Flammability of endotracheal tubes in oxygen and nitrous oxide enriched atmosphere

[Use of high-flow oxygen treatment in the emergency medical service: what are the dangers for users from the perspective of occupational and fire protection?]

INTRODUCTION

The administration of high concentrations of oxygen may harm patients or paramedics by increasing the probability of fire. The presented work investigated the effect of oxygen applied via high flow in different concentrations and flow rates on environmental oxygen concentrations in the patient compartment of an ambulance.

RESULTS

Environmental oxygen concentrations increased rapidly over time and oxygen is stored in blankets and clothes over a long period. Simulation in a fire laboratory showed that also in high oxygen concentration settings fire needs a flame or temperatures above 300 °C. Sparks alone were not able to start a fire.

CONCLUSION

Ventilation of patient compartment and clothes with ambient air are mandatory to reduce dangerous oxygen concentrations in transport of patients on high-flow oxygen treatment.

Operating Room Fires

Operating room fires are rare but devastating events. Guidelines are available for the prevention and management of surgical fires; however, these recommendations are based on expert opinion and case series. The three components of an operating room fire are present in virtually all surgical procedures: an oxidizer (oxygen, nitrous oxide), an ignition source (i.e., laser, “Bovie”), and a fuel. This review analyzes each fire ingredient to determine the optimal clinical strategy to reduce the risk of fire. Surgical checklists, team training, and the specific management of an operating room fire are also reviewed.

Airway Fire During Left Internal Mammary Dissection in Cardiac Surgery: A Case Report

Previous case reports describing fire during left internal mammary artery dissection involved patients with pulmonary blebs and did not involve the airway. We present a case of an airway fire, diagnosed by the sound of a pop, the appearance of a spark, and the development of an airway circuit leak in a patient with a 4-year-old tracheostomy scar who presented for coronary artery bypass with a left internal mammary artery. The case description is followed by a brief discussion of operating room fires and their management.

Use of i-gel for laser ablation of a bronchial lesion

The use of laser for airway lesions requires airway management. Usual options include special laser-resistant endotracheal tubes. The use of supraglottic devices have been described in the literature. Laryngeal mask airway carries the risk of cuff damage during the use of laser. i-gel is made of thermoplastic material and does not require air inflation and thus potentially reduce the risk of cuff rupture. i-gel use in laser surgeries has not been described in the literature. We present successful airway management in laser surgery for bronchial tumour using i-gel.

[Specific aspects of anesthesiological management of laser surgery in otorhinolaryngology]

Transoral laser surgery has become a standard procedure in the treatment of benign and malignant neoplasms of the upper aerodigestive tract. As the laser cuts and coagulates simultaneously, intraoperative bleeding is reduced, thus improving visualization of the operative field. However, the specific risks for patients and personnel that are associated with this technique necessitate strict compliance with safety regulations and precautions. The safe anesthesiological and surgical management of such procedures requires explicit knowledge of the risks inherent to laser use, as well as close communication between surgeon and anesthesiologist throughout all operative and perioperative procedures. Although potentially fatal complications are rare, surgeon and anesthesiologist need to be aware of the dangers at all times and have exact knowledge of emergency measures. The use of suitable laser-resistant endotracheal tubes, total intravenous anesthesia and an optimized breathing gas mixture can contribute to minimize the occurrence of complications in otorhinolaryngology laser surgery.

[Specific aspects of anesthesiological management of laser surgery in otorhinolaryngology]

Transoral laser surgery has become a standard procedure in the treatment of benign and malignant neoplasms of the upper aerodigestive tract. As the laser cuts and coagulates simultaneously, intraoperative bleeding is reduced, thus improving visualization of the operative field. However, the specific risks for patients and personnel that are associated with this technique necessitate strict compliance with safety regulations and precautions. The safe anesthesiological and surgical management of such procedures requires explicit knowledge of the risks inherent to laser use, as well as close communication between surgeon and anesthesiologist throughout all operative and perioperative procedures. Although potentially fatal complications are rare, surgeon and anesthesiologist need to be aware of the dangers at all times and have exact knowledge of emergency measures. The use of suitable laser-resistant endotracheal tubes, total intravenous anesthesia and an optimized breathing gas mixture can contribute to minimize the occurrence of complications in otorhinolaryngology laser surgery.

Management of a fire in the operating room

Operating room (OR) fires remain a significant source of liability for anesthesia providers and injury for patients, despite existing practice guidelines and other improvements in operating room safety. Factors contributing to OR fires are well understood and these occurrences are generally preventable. OR personnel must be familiar with the fire triad which consists of a fuel supply, an oxidizing agent, and an ignition source. Existing evidence shows that OR-related fires can result in significant patient complications and malpractice claims. Steps to reduce fires include taking appropriate safety measures before a patient is brought to the OR, taking proper preventive measures during surgery, and effectively managing fire and patient complications when they occur. Decreasing the incidence of fires should be a team effort involving the entire OR personnel, including surgeons, anesthesia providers, nurses, scrub technologists, and administrators. Communication and coordination among members of the OR team is essential to creating a culture of safety.

Fire in the surgical center

BACKGROUND AND OBJECTIVES

There are several factors in operating rooms that increase the risk of fire. Besides being an oxygen-enriched environment, it contains combustible materials and equipment with available ignition sources. Although fires in operating rooms are a relatively rare event, the consequences are potentially serious and mostly avoidable. We present a case report of a fire occurring in the surgical drape during a blepharoplasty in which oxygen was supplemented by nasal catheter.

CASE REPORT

Female patient, 52-years old, without comorbidities, admitted to hospital for a bilateral blepharoplasty. After monitoring and venoclysis, the patient underwent intravenous sedation and additional oxygen given via spectacle-type catheter at a flow rate of4 L.min(-1), followed by local anesthesia in the eyelids. During surgery, the use of electric scalpel provoked combustion in the surgical drapes and burns on the patient's face.

CONCLUSIONS

Anesthesiologists play an important role preventing fire in operating rooms, as they can recognize possible ignition sources and rationally administer the oxygen, especially in open systems. The first step toward prevention is to be constantly aware of potential fire.

Reducing the oxygen concentration of gases delivered from anaesthetic machines unadapted for medical air

High fractional concentrations of inspired oxygen (FiO(2)) delivered over prolonged periods produce characteristic histological changes in the lungs and airway of exposed animals. Modern medical anaesthetic machines are adapted to deliver medical air (FiO(2)=0.21) for the purpose of reducing FiO(2); anaesthetic machines designed for the veterinary market have not been so adapted. Two inexpensive modifications that allow medical air to be added to the gas flow from veterinary anaesthetic machines are described. The advantages and disadvantages of each modification are discussed.

Fire safety in the operating room

PURPOSE OF REVIEW

Elimination of flammable anesthetic gases has had little effect on operating-room fires except to change their etiology. Electrocautery and lasers, in an oxygen-enriched environment, can ignite even the most fire-resistant materials, including the patient, and the fire triad possibilities in the operating room are nearly limitless. This review will: identify operating room contents capable of acting as ignition/oxidizer/fuel sources, highlight operating room items that are uniquely potent fire triad contributors, and operating room identify settings where fire risk is enhanced by proximity of triad components in time or space.

RECENT FINDINGS

Anesthesiologists are cognizant of the risk of airway surgery fires due to laser ignition of the endotracheal tube and/or its contents. Recently, however, head/neck surgery under monitored anesthesia care has emerged as a high-risk setting for operating room fires; burn injuries represent 20% of monitored anesthesia care-related malpractice claims, 95% of which involved head/neck surgery.

SUMMARY

Operating room fires are infrequent but catastrophic. Operating room fire prevention depends on: (a)understanding how fire triad elements interact to create a fire, (b) recognizing how standard operating-room equipment, materials, and supplemental oxygen can become one of those elements, and (c) vigilance for circumstances that bring fire triad elements into close proximity.

Flooding With Carbon Dioxide Prevents Airway Fire Induced by Diathermy During Open Tracheostomy

BACKGROUND

Open tracheostomy is commonly performed during head and neck surgery, and in critically ill patients. Diathermy-induced airway fire during tracheotomy is rare but may have grave implications. Recommendations to minimize this risk are not always practical. We hypothesized that flooding the surgical field with carbon dioxide is an effective technique in preventing fire.

METHODS

We cut through the trachea of two pigs using diathermy while ventilating with pure oxygen five times with, and five times without, simultaneous flushing of the surgical field with carbon dioxide at 10 L/min. To increase the amount of oxygen in the airway and the likelihood of fire,we deliberately deflated the endotracheal cuff to simulate cuff rupture.

RESULTS

Five times out of five, fire was induced when the diathermy cut through the tracheal wall with no carbon dioxide being used. Five times out of five, fire was not induced when carbon dioxide was used. The difference was significant (p < 0.008).

CONCLUSIONS

Flooding the surgical site with carbon dioxide effectively prevents fire during open tracheostomy using diathermy.

AIRWAY FIRE DURING TRACHEOTOMY

We report a case of airway fire during surgical tracheotomy using diathermy for the incision into the trachea. A literature review of airway fire during tracheotomy was carried out, and the management of airway fire is discussed. Recommendations are made to prevent this adverse outcome.

Surgical Field Fire During a Repair of Bronchoesophageal Fistula

Most surgical fires involve the airway but they can also occur in the surgical field. Herein, we report an intraoperative fire in the surgical field during repair of a bronchoesophageal fistula. During the portion of the surgery after the fistula was divided and the bronchus was open to atmosphere, continuous positive airway pressure was applied to the nondependent lung, and in conjunction with the use of electrocautery and dry sponges in the field, resulted in a fire. Anesthesia for thoracic surgery carries unique risks of fire because these patients frequently require large oxygen concentrations, special interventions for improving oxygenation, and have variable degrees of airway disruption. This report highlights unique safety concerns during anesthesia for thoracic surgery, and addresses more general safety issues relating to fire risk in all surgical patients.

Anesthetic Considerations for Special Thoracic Procedures

Significant advances have been achieved in surgical and anesthetic techniques for the treatment of patients presenting with a variety of complex intrathoracic lesions. Despite the technologic advances, these patients continue to pose a challenge for anesthesiologists to provide safe and effective clinical care. A thorough understanding of the patient's underlying pathology inclusive of a detailed preoperative evaluation and effective communication between the surgical and anesthesia teams would help to ensure a favorable outcome.

Fire during thoracic surgery

A 67-year-old male with bilateral lung lesions presented for median sternotomy. One-lung ventilation was complicated by arterial desaturation. Continuous positive airway pressure with oxygen was applied to the non-ventilated lung to relieve the hypoxaemia. However, the cotton gauze packed inside the operative site was ignited by the electrocautery. The burning gauze was immediately removed without any complication. We report a case of electrocautery-induced fire during thoracic surgery done in supine position and discuss its implication on the choice of oxygen enrichment therapy during one-lung ventilation.

Nd-YAG laser ignition of silicone endobronchial stents

STUDY OBJECTIVES

To test the incendiary characteristics of various silicone endobronchial stents under the impact of the Nd-YAG laser.

DESIGN

In vitro study in the laser laboratory of a university-affiliated city hospital.

SETTING

The experiments were performed in a reaction chamber under controlled oxygen concentrations. The radiolucent and radiopaque Dumon silicone stent (Novatech; Aubagne, France) and the tracheal part of the Dynamic stent (Ruesch AG; Kernen, Germany) were tested. The Dumon stents were either clean, covered with a thin layer of blood, or mounted on fresh pig tracheal wall. The laser was aimed on them perpendicularly from distances of 1.0 cm and 0.5 cm.

INTERVENTIONS

Minimal oxygen concentration to allow ignition and impact time for power outputs (POs) between 10 W and 80 W were determined.

MEASUREMENTS AND RESULTS

The lowest oxygen concentration that allowed ignition of some stents was 40%. The clean radiolucent stent could not be ignited with up to 100% ambient oxygen concentration. Radiopacity, presence of blood, tracheal wall, and metal, as well as higher PO and shorter distance of the laser probe decreased impact time to ignition. The radiopaque blood-covered stent was most easily ignited. For this stent, at a PO of 40 W, impact time to ignition was 1.5 +/- 0.2 s, and at 30 W was 2.6 +/- 0.3 s.

CONCLUSIONS

At ambient oxygen concentrations > or = 40%, silicone stents can catch fire. Depending on the condition of the stent, the distance of the laser probe, and PO, ignition can occur after short impact times. To prevent stent ignition, oxygen concentration should be kept < 40%. When unusual circumstances require working with higher oxygen concentrations, pulse duration needs to be limited or stent removal might be considered before firing the laser.

Endobronchial laser therapy

We have sought to briefly outline the history and current role of laser therapy in airway obstruction. A primary goal in the use of laser therapy is the safe, effective, and rapid palliation of symptoms owing to tracheal or bronchial obstruction. This seems clearly supported in the literature despite some variation in definitions as to measurement of success. Objective criteria for improvement has also been studied, with authors noting improvement in walk tests, spirometric studies, and caliber of airways after treatment in significant percentages of patients. Patient survival, as noted by Ramser and Beamis, may not be the proper endpoint when discussing therapy, which for malignant causes, is meant to be palliative. Noting this, there are many benign conditions that may be effectively treated with laser therapy with a possible "cure" for some lesions defined as "carcinoma in situ." We believe laser therapy in the treatment of airway obstruction is an important tool that has proven beneficial in the therapy of benign and malignant lesions of the airway. Although future studies should prospectively examine survival characteristics, the current evidence firmly supports the use of laser as a useful modality of therapy in our endeavors to provide palliative and potentially curative care to our patients with lung disease.

Prevention of flash fires during facial surgery performed under local anesthesia

As more surgical procedures are being performed under local anesthesia and intravenous sedation, complications associated with these techniques are more likely to be experienced. We report a case of an intraoperative flash fire that occurred while supplemental oxygen was being used in this scenario. A literature review and suggestions for prevention of this complication are discussed.

Apneic anesthesia with intermittent ventilation for microsurgery of the upper airway

Apneic anesthesia with intermittent ventilation (AAIV) has been used in 250 procedures on the larynx and trachea at Indiana University Medical Center since October 1989. Initially employed for laryngeal papilloma removal in children, this anesthetic technique is now used for other procedures and in adult patients. The advantages of AAIV include improved visualization of the airway, absence of combustible material, and lack of vocal cord motion during surgery. No significant complications have occurred with AAIV. The high degree of safety for this anesthetic technique relates largely to the constant monitoring of oxygen saturation using pulse oximetry and the periodic measurement of end-tidal carbon dioxide (CO2) levels. Contraindications to AAIV are age less than 2 years, significant cardiopulmonary disease, and any hypermetabolic state. Relevant pulmonary physiology includes the unique aspects of oxygen and CO2 metabolism in children.

Anesthesia for microlaryngeal surgery: the case for subglottic jet ventilation

Although the techniques for surgery on the endolarynx using suspension and the operating microscope have been fully developed, the safest, and least obtrusive anesthetic technique has yet to be manifested, as evidenced by more than 200 references to anesthesia for microlaryngoscopy in the world literature. This study reviews the physiology, physics, and problems of each anesthetic technique. In light of this review, animal and human studies are reported demonstrating the utility and safety of subglottic ventilation when provided with proper monitoring using an automatic ventilator. A modified Ben-Jet tube is reported, which has a 1-mm ID channel to monitor PCO2 and tracheal pressure. This self-centering 3.0-mm tube, which extends 6 to 8 cm below the glottis, is unobtrusive for the surgeon. The subglottic tube, which is much less likely to be malaligned, is much more acceptable to the anesthesiologist. Anesthesia, by intravenous sedation, utilizes neuromuscular blockade while ventilating through the jet tube powered by an automatic ventilator with an automatic shutdown feature attached to the monitor tube to prevent inadvertent barotrauma. The third phase of this study compared fluoroplastic, used in a prototype jet ventilation tube, with 6-mm Silastic, Red Rubber, and polyvinyl chloride (PVC) tubes when struck by maximum power of CO2, Nd-YAG, and K-532 lasers. The test was performed in a closed chamber in which concentrations of oxygen and nitrogen were controlled. Although damaged by the CO2 laser beam, the fluoroplastic tubes did not continue burning when the laser was turned off in 100% oxygen, even when coated by blood. The other three tubes continued to burn in 23% oxygen. Neither the KTP nor Nd-YAG laser damaged the Teflon tube, while they ignited a sustained flame in 30% oxygen. This study supports the use of fluoroplastic for a laser safe jet ventilation tube. It also demonstrates the danger of tube fires, even in low oxygen concentrations, when using Silastic, rubber, and PVC tubes in laser laryngeal surgery. There was no difference in the flammability of Silastic, rubber or PVC when struck by these lasers in this study. For these reasons, subglottic ventilation using a fluoroplastic, monitored, self-centering, subglottic, jet ventilation tube driven by an automatic ventilator with a shutdown feature, in the event of excessive pressure buildup, is proposed for anesthetizing healthy patients undergoing suspension microlaryngoscopy, and who have no airway obstructing lesion. A large tube with inflatable cuff is indicated when a supraglottic lesion may obstruct the airway.

An evaluation of one method of ventilation for laser therapy to the tracheobronchial tree

Laser therapy has been used extensively for surgery to the respiratory tract since its first application in 1971. At this hospital, the surgeon's preferred technique for laser surgery to the tracheobronchial tree is to use the Nd-YAG laser through a fibreoptic bronchoscope passed through a rigid bronchoscope. General anaesthesia is employed and ventilation is controlled using jet-ventilation by the Sanders technique. Review of the literature failed to locate adequate information on the effect of manoeuvres such as insertion of instruments and the presence of a tracheal obstruction distal to the bronchoscope on the quality of ventilation using this technique. A bench study was undertaken, therefore, in an attempt to mimic such clinical situations and to assess the effect of such manoeuvres on the adequacy and pattern of ventilation. Under all conditions tested 'end-tidal' CO2 concentrations accurately reflected distal 'tracheal' concentrations. The lowest inspired O2 concentration was 50% while entraining air through the bronchoscope. The highest was 86% while entraining oxygen.

Anaesthesia for resection of lesions of the trachea and main bronchi using the neodymium yttrium aluminium garnet (Nd YAG) laser. A report of 75 treatments in 52 patients

The management of anaesthesia and outcome of 75 treatments in 52 patients are discussed. Total intravenous anaesthetic techniques were used with venturi ventilation via a rigid bronchoscope. A number of complications occurred, but there was no death or major surgical complication. All complications except one were apparent intraoperatively or in the recovery room. As the considerable risk of intraoperative hypoxia was considered to outweigh the minimal risk of intratracheal fire or explosion, no attempt was made to limit inspired oxygen concentration (FIO2) during the application of the laser. The results of ventilation/perfusion studies and a recent diagnostic bronchoscopy were very helpful in patient selection.

Anesthetic management of laser airway surgery

This brief review of the anesthesiologist's role in the team effort necessary for the safe treatment of airway tumors by laser beam is provided to acquaint the referring physician or medical oncologist with some of the anesthesiologist's operating room concerns and how they are met. The necessity of bringing the patient to a level of maximum physiologic reserve prior to treatment becomes obvious with information gained by scanning this review. The referring physician or medical oncologist aids the patient and the anesthesiologist and surgeon by performing a thorough preoperative cardiopulmonary evaluation and therapeutic intervention, as indicated by patient need. The review includes a description of the actions of the carbon dioxide (CO2) and neodynium-yttrium aluminum garnet (YAG) lasers, "laser safety" for patients and personnel, monitoring, guarding the airway, ignition dangers, and comments on the use of jet and high frequency jet ventilation (HFJV).