Prehospital Airway Management

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Chapter 33 Prehospital Airway Management

I Introduction

Prehospital airway management ranges from the use of basic airway maneuvers in the management of the unresponsive patient to the need for a surgical airway (i.e., cricothyrotomy) in the “cannot intubate, cannot ventilate” (CICV) situation. Because transport time from the scene of an emergency is often delayed by distance, traffic conditions, and victim extrication, skilled providers can be assets to the most seriously ill or injured patients. However, the scope of practice for emergency medical services (EMS) providers throughout North America varies broadly. In some systems, airway management is provided exclusively by basic emergency medical technicians (EMTs) who are not trained in endotracheal intubation, cricothyrotomy, or extraglottic airway devices, leaving the airway uncontrolled and susceptible to gastric inflation and aspiration induced by bag-mask ventilation, which produces a difficult airway or complete airway obstruction that may be impossible to resolve. Other systems use highly trained paramedics and allow the use of medication-assisted intubation and a variety of airway devices, which opens the door to potential clinical errors and complications such as airway trauma, misplaced tubes, and unrecognized esophageal intubation.

The variability in EMS systems throughout North America is dictated by several factors, including historical system design, state laws, system size, volunteer versus paid provider status, physicians’ preferences, and economic issues. For example, in large urban systems, a lack of high-quality medical direction and monitoring may make medication-assisted intubation difficult to successfully implement and sustain. In rural systems, the frequency of intubation may be low, making it difficult to acquire and maintain the necessary skill levels. Prehospital intubation can be challenging compared with the in-hospital environment. EMS providers work in a variety of conditions that complicate the task of airway management, ventilation, and oxygenation. Extreme weather, enclosed working spaces (e.g., cars, small rooms, hallways), bystander distractions, and a variety of other challenging situations face the EMT and paramedic.1

Some aspects of an EMS system design are essential for maximizing provider competency. The frequency with which any provider performs advanced airway management is critical for maintaining skill competency.2,3 Some systems have reported very low rates of intubation, especially for pediatric patients.46 How can competency be maintained when providers intubate three or four times per year?2,79 Should they intubate when the frequency is so low? System medical directors must answer these questions when designing, evaluating, or refining an EMS system. Physicians must be artful in selecting airway strategies, training providers, monitoring interventions, and maintaining quality.7

II History of Airway Management by Emergency Medical Services

Before the 1950s, prehospital airway management was provided by relatively unskilled providers in most EMS systems throughout the United States. Progressive systems of the time provided bag-mask ventilation with an oropharyngeal or nasopharyngeal airway. In some cases, training was limited to basic first aid without training in airway adjuncts.1012

In the 1960s, the quality of prehospital care came into focus with publication of Accidental Death and Disability: The Neglected Disease of Modern Society by the National Research Council and development of a national standards curriculum for EMTs that defined minimal training and equipment.13 Standards included training in the use of basic equipment such as bag-mask ventilation, oropharyngeal and nasopharyngeal airways, and suction.

In the late 1960s, the concept of advanced-level care was introduced first in Northern Ireland under the leadership of Dr. Frank Pantridge and subsequently implemented in several cities in the United States, including New York, Miami, Seattle, and Pittsburgh. In these systems, paramedics were trained to provide endotracheal intubation in the field along with other advanced life support interventions. Most programs included training in the operating room under the supervision of an anesthesiologist. This innovation was helpful for victims of respiratory and cardiac arrest who were unresponsive. However, there were still challenges for patients with respiratory failure, shock, or other premorbid conditions who were responsive but in need of definitive airway management. In the absence of sedation and rapid-sequence intubation (RSI) protocols, intubation for these conditions was often performed by employing brutane—the use of force to assist in performing a medical procedure, such as intubating the trachea.

In the 1970s, some paramedic systems began to use neuromuscular blocking drugs to manage patients’ airways with great success. These programs provided significant medical oversight that included monitoring successful outcomes and complications associated with endotracheal intubations.14 System medical directors had concerns about the use of medication-assisted intubation, including the issue of increased time at the scene by paramedics and complications such as unrecognized esophageal intubation.1517

Drug-assisted intubation is a relatively new idea that is used on a limited basis in EMS systems in North America. Because success rates for drug-assisted endotracheal intubation vary greatly among EMS groups, it is not routinely recommended.8,9 However, the National Association of EMS Physicians has developed guidelines for implementing drug-assisted intubation programs that include provider training, patient selection, use of standardized protocols and resources for storage and delivery of medications, training in verification and monitoring of end-tidal carbon dioxide, a continuous quality improvement program, and research on a system level to verify effectiveness of the program.18

Alternative airway devices have been used in prehospital care since the advent of prehospital advanced life support. Devices include the esophageal obturator, gastric tube airway, esophageal-tracheal Combitube, and King laryngeal tube (LT) airway. Many studies have demonstrated their relative effectiveness compared with bag-mask ventilation and endotracheal intubation (ETI) ventilation.1921

III Prehospital Care of Airway Patients

Prehospital care of airway patients addresses the spectrum of clinical conditions faced in emergency departments, critical care units, and operating rooms. In the ideal world, providers would be prepared to deal with airway management and ventilation for all possible conditions, but the scope of practice and provider skill levels vary in North America. In other parts of the world, where physicians staff EMS vehicles, skill levels may be more uniform. At the entry level of emergency medical response (EMT-Basic), forced positive pressure with bag-mask ventilation and rapid transport may be the only options available. ETI has been considered the gold standard for definitive airway management, but the diverse skill levels found in prehospital care and the use of extraglottic airway devices in EMS have challenged this idea. High rates of unrecognized esophageal or hypopharyngeal placement or dislodgement have raised concerns about ETI as a default strategy for EMS providers.16,17

B Extraglottic Airway Devices

Use of the King LT as a primary and alternative airway device has been an effective prehospital airway strategy.17,25,26 Because alternative airway devices do not provide definitive protection against aspiration, they typically are used temporarily until ETI can be achieved in the field or in the emergency department. In one case report, the King LT resulted in tongue engorgement when left in place for approximately 3 hours.27

The double-lumen esophageal-tracheal Combitube is an alternative airway device commonly used in EMS. It has been used by Basic and Advanced EMTs as a primary airway device and by paramedics as a rescue device. Effectiveness of the Combitube has varied among studies in prehospital care. Cady and colleagues found it had no effect on patient outcomes compared with ETI.28 In a study of prehospital physicians, the Combitube was superior to ETI in the management of cardiopulmonary arrest.29

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