Anesthesia for Microlaryngeal Surgery: The Case for Subglottic Jet Ventilation

Abstract

Although the techniques for surgery on the endolarynxusing suspension and the operating microscope have been fully developed,1–4 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,5 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 CO, 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.

La sonde de ventilation en jet Hunsaker Mon-Jet est efficace dans les microchirurgies laryngées

“…In 1994, Hunsaker improved on a novel airway device for subglottic ventilation that addressed the major concern of barotrauma, which had previously been an issue with this ventilatory mode and other airway devices. 3 Our series confirms Hunsaker's premise that the Hunsaker Mon-Jet tube, in conjunction with an automatic jet ventilator, is a safe subglottic tube that minimizes the risk of barotrauma. This technique provides surgeons with an essentially unobstructed view of the larynx and a laser-safe environment.…”

“…It is more efficient than supraglottic ventilation, not only providing ventilation in the trachea rather than above the vocal cords, but also venting blood and debris upwards and outwards with the expiratory flow of air, instead of propelling material further down the Several different tubes for subglottic jet ventilation have been designed over the years, but all have had limitations, including malalignment of the tube, resulting in mucosal injection and inadequate ventilation; inability to monitor airway pressures, resulting in barotrauma (presenting as subcutaneous emphysema, pneumothorax, or pneumomediastinum), and airway fire with laser use. 3 The Hunsaker Mon-Jet tube has resolved many of these problems.…”

“…This technology has since been adapted to provide supraglottic, subglottic, and transtracheal jet ventilation for laryngeal surgery using a variety of laryngoscope attachments, subglottic and transtracheal catheters, and varied frequencies of ventilation. 3,4 There has been considerable debate regarding the combination of these ventilatory techniques and devices that provides the best operative visualization and access, utmost airway control, and optimal ventilation. 3,[5][6][7][8] In 1994, Hunsaker introduced a self-centering fluoroplastic laser-safe subglottic tube through which airway pressures and end-tidal CO 2 (ETCO 2 ) could be monitored.…”

“…3,4 There has been considerable debate regarding the combination of these ventilatory techniques and devices that provides the best operative visualization and access, utmost airway control, and optimal ventilation. 3,[5][6][7][8] In 1994, Hunsaker introduced a self-centering fluoroplastic laser-safe subglottic tube through which airway pressures and end-tidal CO 2 (ETCO 2 ) could be monitored. Driven by a dedicated automatic jet ventilator, this tube was specifically designed for use in laryngeal surgery and overcame many of the limitations of other devices.…”

“…Driven by a dedicated automatic jet ventilator, this tube was specifically designed for use in laryngeal surgery and overcame many of the limitations of other devices. 3 In a limited series of 36 patients, the Hunsaker Mon-Jet tube with automatic jet ventilator introduced the combination of excellent visualization with anesthetic safety. 9 Our study is a retrospective review of 552 patients who underwent microlaryngeal surgery with subglottic ventilation using a Hunsaker Mon-Jet tube (Xomed, Jacksonville, FL, USA) in conjunction with an automated jet ventilator.…”