until the cushion is seated at the laryngeal inlet (McNicol, 1991). This method for the insertion of an LMA appears to be especially useful in preschool and young school-age children.

Oropharyngeal Airways

An OPA is the most commonly used device to provide a patent UA. The OPA is formed of symmetrical flanges to keep the device stabilized at the lips, a bite block, and a semicircular portion that follows the oropharyngeal anatomy. An air channel is often provided to facilitate oropharyngeal suctioning. It extends from the lips to the laryngopharynx and supports ventilation by opening the mouth and committing to oral ventilation. The OPA will bypass the nasal cavities, nasopharynx, and soft palate obstruction in inspiration and expiration, lift the tongue and possibly the epiglottis, and support mandibular advancement. It also lengthens the face with 1 to 2 cm and improves FM fit in edentulous patients. OPAs are manufactured in a wide variety of sizes from neonatal to large adult, and they are typically made of plastic or rubber (Fig. 18.8). They should be wide enough to contact two or three teeth on the mandible and maxilla, and they should be slightly compressible so that the pressure exerted by a clenched jaw is distributed over all the teeth, whereas the lumen remains patent. The two most popular disposable OPAs are the Guedel (1933) and the Berman (1949) airways. The Guedel airway has a central air channel and is bulkier, whereas the Berman airway has a central support with open sides. Adult sizes are the #8 (8 cm), #9 (9 cm), #10 (10 cm), and #11 (11 cm), designated according to the height measured horizontally from the flanges to the distal end of the airway. There may be variations in both shape and length between different OPA manufacturers. Traditionally, the appropriate size is estimated by external measurements such as the distance from the tragus of the ear to the angle of the mouth or the distance from the incisors to the angle of the mandible. These measurements do not account for internal individual anatomical discrepancies (tongue size, palate height). In average-height adults a size #9 in men and size #8 in women will provide the best fit.37 An OPA may be too small with the tip at the base of the tongue or too long with the tip in the vallecula, pushing the epiglottis into the glottic opening. The OPA is used in approximately 25% of the FMV attempts. In 1991 Marsh and colleagues studied the etiology of OPA obstruction radiographically in patients with neutral head position. The OPA was impacting with the tongue (41%), vallecula (18%), and epiglottic down-folding (13%).38 There was no way of predicting the site of obstruction from clinical observation. The OPA obstruction was be rectified by airway maneuvers (both CL/HE and jaw thrust), reinsertion, or electing a different size.

The Ovassapian Airway has a large anterior flange to control the tongue and a large central opening at the level of the teeth (open posteriorly) to allow a flexible intubation bronchoscope and ETT to be passed through the airway, while allowing the ETT to disengage from the airway following tracheal intubation.

Oropharyngeal Airways

Oropharyngeal airways displace the base of the tongue from the posterior pharyngeal wall and break contact between the tongue and palate (see Figure 119-2). Size selection is important. An excessively long airway may encroach upon the larynx and cause laryngospasm. An airway that is too short may actually push the tongue posteriorly and exacerbate obstruction. If the airway is held at the side of the face with the flange just anterior to the incisors, the tip should be at or near the angle of the mandible. The airway should be positioned following the curve of the tongue while the tongue is held down and forward with a tongue depressor. Inserting the airway with its concave side facing the palate and then rotating it may traumatize the oral mucosa or damage teeth. Oral airways are poorly tolerated in any patient with a functional gag reflex and may induce vomiting. As a consequence, they are of little more than temporary value in the critically ill child. They may support a patent airway for bag-valve-mask ventilation in preparation for intubation.

Oropharyngeal Airways

Oropharyngeal airways are hard, non-latex plastic that are preformed in different sizes from 40 mm (infant) to 100 mm (large adult). Care should be taken to choose an airway that is the correct size for the child because an airway that is too small displaces the posterior portion of the tongue or epiglottis into the glottic opening, causing upper airway obstruction. Alternatively, if the airway is too large, the airway device may cause damage to laryngeal structures, causing swelling and potential postoperative obstruction (see Fig. 14.13). An oral airway should always be placed midline, without rotating it as it is inserted as is commonly done in adults, since at every age, children have some loose teeth and others that are ready to fall out. Rotating the hard airway may dislodge one or more teeth, leading to a possible pulmonary aspiration. Misplaced oral airways that obstruct venous and/or lymphatic drainage of the tongue can precipitate acute macroglossia.38 Additional causes of acute macroglossia include retained throat packs,39 surgical positioning,40 and the presence of TEE probes.

1 Oropharyngeal Airways

An oropharyngeal airway (OPA) is the most commonly used device to provide a patent upper airway. OPAs are manufactured in a wide variety of sizes from neonatal to large adult, and they are typically made of plastic or rubber (Fig. 15-7). They should be wide enough to make contact with two or three teeth on each of the mandible and maxilla, and they should be slightly compressible so that the pressure exerted by a clenched jaw is distributed over all of the teeth while the lumen remains patent. OPAs are frequently designed with a flange at the buccal (proximal) end to prevent swallowing or over insertion. They also feature a distal semicircular section to follow the curvature of the mouth, tongue, and posterior pharynx so that the tongue is displaced anteriorly (concave side against the tongue). An air channel is often provided to facilitate oropharyngeal suctioning.

The most commonly used OPA in adults is the Guedel Airway (see Fig. 15-7). It has a plastic elliptical tube with a central lumen reinforced by a harder inner plastic tube at the level of the teeth and by plastic ridges along the pharyngeal section. Because the airway is completely enclosed (other than the proximal and distal ends), redundant oral and pharyngeal mucosae cannot occlude or narrow the lumen from the side. Its oval cross section allows the four central incisors to make contact with it during masseter spasm.

The Ovassapian Airway has a large anterior flange to control the tongue and a large opening at the level of the teeth (open posteriorly) to allow a flexible fiberoptic bronchoscope and ETT to be passed through it and later disengaged from the airway (see Fig. 15-7). Consequently, it is often employed during fiberoptic intubations to aid in maintaining upper airway patency.

Use of an OPA seems deceptively simple, but the device must be used correctly. The patient's pharyngeal and laryngeal reflexes should be depressed before insertion to avoid worsening obstruction due to airway reactivity. The mouth is opened, and a tongue blade is placed at the base of the tongue and drawn upward, lifting the tongue off of the posterior pharyngeal wall (Fig. 15-8A). The airway is then placed so that the OPA is just off the posterior wall of the oropharynx, with 1 to 2 cm protruding above the incisors (see Fig. 15-8B). If the flange is at the teeth when the tip is just at the base of the tongue, the airway is too small, and a larger size should be inserted. A jaw thrust is then performed as described previously to lift the tongue off of the pharyngeal wall while the thumbs tap down the airway the last 1 to 2 cm so that the curve of the OPA lies behind the base of the tongue (see Fig. 15-8C). The mandible is then allowed to reduce back into the temporomandibular joint, and the mouth is inspected to ensure that neither the tongue nor the lips are caught between the teeth and the OPA.

An alternative method of placement is to insert the airway backward (convex side toward the tongue) until the tip is close to the pharyngeal wall of the oropharynx. It is then rotated 180 degrees so that the tip rotates and sweeps under the tongue from the side (see Fig. 15-8D). This method is not as reliable as the tongue blade–assisted technique described earlier, and it has the added risk of causing dental trauma in patients with poor dentition.

If the upper airway is not patent after the placement of an OPA, the following situations must be considered. With an OPA that is too small, the pronounced curve may impinge on the base of the tongue, or the tongue may obstruct the native airway distal to the OPA. If a larger OPA still results in obstruction, the curve might have brought the distal end into the vallecula or the OPA might have pushed the epiglottis into the glottic opening or posterior wall of the laryngopharynx. In the lightly anesthetized or awake patient, this stimulation causes coughing or laryngospasm. The best treatment for this problem is to withdraw the OPA 1 to 2 cm. A topical anesthetic spray or a water-soluble local anesthetic lubricant reduces the chance of laryngeal activity, but it should be used judiciously or avoided in patients thought to be at increased risk for aspiration.

Two major complications can occur with the use of OPAs: iatrogenic trauma and airway hyperreactivity. Minor trauma, including pinching of the lips and tongue, is common. Ulceration and necrosis of oropharyngeal structures from pressure and long-term contact (days) have been reported.16 These problems necessitate intermittent surveillance during extended use. Dental injury can result from twisting of the airway, involuntary clenching of the jaw, or direct axial pressure. Dental damage is most common in patients with periodontal disease, dental caries, pronounced degrees of dental proclination, and isolated teeth.

Airway hyperactivity is a potentially lethal complication of OPA use, because oropharyngeal and laryngeal reflexes can be stimulated by the placement of an artificial airway. Coughing, retching, emesis, laryngospasm, and bronchospasm are common reflex responses. Any OPA that touches the epiglottis or vocal cords can cause these responses, but the problem is more common with larger OPAs. Initial management is to partially withdraw the OPA. If an anesthetic is being administered, deepening the plane of anesthesia (most easily accomplished with an intravenous agent) is often effective in blunting airway hyperreactivity. In cases of laryngospasm, it may be necessary to apply mild positive airway pressure and, in trained hands, to cautiously administer small doses of succinylcholine to achieve resolution.

Oral Airway

Oropharyngeal airways should be available in the full range of sizes. An oral airway that is too small will displace the base of the tongue inferiorly toward the pharynx whereas an airway that is too large may reach to the laryngeal inlet and cause trauma and/or laryngeal hyperactivity and laryngospasm. Correct airway size can be assessed by a careful external examination of the child and estimation of the distance from the teeth to the base of the tongue. Although it is now common practice to insert an oral airway convex to the tongue surface (“upside down”) and then rotate it, one should recognize that this maneuver may scrape the hard palate, traumatize the tonsils and/or adenoids, and push the tongue caudally. A less traumatic alternative is to use a tongue depressor to displace the tongue to the floor of the mouth, and then insert the oral airway with its concave side to the tongue surface. Oral airways are often used as “bite blocks” to prevent the clenching of teeth on the endotracheal tube. Such a practice is a particular hazard in children between 5 and 10 years of age who may have loose deciduous teeth. Oral airways are responsible for up to 55% of dental complications.37 Furthermore, an oral airway used as a bite block in long cases may cause tongue necrosis or edema, uvular edema, or lip damage. A dental roll placed between the upper and lower molars will also prevent clenching while minimizing dental trauma.

Oropharyngeal Airway

The oropharyngeal airway is a hard, rigid, plastic device curved to anatomically fit into the oropharynx to relieve upper airway obstruction caused by the tongue or epiglottis contacting the posterior pharyngeal wall. These pieces are designed with a flange which seats just outside the mouth to help prevent complete entrance into the mouth and airway. Just behind the flange is, a straightened area which serves as a bite block. The rest of the device is curved to situate over the tongue and into the oropharynx. The distal end is designed to settle deep at the base of the tongue, and superior to the epiglottis. The entire airway device is hollow to allow for airflow through a central channel. A diversity of shapes and sizes exist to fit neonates, children, and small and large adults. A standardized color coding and sizing system exists for these devices. For example, a large adult Guedel oropharyngeal airway would be a size number 10, or 100 mm, colored red. The most popular oropharyngeal airway is the Guedel airway (Figure 6–13).

Proper selection and insertion of any airway device are very important. To choose the appropriately sized airway for a given patient, “the distance from the flange to the distal tip of the airway should be about the same as from the patient’s lips to the tragus of the ear.”28 Ideally the patient is anesthetized (or obtunded) enough to tolerate placement. These devices may be lubricated, although this is not essential. The patient’s mouth should be opened wide and the head extended on the neck. Carefully place the airway to follow the anatomy and shape of palate and tongue. Sometimes the tongue perturbs placement because it may fold posterior as the airway is advanced. A tongue blade can aid in flattening the tongue and preventing its collapse.29 Another method of placing an oropharyngeal device involves rotating the device 180 degrees, facing the opposite direction, such that the distal end is pointing toward the palate (Figure 6–14). Once advanced beyond the tongue, the device can be rotated to seat properly in the oropharynx.

Specially designed oropharyngeal airways have been developed to assist with intubations requiring the aid of a fiberoptic bronchoscope.30 These airways act as both conduits for the bronchoscope to easily pass through secretions, and, once past the tongue, to approach the larynx. Bite blocks incorporated into these airways prevent damage to both the patient and fiberoptic equipment.28 Several types of fiberoptic intubating oropharyngeal airways exist. The Optosafe has a large enough air passage to allow the bronchoscope, endotracheal tube, and all components to enter through the device. The Ovassapian or Berman airways are open and flexible, to allow the airway to be peeled around and away from the fiberoptic bronchoscope before deployment of an endotracheal tube over the scope (Figure 6–15). Lastly, the Williams Airway Intubator can be used for both fiberoptic intubations, blind intubations, or to relieve airway obstruction.31

Cuffed oropharyngeal airways (COPA) are of the Guedel variety and contain a distal inflatable cuff similar to that of endotracheal tubes, to allow for a more secure fit in the oropharynx. When the cuff is inflated, the tongue and epiglottis are displaced from the posterior pharynx, facilitating air flow through the airway.32 The COPA allows for attachment to the anesthesia machine breathing circuit with its distal connector. Several recent studies have emerged regarding the clinical use and safety concerns for the COPA (Table 6–12).