The critical indication for submental intubation is the requirement for intraoperative maxillomandibular-fixation in the presence of injuries that preclude nasal intubation and in a situation where a tracheostomy is not otherwise required. Twenty five patients were chosen for submental intubation. All patients had a mobile maxillary segment together with additional injuries that precluded nasal intubation. The occlusal fractures occurred at various levels. The injuries that precluded nasal intubation included nasal bones fractures and full thickness nasal lacerations. Two patients had associated fracture of frontal bone and cribriform plate leading to cerebrospinal fluid rhinorrhea. All patients required a period of intraoperative MMF.
Submental intubation was first described by Hernandez Altemir1 in 1986 as an alternative method for short-term tracheostomy, when both oro-tracheal and naso-tracheal intubation are contraindicated, impossible, or may interrupt the surgical access or techniques. Altemir used surgical approach for intubation through a 2 cm submental incision just medial to the lower border of the mandible, approximately one-third of the distance between the symphysis and the angle of the mandible. Potential complications of this approach include damage to adjacent structures, such as sublingual and submandibular ducts, sublingual gland, and lingual nerve.
Several workers used Altemir's technique with good success and with no problems.2,3,4
However, MacInnis & Baig6
found it less satisfactory because of difficult tube passage, bleeding, and sublingual gland involvement. Therefore, they modified their approach to a strict midline submental incision with satisfactory results.6,7
In the present study; we used a midline submental approach. We found the technique to be easy and effective. It provided an excellent uninterrupted approach to the whole face and the oral cavity without any interruption by the tube and it appeared completely safe as regards the patients′ airways. No airway complications or hypoxic episodes occurred during the technique but the patients may be exposed to hypoxia if difficulties are encountered during manipulation of the tube through the incision. Since our cases involved concomitant nasal reconstruction surgery in addition to maxillary or mandibular fixation, by using a submental tube, intraoperative exchange from nasal to oral tube that carries risk of aspiration, can interfere with the surgical field, disturb sterilization & recent repair of fractures; was avoided.
To prevent kinking of the tube, non-kinkable flexometallic or spiral re-inforced tube with removable universal connector should be chosen. Some armoured tubes have irremovable universal connector. They have to be cut off and the cut edges of the reinforcing wire are trimmed.9
Some workers suggested use of two tubes: a conventional oro-tracheal tube securing the patient's airway whereas a second armoured tube is passed through the incision, from exterior to interior. The second tube is then manipulated with McGill forceps into the oro-pharynx and then into the trachea just after removal of the first tube.10
The drawback of this technique is that the cuff of the tracheal tube can be damaged during the manipulation by the McGill forceps.
To overcome the problem of the irremovable connector, a lubricated tube exchanger can be used to replace the submental tracheal tube with a fresh re-inforced armoured one.11
A 100%silicone wire-reinforced tube with a removable connector, originally designed for use with the intubating laryngeal mask airway(ILMA) has also been used for submental intubation. This tube has the advantage that it has a connector that is specifically designed for detachment and re-attachment during insertion of the ILMA, making it ideal for submental tracheal intubation.9
has also recently reported the use of the laryngeal mask airway via the submental route.
Where universal connector is irremovable, after doing the routine orotracheal intubation, the second submental spiral re-inforced tube is passed from exterior to interior and oro-tracheal tube is removed over the tube exchanger. Then the tube exchanger is passed through the second spiral re-inforced tube which is then slid over the tube exchanger into the trachea. This decreases the time, patient is exposed to hypoxia and there are no chances of damage to the cuff of the tracheal tube. By careful removal of the fixed connector by artery forceps, before the start of the anaesthesia, it can be smoothly transformed into a removable connector.
The direction in which this passage is created is also important. The development of mucocele has been reported by Stranc and Skoracki12
in a case where submandibular intubation was done. It was probably due to inclusion of mucosal fragments while making mucocutaneous track because they had done blunt intraoral perforation of the mucous membrane of the mouth and dissected the track from the oral side to the skin. No such complication occurred in our cases when the track was made from exterior to interior.
Accidental dislodgement of the tube may occur during pulling the tube end through the track. This can be avoided by carefully checking the tube position before fixation. The tube should be supported in the oro-pharynx by the anaesthetist's index finger while the tube is being pulled through the track. Accidental extubation and inward displacement of the tube have also been reported while manipulating the mandible during surgery.9,10
In this series we used an orotracheal tube through a submental route during the entire surgery. This technique provided a secure control of the airway and caused no interference in the surgical field. There was no problem in disconnecting the tube and passing it through the submental route. All patients were extubated at the end of the procedure. All the tubes used in this study had removable universal connector. Midline approach for submental orotracheal intubation is preferable for two reasons: first, in this area only a few anatomic structures are present and there is a minimum risk of nerve or vascular damage; second, the scar is less visible behind the symphysis and was well accepted by the patients in our series.7,9
Postoperative airway protection may be needed after maxillofacial surgical procedures when there is an anticipated risk of airway oedema or haematoma, a delayed return of consciousness or a possibility of reoperation within the early postoperative days. Removal of the tracheal tube may therefore be delayed until the patient is fully awake, oedema has subsided and a patent and protected airway is guaranteed. In our series, all the patients were extubated after the surgery. Although it appeared safe and allowed adequate postoperative care, still some authors recommend that submental tube should be avoided after maxillomandibular fixation.2,9
A strong wire cutters should be available at the patients′ side for emergency access to the oral cavity in case tube is dangerously misplaced with an enormous tissue swelling in the oral cavity. Because of rigid plate fixation immediate postoperative maxillomandibular fixation is not done now and is postponed until after extubation. Nevertheless, some authors recommend that the submental tracheal tube may be left in the postoperative period as it appears to be better tolerated than oro-tracheal tube, more easily fixed and avoids the chances of patient biting the oral tube.13
The morbidity associated with submental tracheal intubation is low. It also avoids the risks of iatrogenic meningitis or trauma of the anterior skull base after nasotracheal intubation.15
No episodes of potential complications e.g., accidental extubation, leaking cuff, damage to adjacent structures such as the submandibular and sublingual ducts and lingual nerve, oro-cutaneous fistula and anomalous scar formation have been reported.15,16
In this series venous bleeding was encountered in one patient when the pilot tube cuff was pulled out of the mouth, which responded to simple pressure with gauze packs. Infection of the submental wound occurred in two patients who responded to local measures & recovered in 4-5 days.13,15
No other complications were encountered in the intra-operative or postoperative period.
The advantages of submental intubation as compared to tracheostomy are that the potential complications associated with tracheostomy such as loss of airway, haemorrhage, surgical emphysema, pneumomediastinum, pneumothorax, recurrent laryngeal nerve damage, injury to cervical vessels or the thyroid gland, tracheal stenosis, stomal and respiratory infections, tracheoesophageal fistula and a scar in an obvious location, which can be depressed or hypertrophic, are avoided.7,15
Although these complications are usually rare, they are completely eliminated with the use of submental intubation. Loss of airway and haemorrhage are still potential risks with submental intubation; although the risk of haemorrhage causing loss of airway is much less because of the relative differences in anatomy and any blood collected will pool in the oral cavity rather than directly into the trachea.7
This method of intubation is contraindicated for patients who require a long period of assisted ventilation, i.e. multitrauma patients with severe neurological damage or major thoracic trauma, and patients expected to need repeated operations.16
In such cases a tracheostomy is a safer procedure than endotracheal intubation. Submental intubation is therefore recommended in patients suffering from maxillofacial trauma who will not require prolonged airway management.
In conclusion submental tracheal intubation is an effective and useful technique for airway control. It can be used as a good alternative to short term tracheostomy in selected maxillofacial fracture patients when tracheal intubation through both the oral and nasal routes is contraindicated. It provides a safe and reliable route for the endotracheal intubation and avoids the difficulties and morbidity of nasotracheal intubation and tracheostomy. It also allows operative control of the dental occlusion and concomitant surgery of the nasal pyramid in major maxillofacial trauma patients. It is useful both in the emergency setting and for elective procedures. The simplicity of the technique lies in the fact that no specialized equipment or technical expertise is required.
The midline approach is preferable as there is less risk of damage to the submandibular and sublingual ducts and lingual nerves. The scar is in a more favourable position, and the midline is usually relatively avascular hence midline submental intubation should be chosen in selected cases of maxillofacial fractures.6,7,16