Submental intubation with intubating laryngeal mask airway as conduit: An airway option for oral submucous fibrosis release.

The main anesthetic concern with oral submucous fibrosis is progressive restriction of mouth opening due to fibrosis producing difficult airway. Securing airway by nasotracheal intubation and tracheostomy are associated with potential complications. Flexible fiberoscope is not available in all the institutes. Submental intubation using intubating laryngeal mask airway is an acceptable alternative technique in such situations. It also provides an unobstructed surgical field.

INTRODUCTION

Securing the airway for oral submucous fibrosis is a challenging task and is the major component of intra-operative management. Nasotracheal intubation is not always possible and if done bleeding is a potential complication. If we consider tracheostomy, it is invasive and unnecessary for patients who are not the candidates for elective postoperative ventilation. Other problem is that many patients hesitate to give consent for tracheostomy due to the fear of complications such as hemorrhage, tracheal stenosis, loss of speech, etc., Hence, submental intubation is an acceptable alternative technique. This technique was popularized as an alternative route for tracheostomy, oral or nasal intubation, especially in cases of major facial trauma. Since its first application of this technique, <30 years ago, many authors have studied the clinical use of this procedure.[1] We present this case management of a patient with oral submucous fibrosis with restricted mouth opening posted for fibrosis release, what is unique about this case is that submental intubation is performed using intubating laryngeal mask airway (ILMA) as a conduit.

CASE REPORT

The 46-year-old male presented to the dental outpatients department of our hospital with progressive restriction of mouth opening and difficulty in feeding for 6 months. He was a chronic smoker and a betel nut chewer for 20 years. He was diagnosed to have oral submucous fibrosis and posted for fibrosis release and reconstruction. On examination, he weighed 56 kg and had restricted mouth opening with inter-incisor gap of 2 cm, modified Mallampatti Scale IV, other clinical assessment of airway were normal. The patient was fully evaluated and planned for general anesthesia with an awake, blind nasotracheal intubation (Plan A). Alternative airway options were to use a LMA (Plan B) or to do a tracheostomy (Plan C). Fibroptic bronchoscope being the gold standard equipment in managing this kind of cases was not available for this case. Informed written consent for anesthesia risk and emergency tracheostomy were obtained from the patient.

The patient was premedicated with tablet alprazolam 0.25 mg and tablet ranitidine 150 mg, the night before surgery and was fasted for 8 h. On the morning of surgery, the patient was explained about the procedure. Injection glycopyrrolate 0.2 mg and injection metoclopramide 10 mg were given intramuscularly 30 min before the procedure. Patient was shifted to the operating room, and routine standard monitors were attached. An 18-gauge cannula was inserted in a peripheral vein and a normal saline drip was connected. To keep the patient comfortable, co-operative and calm, intravenous dexmedetomidine 50 μg was given slowly over 10 min. Airway preparation was done using 10% lignocaine spray and oxymetazoline spray. Recurrent laryngeal nerves and superior laryngeal nerves were blocked using 1% lignocaine.

Initially, we tried wake blind nasotracheal intubation but we failed. With the surgeon's request to avoid tracheostomy and to provide unobstructed surgical field, a working plan was made to place an LMA and intubate orally with subsequent submental retrieval of the endotracheal tube (ETT). Hence, the plane of anesthesia was deepened with fentanyl 100 μg and propofol 150 mg and ventilation was checked to be adequate, following which a size 4 ILMA was inserted. Then the patient was intubated with a 7.5 mm cuffed conventional polyvinyl chloride (PVC) ETT using an airway exchanger. The position of the tube was checked by auscultation and capnography.

The patient was ventilated with oxygen, nitrous oxide mixture and sevoflurane 0.8-1% to maintain end-tidal CO2 between 30 and 35 mmHg. Meanwhile, the oral cavity and anterior neck were prepared with antiseptic solution and then draped. A small 1 cm incision was made in the submental region in the midline and extended into the oral cavity by blunt dissection. Using an artery forceps, the tube was retrieved through the submental incision [Figure 1] and connected to a ventilator. The position of the tube was checked by auscultation and confirmed by capnography. The tube was secured using sutures. Anesthesia was supplemented with fentanyl 25 μg/h, dexmedetomidine 30 μg/h; atracurium titrated to the patient's response.

Figure 1

Exit of endotracheal tube through submental region

At the end of the surgery, the ETT was retrieved back to the oral cavity; the submental incision was closed in layers. After adequate recovery and reversal of motor block, ETT was removed. Patient was observed in postoperative recovery room for an hour and then shifted to the ward. Supplemental oxygen was given for 6 h using Hudson mask.

DISCUSSION

Sub mental route was found to be a simple in many trials[234] as quick and safe approach to airway management. Arya et al.[5] had tried the retrograde submental intubation in a patient with restricted mouth opening. MacInnis and Baig[4] reported that their experience with standard technique described by Hernández Altemir was less than satisfactory due to associated bleeding, difficult tube passage and sublingual gland involvement. Instead of slight lateral exit wound submentally, they modified the technique to strict midline approach in 15 patients with satisfactory results. Hence, we used this modified submental intubation technique in our patient.

Accidental extubation, tube obstruction and damaged tube (leaking cuff) are more difficult to manage in submental route. ETT exchanger had been used successfully to replace the damaged tracheal tube by the submental approach.[6]

We have used dexmedetomidine as an anxiolytic agent to obtund stress response to awake intubation. Ryu et al.[7] have compared dexmedetomidine and remifentanil for awake fibroptic bronchoscopy and they have concluded that dexmedetomidine was associated with fewer incidence of oxygen desaturation than with remifentanil.

We used ILMA to facilitate endotracheal intubation. The role of ILMA in restricted mouth opening and difficult to intubate cases have been emphasized in various studies.[8910] Lu et al.[8] described no difficulty in placing an ILMA with mouth opening 2 cm or more. Whereas, Bindra et al.[9] recommended 1.5 cm mouth opening for ILMA placement. Various methods have been used for intubation through ILMA namely specialized flexometallic tubes, standard short bevel flexometallic tubes, standard PVC ETTs, gum elastic bougie through ILMA, Cook airway exchanger, fiberoptic bronchoscope through ILMA.[111213] Joffe and Liew[14] compared the easiness of Aintree and Arndt airway exchanger guided intubation through LMA supreme with 90% success rate with each. In our case, we anticipated difficult laryngoscopy and so we proceeded with ILMA. Blind tracheal intubation was facilitated with the airway exchanger as a conduit.

CONCLUSION

Submental intubation with ILMA as conduit is an alternative to nasotracheal intubation for oral surgeries in difficult airway scenario.