Abstract
Objective
The aim of this study was to evaluate the fire risk for an electrosurgical device (Bovie) as compared with a bipolar radiofrequency ablation wand (Coblator) in a mechanical model of oropharyngeal surgery.
Methods
An endotracheal tube was inserted into the cranial end of a degutted, whole raw chicken through which 100% oxygen was piped at 10 L/min. An electrosurgical device (15 W, coagulate mode) and bipolar radiofrequency ablation wand (9, 7, and 3 in ablate mode; 5 and 3 in coagulate mode) were activated in the central cavity. All experimental conditions were tested for 4 minutes, or until a positive result was achieved. All trials were repeated to ensure accuracy.
Results
Ignition was obtained with a sustained fire when using the electrosurgical device for between 25 and 80 seconds. Under all 5 experimental conditions, no ignition or sustained fire could be produced using the radiofrequency ablation wand. After 20 sustained minutes of continuous plasma ablation in the chicken cavity without ignition, the electrosurgical device was able to ignite a fire in 25 seconds in the same cavity.
Conclusions
Although electrosurgical devices present a significant risk of fire during open cavity surgery in oxygen-enriched environments, that risk seems to be eliminated with bipolar radiofrequency plasma ablation.
1
Introduction
Airway and oropharyngeal fires are rare but potentially devastating complications of head and neck surgery. Fires have been reported during tracheostomy, adenotonsillectomy, and skin surgery of the head and neck . An ignition source, fuel, and oxidizer are required for any fire. Traditional electrosurgical devices are a potential ignition source when used in oral cavity/oropharyngeal or airway surgery. Alternative devices for surgical dissection may reduce the risk of airway fire by removing the ignition source. In this study, we used a physical model to study the fire risk for an electrosurgical device (Bovie; ValleyLab, Boulder, CA) as compared with a bipolar radiofrequency (RF) ablation wand (Coblator; ArthroCare Corporation, Sunnyvale, CA) in a mechanical model of oropharyngeal surgery.
2
Materials and methods
2.1
Electrosurgical trial
A degutted, whole raw chicken was grounded to an electrosurgical device grounding pad. A 6.0 polyvinyl chloride endotracheal tube (ETT) (Mallinckrodt, Hazelwood, MO) was placed into the cranial end of the degutted central cavity ( Fig. 1 ). For each trial, 100% oxygen (10 L/min) was piped through the ETT. This was calibrated through a standard anesthesia delivery device with F io 2 monitoring through the circuitry. Three tonsil sponges (Allegiance Healthcare Corp, McGaw Park, IL) were placed inside the chicken cavity to provide an additional source of combustible material. For each trial, the central cavity of the chicken was preoxygenated for a period of 1 minute by flowing oxygen through the ETT. Next, the electrosurgical device (ValleyLab, Boulder, CO) was placed into the chicken cavity, and raw chicken tissue near the tip of the ETT was cauterized at a setting of 15 W ( Fig. 2 ). The time to ignition of the ETT or any part of the experimental setup and the time required for a sustained fire were recorded. Each trial was repeated in a separate chicken to ensure accuracy.
2.2
Bipolar RF ablation trial
Using a fresh (not previously ignited) chicken, the experimental setup was recreated in the same manner described in Section 2.1 . The volume of the central cavity was similar in all chickens used for both experimental conditions, measuring between 400 and 425 mL. After the same period of preoxygenation, a bipolar RF ablation wand (Coblator) was then placed into the chicken cavity and used to ablate chicken tissue near the open tip of the ETT ( Fig. 3 ). Saline solution was delivered through the wand during each trial to create a plasma field, mimicking normal intraoperative function of the RF ablation wand. Ablation of the chicken tissue was performed at settings of 9, 7, and 3 in the ablate mode and at settings of 5 and 3 in the coagulate mode. Each experimental condition was tested for 4 minutes, at which point the trial was defined as “negative” if no ignition or sustained fire occurred. Each trial was then repeated in a separate chicken to ensure accuracy and repeatability.
2.3
Confirmation of positive testing
Immediately after completion of the bipolar RF ablation trials, and using the same chicken, an electrosurgical device (Bovie) was placed into the chicken cavity and tested again at a setting of 15 W as described in Section 2.1 . Time required for ignition and sustained flame was recorded. Finally, an extended continuous RF ablation trial was conducted, during which time ablation was performed for 20 consecutive minutes near the opening of the ETT in the chicken cavity, followed by electrocautery at the same location.
2
Materials and methods
2.1
Electrosurgical trial
A degutted, whole raw chicken was grounded to an electrosurgical device grounding pad. A 6.0 polyvinyl chloride endotracheal tube (ETT) (Mallinckrodt, Hazelwood, MO) was placed into the cranial end of the degutted central cavity ( Fig. 1 ). For each trial, 100% oxygen (10 L/min) was piped through the ETT. This was calibrated through a standard anesthesia delivery device with F io 2 monitoring through the circuitry. Three tonsil sponges (Allegiance Healthcare Corp, McGaw Park, IL) were placed inside the chicken cavity to provide an additional source of combustible material. For each trial, the central cavity of the chicken was preoxygenated for a period of 1 minute by flowing oxygen through the ETT. Next, the electrosurgical device (ValleyLab, Boulder, CO) was placed into the chicken cavity, and raw chicken tissue near the tip of the ETT was cauterized at a setting of 15 W ( Fig. 2 ). The time to ignition of the ETT or any part of the experimental setup and the time required for a sustained fire were recorded. Each trial was repeated in a separate chicken to ensure accuracy.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
