Chapter 6 – Airway Management

Abstract

Chapter 6 Airway Management

Michael J. Murray

Introduction

There is a great deal of information about the management of the airway during many different scenarios, but very little of that information addresses the management of the airway during a mass casualty event following a disaster. There are guidelines for managing a difficult airway,¹ for managing a failed intubation,² and for managing the airway of a patient who has sustained trauma,³ but one can find very little information about how to manage the airway during a mass casualty event (MCE). In 2015 two journals devoted entire issues to airway management but neither journal has any information about airway management following a disaster.⁴^, ⁵ when a health care facility may have a multitude of patients who require emergent airway management to minimize morbidity and mortality. The lack of such information is surprising because following a major disaster that results in an MCE, health care providers consistently state that better preparedness would have resulted in decreased morbidity and mortality.⁶ One interpretation of this lack of information is that mass casualty events that generate a multitude of patients that require emergency airway management are so rare that there is no way that health care providers can prepare for, and anticipate, such events. However, if one performs a hazard-analysis risk-management assessment, although the chances of such events occurring are quite low, when they do occur, the resulting morbidity and mortality are incredible.⁷ For example, the worst disaster in the past 100 years was the 1918 Spanish influenza pandemic, during which 20% of the world’s population was infected with the virus, which killed one of every 40 people in the world; the mortality rate was in the thousands per 100 000. The numbers of patients requiring respiratory care was enormous. Likewise, the polio epidemic in the 1950s resulted in so many patients requiring mechanical ventilation that patients were housed in hospital auditoriums. In more recent times the SARS⁸ and H5N1⁹ epidemics had the potential to create equally large numbers of patients requiring respiratory care. In addition to natural biologic events, there is always the potential for rogue nations and terrorists to use biologic agents or chemical agents that would result in a large number of patients requiring emergency airway management. For example, the recent use of chlorine gas by Syria against Kurdish fighters in March of 2015,¹⁰ and the use of sarin by the Aum Shinrikyo cult in the subway system of Tokyo in 1994¹¹ underscore the fact that such agents could be used again in the future. Finally, one cannot discount the possibility of an industrial disaster that would precipitate an MCE in which the majority of patients would require emergency airway management , e.g. the isocyanate gas leak in Bhopal, India that affected tens of thousands of individuals.¹²

This chapter focuses therefore, not on how one would manage several patients who might require emergent airway management (a mass casualty incident), but potentially hundreds of patients (a mass casualty event) who might require emergency airway management.

Disaster Management

Prevention/Mitigation

While there is little that we as health care providers can do to prevent or mitigate disasters that would result in a large number of patients who might require emergent respiratory care following a disaster, one should at least be aware of what resources are available should the unthinkable occur. Aside from the need for surge capacity, a need that would be addressed by the community’s emergency response plan, as occurred in Paris following the terrorist attacks of November 13, 2015,¹³ the greatest need in terms of equipment would be for ventilators. The Center for Disease Control and Prevention’s (CDC) Strategic National Stockpile is a repository of ventilators that would be used to supplement the supply currently in use by the nation’s acute care facilities. These ventilators can be requested and allocated to areas of need and could be delivered within several hours (~12 h) to a facility that required them.¹⁴

Preparedness

Preparing for an MCE that would require the emergency airway management of dozens if not hundreds of patients is difficult. Anesthesia departments’ emergency response plans typically do not contain guidance for this scenario. The primary reason for “emergency preparedness,” the second component of an over-all disaster response plan, is to prepare for different scenarios, especially one that though unlikely, would result in considerable morbidity and mortality. Therefore, it might behoove a hospital when planning its biannual emergency response drill, as required by The Joint Commission (TJC), to plan a “disaster drill” that would include a large number of patients coming to the hospital in respiratory distress. Anesthesia providers – anesthesiologists, CRNAs, and anesthesia assistants – would have the requisite skills to provide assistance in managing the airway in most mass casualty situations. However, these individuals probably have little or no experience managing an airway while wearing personal protective equipment (PPE). Ambulatory patients coming to a hospital following exposure to a chemical agent such as sarin, would be asked to disrobe and undergo decontamination before being seen by a health care provider. However, those patients with significant nerve agent poisoning may have acute respiratory failure requiring emergency airway management by an individual wearing a hazardous materials (HAZMAT) suit. Once the life threatening condition is treated, then patients’ clothing is removed and the patient decontaminated.¹⁵

HAZMAT PPE presents several challenges. The suits are not insulated and external temperatures can significantly impede performance. The gloves are usually constructed from Teflon, polyvinyl chloride or rubber, and polyethylene and although they are impermeable to most chemical agents, they significantly decrease manual dexterity. Similarly, the face hoods or masks may impair visual acuity. Prior training wearing these suits is recommended to improve performance during an actual mass casualty event. As will be discussed later, consideration should be given to securing the airway with a supraglottic airway (SGA) device, disrobing and decontaminating the patient, and placing a tracheal tube at a later time under better circumstances.¹⁵

There is more to emergency preparedness though, than just practicing airway management while wearing PPE. The anesthesiologist in charge of a department’s disaster management plan should incorporate a section that addresses the airway management issues that might arise in an MCE following a disaster. Issues that should be addressed include personnel, equipment and supplies, human factors, training, and diagnosis-management paradigms.

Personnel

In order to mount an adequate response to an MCE in which there are scores of patients with respiratory compromise, it is probably most important that a facility or an emergency response system have an adequate number of well-trained individuals. In one study of pre-hospital airway management in emergency and trauma patients, there was no deficiency of equipment, but a majority of the emergency response personnel had inadequate training in airway management.¹⁶

Equipment and Supplies

The hospital must have the ability to establish a triage site outside the emergency department that has the capacity to evaluate, decontaminate, and treat patients before they are allowed to enter the facility. Obviously, in order to respond to a mass casualty event, defined as an event that overwhelms the hospital’s ability to provide the usual standard of care, there must be an adequate supply of 100% oxygen (pressurized outlets or cylinders) along with tubing, facemasks, equipment for mask ventilation etc.¹⁷ In an MCE the use of supraglottic airways (SGAs) may be lifesaving in that more patients can have a definitive airway device placed and ventilated with 100% oxygen. One might argue that the same could be achieved with bag-mask ventilation but only about one-third of novice providers are able to do so effectively. Even with additional training success rates increase to only 80–90%.¹⁸

There are several different SGAs that potentially could be used in an MCE, but the number of choices should be limited. The Supreme LMA® and the I-gel LMA® have been found to be superior to other LMAs when placed by novice operators.¹⁹ They have the additional advantage that they can be placed in the dark if need be, e.g. if facilities lose electrical power and lighting is suboptimal.²⁰

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