Managing the Airway During Cardiac Arrest

Abstract

FOR DECADES, AN AXIOM OF CARE IN THE RESUSCITATION of cardiopulmonary arrest was “airway first.” Airway management seeks to maintain or create an open pathway to the lungs to ensure adequate oxygenation and ventilation, commonly using the strategy of bag-valve-mask ventilation. However, because maintaining an open pathway for gas exchange is difficult with this approach and does not protect the lungs from aspiration of gastric contents, more advanced airway maneuvers are often used. These techniques usually involve endotracheal intubation or supraglottic airway placement. The latter device is inserted blindly through the mouth, sealing the hypopharynx to facilitate oxygen delivery without a direct conduit through the glottis. Paralleling practice in the hospital, most emergency medical services systems in North America prioritize the use of advanced airways (endotracheal intubation or a supraglottic airway). In this issue of JAMA, the study by Hasegawa et al examines 2 advanced airway management approaches in the treatment of patients with out-of-hospital cardiac arrest. Out-of-hospital airway management in North America started with paramedics using ineffective, blindly inserted devices, notably the esophageal-obturator airway. In the 1970s, demonstration projects in Pittsburgh, Pennsylvania, Columbus, Ohio, San Diego, California, and Boston, Massachusetts, provided the impetus to encourage wide use of paramedic endotracheal intubation. The initial demonstration projects of paramedic intubation were designed to evaluate the feasibility of the concept—there were few follow-up studies to verify the safety or effectiveness of the technique. Despite these limited data, early paramedic intubation became a centerpiece of out-of-hospital care for treatment of cardiac arrest. Over the last 5 years, emergency medical services personnel have experimented with initial supraglottic airway insertion rather than intubation to minimize interruptions in cardiopulmonary resuscitation chest compressions. Recent studies have questioned the wisdom of the wide use of out-of-hospital endotracheal intubation in many severely ill or injured patients. Out-of-hospital endotracheal intubation adverse events include unrecognized esophageal placement, tube dislodgement, iatrogenic hypoxia and bradycardia, and frequent need for multiple tube insertion attempts. Endotracheal intubation during cardiac arrest can interfere with cardiopulmonary resuscitation continuity of chest compression or facilitate inadvertent hyperventilation, both of which can adversely influence cardiac arrest survival. Out-of-hospital endotracheal intubation has added pragmatic constraints. Intubation is a difficult technique, requiring mastery of motor skills and decision making. Paramedics deliver this care in uncontrolled settings; while paramedic students seek to learn intubation under the mentorship of anesthesiologists in the operating room, access to this controlled learning setting is limited. Many paramedic students complete their training with little exposure to live endotracheal intubation. Also limiting advanced airway skills is usual practice, in which endotracheal intubation opportunities can be sparse, further affecting the effectiveness when needed. For instance, in Pennsylvania, paramedics perform a median of 1 endotracheal intubation per year. Complicating matters are recent studies that fail to demonstrate a benefit of paramedic endotracheal intubation in traumatic brain-injured or cardiac arrest cohorts. Although the use of supraglottic airway devices was intended to circumvent many of the adverse effects of endotracheal intubation, a recent animal study suggests potential neurologic harm from use of these devices. In the current study involving 649 654 adults with out-ofhospital cardiac arrest in Japan, Hasegawa et al observed that 30-day neurologically favorable survival was higher among those who received bag-valve-mask ventilation alone (2.9% among 367 837 patients) compared with those who received endotracheal intubation (1.0% among 41 972 patients) or supraglottic airway insertion (1.1% among 239 550 patients). This natural experiment from the All-Japan Utstein Registry has several strengths, including a diverse national enrollment, important functional assessment of those treated, and use of propensity score matching to help address selection bias. Although not the first report to suggest higher survival with basic bag-valve-mask ventilation, the study is large, methodologically rigorous, and compelling.