Submental Intubation: Clinical Anatomy and Video Technical Note

Abstract

Airway management in patients with complex craniofacial injuries is a challenge for surgeons and anesthesiologists. The need to ventilate without interfering with dental occlusion or worsening skull base injuries makes orotracheal and nasotracheal intubations unsuitable in some situations. As an alternative, tracheotomy ensures airway safety without interfering with the operative field in craniofacial traumas. However, the procedure is associated with significant morbidity such as hemorrhage, pneumothorax, infection, or tracheal stenosis [1-3]. In this context, submental intubation appears as a suitable alternative. Its speed of execution and low morbidity have led to its widespread use in craniofacial and head and neck surgery. However, many surgical and anesthesia teams involved in trauma management remain unfamiliar with the submental intubation procedure, whereas it requires excellent coordination between surgeons and anesthesiologists. This technical report aims to focus on the clinical anatomy of the submental region and to present a step-by-step description of the surgical procedure based on video.

The anatomical basis of the submental intubation procedure concerns submental and retro-symphyseal regions. The submental triangle, also referred to as the suprahyoid triangle, is defined as a sub-region of the anterior cervical area [4]. It is, with the submandibular triangle, the carotid triangle, and the muscular triangle, one of the four triangles forming the anterior triangle of the neck, which contains some important vascular structures. The submental triangle is a median suprahyoid area lying inferior to the chin. It is inferiorly limited by the body of the hyoid bone and laterally by the right and left anterior bellies of the digastric muscles. The digastric anterior bellies taper superiorly and forward towards the apex of the triangle. The apex of the submental triangle is located at the lower extremity of the mandibular symphysis. The hyoid bone forms the base of the triangle, while the roof is composed of the two mylohyoid muscles, joining in a median fibrous raphe.

If surgeons ensure strict adherence to the median approach, the risk of injury is minimal. Mylohyoid muscles constitute the mouth floor's inferior limit. The mouth floor is limited forward and laterally by the inner part of the mandible, from the symphyseal to the retromolar regions. The upper part of the mouth floor is composed of oral mucosa and the base of the tongue. The anterior part of the mouth floor is devoid of significant structures, except for the orifices of submandibular and sublingual canals, on either side of the lingual frenulum.

The most delicate step is the SMAS dissection, yet the risk of harming important structures is prevented through precise midline dissection, avoiding cutting, and employing blunt-tipped instruments. Once the floor of the mouth has been reached, forceps are located through the buccal mucosa. Care should be taken to remain anterior to submandibular and sublingual gland orifices. The mucosa is then incised with a scalpel—Figure 2. Long forceps are introduced from the initial incision to the oral cavity, and after informing the anesthesiologists, the ventilation tube is disconnected from the respirator. The balloon is first passed with the forceps from the buccal floor to the submental area in order to prevent it damaging or cooling around the probe. Then the same procedure is followed for the intubation tube; proximal end of the tube is passed through the floor of the mouth. Throughout the transfer procedure of the tube, an assistant should hold the tube in place to avoid accidental extubation. The tube is then reconnected to the ventilator and fixed to the skin—Figure 3.

Placement of the intubation tube is always an essential concern in surgeries involving the maxillofacial region. It has to ensure secure ventilation of the patient and must not compromise access to the surgical field. Craniomaxillofacial injuries are particularly concerned by this dual challenge [6, 7]. As an alternative to orotracheal intubation, nasotracheal intubation allows for ensuring airway ventilation without interfering with dental occlusion. However, the procedure is contraindicated in cases of basilar skull trauma due to the incidence of accidental intracranial placement through the cribriform plate and severe facial trauma, especially those involving nasal bones due to the risk of secondary displacement [8, 9]. Submental intubation was first described by Hernandez Altemir in 1986 [10]. Since its introduction, it has been used as an attractive option for intraoperative airway control in complex maxillofacial injuries. Craniofacial trauma is the most common indication for submental intubation [6, 7]. In this indication we find facial fractures with osteo-meningeal breach risk, such as Le Fort 2, 3, and naso-orbito-ethmoidal fractures [11]. The procedure is also applied to skull base surgery, orthognathic surgery with simultaneous rhinoplasty, or nasal anatomic anomalies precluding nasotracheal intubation, which is a relatively common situation in maxillofacial surgery [12]. The advantages of submental intubation over tracheotomy lie in its lower complexity of execution and morbidity. Short-term complications during tracheotomy include hemorrhage, recurrent laryngeal nerve damage, and subcutaneous emphysema, while long-term complications include tracheal stenosis and unsightly scars [3]. In contrast, complications related to submental intubation are comparatively milder and occur less frequently. They may include postoperative superficial infection, floor hematoma, transient lingual nerve paresthesia, and injury to the salivary gland ducts with the possibility of remote mucocele formation [13]. Complications concerning the intubation tube include the risk of damaging the tube or the balloon and accidental extubation [14]. These risks are prevented by careful execution of the procedure with secure fixation to the skin as previously described. The risk for tube obstruction is prevented by the use of armored tubes. Submental intubation is a quick and relatively simple surgical procedure. The primary challenge lies in achieving excellent cooperation between anesthesiologists and surgeons, as well as in the non-traumatic handling of ventilation equipment. Nevertheless, despite the widespread adoption of this procedure in recent years, some teams remain unfamiliar with it. Although the technique is well described in the literature, there are no video supports accompanying textual descriptions. This technical note therefore offers an illustrative video, with a step-by-step surgical technique description and a clinical anatomic review. Submental intubation is a reliable and minimally invasive alternative to tracheotomy in patients undergoing complex maxillofacial surgeries and who don't require prolonged ventilatory support. It permits ensuring ventilation while allowing for intraoperative evaluation of the dental occlusion. Craniofacial and head and neck surgeons are the most involved in this technique. Craniofacial traumas often result in dental disarrangement with associated skull-base or centrofacial fractures, which contraindicate orotracheal and nasotracheal intubation. Its execution is less complex compared with tracheotomy, resulting in a low complication rate. When performed proficiently, it entails very low morbidity, aside from a discreet scar beneath the chin.

The authors declare no conflicts of interest.

The patient appearing in this report has provided written informed consent granting the authors permission to share photographs/videos and details of his case.