Airway management is one of the most anxiety provoking procedures performed by trauma professionals. The main fear is that the airway will be lost during attempts to secure it and patient demise will soon follow. Add some facial fractures, bleeding, and an “unfavorable body habitus”, and the average prehospital or ED provider is really on edge.
The next most common fear is that providing a definitive airway in a patient with a known (or even suspected) cervical spine injury could cause a catastrophic neurologic injury. This was first addressed back in 1989 (before the time of video laryngoscopy, and when flexible scopes were rarely available in the ED). The authors found no verifiable reports of such an injury in the entire English literature.
Over the years, a few case reports have cropped up. As in so much of the medical literature, causality is hard to prove. The patient was normal before anesthesia, and afterwards they were not. Had to be the intubation, right?
Not so fast! Let’s break it down and look at what we do know. Biomechanical studies have shown that the manipulation that occurs in direct laryngoscopy isn’t as bad as it looks. Studies in uninjured models are enlightening (minimal movement with blade insertion, slight rotational movements with blade elevation, and a little more rotation during the intubation). Most of this (slight) movement occurs from occiput to C2, with little motion at all at C3 and below.
But that was on an uninjured model. What about ones that simulate an injured spine? Specifically an injury in the upper spine area that we know moves?
- Cricoid pressure caused no appreciable changes in the spine
- Chin lift and jaw thrust reduced space available for the cord (SAC) by 1 and 2.5mm, respectively, and caused an angulation of about 4-5 degrees
- SAC narrowed by only 1.5mm, even with maximum flexion and extension
- Oral and nasal intubation narrowed SAC by 1.6mm, and resulted in a maximum of 2.5 degrees of rotation
- Video laryngoscopy results in about half of the rotational movement of direct laryngoscopy
But what about these sporadic reports of neurologic deficits after intubation? What is often neglected is that spinal blood flow and long-term neck positioning have a major impact on cord function. Even relatively mild malpositioning of the cervical spine for extended periods during an OR case have been documented.
Bottom line: From a mechanical standpoint, even in unstable spine models, the maneuvers we use in preparation for intubation cause more movement of the spine than does the intubation procedure itself. The true number of spinal cord injuries actually (and provably) caused by intubation approaches zero. The literature suggests that video laryngoscopy results in less overall movement during intubation, but it doesn’t seem to have an impact on cord injury (you can’t get less than zero).
- Spinal cord injury and direct laryngoscopy – the legend lives on. Br J Anesth 84(6):705-709.
- Airway management in adults after cervical spine trauma. Anesthesiology 104(6):1293-1318, 2006.
Intubation is the one procedure that provokes the most anxiety for trauma professionals. What about those facial fractures? What if you can’t get it? Video-assisted intubation is now readily available and at a reasonable cost. And it seems like a great idea, but does it make intubation easier?
A paper to be presented at the AAST next week looked at intubation success among relatively inexperienced users, junior residents. They compared success rates of video assisted (VA) intubation in an ICU (74 patients) with direct laryngoscopic (DL) intubation performed in an ED (54 patients).
All patients were successfully intubated by the junior resident, or by a more senior backup if they were unsuccessful (fellow or attending). The junior residents were successful in 96% of the VA intubations, but in only 76% of DL intubations. Less experienced residents (<20 intubations) were successful in all 96% of the VA intubations but in only 40% of the DL. And the least experienced, those who had done less than 5 intubations, obtained an airway with VA 37% of the time vs 7% for DL. The number of desaturations to less than 80% and hospital mortality was the same for the two groups.
Bottom line: Video assisted intubation is superior to the old-fashioned direct laryngoscopic technique. Even inexperienced providers have a better success rate with the video assisted technique. Over the next few years, it will become the standard for intubating patients, both in the field by medics and in the hospital.
Reference: The emergent airway: video-assisted intubation is superior to direct laryngoscopy for teaching junior residents. AAST 2011 Paper #65.
How far we have come! It’s now commonplace to intubate trauma patients in the ED using rapid sequence induction followed by orotracheal tube placement. However, 20 years ago we were still gnashing our teeth about safety.
In 1991, the group at UMDNJ Newark looked at 100 consecutive trauma patients with suspected head injury who were paralyzed and intubated in the ED. Half of the intubations were performed by a surgeon, the other half by an anesthesiologist. Fifty seven patients were intubated orally and 40 nasally(!). Three required cricothyroidotomy after failure to intubate due to facial fractures.
The majority of these patients had head scans performed; 59% were positive and 15 required emergent neurosurgical procedures. No patients were found to have a neurologic deficit from the intubation even though seven were eventually found to have cervical spine injuries. Only one patient developed an aspiration pneumonia.
The authors concluded that paralysis and intubation in the ED was safe. It helped facilitate the diagnostic workup because they could control combative patients. Up to that time, the only alternative was heavy sedation, which carried its own risks.
Interesting points on how far we have advanced:
- Intubation in the ED did not used to be routine. There was a great deal of anxiety before this procedure
- Nasal intubation was still fairly commonplace
- The cricothyroidotomy rate was high
- Intubation was usually performed by a surgeon or anesthesiologist