Incendiary characteristics of endotracheal tubes with the carbon dioxide laser. An experimental study

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.

Use of the laser in neurosurgery

The laser has become the neurosurgical tool of the 1980s. In neurosurgery, the most important attribute of the laser is its ability to precisely vaporize tissue with minimal mechanical and thermal damage to the surrounding sensitive structures. Although the Nd:YAG laser has use in this medical specialty, the CO2 laser, with its immediate absorption in water, with resultant minimization of scatter and spread to surrounding and deeper tissue, is the most useful laser in neurosurgery and the focus of this article.

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.

Heat sink protection against lasering endotracheal cuffs

The ignition of an endotracheal cuff by CO2 laser impaction has proved troublesome in several ignition sequences. Metal foil tape wrapped around the shaft of the tube will provide adequate protection for it, but the tape does not extend to the thin-walled cuff. When normal saline solution is used instead of air to fill the cuff, heat is rapidly conducted away from the wall and the cuff is prevented from reaching its kindling temperature. If penetration should occur, a fine jet of saline solution instantaneously sprays the field, extinguishing any early combustion. The reaction time of the surgeon or an assistant is not a factor in prevention of thermal injury, no new equipment is required and preparation time is minimal.