Submental intubation for airway management of patients with complex caniomaxillofacial injuries: Our experience.

CONTEXT: There is paucity of data regarding the role of submental intubation (SI) in the airway management of patients with craniomaxillofacial trauma from India. AIMS: To study the characteristics of patients presenting with craniomaxillofacial injuries requiring submental intubation, the duration of SI procedure and complications of this technique. SETTINGS AND
DESIGN: Tertiary level, teaching institute, retrospective, observational study.
MATERIALS AND METHODS: Forty patients requiring submental intubation between June, 2007 and December, 2009. The primary outcome measure was the time required for submental intubation defined as starting from the completion of the orotracheal intubation to the fixation of the submental tube. The secondary outcome measures included characteristics of patients with craniomaxillofacial injuries, intraoperative and postoperative complications of the SI technique. STATISTICAL ANALYSIS USED: Data are presented as mean± standard deviation and frequency and percentages, where relevant.
RESULTS: Most of the patients were young (average age = 35.15 ± 12.02 years), males (75%) and sustained craniomaxillofacial injuries due to road traffic accidents (85%). The 40 patients included in this audit had 56 injuries recorded at the time of admission including, orthopedic injuries in 65% and head injuries in 55% of patients. The mean time required for completion of SI was 8.90 min. The complications observed included, intraoperative tube migration, development of extra oral fistula, and sialocele, in one patient each.
CONCLUSIONS: Submental intubation is a simple, safe, quick, and relatively harmless alternative to tracheostomy for securing the airway in selected patients with craniofacial trauma. Familiarity with the submental intubation technique will help the anesthesiologist to avoid tracheostomy in selected patients with craniofacial trauma who do not require long-term mechanical ventilation.

INTRODUCTION

Road traffic accidents are reported as the main cause of facial injuries in the literature from developing countries, whereas interpersonal violence remains the leading etiological source in the developed world.[1] With regard to the anatomical sites, mandibular and zygomatic complex fractures account for the majority of all facial fractures and their occurrence varies according to the mechanism of injury and patient factors, particularly, gender, and age.[2] The anesthetic management of patients with maxillofacial injuries presents unique challenges to the anesthesiologists, especially with regard to the airway management in these patients.

The treatment of maxillofacial injuries requires reduction and stabilization of maxillary and mandibular fractures by placing the patient's teeth in proper occlusion (which should be maintained and checked frequently intra operatively) but oral intubation significantly impedes this.[3] Different methods of intubation suitable for facial trauma cases include orotracheal, nasotracheal intubation, elective short-term tracheostomy, retromolar, submandibular, and submental intubation (SI). In patients with craniomaxillofacial trauma, neither nasal or orotracheal intubation may be possible and tracheostomy is the only alternative.

The submental route of intubation has emerged as an attractive alternative to tracheostomy in the airway management of patients with maxillofacial injuries since its introduction in 1986 by Altimer.[4] This retrospective audit was performed to demonstrate the feasibility and the reliability of submental tracheal intubation as a method for airway management during general anesthesia in patients with craniomaxillofacial injuries. We also studied the characteristics of patients presenting with such injuries and complications of the SI technique.

MATERIALS AND METHODS

We reviewed the patient records and anesthesia charts of forty patients with maxillofacial injuries requiring submental endotracheal intubation between June, 2007 and December, 2009. The data collected included the patient's name, age, gender, etiology of maxillofacial injury, preoperative Glasgow coma scale (GCS) score, indication for surgery, and co-existing injuries at the time of hospital admission. Intraoperative records were screened for any difficulty during endotracheal intubation, the type of endotracheal tube used for SI, time required for submental intubation (SI), duration of disconnection of the breathing circuit from the endotracheal tube, and duration of surgical procedure. Any episodes of arterial hemoglobin desaturation or bradycardia during conversion of oral to submental intubation were also noted.

The primary outcome measure was the time required for submental intubation defined as starting from the completion of the orotracheal intubation to the fixation of the submental tube. The conversion of oral intubation to the SI involves a period of disconnection of the patient from the anesthetic circuit. This period is important and if prolonged it may have an adverse effect on the patient's outcome. The goal of the operating team is to reduce the duration of the SI technique and the period of disconnection from the anesthetic circuit; hence, we decided to record these durations in our study. The secondary outcome measures included patient characteristics, intraoperative complications of the technique, for example accidental extubation, arterial hemoglobin desaturation during the procedure, endobronchial intubation, endotracheal tube migration, injury to the endotracheal tube or its cuff and post-operative complications including hemorrhage; injury to the sublingual gland, Wharton's duct or lingual nerve, orotracheal fistula formation, infection; and improper healing of intraoral and submental scars.

All the patients were posted as elective surgical procedures and underwent a complete preoperative examination with special reference to airway assessment as these patients usually have a difficult airway. All equipment to manage a difficult airway was prepared in advance if the patient had an anticipated difficult airway. The endotracheal tube connector of an appropriate-sized flexometallic or polyvinylchloride tube was disconnected using an artery clamp prior to intubation and then reconnected to the tube to prepare the tube for the submental intubation.

A standard technique was used for the conversion of oral intubation to SI.A skin incision of two centimeters was made two centimeters below the inferior border of mandible and blunt dissection was carried out with a curved hemostat toward the medial surface of the mandible. Mouth opening was maintained with the help of a bite block and tongue was retracted with tongue depressors. When the tip of hemostat was visible through lingual mucosa in the lingual vestibule (between Wharton's duct and medial surface of mandible in the region of mandibular canine tooth), an incision was made over the mucosa and passage for the tube was created. The pilot balloon was clamped to the hemostat and was pulled out of the oral cavity through the incision after disconnecting the endotracheal tube connector. The endotracheal tube was secured with 2-0 silk and the tube connector was then firmly reattached to the tube before reconnecting to the anesthetic circuit.

A pharyngeal pack was inserted to seal the pharynx from blood and debris during surgery. At the end of the operation, the stay suture was removed and tracheal tube was pulled back to the oral cavity after removal of the tube connector, followed by the pilot balloon. The orotracheal tube was reconnected to the anesthetic circuit and the submental incision was sutured loosely to allow certain degree of drainage. Neuromuscular blockade was reversed with injection atropine 0.02 mg/kg and injection neostigmine 0.05 mg/kg intravenously. Patients were allowed to regain consciousness and trachea was extubated after the return of protective reflexes. The postoperative complications were recorded from the patients’ hospital records by reviewing the follow up data till a period of 6 months after discharge from the hospital. Data were compiled and analyzed using Microsoft Excel, version 2007.

RESULTS

The average age of the patients included in this study was 35.15 ± 12.02 years. Most of the patients were young, males (75%). The commonest etiology of maxillofacial injuries in the study population was road traffic accidents (85%). Four patients developed the injuries after fall from height while two patients were injured after history of interpersonal violence. The median preoperative GCS was 15/15. One patient had a GCS of 8/15 and was intubated preoperatively [Table 1]. The 40 patients included in this audit had 56 injuries recorded at the time of admission [Figure 1]. The commonest co-existing injuries were orthopedic injuries, which were observed in 65% of patients, followed by head injuries in 55% of patients. Three patients (7.5%) had surgical injuries and five patients had chest injuries (12.5%). The types of maxillofacial injuries requiring surgical intervention are listed in Table 2.

Table 1

Patient characteristics

Figure 1

Distribution of patients according to the co-existing injuries at the time of hospital admission

Table 2

Type of maxillofacial injury requiring surgery

Figure 2 depicts the distribution of the study population according to the time required for submental intubation [Figure 2]. The mean time required for completion of SI was 8.90 min. The minimum duration required for SI was 7 min (nine patients); while the maximum duration of procedure was 11 min (six patients). The average time for anesthesia circuit disconnection during SI procedure was 1.5 ± 0.35 min. The average duration of the surgical procedures was 3.98 ± 1.41 h. Reinforced flexometallic tubes were used for the SI technique in majority of the patients (80%).

Figure 2

Distribution of patients according to the time required for the submental intubation technique

No accidental extubations or tube injuries occurred intraoperatively. No episodes of intraoperative hemoglobin desaturation or bradycardia were observed during the SI procedure. The endotracheal tube migration occurred intraoperatively in one patient during manipulation of the mandible. This was recognized as an increase in the airway pressures and decrease in the end tidal carbon dioxide (ETCO2) value along with transient decrease in hemoglobin saturation to 96% intraoperatively. Extra oral fistula was observed in one patient, 2 days after discharge (14 days postoperatively) due to improper closure of wound intraoperatively. One patient developed a sialoceledue to injury to submandibular gland due to the posterior placement of incision. The submental incisions healed in all patients with minimal scarring and no other complications were observed during the mean follow up period of 6 months.

DISCUSSION

Craniofacial trauma predominantly affects males in the age group of 20 to 30 years. Earlier studies from various parts of India have reported similar results as ours with respect to the age of patients, male predominance, and the commonest etiology of maxillofacial injuries.[5678] Most of the patients with craniofacial trauma belong to the economically productive age group; hence, it is desirable to avoid long-term morbidity as may result after a tracheostomy for the airway management in these patients.

Management of the airway is a major concern in patients with craniomaxillofacial trauma (gunshot wounds, facial fractures, cervical spine injuries, and laryngotracheal injuries) because a compromised airway can lead to death.[9] No single technique has been described as the gold standard for the airway management in patients with craniofacial trauma and the anesthesiologist has to choose the best option depending on the patient's condition. In general, oral endotracheal intubation is usually not a viable option, but nasotracheal intubation, tracheotomies, submental, and submandibular intubation can be performed. Nasotracheal intubation is contraindicated in patients with epistaxis, nasal bone fractures, or cerebrospinal fluid rhinorrhea, which are conditions that are commonly encountered in patients with craniomaxillofacial injuries. Oral endotracheal intubation will interfere with the surgical field when intra operative control of dental occlusion is required. A tracheostomy may be used in patients requiring maxillofacial surgery but it is associated with considerable risk of iatrogenic complications, including, hemorrhage, surgical emphysema, recurrent laryngeal nerve injury, tube blockage, tracheal stenosis, and poor scar appearance.[8]

Submental intubation was described as an alternative route for oral or nasal intubation especially in case of major facial trauma by Hernandez Altemir in 1986.[4] Other reported indications for SI include systemic pathology or simultaneous orthognathic and plastic surgery.[10] This technique provides a secure airway, an unobstructed intraoral surgical field and allows maxillomandibular fixation while avoiding the drawbacks and complications of nasotracheal intubation (risks of iatrogenic meningitis or trauma of the anterior skull base) and tracheostomy (such as tracheal stenosis, injury to cervical vessels or the thyroid gland).[11] SI has a low morbidity and it does not impede the surgical field, allowing for temporary maxillomandibular fixation (jaw wiring), assessment of proper dental occlusion intra-operatively, and nasal manipulation and bone grafting, either simultaneously or as an independent procedure.[12]

In our study, the mean time required for completion of SI procedure was 8.90 min. The earlier studies have reported the average duration of SI ranging from 5.9[6] to 9 min.[7] The average duration of disconnection of the endotracheal tube from the ventilation circuit was 1.5±0.35 min that was comparable to values reported in the literature.[68] The duration of disconnection from the anesthetic circuit is important as the patient is vulnerable to hypoxic injury during this period; if this duration is prolonged due to any reasons. The anesthesia technique during the SI procedure demands adequate preoxygenation of the patient prior to endotracheal intubation and the discontinuation of nitrous oxide if it is being used, before beginning the SI technique; as a safeguard against the development of hypoxia. We used reinforced flexometallic endotracheal tubes in most of the patients in the study as there is less chance of tube kinking with these tubes. Some flexometallic tubes are unsuitable for SI as their connectors are not detachable. Careful selection and preoperative endotracheal tube preparation is vital to the SI technique. The use of polyvinylchloride tubes for SI in eight patients in our study was not associated with any episodes of endotracheal tube kinking but based on the experience of previous investigators[678] we would recommend the use of flexometallic endotracheal tubes for SI.

None of the patients in the study had hemoglobin desaturation or bradycardia during the submental intubation procedure or intra operatively. Tube migration intraoperatively was noticed in one patient and presented as increased airway pressures. This was recognized and remedied immediately by alerting the surgeons who helped in correct re-positioning of the tube. Tube migration is a known complication of the SI or submandibular intubation technique and has been reported earlier by Amin et al.[12] The role of monitoring airway pressures, ETCO2, SpO2 and alertness of the anesthesiologist in the detection of tube migration in operative procedures that require sharing of the airway with the surgeons cannot be over emphasized.

One patient required postoperative mechanical ventilation in view of low GCS and flail chest and tracheostomy was done on this patient on the first post operative day. Tracheal extubation was done in the operation room in all the other patients successfully. The decision to extubate in the operation theatre was taken in consultation with the surgeon and the attending anesthesiologist based on the intraoperative events and the preoperative clinical condition of the patient.

Several investigators have successfully used Altemir's technique earlier with no major complications. However, Maclnnis and Baig found it less than satisfactory in their first two patients because of difficult tube passage, bleeding and sublingual gland involvement.[11] They modified the approach in their next 15 cases to a strict midline submental incision with satisfactory results.

In our study, no hypoxic episodes or bradycardia occurred during the technique or the operation. The complications observed on follow up of the patients included development of sialocele and extra oral fistula in one patient each. One patient required prolonged mechanical ventilation and succumbed to ventilator associated pneumonia and sepsis on the eighteenth postoperative day. This patient had a low preoperative GCS (8/15) and was intubated preoperatively and the oral endotracheal intubation was converted to SI intraoperatively. All other patients had acceptable scars without keloid or hypertrophic scar formation. Our experience confirms that careful blunt dissection close to the medial border of the mandible and good knowledge of anatomy can help to avoid damage to the structures of the floor of the mouth.

Complications of SI technique include minor bleeding during the procedure, localized infection[313] and sepsis, mucocele formation, poor wound healing or scarring, and postoperative salivary fistula.[14] The other reported complications include damage to the cuff of the tracheal tube during the manipulation by the McGill forceps,[15] accidental extubation[7] and inward displacement of the tube while manipulating the mandible during surgery.[12] In a recent literature review on SI by Jundt et al.,[16] the three most commonly reported complications of this technique were, superficial skin infections, damage to the tube apparatus and fistula formation. Contraindications to SI technique include patients who require prolonged mechanical ventilation, infection at the site of incision, deranged bleeding parameters, disrupted laryngo tracheal anatomy and severe traumatic wound on the floor of the mouth.

The strengths of our study were that we studied both, the intra operative as well as the postoperative complications of the submental intubation technique. The limitations of the study were that we did not record the final outcome of these patients and the follow up data was collected only for a period of 6 months.

We found the SI technique easy and effective as it provided an excellent approach to the whole face, and the oral cavity while securing the patient's airway. The SI technique is simple and does not require any special equipment. The low incidence of operative and postoperative complications with the SI technique make it an attractive alternative to tracheostomy or nasal intubation in selected patients with craniomaxillofacial trauma for intra operative airway management.

Although it is not a replacement for tracheostomy, the submental intubation technique may be a better option in certain patients with facial trauma or orthognathic surgery as it is a simple and quick alternative to tracheostomy with low morbidity. The anesthesiologist and emergency physician should be well versed with this technique as it can improve patient management.