The resistance to carbon dioxide laser ignition of a new endotracheal tube: Xomed Laser-Shield II

Development of an Improved LASER-Resistant Endotracheal Tube

OBJECTIVES

Surgical fires, particularly within Otolaryngology, remain a surprisingly frequent and devastating complication of laser-related surgery in the oropharynx and airway; Current estimates suggest anywhere from 200 to 600 surgical fires per year in the United States, with 20%-30% of these occurring as a complication of laser surgery and 90%-95% of these occurring in the head and neck region. Unfortunately, the complications of laser surgery in the airway may include respiratory failure, airway burns with stenosis, and may result in mortality. The most commonly utilized endotracheal tube for protection against inadvertent laser strikes, the Laser-Shield II tube (Medtronic), was removed from the commercial marketplace in 2016 after cases of airway fires were reported as a result of feature deficiencies in the product (FDA MAUDE Database review). Since the demise of the Laser-Shield II tube, alternatives such as the Mallinckrodt laser tube and handmade reinforced tubes have been utilized, although shortcomings in design and features have made these options less appealing to practicing Otolaryngologists. Creating a laser-safe endotracheal tube is critical for safe upper airway surgery. This paper evaluates new technologies, materials, and technical innovations in endotracheal tubes that may advance patient safety in laser-assisted Otolaryngology procedures.

STUDY TYPE

This paper evaluates new technologies, materials, and technical innovations in endotracheal tubes that may advance patient safety in laser-assisted Otolaryngology procedures.

METHODS

First, this article reviews the background of laser surgery in Otolaryngology and the consequent risk of surgical fire with resultant development of laser-resistant endotracheal tubes and commercial availability. Next, a review of claims and national database review of product failures related to previous laser-resistant endotracheal tubes is performed through the FDA MAUDE database. This includes an evaluation of cases: review of techniques in laser airway surgery including spontaneous ventilation, decreased O2 concentration, currently available endotracheal tubes including "handmade" fixes for perceived safety risks, and determination of failure points for previous laser-resistant endotracheal tubes. Third, the paper reviews the requested features of an "ideal" laser-resistant endotracheal tube. Finally, the paper reviews failure testing from an initial, unsuccessful attempt at material development and the consequent development of alternative technologies that address failure points from previous endotracheal tubes and addresses requested features with a detailed analysis of FDA-approval required testing. Extensive lab testing of the new tube predicts a significant reduction of risk in vivo with inability to perforate the shaft or cuff of the tubes under standard working conditions.

RESULTS

While no iteration of a laser-resistant endotracheal tube is entirely laser safe, advances in technology can improve the safety profile of these devices. The new tube contains a double cuff, a soft and flexible shaft to minimize laryngeal insertion trauma, a smooth external surface, a tight-to-shaft balloon, and methylene blue dye in the cuff to alert the user to inadvertent penetration. These characteristics were the most requested by laryngologists in the development of a new laser-resistant tube. The newest endotracheal tube brings the features most requested by Otolaryngologists in a laser-resistant tube, and improves the safety profile over previous tubes.

CONCLUSION

Development of a new endotracheal tube represents an advancement in safety for the Otolaryngologist in laser airway surgery. Understanding the previous history and the science behind surgical fire formation is essential in advancing safety for patients in the future.

LEVEL OF EVIDENCE

N/A Laryngoscope, 134:S1-S12, 2024.

A Comparison of Laser-Protected Endotracheal Tubes

OBJECTIVES

To compare the physical characteristics of 3 laser-protected endotracheal tubes (LPETs) commonly used in endoscopic laser surgery. To report potential intraoperative problems related to LPET use and suggest practical solutions.

STUDY DESIGN

Comparative analysis.

SETTING

Academic laboratory.

SUBJECTS AND METHODS

Physical characteristics of the Mallinckrodt Laser-Flex (MTL), Medtronic Laser-Shield II (ML-II), and Rusch LaserTubus (RL) were compared. The effect of bending LPETs on airflow resistance was estimated with a pressure transducer. The force required to pull each tube through the glottis and the pressure exerted during this maneuver were measured in a fresh cadaveric human larynx.

RESULTS

The design features and physical characteristics of LPETs differ, including varying balloon-tip lengths. Bending LPETs to acute angles caused significant pressure increase within the RL tube (Δ 3.42 cm H₂O) and minimal change within the ML-II (Δ 0.12 cm H₂O) and MTL (Δ 0.21 cm H₂O) tubes. The average force required to pull the RL (48.12 g, P = .003) and MTL (282.4 g, P = .001) tubes through the glottis was 7.6× and 44.5× greater than that for the ML-II (6.39 g). When pulled through the vocal folds, the ML-II cuff exerted no detectable pressure, whereas higher pressures were measured for the RL (2.2 cm H₂O) and MTL (6.5 cm H₂O) tubes.

CONCLUSION

The ML-II tube had the most favorable characteristics, with minimal pressure during extubation and resistance to kinking. The RL tube kinks readily with a resultant increase in resistance to airflow. The MTL tube extends farther into the trachea due to a relatively elongated balloon-tip configuration. Future LPET designs should incorporate features that avoid intraoperative difficulties related to airway protection and ventilation.

Surgical fires in laser laryngeal surgery: are we safe enough?

OBJECTIVE

Laser surgery of the larynx and airway remains high risk for the formation of operating room fire. Traditional methods of fire prevention have included use of "laser safe" tubes, inflation of a protective cuff with saline, and wet pledgets to protect the endotracheal tube from laser strikes. We tested a mechanical model of laser laryngeal surgery to evaluate the fire risk.

STUDY DESIGN

Mechanical model.

SETTING

Laboratory.

SUBJECTS AND METHODS

An intubation mannequin was positioned for suspension microlaryngoscopy. A Laser-Shield II cuffed endotracheal tube was placed through the larynx and the cuff inflated using saline. Wet pledgets covered the inflated cuff. A CO2 laser created an inadvertent cuff strike at varying oxygen concentrations. Risk reduction measures were implemented to discern any notable change in the outcome after fire.

RESULTS

At 100% FiO2 an immediate fire with sustained flame was created and at 40% FiO2 a near immediate sustained flame was created. At 29% FiO2, a small nonsustained flame was noted. At room air, no fire was created. There was no discernible difference in the severity of laryngeal damage after the fire occurred whether the tube was immediately pulled from the mannequin or if saline was poured down the airway as a first response.

CONCLUSIONS

While "laser safe" tubes provide a layer of protection against fires, they are not fire proof. Inadvertent cuff perforation may result in fire formation in low-level oxygen enriched environments. Placement of wet pledgets do not provide absolute protection. Endotracheal tube (ETT) cuffs should be placed distally well away from an inadvertent laser strike while maintaining the minimum supplemental oxygen necessary.

Laser surgery and fire hazards in ear, nose, and throat surgeries

Operating room fires are rare but can be devastating. These fires can occur during almost any surgical procedure but are more likely during airway surgery, during head and neck surgery, and if volatile flammable liquids are used. Each team in the operating room (ie, anesthesia, surgery, and nursing) has special expertise and responsibility in preventing and responding to a fire. Fires can be prevented by ongoing education and an interdisciplinary discussion of risks and responsibilities prior to each high-risk case.

Value of endotracheal tube safety in laryngeal laser surgery

BACKGROUND AND OBJECTIVES

Due to the increased popularity of laryngeal laser therapy, surgeons and anesthesiologists are inevitably confronted with questions concerning the choice of the most efficient endotracheal tube (ETT) for laryngeal laser surgery, especially with regard to possible endolaryngeal tube fires, or combustions. The purpose of this study was to determine the current practice in endolaryngeal laser surgery in Germany.

STUDY DESIGN/MATERIALS AND METHODS

A questionnaire was sent to 152 ENT Departments in Germany, care was taken that the responders could send back the questionnaire anonymously. Among other questions the participants were asked for the number of lasersurgical treatments of the larynx performed in the past, the usual type of ETTs in use, whether other safety precautions were taken during CO2 laser surgery of the larynx and for intraoperative complications like tube ignition, fires or combustions.

RESULTS

Eighty six of the 152 addressed ENT departments replied. In laryngeal laser surgery, 59/86 departments regularly use special laser tubes in daily routine (74.5%). In about 20,000 lasersurgical procedures, 15 incidents of ETT fire have been reported. In six of the reported 15 cases a tube fire occurred despite the fact that special laser tubes had been utilized.

CONCLUSIONS

The present study could demonstrate that the use of special laser tubes does not necessarily protect against ETT fire. Thus, even when using special laser tubes other safety measures should be taken. In view of the maximum safety for the patient it has to be stated, that the safety during surgery correlates definitely with the experience of the surgeon. The weakest point of ETTs is usually situated in the cuff region.

The use of CO2 laser in the treatment of gingival fibromatosis: a case report

A case is described of gingival fibromatosis in a 10-year-old boy, in which gingival tissue was removed using a CO2 laser. The advantages of this method over conventional surgery were minimal bleeding and pain, allowing treatment of all quadrants in one visit. The disadvantages were the potential risks to the teeth and to the endotracheal tube. In this case laser treatment achieved a good result with minimal post-operative discomfort, which is an important consideration for children.