The surgical application of lasers by otolaryngologists is most important to the anaesthesiologist as the airway is shared by both the surgeon and the anaesthesiologist. Laser surgery is best employed to resect subglottic stenosis (Myers and Cotton Grade 2 and 3) and subglottic haemangiomas. The CO2 laser beam is absorbed strongly by water, blood and biological tissue. It produces radiation with a wavelength of 10 mm damaging tissue surfaces to a depth of 200 mm. Hence it is suitable for removing lesions on the vocal cords. Performing CO2 laser airway surgery has a higher rate of ventilatory complications with jet ventilation than with a standard endotracheal tube. For the safe conduct of anaesthesia the technique should be based on the experience of the operator and characteristics of the stenosis. One such management is discussed in the following case report.

A 20 year old female presented with respiratory distress and stridor following an alleged history of phenol ingestion. An emergency tracheostomy was conducted as intubation was not possible due to distorted airway following corrosive injury due to phenol. Also patient had oesophageal stricture on further investigation following admission. A feeding jejunostomy was done under general anaesthesia. The patient was decannulated of the tracheostomy tube gradually.

But 9 months later patient had episode of respiratory distress but no stridor. So this patient was admitted and an indirect laryngoscopy was done. It revealed that there was very narrow supraglottic opening and sclerotic bands from epiglottis to posterior pharyngeal wall, vallecula and aryepiglottic fold. Hence patient was posted for a laser excision of the obstruction the next day. A high risk consent as well as tracheostomy consent were taken. The patient was monitored with pulse oximetry, non-invasive blood pressure and cardioscope. General anaesthesia was induced with propofol and vecuronium. It was a difficult intubation, hence all sizes of red rubber tubes were kept ready. Mask ventilation was barely possible. Oxygenation was adequately maintained. On direct laryngoscopy the narrow opening did not allow the passage of even the smallest of the red rubber endotracheal tube (2.5 no. ID) with a metal foil wrapped around it probably due to subglottic stenosis which was not anticipated. Since the patient had already undergone a tracheostomy before, there was scarring and hence a higher chance of bleeding and further complication with a repeat tracheostomy. So considering the apnoea time it was decided to place a 3 no. rigid bronchoscope at the opening and try ventilating with a Sanders injector using a 16 no. needle. This technique succeeded and it was decided to proceed with the procedure. The patient’s eyes were taped, closed and covered with moist gauze piece. Nontarget tissue was protected with moist gauze covering. Also alignment of the laser (CO2 laser) was checked and patient immobility ensured (Fig. 1).

Fig. 1 : Patient positioned with bronchoscope, Sander’s jet ventilation and laser apparatus with adequate precautions.

Anaesthesia was maintained with propofol and fentanyl infusion. Laser excisions of the bands were carried out with intermittent ventilation from the side port using the Sanders injector. Once the opening was sufficiently wide (Fig. 2), the bronchoscope was removed and then a 6.5 no. ID red rubber endotracheal tube with a metal foil wrapped around was inserted by direct laryngoscopy and airway was secured. Following complete excision of the stenosis, a 7 no. ID portex endotracheal tube was gently placed after removing the red rubber tube. The patient was reversed and smoothly extubated on table after spraying the cords with lignocaine to avoid post operative croup. Also post operatively humidification of inspired supplemental oxygen was provided.

A rigid bronchoscope allows better visualization, access, control of bleeding, suctioning and irrigation in laser surgeries.1 Also to reduce the incidence of fire during laser surgery on the airway, not more than 30% oxygen should be used in gas mixture.2 Thus while using the jet venturi ventilation technique the chances of ignition in the airway with the high jet flow of oxygen are variable.3 But the literature on ventilation and anaesthesia technique for bronchoscopic laser surgery is not consistent.

Polyvinyl chloride (PVC) tubes burn more vigorously producing hydrogen chloride which is a pulmonary toxin. Hence it is preferred to intubate patients with red tubber tubes wrapped in metal foil or with silicone tubes.4 Metal tubes are the only non-combustible tubes. But they also have lot of disadvantages.5 In India, we have no experience of metal tubes. Further the management of subglottic laser surgery presents challenges for the anaesthesiologist.

Fig. 2 : View of the subglottic stenosis mid-way through the Laser apparatus showing partial excision of stenosis.

Performing CO2 laser airway surgery has a higher rate of ventilatory complications with jet ventilation than with a standard endotracheal tube. Jet ventilation produces barotrauma to the tracheobronchial tree and lungs if the airway does not remain patent.6 It is necessary that the laryngeal pathology does not interfere with the escape of the jet ventilation gases from the tracheobronchial tree. But mucosal dehydration is common with jet ventilation and leads to increased risk of postoperative laryngeal web formation. Hence good humidification of inspired gases postoperatively and good systemic hydration is desirable. Also particulate blasting of blood and dissected tissue down the tracheal tree can occur with jet ventilation.6-8 It has also been suggested that patients undergoing laser excisions of airway tumours during jet ventilation may absorb carbon monoxide from entrained laser smoke in the pharyngeal area.9 But the biggest advantage is that the patient can be ventilated without an endotracheal tube and without obstructing equipment in the larynx offering unparallel access to laryngotracheobronchial tree for both diagnosis and surgery.10,11

In this case report we have tried to highlight the importance of providing adequate oxygenation and maintaining the airway inspite of being in a state of “can’t intubate and can barely ventilate” initially and still carried out a successful excision of subglottic stenosis by laser surgery without a tracheostomy or any other post operative complications. The risk associated with this type of procedure is higher due to compromised airway and use of laser with jet ventilation as well and hence it is to be undertaken only in the presence of an experienced senior anaesthesiologist.