Incendiary characteristics of endotracheal tubes with the carbon dioxide laser. Supplemental report

Evaluating the Effects of a 532-nm Fiber-Based KTP Laser on Transoral Laser Surgery Supplies

Objective

The KTP laser has become commonplace in transoral head and neck surgery. The interactions of this laser with commonly used supplies in transoral surgery have not been formally examined. This study evaluates the effects of the KTP laser on surgical supplies.

Study Design

Experimental study.

Setting

The study was conducted in an empty operating room at a university-affiliated medical center.

Methods

An Aura XP 532-nm KTP laser with a 600-nm fiber was used in pulsed and continuous modes. The beam was focused at the shaft and balloon of 3 “laser-safe” endotracheal tubes (ETTs), a polyvinyl chloride (PVC) ETT, and a Codman surgical patty. Time to penetrate was recorded.

Results

The KTP laser beam was unable to penetrate any of the laser-resistant ETTs. It did react with the black number markings on the PVC ETT by producing sparks but was unable to penetrate the shaft of the ETT. The KTP laser was nonreactive with all ETT cuffs except in 1 of 3 trials with the outer balloon cuff of a Rusch Lasertubus ETT when the laser was used in a continuous mode. The KTP laser caused the production of a flame upon contact with the blue radiopaque strip of the surgical patty, even when the patty was wet.

Conclusion

This study demonstrates that a number of safe ETT options may be used during transoral laser microsurgery with a KTP laser. In addition, Codman surgical patties are shown to be a significant fire risk in KTP laser surgery.

Laser safety in head and neck cancer surgery

The use of trans-oral laser techniques for the resection of head and neck carcinomas has increased exponentially over the last four decades. Inadvertent laser damage to the patient or operating theatre staff is an acknowledged risk. However, no data exist to verify the safety margin of commonly employed precautions. The aims of this study was to assess the safety margins of protective strategies commonly adopted when using CO(2) lasers to resect tumours of the head and neck. A Sigmacon Acupulse Lumenis CO(2) laser was evaluated. The beam was focused to 2 mm diameter at 402 mm focal length. Gauze swabs, neurosurgical patties, surgical gloves, paper drapes and conventional endotracheal (ET) tubes were tested against the following laser variables: power, beam characteristics and angle of beam incidence (90 & 45°). Laser penetration time through the material under test was recorded in seconds (s). All the materials where tested dry and some, when appropriate, were tested wet. The mean of three recordings was calculated. The results demonstrated dry gauze swabs, neurosurgical patties and paper drapes provided 0 s protection at 2 W (lowest power). However, when wet, the laser failed to penetrate the swabs and neurosurgical patties, even after 180 s of continuous application. Gloves (single or double layer), and ET cuffs were penetrated in less than 1 s at 2 W. Time to penetrate a size 6.0 ET tube at 2 W continuous setting increased from <1 s at 90° to 42 s at 45°. These data are essential for anyone using CO(2) lasers for the resection of head and neck tumours. The importance of keeping laser consumables wet throughout the procedure is highlighted. The angle at which the laser hits the ET tube may impart some protection against airway fire but the data support the need to cover the ET tube with damp swabs or neuropatties when possible.

Safe anesthesia for endoscopic laryngeal laser surgery

Anesthesia safety for endoscopic laryngeal laser surgery has been a major limiting factor for laser applications in the larynx and the hypopharynx. Several anesthesia techniques have been proposed and each technique appears to have its own limitations. This paper will deal with the distinct advantages offered by the malleable copper tube which is used for delivery of the open Venturi system anesthesia for endoscopic laser surgery. A retrospective study of 100 patients who have undergone this modality of anesthesia at our institution will be presented. Our conclusion from this study shows clearly the superiority of the copper tube over the conventional aluminium-foil-wrapped endotracheal tube in safety and the exposure of the larynx during surgery.

Injuries to the bronchi and lungs caused by laser-ignited endotracheal tube fires

A CO2 laser attached to an operating room microscope was used to produce extraluminal and intraluminal ignition of various endotracheal tubes in dogs. Extraluminal ignition was produced in Silastic and red rubber endotracheal tubes. The red rubber tube ignited before the tube lumen was penetrated. The Silastic tube failed to ignite while the cuff was inflated. When the cuff was deflated, ignition occurred before the lumen was penetrated. No lung or bronchial injuries were detected in the red rubber or Silastic endotracheal tube extraluminal fires. Intraluminal fires were produced in Silastic, red rubber, and polyvinylchloride (PVC) endotracheal tubes. Microscopic examination of the bronchi and lungs revealed severe injuries in dogs intubated with the PVC and red rubber endotracheal tubes. No injuries to the bronchi and lungs were detected in the Silastic tube group, although the potentially toxic effects of silica ash require further investigation.

Comparison of tracheal damage from laser-ignited endotracheal tube fires

Studies were undertaken by the Departments of Otolaryngology-Head and Neck Surgery and Anesthesiology at Northwestern University Medical School and the Medical College of Wisconsin (Milwaukee) to compare the potential for tissue injury to the trachea and lungs of canines. Polyvinylchloride (PVC), Rusch red rubber, and silicone tubes were tested. The effects of an intraluminal tube fire on the larynx and trachea were documented with laryngeal and bronchoscopic photographs taken immediately postburn and at the time of sacrifice six hours later. The most severe burns were associated with the PVC tube. Silica ash was seen in the airway after the silicone tube fires and raises the possibility of future problems with silicosis. Histological examination of the trachea showed acute injury in all of the animals; specimens from the dogs with the PVC tube fires demonstrated the most severe cellular damage.