Anaesthesia for microsurgery of the larynx. General anaesthesia combined with neuroleptanalgesia

Anesthesia for microlaryngeal surgery: the case for subglottic jet ventilation

Although the techniques for surgery on the endolarynx using suspension and the operating microscope have been fully developed, the safest, and least obtrusive anesthetic technique has yet to be manifested, as evidenced by more than 200 references to anesthesia for microlaryngoscopy in the world literature. This study reviews the physiology, physics, and problems of each anesthetic technique. In light of this review, animal and human studies are reported demonstrating the utility and safety of subglottic ventilation when provided with proper monitoring using an automatic ventilator. A modified Ben-Jet tube is reported, which has a 1-mm ID channel to monitor PCO2 and tracheal pressure. This self-centering 3.0-mm tube, which extends 6 to 8 cm below the glottis, is unobtrusive for the surgeon. The subglottic tube, which is much less likely to be malaligned, is much more acceptable to the anesthesiologist. Anesthesia, by intravenous sedation, utilizes neuromuscular blockade while ventilating through the jet tube powered by an automatic ventilator with an automatic shutdown feature attached to the monitor tube to prevent inadvertent barotrauma. The third phase of this study compared fluoroplastic, used in a prototype jet ventilation tube, with 6-mm Silastic, Red Rubber, and polyvinyl chloride (PVC) tubes when struck by maximum power of CO2, Nd-YAG, and K-532 lasers. The test was performed in a closed chamber in which concentrations of oxygen and nitrogen were controlled. Although damaged by the CO2 laser beam, the fluoroplastic tubes did not continue burning when the laser was turned off in 100% oxygen, even when coated by blood. The other three tubes continued to burn in 23% oxygen. Neither the KTP nor Nd-YAG laser damaged the Teflon tube, while they ignited a sustained flame in 30% oxygen. This study supports the use of fluoroplastic for a laser safe jet ventilation tube. It also demonstrates the danger of tube fires, even in low oxygen concentrations, when using Silastic, rubber, and PVC tubes in laser laryngeal surgery. There was no difference in the flammability of Silastic, rubber or PVC when struck by these lasers in this study. For these reasons, subglottic ventilation using a fluoroplastic, monitored, self-centering, subglottic, jet ventilation tube driven by an automatic ventilator with a shutdown feature, in the event of excessive pressure buildup, is proposed for anesthetizing healthy patients undergoing suspension microlaryngoscopy, and who have no airway obstructing lesion. A large tube with inflatable cuff is indicated when a supraglottic lesion may obstruct the airway.

Anaesthetic experience using a standard technique for laryngeal surgery in infants and children

A 12 year review is presented of 1922 anaesthetic experiences on 285 patients presenting for microlaryngeal operations at the Hospital For Sick Children, Toronto. The lesions treated were laryngeal growths, 198 cases (69.5 per cent): subglottic stenosis, 81 cases (28.4 per cent); and posterior laryngeal cleft, 6 cases (2.1 per cent). The anaesthetic technique consisted of topical analgesia with lidocaine spray (3 mg kg-1) and pharyngeal insufflation of halothane and methoxyflurane both 1-1.5 per cent in oxygen through a special channel in the blade of a Jako Pilling microlaryngoscope in spontaneously breathing patients. Arterial blood gases sampled after 15 and 40 minutes of anaesthesia showed Paco2 = 6.29 +/- 0.31 kPa (47.1 +/-2.39 torr) and 6.44 +/- 0.16kPa (278 +/- 36.2 torr) respectively. Surgical exposure of the larynx was good allowing for a shorter operative time with minimal perioperative complications, in only 94 (4.89 per cent) of the 1922 anaesthetics.

A cuffed nasotracheal tube for microlaryngeal surgery

A technique of general anaesthetia for microlaryngeal surgery which entails the use of a specially designed long 5 mm cuffed nasotracheal tube is described.

Althesin in shared airway anaesthesia

The anaesthetic management for surgical procedures involving the larynx and/or trachea and the problem of the shared airway are outlined. The use of intravenous Althesin on 31 patients (43 administrations) is described. It is suggested that Althesin has a place in the management of these patients.

Anaesthesia for laryngoscopy and microlaryngeal surgery in children

The problems of anaesthesia for laryngoscopy and microlaryngeal surgery in children are discussed. The author's current techniques are described. For laryngoscopy, deep inhalational anaesthesia with halothane, combined with the topical application of lignocaine, is most commonly used. Microlaryngeal surgery may be performed using a pharyngeal insufflation technique to give unobstructed surgical access to the larynx. In other cases, tracheal intubation is acceptable to the surgeon, and may be used with spontaneous respiration or with muscle paralysis and controlled ventilation. Other methods, past and present, are reviewed.