Endotracheal tube fire during tracheostomy: a case report. (Original Article).

Abstract

Electrosurgery in the presence of volatile anesthetic gases has been associated with operating-room fires. We report a case in which an operating-room fire occurred while an intubated patient underwent electrosurgical tracheostomy. The fire in this case was caused by a combination of an oxygen-rich environment, a polyvinyl chloride tube, and heat generated by an electrosurgical unit. We also discuss factors that increase the risk of this type of fire and the management steps that should be undertaken in the event that such afire occurs, and we briefly review the literature on this subject.

Introduction

Electrocautery procedures are a known cause of operating-room fires. In the presence of a volatile anesthetic mixture, electrocautery can result in the ignition of plastic, rubber, paper, and other combustible or flammable materials.

Seven previous cases of endotracheal tube fire have been reported in the literature. (1-7) In five of these cases, fire occurred during a tracheostomy. (3-7) When tracheostomy is performed on an intubated patient, an airway fire can occur when electrocautery is used to incise the trachea in close proximity to the endotracheal tube. In this article, we report a new case of endotracheal tube fire during tracheostomy.

Case report

A 35-year-old woman was scheduled for elective tracheostomy. The woman had undergone an exploratory laparotomy 17 days earlier. She subsequently developed sepsis and adult respiratory distress syndrome and was admitted to the intensive care unit (ICU). Her lungs were ventilated through an in situ 7.5-mm internal-diameter polyvinyl chloride endotracheal tube.

Our preoperative airway examination revealed that her oropharynx was filled with secretions and her lips were swollen. Other measurements revealed the following: blood pressure: 150/90 mm Hg; heart rate: 95 beats/min; arterial blood gases on [FiO.sub.2]: 100%; positive end-expiratory pressure: 15 cm [H.sub.2]O; tidal volume: 570 ml; respiratory rate: 20 breaths/min; pH: 7.44; [PCO.sub.2]: 50 mm Hg; [PO.sub.2]: 52.6 mm Hg; [HCO.sub.3]: 34.2 mEq/L; and base excess: +9.0 mEq/L.

General anesthesia was induced with 6 mg of intravenous vecuronium and maintained with isoflurane and a 100% [O.sub.2]-air mixture. The patient was placed in the supine position and prepared and draped for tracheostomy in the usual fashion. A grounding pad was placed on the patient. A transverse skin incision was made two finger breadths (~2 cm) above the sternal notch by electrocautery. The incision was carried down to the level of the strap muscles, which were retracted laterally. The thyroid isthmus was cut and transfixed. Electrocautery was then used to coagulate a vessel overlying the trachea and to subsequently enter the trachea. Before incising the trachea, 100% oxygen was used to ventilate the patient in order to maximize oxygen saturation. This was done in anticipation of the short period of apnea that occurs when the surgeon switches from an oral endotracheal tube to a tracheostomy tube.

When the trachea was entered, a small explosion occurred that ignited the endotracheal tube. The oxygen source was immediately disconnected, and the tube was removed. Immediate inspection of the airway revealed that there was no ongoing fire. Once the patient's safety was assured, the tracheostomy proceeded and was quickly completed. A size 6 Shiley tracheostomy tube with cuff was placed and secured, and the cuff was inflated.

The patient showed no outward signs of deterioration as a result of the fire. Direct laryngoscopy was performed to assess any damage. Examination of the oral cavity detected a charring of the postpharyngeal wall. The anterior segment of the trachea surrounding the tracheostomy was also charred, but the distal airway was not damaged. The cuff of the endotracheal tube was perforated and had melted, and the proximal lumen was full of black char.

The patient was taken back to the ICU. She underwent a chest x-ray, which showed no change from her preoperative radiograph. Flexible endoscopy on postoperative day 3 showed a mild staining of the epiglottis, but the remainder of the larynx appeared to be normal. The patient later developed pneumothorax and received a chest tube on the left side. The patient was kept in the ICU as a result of a prolonged illness unrelated to her tracheostomy. Despite her multiple medical conditions, she remains alive with the tracheostomy tube still in place. She still has no evidence of airway damage or tracheal stenosis.

Discussion

In much of the medical literature, the terms electrosurgery and electrocautery are used interchangeably. However, they have different meanings. Electrosurgery describes the act of coagulating or cutting by passing a high-frequency current through tissue. Electrocautery describes the transfer of heat from a preheated object (e.g., Shaw scalpel) to tissue.

There are two types of electrosurgical units--unipolar and bipolar:

* Unipolar units are made up of three basic parts: a generator, an active electrode, and a grounding pad. The generator produces a high-density current that passes through the active electrode to the tip of the instrument. The grounding pad collects the current and completes the circuit.

When a unipolar unit is used in the cutting mode, the high-frequency current passes through the target tissue, and the active electrode functions as a bloodless knife by disintegrating the cells at the edges of the wound. A mild thermal injury occurs away from the plane of the cutting, and blood vessels thrombose. When the unit is set to coagulation mode, hemostasis is achieved without cutting. The cells undergo rapid dehydration, and the vessels coagulate. However, in some cases, damage to adjacent tissue can be extensive. (8)

* Bipolar units are made up of a generator and two electrodes, which are located at either end of a forceps. Current flows from one tip of the forceps and is collected by the other to complete the circuit. The flow of current is limited to the ends of the forceps, which minimizes the damage to surrounding tissue.

Electrosurgery can lead to a localized fire when a small amount of flammable material is heated to its ignition temperature. Electrosurgery can also cause combustion by producing a spark. A spark passing through a volume of air equal to 1 mm can reach a temperature of 1,0000[degrees] C in 1 msec, which is certainly sufficient to ignite flammable material. (5)

Only seven previous cases of electrocautery-induced endotracheal tube ignition have been reported in the literature (table). Two of these fires occurred during electrosurgical tonsillectomy. (1,2) The other five cases occurred during tracheostomy. (3-7) In four of the latter five cases, flashes of fire were visible outside the tracheostomy site, indicating that the flames were vented. No smoke was seen in any of these five cases. Finally, none of the five tracheostomy patients sustained any distal airway bums, and in all cases, tracheal burns were at worst superficial, localized, and inconsequential.

When an airway fire occurs during tracheostomy with an endotracheal tube in situ just proximal to the tracheostomy opening, a "blowtorch" flame is often seen venting out through the tracheostomy opening. This venting can prevent extensive burn injury to the distal aspect of the tracheobronchial tree. (1) However, if a fire is not extinguished completely or if the heat does not dissipate quickly, a thermal injury will probably occur.

An endotracheal tube fire is potentially fatal. In order for combustion to take place, an ignition source (electrosurgical unit), a carbon source (endotracheal tube), and oxygen must all be present in close proximity. (5) A common feature of all previously reported cases is a high oxygen concentration in the immediate environment surrounding the tube. In such an oxygen-rich environment, a spark or high temperature induced by electrosurgery can cause an endotracheal tube to ignite. In our patient, the incision of the trachea by electrocautery perforated the endotracheal tube cuff, which resulted in a back-flow of oxygen around the tube and caused the fire.

Certain precautions can be taken to reduce the risk of endotracheal tube fire during electrosurgery. Whenever tracheostomy is performed on an intubated patient, electrosurgery should not be used as the dissection proceeds close to the trachea, and it should never be used to open the trachea. It is also desirable to ventilate the patient with the lowest practical oxygen concentration. (9)

Every surgeon should be well aware of the procedure to follow in the event of such an emergency. When an endotracheal tube fire is recognized, the surgeon should immediately turn off the electrosurgical unit and remove the electrode from the site of the fire. The anesthesiologist should disconnect the oxygen supply and remove the endotracheal tube from the airway, anticipating that reintubation, if necessary, might be difficult. Examination of the oral cavity, direct laryngoscopy, flexible endoscopy, and rigid bronchoscopy should be performed to evaluate the extent of damage. An immediate chest x-ray should be obtained to rule out pneumothorax. Close monitoring for a few days in the ICU will help detect any late respiratory deterioration. Antibiotics and steroids are recommended to reduce the risk of infection and to subdue inflammation.

Acknowledgment

The authors are thankful to Shaikh Rahmatullah, a secretary in the Otolaryngology--Head and Neck Surgery unit at the Aga Khan University, for his cooperation and clerical assistance. He helped make all necessary changes in the manuscript with pleasure.

From the Department of Surgery, Otolaryngology--Head and Neck Surgery, The Aga Khan University Hospital, Karachi, Pakistan.

Reprint requests: Dr. M. Awan, Senior Instructor, Department of Surgery, Otolaryngology--Head and Neck Surgery, The Aga Khan University Hospital, Stadium Rd., Karachi-74800, Pakistan. Phone: [phone]; fax: [phone]; e-mail: [e-mail]

References

(1.) Boyd CH. A fire in the mouth. A hazard of the use of antistatic endotracheal tubes. Anaesthesia 1969;24:441-6.

(2.) Simpson JI, Wolf GL. Endotracheal tube fire ignited by pharyngeal electrocautery. Anesthesiology 1986;65:76-7.

(3.) Bowdle TA, Glenn M, Colston H, Eisele D. Fire following use of electrocautery during emergency percutaneous transtracheal ventilation. Anesthesiology 1987;66:697-8.

(4.) Bailey MK, Bromley HR, Allison JG, et al. Electrocautery-induced airway fire during tracheostomy. Anesth Analg 1990;71:702-4.

(5.) Le Clair J, Gartner S, Halma G. Endotracheal tube cuff ignited by electrocautery during tracheostomy. AANA J 1990;58:259-61.

(6.) Aly A, Mcllwain M, Duncavage J. Electrosurgery-induced endotracheal tube ignition during tracheotomy. Ann Otol Rhinol Laryngol 1991;100:31-3.

(7.) Lim HJ, Miller GM, Rainbird A. Airway fire during elective tracheostomy. Anaesth Intensive Care 1997;25:150-2.

(8.) Cox CE. Operative surgery. Antisepsis, technique, sutures, and drains. In: Sabiston DC, ed. Textbook of Surgery. Philadelphia: W.B. Saunders, 1986:255-6.

(9.) Chee WK, Benumof JL. Airway fire during tracheostomy: Extubation may be contraindicated. Anesthesiology 1998;89:1576-8.

Table. A comparison of reported cases of endotracheal tube fire during
electrocautery

                            Type of        Venting         Site of
Author                      surgery        route           flame

Boyd, 1969 (1)              Tonsillectomy  Pharynx, mouth  Lips
Simpson and Wolf, 1986 (2)  Tonsillectomy  Pharynx, mouth  Pharynx, lips

Bowdle et al, 1987 (3)      Tracheostomy   Tube opening    Tracheostomy
Bailey et al, 1990 (4)      Tracheostomy   Tube opening    Tracheostomy
Le Clair et al, 1990 (5)    Tracheostomy   Tube opening    Tracheostomy
Aly et al, 1991 (6)         Tracheostomy   Tube opening    Tracheostomy
Lim et al, 1997 (7)         Tracheostomy   Tube opening    Tracheostomy
Awan and Ahmed, 2002 (*)    Tracheostomy   Tube opening    Tracheostomy


                            Site of              Extent of
Author                      burns                airway burns

Boyd, 1969 (1)              Pharynx, uvula       Superficial
Simpson and Wolf, 1986 (2)  Pharynx, uvula,      Superficial
                            tongue
Bowdle et al, 1987 (3)      Skin of the neck     None
Bailey et al, 1990 (4)      Trachea              Superficial
Le Clair et al, 1990 (5)    Trachea              Superficial
Aly et al, 1991 (6)         Trachea              Superficial
Lim et al, 1997 (7)         None                 None
Awan and Ahmed, 2002 (*)    Anterior trachea,    Superficial
                            postpharyngeal wall

(*) Present study.