Bag-Valve-Mask is better than ET Intubation or even supraglottic airways in cardiac arrest. Or at least that is the conclusion of an important new study, Association of Prehospital Advanced Airway Management With Neurologic Outcome and Survival in Patients With Out-of-Hospital Cardiac Arrest, just published in the January 16. 2013 issue of the Journal of the American Medical Association.
The article again raises questions about the importance of ALS interventions in cardiac arrest, and makes us wonder if we are doing more harm than good with aggressive airway intervention.
I need to take a statistics class someday so I can better understand studies or at least make more sense of them, so I will leave others to comment on the technical points. Here are the results as I understand them:
The researchers looked at 649,654 consecutive out of hospital cardiac arrests in Japan over a six-year period (2005-2010). The primary end point was favorable neurological status one month after the arrest.
57% had bag-valve mask, 6% had endotracheal intubation and 37% had supraglottic airways.
Here is the outcome:
Neurologically Favorable Status
Bag Valve 2.9%
An accompanying editorial by noted airway researcher Hanry Wang and Donald Yealy called the study large, methodically rigorous and compelling.
The authors write:
“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.
I eagerly await responses more educated than mine to this study. At this point all I can do is speculate as to the reasons for this outcome based on commentary in the studies and my own thoughts.
Perhaps, while ET and supraglottic may be better airways the time taken to get them may come at the cost of effective CPR in the critical spare seconds patients have to be brought back from the precipice of permanent harm.
Perhaps while ET and supraglottic airways may save some patients, poor insertion may kill others who might have been saved.
Perhaps the supraglottic airways were more likely to be used in patients with a difficult airway (I don’t think this is true, but I was surprised and disappointed at the poor results of the supraglottic airways).
Perhaps, as the authors suggest, advanced airways may give the responders the avenue to kill the patients through hyperventilation and hyperoxemia.
I thought that perhaps the advanced airways were also accompanied by epinephrine, which has been shown to increase mortality, but then I saw in the study the use of epinephrine was evenly divided among the groups. The baseline characteristics of propensity-matched patients (whatever that means) were quite similar according to a large chart in the article.
I also thought that perhaps the bag value mask survivors included all those patients who were brought back by defibrillation before an advanced airway could even be inserted.
(I believe the paper says this is not the case due to statistical adjustments, but I don’t quite understand that. From the article: “endotracheal intubation and supraglottic airways were similarly associated with a decreased chance of favorable neurological outcome. The observed associations were large and persisted across different analytic assumptions.”)
The answers to some of these questions may lay in the study, but I await others to explain them to me.
In the meantime, I agree with the editorial writers conclusion that:
The study by Hasegawa et al sends a clear message. Emergency medical services professionals across the world must engage in the scientific process. A large, well-designed research effort is needed to define the benefit from endotracheal intubation, supraglottic airway insertion, or more simple actions during resuscitation after cardiac arrest. Absent this investment, the emergency medical services community risks turning a blind eye and embracing ineffective or harmful airway interventions. Patients with cardiac arrest and the out-of-hospital rescuers who care for them deserve to know what is best.
What do you think?
See Vince D’s excellent comments below. He also provided this link to the first expert commentary on the study: