Airway & Respiratory, Columns, Patient Care, Trauma

Three Airway Modalities in Difficult Airways Editor’s Note: These studies were conducted through the University of Iowa Dept. of Emergency Medicine, not at the Mayo Clinic. We apologize for the error.

Review of: Russi CS, Miller L, Hartley MJ: “A Comparison of the King-LT to Endotracheal Intubation and Combitube in a Simulated Difficult Airway.” Prehospital Emergency Care. 12(1):35 41, 2008.

The Science
This study conducted by the Department of Emergency Medicine at the Mayo Clinic in Rochester, Minn. sought to compare the time to establish an airway using three different modalities. The compared standard endotracheal intubation (ETT), Combitube (ETC) and King LT-D Airway (LT-D) using a Laerdal Air Man Difficult Airway Simulator.

Sixty-nine providers (39 paramedics, six EMT-Bs and 18 firefighter/EMT-Bs) rotated through a trauma intubation scenario in which a cervical collar was in place and timed from the point when the proctor said “start” until tube placement was verified. Following this, researchers surveyed each provider to assess the ease of use and how comfortable the providers were with each modality.

The average times for paramedics were 91.3 seconds for the ETT, 53.7 seconds for the ETC, and 27.0 seconds for the LT-D. EMT-B placement times were 46.4 seconds for the ETC and 22.5 for the LT-D. Paramedics successfully placed the ETT in 68.9% of attempts compared to 100% success in placing the LT-D. Likewise, EMT-Bs placed the ETC with 87.5% success rate and 100% for the LT-D.

The researchers quite obviously concluded the King LT-D has significant time advantages and successful placement over traditional intubation and the Combitube.

The Street
I’ll admit I wasn’t a fan of the King LT-D Airway when it first came on the market. But, since then the device has been modified, and I believe those modifications have markedly improved it.

I’m questioned almost every day whether to adopt the King LT-D at the BLS level and how it compares to the Combitube. Now we have comparative data of the two most common non-visualized airways on the market. This head-to-head comparison of the two devices as well as how they match up to the traditional intubation has been long awaited. It was no surprise to see that both non-visualized airways took less time to insert than endotracheal intubation. The 2005 American Heart Association guidelines state that establishing an airway should not take more than 30 seconds because interruption of chest compressions lowers coronary perfusion and worsens the already high mortality of cardiac arrest. In this study, the King LT-D appears to meet that goal.

This study centered on trauma, but we have data from San Diego that endotracheal intubation of patients with traumatic brain injury results in greater mortality and morbidity secondary to unrecognized hypoxia and bradycardia. Although the time to place the tube wasn’t studied in San Diego it’s reasonable to surmise that it was at least as long as that documented in this study — and probably longer.

With all that said, the study does have some weaknesses, most of which the authors admit. First, all providers progressed through the devices in the same order. That is, they all used intubation, followed by ETC then followed by LT-D. This could have resulted in them becoming attuned to the nuances of the manikin. But another limitation the authors didn’t mention is the fact that they failed to use the difficult airway features of the manikin, such as swelling of the tongue and trismus (clenching of the teeth). It would be highly informative to see how this would affect the data.

I expect to get a flurry of e-mails and comments that I’m leading the charge to remove intubation from the paramedics, but this data is hard to argue with. Regions Hospital in St. Paul, Minn. is currently conducting a study in which the paramedics administer RSI drugs followed by insertion of the King LT-D. I’m anxiously awaiting their result. Until then, I support the adoption of early use of a non-visualized airway over endotracheal intubation, and the King LT-D appears to have a clear advantage in terms of ease and time of insertion.