Submental Intubation in Maxillofacial Trauma: A Step-by-Step Guide
Introduction and Background
Why is airway management in craniofacial trauma considered challenging?
Airway management in craniofacial trauma is challenging because the reconstruction of facial fractures requires intermaxillary fixation to access for the correct alignment of both the internal occlusion and fracture fragments. This necessitates the avoidance of oral and even sometimes nasal endotracheal tubes.
It is an unavoidable shared airway.
Why are standard oral and nasal intubation methods often unsuitable for these surgeries?
The internal articulation needed to assess fractured alignment during surgery is hindered by the presence of an oral tube. Nasal intubation is contraindicated in patients with skull base fractures, combined maxillary and nasal fractures, and those with altered nasal anatomy.
Why is tracheostomy not the first choice for short-term airway management in these cases?
Even though tracheostomy meets all the requirements for these surgeries, it is usually not recommended because the requirement is short-term, mainly intraoperative. Additionally, tracheostomy is associated with significant morbidities. Submental intubation is considered a safe alternative.
Pre-Operative Preparation and Initial Intubation
What are the initial considerations for a patient with facial trauma requiring intubation?
Patients with facial trauma usually have varying degrees of difficult airways. They may have restricted mouth opening because of pain, loose teeth, and the presence of a fractured maxilla or mandible adds to the difficulty. In all patients, you should rule out cervical spine injury and select an appropriate technique to secure the airway, either direct laryngoscopy or use of a video laryngoscope.
How should the reinforced endotracheal tube be prepared before induction?
Preparation of the tube should be done before induction. A flexometallic (reinforced) tube is usually used. Before use, detach the connector using a curved artery forceps, as it is not easy to disconnect by hand.
Insert the tip of the artery forceps between the connector and the tube and glide it around the whole circumference to loosen the attachment. Then you can remove the connector and reconnect it. This procedure, if done early, makes it easy to remove and reinsert the connector during the procedure.
What is the standard induction and intubation process for these patients?
For most patients, IV induction is enough and oral intubation is mandatory. All patients are pre-oxygenated and induced with proper agents. If difficulty is anticipated, suxamethonium can be used; otherwise, a long-acting relaxant can be used. Intubation is performed with direct laryngoscopy or a videolaryngoscope, and orotracheal intubation should be done with the prepared endotracheal tube.
The Submental Intubation Procedure
How is the incision site for the submental route chosen?
To decide where to put the incision, mark the lower part of the mandible and the midline of the chin. Choose a point 2 centimeters away from the lower border of mandible and 2 centimeters from the midline. A horizontal skin incision is made at this site.
How is the track created from the skin incision to the oral cavity?
The point of entry is the skin incision, and the point of exit is in the oral cavity at the junction of the canine and premolar teeth on the lingual aspect of the mandible at the gingiva.
Palpate with two fingers; the thumb can be kept at the site of incision and the index finger is kept at the selected site at the gingiva inside the mouth. A skin incision is made, and skin and subcutaneous tissue are incised.
Proceed with blunt dissection using a tonsil artery forceps until the lower border of mandible is reached. Then dissect towards the oral cavity to the finger at the gingiva along the inner aspect of mandible, scraping the bone. This is important because going away from the mandible risks injury to the salivary duct and the lingual nerves.
As you enter the oral cavity at the gingiva, you can open the forceps and widen the opening, seeing the protruding tip of the tonsil forceps inside the mouth.
What is the step-by-step process for bringing the endotracheal tube externally?
- Start ventilation with 100% oxygen, as the circuit has to be disconnected during the procedure.
- Perform oral suction and deflate the pilot balloon.
- Grasp the tip of the pilot balloon with the tonsil forceps and pull it out through the skin incision.
- Reintroduce the forceps into the oral cavity through the same track.
- Disconnect the circuit and detach the tube connector.
- Curve the tube tip to the forceps and pull it out extraorally.
- Once the tube is brought out, reattach the connector. If there is blood inside the tube, suction it out and resume ventilation.
What is a critical step to perform immediately after the tube is externalized?
One important point to remember is that during the procedure, the endotracheal tube often goes into a bronchus. It is mandatory that you auscultate the chest and make sure the breath sounds are equal on both sides to rule out endobronchial intubation. The tube is then sutured to the skin extraorally.
Procedure at the End of Surgery
How is the tube managed at the end of the surgical procedure?
At the end of surgery, the endotracheal tube and the pilot balloon have to be brought back to the oral cavity. To do this, the tube connector is disconnected, and the tube is pulled back into the oral cavity. Then, reattach the connector.
Next, deflate the pilot balloon, which is also pulled back into the oral cavity. Now, with both the tube and pilot balloon inside the oral cavity, you can secure the tube with tape and resume ventilation.
Finally, suture the submental skin incision to ensure an aesthetic scar. The intraoral wound is usually not sutured and is left open. Extubation is typically done in the OT or the PACU when extubation criteria are fulfilled.
Complications, Prevention, and Outcomes
What are the potential complications of submental intubation?
The most common complication is airway compromise, like kinking of the tube which can lead to hypoxia. Other complications include:
- Accidental extubation.
- Injury to the marginal mandibular and lingual nerves, and the salivary duct during blunt dissection.
- Postoperative infection and scarring.
How can the complications of submental intubation be prevented?
- Using a reinforced endotracheal tube prevents collapse and kinking.
- Blunt dissection close to the mandible avoids injury to the floor of the mouth, submandibular gland, and nerves.
- Intraoperative tube displacement can be prevented by securing the tube to the skin with sutures.
- Frequent observation of the depth of insertion from the skin will prevent endobronchial intubation. Marking the tube at skin level and frequent checking during surgery is advisable.
What do studies and literature show about the success and outcomes of submental intubation?
A literature review of around 912 cases has shown that the success rate of submental intubation is 100%, and the mean time required is 8 minutes. Only minor complications are reported, mostly superficial skin infections. It is also seen that the submental scar is better tolerated by patients than a tracheostomy scar.