Myers LA, Gallet CG, Kolb LJ, et al. Determinants of success and failure in prehospital endotracheal intubation. West J Emerg Med. 2016;17(5):640–647.
The documentation of 200 intubation attempts on 150 patients cared for by a multisite EMS agency was reviewed by the authors to determine what factors were associated with success and failure of prehospital intubation. They defined an attempt as the laryngoscope blade entering the mouth. Overall success rate was 75%. The use, on an adult, of an endotracheal (ET) tube size < 7.0 was four times more likely to be successful than a larger tube. Success was 13 times more likely when at least some of the glottis (vocal cords) was visible. And a paramedic paired with another paramedic was more than three times as likely to succeed than one paired with an EMT.
Doc Wesley Comments
It’s important first to remember that this represents one service’s retrospective review of their performance and its applicability to any other service should generally be avoided. However, it sets a benchmark for comparison. Every EMS agency should be collecting this information and using it to modify their education, competency evaluations and protocols.
Although it wasn’t surprising to see that improved visualization of the vocal cords resulted in significant improvement in success, the other findings should give us pause to consider our own practice.
I recently reviewed over 200 intubations from my own service and found that for 95% of male adults, my medics choose a 7.5 ET tube. For 85% of female patients, they chose a 7.0. We have an overall success rate similar to that of this study. Traditional training on ET tube sizes is based on optimal conditions in the operating room, where we know that intubation has far fewer challenges than those performed in the streets. I remember being told to always have a second tube handy at least a half size smaller in case my first attempt fails. How many medics do that routinely? I suspect few, since we usually have a non-visualized airway device ready to insert if our attempt fails.
Perhaps the “optimal” size ET tube for adult males should be 7.0 and 6.5 for females. Our goal in the streets is to get the airway secured. The tube can always be changed out later for a larger size in the ED.
But, what about the crew configuration? First, I believe that intubation success rates are linked more to confidence than competence. When you don’t feel confident you’ll be more apt to make only one attempt, then bail to the rescue airway device. Having two medics on scene increases confidence as each trusts the other to be able to take over if they fail.
Finally, the administration of induction agents and paralytics (for rapid sequence intubation) increases the burden on the lone medic to not only draw up the med and administer it, but then switch roles to manage the airway. This can cause medics to question their confidence in doing both and therefore opt not to intubate or only make one attempt.
Medic Wesley Comments
Like Doc, the crew composition is what I found interesting. Although I support the overall EMT/paramedic crew in almost every situation, intubation is a tough skill even for two medics.
Having worked for this particular service, I know that crew resource management (CRM) is a huge part of all training activities. But safety for patients and providers is paramount. The following description from Safer Healthcare defines what’s expected utilizing this tool:
“CRM in healthcare is concerned not so much with the technical knowledge and skills required to operate equipment or perform specific operations, but rather with the cognitive and interpersonal skills needed to effectively manage a team-based, high-risk activity. In this context, cognitive skills are defined as the mental processes used for gaining and maintaining situational awareness, for solving problems and making decisions. Interpersonal skills are regarded as communications and a range of behavioral activities associated with teamwork.”1
There’s a high turnover of paramedics advancing their careers and EMTs who are just starting their careers. Inconsistency of education and experience makes the mix of EMT/paramedic crews somewhat less stable. Consistency and practice are two critical elements in CRM, and often lack of experience may be the wrench in the works. A paramedic working with an EMT may feel as if the majority of the success is dependent on them. So as the scene time ticks away, the paramedic provider may feel that it’s best to limit ET attempts and go to the failed airway device quicker.
I personally believe that once crews are more comfortable with the concept of CRM, the success of intubation as well as other aspects of patient care will improve.
1. Effecting positive behavioral and cultural change… Crew Resource Management. (2016.) Safer Healthcare. Retrieved Nov. 20, 2016, from www.saferhealthcare.com/crew-resource-management/crew-resource-management-healthcare/.