Modified Retrograde Nasal Intubation: A New Airway Technique and Devices
Nasotracheal intubation remains an underused but invaluable technique for securely managing the airway during oral and maxillofacial surgery. In this article, we present a modified clinical technique that allows for the potential introduction into clinical practice of 2 new airway devices: a nasal laryngeal mask airway and an interchangeable oral/nasal endotracheal tube. We hypothesize that with the use of proper techniques, these devices can add new and safer alternatives for securing an airway by the nasal route. The advantage of this novel technique is that the airway is secured by the oral route prior to performing a modified retrograde nasal intubation, eliminating the danger of profuse epistaxis precipitating a “cannot intubate, cannot ventilate” scenario. In addition, the design and materials used in the components of the devices may minimize trauma. The authors aim to inform clinicians about the indications, physical characteristics, and insertion/removal techniques related to these new devices.
A century ago, in 1920, Magill and Rowbotham1 pioneered the concept of nasotracheal intubation (NTI). By blindly inserting a red rubber oral tube with a lateral bevel through the nostril and using Magill forceps to direct the tube into the trachea, they provided a ground-breaking airway management solution for many surgical interventions requiring concurrent access to the oral and maxillofacial complex.
NTI is a safe technique in skilled hands; however, the passage of a bevelled endotracheal tube (ETT) through the nasopharynx may cause several complications including epistaxis, which has a reported incidence as high as 86%.2 Piepho et al3 elaborated on this in a case report involving an adult male patient undergoing NTI who developed severe epistaxis after the tube had passed through the nasopharynx. Laryngoscopy revealed a Cormack-Lehane grade 4 airway, and as a result of this combination, NTI failed. Attempts with a laryngeal mask airway (LMA)–Fastrach (Teleflex, Westmeath, Ireland) and Bonfils Optical Stylet (Karl Storz, Tuttlingen, Germany) for orotracheal intubation also failed, and the airway was finally successfully controlled by cricothyrotomy. Piepho et al3 concluded that laryngoscopy should be performed first and then NTI attempted if a Cormack-Lehane grade 1 or 2 view of the vocal cords is obtained, whereas other means of protecting the airway (eg, fiber-optic or supraglottic techniques) should be used for grade 3 or 4 views.
Anesthesiologists often face further challenges during nonelective trauma cases for oral and maxillofacial surgery. Trauma frequently causes significant airway edema and, along with associated cervical spine injury, can make intubation difficult. Midfacial maxillary fractures may initially require orotracheal intubation for emergency airway management, followed by conversion to NTI to better facilitate proper alignment and surgical fixation. Attempting NTI may cause profuse epistaxis and create a false nasal passage, among many other more serious complications. Under such conditions, performing initial NTI prior to securing the airway orally may be contraindicated.
To avoid the complications of NTI, anesthesiologists often use a flexible laryngeal mask airway (FLMA) or orotracheal intubation with an oral RAE ETT, named after its inventors Ring, Adair, and Elwyn. However, these alternate airway devices may complicate surgery in the following ways: (1) the tube may remain in the surgical field, (2) accidental dislodgement of or damage to the airway device may occur as a result of sharing the surgical field, (3) the tube may preclude the ability to check the patient's occlusion, and (4) use of an LMA leaves patients vulnerable to laryngospasm.
Current Methods for NTI
At present, the standard option to intubate via the nasal route is to use a preformed nasal RAE or nasotracheal tube (NTT) passed through the nasopharynx prior to the glottis and trachea. With difficult airways and/or maxillofacial trauma, retrograde nasal intubation4 has been described and involves the insertion of a guide wire through the cricothyroid membrane, which is then passed upward through the pharynx and delivered out of a nostril in a retrograde manner. The NTT is then advanced into position using the wire as a guide.
There are multiple reports of various methods to convert from an orotracheal tube (OTT) to a NTT for patients with difficult airways.5–7 Most methods use a Frova Intubating Introducer (Cook Medical, Bloomington, Ind) or airway exchange catheter placed inside or alongside the OTT, enabling rapid reintubation orally if necessary once the OTT is withdrawn and advancement of the NTT attempted. Hemorrhage, pneumothorax, mediastinitis, and death have all been reported complications from trauma associated with the use of airway exchange catheters.8,9 Other alternatives for converting from orotracheal intubation to NTI include invasive surgical methods such as a tracheostomy and submental or submandibular intubation, which may be useful options for patients with severe facial trauma.
The idea of a nasal laryngeal mask airway (NLMA) was first introduced in 1997. After placing an FLMA, Marchionni et al10 performed a modified retrograde nasal intubation (MRNI) with a Foley catheter, successfully converting the FLMA into an improvised NLMA. In 2007, Arisaka et al11 used a nasogastric tube instead of a Foley catheter for the MRNI. An article published in 2000 by Agrò et al12 demonstrated that a modified reinforced ETT using a Foley catheter for MRNI could convert the OTT into a NTT. These studies provide a proof-of-principle demonstration of the efficacy of MRNI.
New Airway Management Options
Developers of the Genesis Airway devices (Genesis Airway, Sunshine Coast, Australia) proposed 2 novel products designed to address the challenges of anesthesia for oral and maxillofacial surgery: the oral/nasal endotracheal tube (ONETT) and the NLMA. The ONETT (Figure 1) incorporates a flexible cuffed reinforced endotracheal tube with a removable 15-mm connector and a bevel with a soft, curved atraumatic tip that faces posteriorly to increase first-pass intubation rates,13 a soft curved introducer, and an additional 28-cm section of flexible reinforced tubing with a 15-mm connector at the proximal end and a threaded connector at the distal end to prevent accidental disconnection once joined to the introducer, ETT, or NLMA. The NLMA (Figure 2) uses the same armamentarium but replaces the reinforced ETT with an FLMA that also has a removable 15-mm connector. A comparison of the indications, design, and structure of the preformed nasal RAE ETT (the standard ETT used for NTI), the ONETT, and the NLMA are presented in the Table.
Citation: Anesthesia Progress 68, 2; 10.2344/anpr-68-02-03
Citation: Anesthesia Progress 68, 2; 10.2344/anpr-68-02-03
We present a modified intubation method for the ONETT and NLMA, in which the airway is secured or a supraglottic airway device is placed orally prior to MRNI (steps 1–9 described below).
Use of the ONETT/NLMA (Figures 3 and 4)
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The FLMA or reinforced ETT are inserted into position in the customary fashion and connected to the anesthetic circuit with the 15-mm connector to confirm success and facilitate ventilation.
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The soft curved introducer is attached to the threaded connector at the distal end of the extra section of reinforced tubing with the 15-mm connector on the proximal end.
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After selecting the most patent nostril, the introducer is passed through the nasopharynx until it is visible in the posterior oropharynx. The introducer is grasped with Magill forceps and delivered through the mouth until the distal 5 cm of the reinforced tubing is withdrawn, at which point the introducer is disconnected.
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The 15-mm connector is removed from the FLMA/reinforced ETT, which is then connected to the threaded distal end of the reinforced tubing.
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The anesthetic circuit is reconnected to the proximal end of the reinforced tubing section exiting the nose.
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The proximal FLMA/reinforced ETT tubing is stabilized in the oropharynx with forceps to prevent dislodgement, while the redundant loop of tubing is withdrawn from the nose using gentle traction on the proximal reinforced tubing section.
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The proximal end of the FLMA/reinforced ETT tubing is withdrawn beyond the nares.
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The 28-cm section of the reinforced tubing is then disconnected, and the 15-mm ISO connector is replaced on the proximal end of the FLMA/reinforced ETT tubing.
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The FLMA/reinforced ETT is reconnected to the anesthetic circuit.
Citation: Anesthesia Progress 68, 2; 10.2344/anpr-68-02-03
Citation: Anesthesia Progress 68, 2; 10.2344/anpr-68-02-03
The pilot balloon and cuff inflation valve for the NLMA and ONETT may be stored in the oropharynx or prepared as part of the surgical field and stored behind the sterile drapes if the operators elect to keep it out of the mouth to check cuff pressures for longer procedures. Note that labeling of the ONETT/NLMA is strongly advised, so that it is not mistaken for a standard NTT and removal through the nose is attempted.
Removal of the ONETT/NLMA
To reconvert from the nasal to the oral route, the previous steps can be followed in reverse order. Alternatively, the proximal tubing can be withdrawn from the nasopharynx and delivered through the mouth after removing the 15-mm connector and stabilizing the tubing section approximating the glottis. The airway devices (FMLA/RETT) can then be removed in the usual manner.
An additional method of removing the ONETT specifically while still in place nasally is to deflate the cuff and then cut and remove the pilot balloon and inflation valve to allow extubation through the nasopharynx. This method may be suitable for awake extubation in cases in which easy access to the oral cavity is not possible, such as when the patient remains in intermaxillary fixation.
DISCUSSION
The intention of this article is to inform clinicians about the indications, physical characteristics (design and structure), and insertion techniques related to 2 novel airway devices, the ONETT and NLMA. Concerned with the increasing number of airway management devices being introduced into clinical practice with little or no evidence of clinical efficacy or safety, the Difficult Airway Society (United Kingdom) formed the Airway Device Evaluation Project Team (ADEPT) in 2011. This team formulated a process to analyze airway devices before procurement, emphasizing that (1) products with documented evidence of efficacy and safety should be preferred, and (2) anesthesiologists should play a more active role in device evaluation and selection.14,15 To adhere to ADEPT guidelines, the physical characteristics of the NLMA and ONETT components must be compared with existing devices (Food and Drug Administration–approved predicates) before studying them in manikins and patients. Clinical studies for the predicate devices of the NLMA and ONETT (the introducer,16,17 reinforced airway tubing,18 and ETT with posterior facing bevel13) demonstrate their likely efficacy and safety. Furthermore, both the NLMA and ONETT have been approved by the Australian Therapeutic Goods Administration, which suggests that the physical characteristics and technique are considered to be safe.
Potential Advantages
Potential advantages of successfully placing an airway device orally and then performing the MRNI include the following:
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orotracheal intubation and placing an oral FLMA is technically easier to perform than NTI,19
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the airway is secured/protected prior to creating the risk for profuse epistaxis,
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establishing a definitive airway by the oral route is less time-consuming,19
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there is a lower incidence of oxygen desaturation,19 and
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there is a higher first-pass intubation success rate with the oral route as compared with the nasal route.19
Reducing NTI Complications
The complications of standard NTI are numerous and include significant issues such as severe epistaxis (4% reported with standard ETTs20), turbinectomy, creation of a false nasal passage, accidental intracranial placement of the ETT, and retropharyngeal dissection. Epistaxis is commonly used as an indicator for nasal trauma, and in more than 40 MRNIs discussed in the literature, only 1 case (<2.5%) of minor epistaxis was reported.10–12 There are several potential explanations for the reduced incidence of epistaxis. It is possible that the passage of the Foley catheter or nasogastric tube (whichever was used) through the nose before being attached to the flexible ETT or LMA tubing dilates the passageways of the nasal cavity and nasopharynx. Alternatively, retrograde passage of the flexible tubing through the nasopharynx may be less traumatic as compared with anterograde, or perhaps it is a combination of both factors. By comparison, the incidence of epistaxis was reported as 35%,20 52%,21 and 86%2 when using standard endotracheal tubes for NTI. The lowest reported incidences of epistaxis complicating NTI result from the use of specialized ETTs designed specifically for nasal intubation. The Parker Flex-Tip tube (Parker Medical, Englewood, Colo) and the Bubble-tip Airguide ETT (POLAMEDCO, Inglewood, Calif) had reported epistaxis rates of 11.8%20 and 18%,22 respectively.
The more serious complications of NTI mentioned above are all hypothesized to be reduced by the use of a soft, curved introducer. For this purpose, the developers of the Genesis Airway devices recommend using a customized curved blunt introducer on the end of the flexible 28-cm section of reinforced tubing (Figures 1 and 2) to facilitate passage through the nasopharynx, rather than a Foley catheter or nasogastric tube. Numerous studies of both a curved blunt introducer attached to an NTT prior to NTI and the use of a reinforced endotracheal tube have been shown to reduce NTI-related epistaxis when compared with a preformed NTT.16–18 As with all nasal airway devices, the anesthesiologist must remain vigilant that the tubing exiting the nostril is well positioned and does not exert undue pressure resulting in perinasal tip necrosis.
CONCERNS WITH THE NLMA/ONETT
LMAs are supraglottic airway devices regardless of whether the tube is passed via the oral or nasal route. As such, they do not provide a secure airway in the same sense as an ETT but rather airway protection. Should the anesthesiologist become concerned about the compromise of the protected airway with an NLMA in place, several options are available. The authors recognize that the NLMA may be repositioned and/or the depth of anesthesia altered similar to an oral LMA but perhaps not as easily. The NLMA may be quickly removed by removing the 15-mm connector and pulling the flexible tubing from the oropharynx, which simultaneously removes both the laryngeal and nasal NLMA components. Finally, an NLMA and ONETT that use the same-size reinforced tubing with identical internal diameters are interchangeable, allowing easy transition from an NLMA to an NTT.
The FLMA used for the nasal LMA is a first-generation laryngeal mask airway device. The National Audit Projects (NAP4) report captured detailed reports of major complications of airway management in the United Kingdom between September 2008 and August 2009 and alludes to the benefits of second-generation LMAs in reducing the incidence of aspiration. At present, the LMA ProSeal (Teleflex, Athlone Co., Westmeath, Ireland) is the only flexible second-generation LMA; however, its design, structure, and limited flexibility make it unsuitable for use as a nasal LMA. This is a potential limitation of the NLMA, as one major drawback with using first-generation LMAs as compared with second-generation devices is the increased risk of aspiration, which is reported to occur in 2 in 10,000 cases.23 However, as indicated by the NAP4, in most cases of aspiration, 1 or more predisposing factors existed, and the use of any LMA was inappropriate.
Agrò et al12 developed an endotracheal tube in which the pilot balloon and inflation valve could be detached and reattached once the tube was delivered in a modified retrograde manner through the nose. This type of device may be adopted in the future for the ONETT to address the problem of the pilot balloon remaining in the surgical field.
CONCLUSION
This article proposes that with correct patient selection and prior training on manikins, the proposed technique of MRNI with the NLMA and ONETT has the potential to protect the patient's airway in an easy, quick, and less-traumatic manner than currently used methods for NTI. Limited studies also support that these devices, coupled with the method described, significantly reduce the incidence of epistaxis. However, verification of these proposed advantages requires further research.
We recommend clinical comparison studies to better assess the advantages, efficiency, and complications related to MRNI. We also advise that the NLMA and ONETT should not be used by practitioners who are not experienced in NTI or in the use of LMAs without sufficient training.
Oral/nasal endotracheal tube. (A) A 28-cm section of flexible reinforced tubing. (B) Stylet. (C) The 15-mm ISO connector. (D) Reinforced endotracheal tube with posterior-facing bevel. (E) Introducer.
Nasal laryngeal mask airway. (A) A 28-cm section of flexible reinforced tubing. (B) flexible laryngeal mask airway. (C) The 15-mm ISO connector. (D) Introducer.
Insertion technique for the oral/nasal endotracheal tube.
Insertion technique for the nasal laryngeal mask airway.
Contributor Notes