Recently, I came across a destitute colleague who had just responded to a code for a cardiac arrest. During the arrest, the patient was intubated successfully, without interruption of compressions. I was puzzled. Why was my colleague distressed? Surely, she had done her job well, securing the airway in a prompt and efficient manner.
As it turns out, another provider had questioned numerous elements of her care. First, the other provider debated whether to give a paralytic. The other provider vehemently argued that a paralytic was indicated to “best optimize the chance of success.” My colleague did not feel that a paralytic was indicated in cardiac arrest, and intubated without the use of any additional medications.
After the argument about the paralytic, the other provider then had the nerve to question whether the patient should have even been intubated at all! In point of fact, intubation in cardiac arrest is quite controversial, and my downtrodden colleague had every right to feel frustrated.
Although endotracheal intubation has long been regarded as the “gold standard” for cardiac arrest, recent guidelines de-emphasize the procedure, especially if intubation is to be achieved at the expense of other evidence-based interventions (i.e., CPR and electrical therapy) associated with improved survival and better neurological outcomes.(1,2)
Now I will admit that when I first read this recommendation, it was difficult to digest. As a paramedic, anesthesiologist, and intensivist, I’ve never thought twice about securing an airway with an endotracheal tube during a cardiac arrest. Historically, to do otherwise would be considered malpractice! However, when one examines the recent literature, it is understandable why intubation for cardiac arrest remains a provocative topic. For starters, the reader is referred to a comprehensive and well-written review on this topic by Dr. J.V. Nable et al.(1)
Intubation has not been shown to positively impact outcomes for cardiac arrest patients, and there are several explanations for this somewhat counterintuitive finding.
First, intubation during cardiac arrest is not always straightforward, and in at least one study, 30% of patients required more than one attempt.(3)
Second, the learning curve to attain competence is steep—one study suggests up to 60 intubations are required to become proficient—and in some systems, EMS providers do not have opportunities maintain this skill.(4) As Nable et al write, “maintaining proficiency in endotracheal intubation is a significant barrier for many prehospital providers.”(1) In Wang et al, intubation success by medics was only 78%.(3)
Third, intubation is followed by positive pressure ventilation (PPV), and PPV has been shown to decrease preload, lower cardiac output, and negatively impact the effectiveness of chest compressions.(1)
Fourth, intubation may require interruption of chest compressions, and this has clearly been linked with worse outcomes.(5) For the abovementioned reasons, in some countries, such as the U.K., a case has been made for abandoning intubation altogether in cardiac arrest.(6)
Coming back to my colleague’s dilemma regarding paralysis for intubation in cardiac arrest, this is also a contentious topic. On one hand, paralysis may enhance intubating conditions and facilitate prompt control of the airway, thereby avoiding airway trauma with multiple laryngoscopic attempts, and preventing aspiration. Moreover, the most feared complication of paralysis—the “can’t intubate, can’t ventilate” scenario—is relatively rare. In one study of more than 6,000 trauma patients at our institution (University of Maryland R Adams Cowley Shock Trauma Center in Baltimore), only four patients required a surgical airway.(7)
On the other hand, the hazards of positive pressure ventilation, hyperkalemia associated with succinylcholine, and the rare instance of failed intubation in a paralyzed patient with a difficult airway, all pose an unacceptable risk/benefit in cardiac arrest. The decision to use paralytics is as difficult as deciding to intubate in cardiac arrest, and the use of these agents can only be recommended for the most highly trained providers.
What about supraglottic airways? This class of airways includes the laryngeal mask airway (LMA), Combitube, laryngeal tube and other various proprietary devices. Although these devices do not represent a “definitive airway,” several studies have shown equivalent outcomes when these devices were compared to endotracheal intubation in cardiac arrest.(1,8) Supraglottic airways have several advantages over intubation. Learning curves are easier, the devices can be placed faster, and there may be fewer complications during device insertion.(9)
To date, no one device has been shown to be conclusively superior to another. Patients eligible for placement of a supraglottic airway require adequate mouth opening, no underlying severe lung disease (i.e., decreased lung compliance), and low risk for aspiration.(1)
At the end of the day, airway management for cardiac arrest may be achieved according to the proficiency and resources available to the provider. EMS providers should not be discouraged by the literature! Airway management is still important. In one study by Wong et al, the best short-term survival was seen in patients who had an advanced airway placed within five minutes of the arrest.(10)
Other studies have failed to show any difference between intubation and use of bag-valve mask ventilation (BVM).(11) However the airway is managed, current recommendations still emphasize the importance of providing ventilatory support during cardiac arrest.(2) In jurisdictions where intubation is used for cardiac arrest, providers should perform the procedure with “sufficient frequency to maintain competence within a highly managed system that actively monitors success rates, complications and patient outcomes.”(9)
If intubation is to be considered in cardiac arrest, it should only be attempted if:
- The provider is proficient;
- There are no interruptions in chest compressions; and
- The attempt takes no more than 10 seconds.(2)
Survivors of cardiac arrest who require intensive care management will usually require definitive airway management with endotracheal intubation at some point, but early in the arrest, providers should focus on providing high-quality CPR.(12)
1. Nable JV, Lawner BJ, Stephens CT. Airway management in cardiac arrest. Emerg Med Clin N Am. 2012;30:77–90.
2. Neumar RW, Otto CW, Link MS. Part 8: Adult advanced cardiac life support: 2010 American Heart Association guidelines for cardiopulmonary resuscitation. Circulation. 2010;1222(183):S727–S767.
3. Wang HE, Yealy DM. How many attempts are required to accomplish out-of-hospital endotracheal intubation? Acad Emerg Med. 2006;13:373–377.
4. West MR, Jonas MM, Adams AP, et al. A new tracheal tube for difficult intubation. Br J Anaesth. 1996;76:673–679.
5. Kellum MJ, Kennedy KW, Ewy GA. Cardiocerebral resuscitation improves survival of patients with out-of-hospital cardiac arrest. Am J Med. 2006;119:335–340.
6. Deakin CD, Clarke T, Nolan J. A critical reassessment of ambulance service airway management in prehospital care: Joint Royal Colleges Ambulance Liaison Committee Airway Working Group. Emerg Med J. 2008;27:226–233.
7. Stephens CT, Kahntroff S, Dutton RP. The success of emergency endotracheal intubation in trauma patients: A 10-year experience at a major trauma center. Anesth Analg. 2009;109:866–872.
8. Kajino K, Iwami T, Ktamura T, et al. Comparison of supraglottic airway verus endotracheal intubation for the pre-hospital treatment of out-of-hospital cardiac arrest. Critical Care. 2011;15:R236.
9. Thomas MJC. Prehospital intubation in cardiac arrest: The debate continues. Resuscitation. 2011;82:367-368.
10. Wong ML, Carey S, Mader TJ, et al. Time to invasive airway placement and resuscitation outcomes after inhospital cardiopulmonary arrest. Resuscitation. 2010;81:182–186.
11. Shin SS, Ahn KO, Song KJ, et al. Out-of-hospital airway managemetn and cardiac arrest outcomes: A propensity score matched analysis. Resuscitation. 2011. Accessed 18 Feb 2012.
12. Morley PT. The key to advanced airways during cardiac arrest: Well trained and early. Critical Care. 2012;16:104.