Induction of anesthesia in a case of impossible mask ventilation.

Sir,

Awake fiberoptic Bronchoscopy is often regarded as a technique of choice for tracheal intubation in patients with known airway difficulty,[1] especially if mask ventilation is almost impossible. However, a subset of these patients may refuse to undergo awake procedures.[2] An alternate method for safe induction of anesthesia in such a patient is being discussed. We report a case of osteosarcoma of maxilla with obvious airway difficulty being managed by a “dedicated airway” without the need for flexible fiberoptic bronchoscope. Recently, a 56-year-old female with osteosarcoma of left maxilla was scheduled for elective total maxillectomy. She had a rapidly progressive swelling over the left side of face with complete obliteration of left nostril and a big mass protruding into the oral cavity which prevented closure of her mouth. Physical examination revealed a hard swelling measuring 10 × 10 cm occupying whole of the left cheek extending up to medial canthus and zygomatic arch superiorly [Figure 1]. A mass measuring 5 × 5 cm was bulging inferiorly from the palate into the oral cavity and occupying left upper alveolus from central incisor to 3rd molar tooth [Figure 2]. Airway examination showed normal mento-hyoid and mento-thyroid distance. However, mallampati class could not be assessed because of the oral swelling. Indirect laryngoscopy was also not possible. Soft tissue X-ray neck, lateral view, was normal except for the compromised oropharyngeal space. Computed tomography revealed expansile and destructive mass lesion involving left nasal cavity and maxilla; reaching up to skin. As difficulty in mask ventilation and direct laryngoscopy was anticipated, the need for awake fiberoptic intubation was considered and procedure was explained to the patient during pre-anesthesia check up in the previous evening.

Figure 1

A 10 × 10 cm swelling occupying whole of the left cheek, superiorly, extending up to medial canthus and zygomatic arch; medially, causing obliteration of left nasal passage and marked deviation of nasal septum to the right. The patient could not close the mouth completely due to the intraoral extension of mass.

Figure 2

Arrow pointing 5 × 5 cm mass bulging inferiorly from the palate into the oral cavity and occupying left upper alveolus from central incisor to 3rd molar tooth

The patient was premedicated with oral diazepam 5 mg, the night before surgery. Aspiration prophylaxis was achieved with oral ranitidine 150 mg and oral metoclopromide 10 mg in the morning of surgery. Difficult airway cart including fiberoptic bronchoscope was prepared. However, the patient was very apprehensive and she refused to comply for awake intubation. Subsequently, an alternate method of inhalational induction maintaining spontaneous ventilation was planned and was explained to the patient. Intravenous glycopyrolate 0.4 mg was administered as anti-sialagogue along with airway nebulization using 5 ml of 4% lignocaine over 10 min for better acceptance of the procedure by the patient and lesser requirement of inhalational anesthetic agent. Right nasal passage was decongested with 0.1% xylometazoline drops. After shifting the patient to the operating room, standard anesthesia monitoring including electrocardiogram, automated noninvasive blood pressure and pulse oximetery was carried out. Anesthetic depth was monitored using bispectral index. Intravenous fentanyl 50 μg was used for sedation. A dedicated nasopharyngeal airway sized 6 with a 6-mm endotracheal tube connector wedged into its flared end was lubricated with 2% lignocaine gel and then introduced into the right nasal passage. Breathing circuit was then attached to the airway and anesthesia was induced with sevoflurane in 100% oxygen maintaining spontaneous respiration. Positive pressure manual ventilation was checked after occluding the mouth with gauge packs, keeping the head in sniffing position. Once adequacy of ventilation was confirmed by capnography and clinically, anesthetic depth was further increased to attain minimum alveolar concentration of 2 and BIS 46. Subsequently, a check laryngoscopy was performed and vocal cords could be visualized with a Cormack and Lehane view of grade 2a. Bispectral index at the time of laryngoscopy was 46. Cords were further anesthetized using 10% lignocaine spray and then trachea was intubated with 7.5 mm ID cuffed endotracheal tube which was confirmed by capnography. There was no event of desaturation (≤95%) and hypercapnia (end-tidal carbon dioxide ≥ 45 mmHg) during the procedure.

Awake fiberoptic laryngoscopy is considered as gold standard technique for difficult airway management.[1] However, this requires expertise and may be more difficult in uncooperative patients.[23] The technique not only requires adequate preparation of airway by procedures like bilateral superior laryngeal nerve block, glossopharyngeal nerve block and transtracheal block,[2] but may also need multiple attempts. As these procedures may be frightening for the patients, in spite of the best possible efforts a few patients may fail to give consent for awake procedures like fiberoptic laryngoscopy and retrograde intubation. In such cases, induction of anesthesia, while maintaining spontaneous ventilation through standard or Patil's endoscopic facemask, could be performed to facilitate fiberoptic laryngoscopy.[4] But the situations where facemask could not be applied properly pose a challenge to the anesthesiologist for smooth induction and endotracheal intubation.

In our patient due to a large maxillary and oral mass, there was a gross facial asymmetry along with fixed open deformity of the mouth. This resulted in adequate seal with facemask and induction of anesthesia using facemask almost impossible. Therefore, a dedicated airway (an upper airway device dedicated to the maintenance of airway patency while other major airway interventions are anticipated or are in progress) was strongly warranted. This device should be compatible both in spontaneous and controlled ventilation.[5] The term “dedicated airway” was first used in connection with nasal fiberoptic intubation using the cuffed nasopharyngeal airway.[6] However, introduction of cuffed nasopharyngeal airway was difficult in our patient due to narrowed right nasal cavity and complete obliteration of left nasal passage by the tumor. Other types of dedicated airway like laryngeal mask airway (LMA)[78] and cuffed oropharyngeal airway (COPA)[89] were also not useful, due to the mass protruding in the oral cavity. Further, as a tool to facilitate intubation, nasopharyngeal airway is potentially superior to both LMA and COPA as it may be inserted in a spontaneously breathing patient, either awake or anesthetized.[10]

In view of the above mentioned facts, we selected nasopharyngeal airway as a primary tool to maintain airway during inhalational induction. To avoid nasal trauma, a smaller sized (6 mm ID), uncuffed nasopharyngeal airway was introduced in the patent nostril using 2% lignocaine gel as a lubricant for the tube. Though the technique of delivering positive pressure ventilation via nasopharyngeal airway with mouth and opposite nostril being closed using one hand has been described,[10] we modified it according to the need in our patient. As the left nasal cavity was completely blocked, there was no need to close the left nostril. However, inability to close the mouth (due to the oral extension of mass) was managed by sealing it with gauge packs. Positive pressure ventilation was possible at normal pressure and trachea was successfully intubated under deeper plane of anesthesia by direct laryngoscopy. Saturation remained 100% throughout the procedure.

In conclusion, we advocate the use of nasopharyngeal airway as a dedicated airway for safe inhalational induction and maintenance of anesthesia, until trachea could be secured. In a difficult airway where proper seal with facemask is not possible or in situations where the patient refuses awake intubation techniques, nasopharyngeal airway can be considered as a safe, cheap and acceptable alternative which avoids the psychological distress of awake intubation procedure.