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

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.

The Effect of Laser-Resistant Endotracheal Tube Design on Airflow Dynamics: A Benchtop and Clinical Study

OBJECTIVE

Compare ventilation pressures of 2 endotracheal tube designs used in laser airway surgery in clinical practice and with a benchtop model to elucidate differences and understand the design elements that impact airflow dynamics.

METHODS

Ventilatory and aerodynamic characteristics of the laser resistant stainless-steel endotracheal tube (LRSS-ET) design and the laser resistant aluminum-wrapped silicone endotracheal tube (LRAS-ET) design were compared. Ventilatory parameters were collected for 32 patients undergoing laser-assisted airway surgery through retrospective chart review. An in vitro benchtop simulation measured average resistance and centerline turbulence intensity of both designs at various diameters and physiological frequencies.

RESULTS

Baseline patient characteristics did not differ between the 2 groups. Clinically, the median LRAS-ET peak inspiratory pressure (PIP; 21.00 cm H2O) was significantly decreased compared to LRSS-ET PIP (34.67 cm H2O). In benchtop simulation, the average PIP of the LRAS-ET was significantly lower at all sizes and frequencies. The LRSS-ET consistently demonstrated an increased resistance, although no patterns were observed in turbulence intensity data between both designs.

CONCLUSION

The benchtop model demonstrated increased resistance in the LRSS-ET compared to the LRAS-ET at all comparable sizes. This finding is supported by retrospective ventilatory pressures during laser airway surgery, which show significantly increased PIPs when comparing identically sized inner diameters. Given the equivocal turbulence intensity data, these differences in resistance and pressures are likely caused by wall roughness and intraluminal presence of tubing, not inlet or outlet geometries. The decreased PIPs of the LRAS-ET should assist in following lung protective ventilator management strategies and reduce risk of pulmonary injury and hemodynamic instability to the patient.

Early Neurocognitive Function With Propofol or Desflurane Anesthesia After Laser Laryngeal Surgery With Low Inspired Oxygen

PURPOSE

The effects of general anesthetics on cognitive impairment are unclear and complicated. Laser laryngeal surgery (LLS) requires the administration of low levels of oxygen, which may increase the risk of desaturation and brain function impairment. This prospective randomized trial aimed to compare the effects of desflurane and propofol-based general anesthesia on the occurrence of early postoperative cognitive decline in elderly patients undergoing LLS.

METHODS

Seventy-three patients classified as American Society of Anesthesiologists grade I or II and at least 65 years of age were randomly allocated to receive either desflurane-based (Group D) or propofol-based (Group P) anesthesia during LLS. The standard anesthesia protocol was performed, with a bispectral index between 40 and 60 and a mean arterial pressure within 20% of baseline values. Intraoperative regional oxygen saturation values were recorded. Each patient was assessed using the mini-mental state examination (MMSE) test during the preoperative period (baseline), 30 min after extubation in the postanesthesia care unit, and 1, 3, and 24 h after surgery.

RESULTS

MMSE scores improved slightly in both groups compared to baseline during the early postoperative period, but these increases were not statistically significant. No significant differences were identified in MMSE scores between groups. Only three patients (9.6%) in group D and one patient (3.1%) in group P developed cognitive impairment (p = 0.583).

CONCLUSION

Low intraoperative inspired oxygen concentration during short-duration LLS did not reduce early postoperative cognitive function in elderly patients. Desflurane or propofol-based anesthesia had similar effects on early neurocognition after LLS.

LEVEL OF EVIDENCE

2 Laryngoscope, 133:640-646, 2023.

[Laryngeal-preservation surgery in laryngeal cancer]

After oral cavity and pharyngeal cancer, laryngeal cancer is the third most common malignant tumor in the head and neck region. According to the current German S3 guideline on the diagnosis, treatment, and follow-up of laryngeal cancer, larynx-preserving surgical interventions are part of the standard treatment of this disease, even in advanced tumor stages. However, in order to achieve the desired function-preserving effect, an exact indication is of crucial importance. In this article, the most important larynx-preserving interventions and their indications but also the respective contraindications are presented, with the aim of illuminating the surgical treatment options up to just before total laryngectomy.

Establishing the Ideal Conditions to Create an Airway Fire Using a Porcine Airway Model

Objective

Airway fires are a rare but devastating complication of airway surgery. Although protocols for managing airway fires have been discussed, the ideal conditions for igniting airway fires remain unclear. This study examined the oxygen level required to ignite a fire during a tracheostomy.

Study Design

Porcine Model.

Setting

Laboratory.

Methods

Porcine tracheas were intubated with a 7.5 air-filled polyvinyl endotracheal tube. A tracheostomy was performed. Monopolar and bipolar cautery were used in independent experiments to assess the ignition capacity. Seven trials were performed for each fraction of inspired oxygen (FiO₂): 1.0, 0.9, 0.7, 0.6, 0.5, 0.4, and 0.3. The primary outcome was ignition of a fire. The time was started once the cautery function was turned on. The time was stopped when a flame was produced. Thirty seconds was used as the cut-off for "no fire."

Results

The average time to ignition for monopolar cautery at FiO₂ of 1.0, 0.9, 0.8, 0.7, and 0.6 was found to be 9.9, 6.6, 6.9, 9.6, and 8.4 s, respectively. FiO₂ ≤ 0.5 did not produce a flame. No flame was created using the bipolar device. Dry tissue eschar shortened the time to ignition, whereas moisture in the tissue prolonged the time to ignition. However, these differences were not quantified.

Conclusion

Dry tissue eschar, monopolar cautery, and FiO₂ ≥ 0.6 are more likely to result in airway fires.

The i-gel supraglottic airway device improves airway management during endobronchial ablative therapy under general anesthesia: a case report

Endobronchial ablative therapy (EAT) in patients with preexisting obstructive airway disease can cause hypoxemia because bronchoscope insertion interferes with ventilation and a low fraction of inspired oxygen (FiO₂) is essential to avoid airway fire. A man in his early 50s with moderately severe obstructive airway disease was scheduled for EAT for treatment of tracheal papillomatosis. Ventilation and oxygenation would have been difficult because of narrowing of the endotracheal tube by bronchoscopic insertion and a low FiO₂; therefore, an i-gel supraglottic airway device with a larger inner diameter was inserted. All visible intratracheal papillomas were ablated by a potassium titanyl phosphate laser through the bronchoscopic port that passed through the lumen of the i-gel at an FiO₂ of 0.3. During anesthesia for EAT, the i-gel supraglottic airway device provided a wider lumen for ventilation. We were thus able to provide stable ventilation at an FiO₂ of 0.3 during EAT in this patient with obstructive airway disease, avoiding airway fire and hypoxemia.

Humidified rapid-insufflation ventilatory exchange is a means of oxygenation during rigid bronchoscopy: A case series

Humidified rapid-insufflation ventilatory exchange (HRIVE) is an option for maintenance of oxygenation. This technique allows for oxygenation while the patient is apnoeic due to continuous positive airway pressure and gas exchange through flow-dependent dead space flushing. There is no study about the usage of HRIVE during rigid bronchoscopy. This retrospective study looked at rigid bronchoscopy cases utilizing HRIVE. Data points assessing adequacy of oxygenation and ventilation were recorded at time points: oxygen saturation (SpO2), partial pressure of oxygen (PaO2) and partial pressure of carbon dioxide (PaCO2). Our nine cases had an average baseline SpO2 of 99.26%, 95.56% at 10 min into HRIVE and 95.27% at the end of HRIVE. The average baseline PaO2 was 309.01 mmHg, 124.99 mmHg at 10 min into HRIVE and 128.17 mmHg at the end of HRIVE. The average baseline PaCO2 was 43.26 mmHg, 68.76 mmHg at 10 min into HRIVE and 75.52 mmHg at the end of HRIVE. The average pre-HRIVE end-tidal CO2 (ETCO2) was 38.56 mmHg and the average post-HRIVE ETCO2 was 61.22 mmHg. The average baseline pH was 7.36, 7.22 at 10 min into HRIVE and 7.19 at the end of HRIVE. In this small cohort study, HRIVE was able to maintain adequate oxygenation via the rigid bronchoscope in a select group of patients. Hypercapnia and respiratory acidosis did result after 10 min, which may predispose certain patient populations to complications. HRIVE potentially offers an additional option of oxygenation via the rigid bronchoscope.

Risk of airway fire with the use of KTP laser and high flow humidified oxygen delivery in a laryngeal surgery model

Airway surgery presents a unique environment for operating room fire to occur. This study aims to explore the factors of combustion when using KTP laser with high flow oxygen in an ex-vivo model. The variables tested were varying tissue type, tissue condition, oxygen concentration, laser setting, and smoke evacuation in a stainless-steel model. Outcome measures were time of lasing to the first spark and/or flame. A multivariate Cox proportional hazard model was used to determine the risk of spark and flame across the different risk factors. For every 10% increase in oxygen concentration above 60% the risk of flame increased by a factor of 2.3. Continuous laser setting at 2.6 W increased the risk by a factor of 72.8. The risk of lasing adipose tissue is 7.3 times higher than that of muscle. Charred tissue increases the risk of flame by a factor of 92.8. Flame occurred without a preceding spark 93.6% of the time. Using KTP laser in the pulsed mode with low wattages, minimising lasing time, reducing the oxygen concentration and avoiding lasing adipose or charred tissue produce a relatively low estimated risk of spark or flame.

Anesthesia for thoracic surgery in infants and children

The management of infants and children presenting for thoracic surgery poses a variety of challenges for anesthesiologists. A thorough understanding of the implications of developmental changes in cardiopulmonary anatomy and physiology, associated comorbid conditions, and the proposed surgical intervention is essential in order to provide safe and effective clinical care. This narrative review discusses the perioperative anesthetic management of pediatric patients undergoing noncardiac thoracic surgery, beginning with the preoperative assessment. The considerations for the implementation and management of one-lung ventilation (OLV) will be reviewed, and as will the anesthetic implications of different surgical procedures including bronchoscopy, mediastinoscopy, thoracotomy, and thoracoscopy. We will also discuss pediatric-specific disease processes presenting in neonates, infants, and children, with an emphasis on those with unique impact on anesthetic management.

Fire safety study on high-flow nasal oxygen in shared-airway surgeries with diathermy and laser: simulation based on a physical model

High-flow nasal oxygen (HFNO) has been used in "tubeless" shared-airway surgeries but whether HFNO increased the fire hazard is yet to be examined. We used a physical model for simulation to explore fire safety through a series of ignition trials. An HFNO device was attached to a 3D-printed nose with nostrils connected to a degutted raw chicken. The HFNO device was set at twenty combinations of different oxygen concentration and gas flow rate. An electrocautery and diode laser were applied separately to a fat cube in the cavity of the chicken. Ten 30 s trials of continuous energy source application were conducted. An additional trial of continuous energy application was conducted if no ignition was observed for all the ten trials. A total of eight short flashes were observed in one hundred electrocautery tests; however, no continuous fire was observed among them. There were thirty-six events of ignition in one hundred trials with laser, twelve of which turned into violent self-sustained fires. The factors found to be related to a significantly increased chance of ignition included laser application, lower gas flow, and higher FiO₂. The native tissue and smoke can ignite and turn into violent self-sustained fires under HFNO and continuous laser strikes, even in the absence of combustible materials. The results suggest that airway surgeries must be performed safely with HFNO if only a short intermittent laser is used in low FiO₂.

Surgical fires: Still a burning issue in England and Wales

A significant number of surgical fires occur each year and can have devastating effects on patients. The National Reporting and Learning System database identified 37 reports of surgical fires in England and Wales between January 2012 and December 2018 - over 52% resulting in some degree of harm. Surgical fires remain preventable adverse events that can be avoided by adherence to effective preventative strategies and improved education. This article surveys the existing literature, addressing the fire triad and how to effectively manage and prevent a surgical fire.

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.

Early experience with high-flow nasal oxygen therapy (HFNOT) in pediatric endoscopic airway surgery

OBJECTIVE

Reporting our institutional experience with high-flow nasal oxygen therapy (HFNOT), a recently-introduced technique, for endoscopic airway approaches.

METHODS

Prospective collection of data of children (<16 years) undergoing endoscopic between January 2016 and August 2017 at a tertiary referral university hospital.

RESULTS

HFNOT was used in 6 children who underwent 14 procedures for different forms and causes of upper airway obstruction of various origins. No intraoperative complications; related to oxygenation were observed, and the surgical procedures could be carried out as; initially planned.

CONCLUSIONS

We found that HFNOT is an effective and safe technique with a variety of potential applications in the field of endoscopic pediatric airway surgery.

Surgical Fires in Otolaryngology: A Systematic and Narrative Review

Objective

To bring attention to the epidemiology, prevention, management, and consequences of surgical fires in otolaryngology by reviewing the literature.

Data Sources

PubMed, EMBASE, Web of Science, and Scopus.

Review Methods

Comprehensive search terms were developed, and searches were performed from data source inception through August 2016. A total of 4506 articles were identified; 2351 duplicates were removed; and 2155 titles and abstracts were independently reviewed. Reference review was also performed. Eligible manuscripts described surgical fires involving patients undergoing otolaryngologic procedures.

Results

Seventy-two articles describing 87 otolaryngologic surgical fire cases were identified. These occurred during oral cavity or oropharyngeal procedures (11%), endoscopic laryngotracheal procedures (25%), tracheostomies (36%), “other” general anesthesia procedures (3%), and monitored anesthesia care or local procedures (24%). Oxidizing agents consisted of oxygen alone (n = 63 of 81, 78%), oxygen and nitric oxide (n = 17 of 81, 21%), and room air (n = 1 of 81, 1%). The fractional inspired oxygen delivered was >30% in 97% of surgical fires in non–nitrous oxide general anesthesia cases (n = 35 of 36). Laser-safe tubes were used in only 12% of endoscopic laryngotracheal cases with endotracheal tube descriptions (n = 2 of 17). Eighty-six percent of patients experienced acute complications (n = 76 of 87), including 1 intraoperative death, and 22% of patients (n = 17 of 77) experienced long-term complications.

Conclusion

Surgical fires in otolaryngology persist despite aggressive multi-institutional efforts to curb their incidence. Guideline recommendations to minimize the concentration of delivered oxygen and use laser-safe tubes when indicated were not observed in many cases. Improved institutional fire safety practices are needed nationally and internationally.

The anesthesia of trachea and bronchus surgery

The trachea and bronchus surgery is generally performed due to stenosis, traumatic injury, foreign body and tumors. Preoperative evaluation and anesthesia management are very important issues because of higher mortality and morbidity rates. Patients may be asymptomatic, but airway difficulties, hypoxia, stridor, cough, hemoptysis are common conditions in these patient population. The collaboration between the surgeon and the anesthesiologist is very substantial and necessary. Anesthetic techniques include various applications such as one lung ventilation, fiberoptic intubation, jet ventilation, and apneic oxygenation, general anesthesia with or without neuromuscular blockade. In this review, anesthesia management of the trachea and bronchus surgery is evaluated in the light of new knowledge.

The Importance of State and Context in Safe Interoperable Medical Systems

This paper describes why “device state” and “patient context” information are necessary components of device models for safe interoperability. This paper includes a discussion of the importance of describing the roles of devices with respect to interactions (including human user workflows involving devices, and device to device communication) within a system, particularly those intended for use at the point-of-care, and how this role information is communicated. In addition, it describes the importance of clinical scenarios in creating device models for interoperable devices.

Hemostasis in Laryngeal Surgery

The larynx is a highly vascularized organ supplied by the superior and inferior laryngeal arteries. Both microphonosurgery and external laryngeal surgery require excellent hemostasis. Topical agents including adrenalin and fibrin-based products as well as surgical instrumentation, such as coagulation devices or in some cases embolization, are in the surgeon's armamentarium and facilitate efficient and successful surgery.