Prehospital Spinal Clearance Part III

The evidence is here...

You have heard me mention the NEXUS study a few times, and in this post I am going to finally explain exactly what it is and ask if its the solution.

NEXUS stands for National Emergency X-Radiography Utilization Study. This study has been used in a few different aspects of emergency medicine, but has definitely shown its worth in the prehospital environment. [1]

Fear of failure to identify cervical spine injury has led to extremely liberal use of radiography in patients with blunt trauma and remotely possible neck injury. A number of previous retrospective and small prospective studies have tried to address the question of whether any clinical criteria can identify patients, from among this group, at sufficiently low risk that cervical spine radiography is unnecessary. The National Emergency X-Radiography Utilization Study (NEXUS) is a very large, federally supported, multicenter, prospective study designed to define the sensitivity, for detecting significant cervical spine injury, of criteria previously shown to have high negative predictive value. Done at 23 different emergency departments across the United States and projected to enroll more than 20 times as many patients with cervical spine injury than any previous study, NEXUS should be able to answer definitively questions about the validity and reliability of clinical criteria used as a preliminary screen for cervical spine injury.

The following image is of a flowchart that utilizes the NEXUS guidelines to determine whether or not to implicate spinal immobilization. It is almost identical to the one found in my Prehospital Trauma Life Support (PHTLS) book.

I know its hard to read, you can use the instructions on the right side of this page for larger viewing.

This criteria has come from the results of the study and has shown to be successfully implemented in the protocols of a few EMS agencies nationwide. The criterion is very similar to the NEXUS criteria for x-ray in the emergency department. Even though the criteria was initially intended to rule out the need for an x-ray for spinal clearance, it is being used to rule out the need for spinal immobilization. The following is the intended use of the NEXUS criteria.

According to the NEXUS Low-Risk Criteria, cervical spine radiography is indicated for trauma patients unless they exhibit ALL of the following criteria:

1. No posterior midline cervical spine tenderness
and
2. No evidence of intoxication
and
3. Normal level of alertness
and
4. No focal neurological deficit
and
5. No painful distracting injuries

Explanations:
These are for purposes of clarity only. There are not precise
definitions for the individual NEXUS Criteria, which are subject
to interpretation by individual physicians.

1. Midline posterior bony cervical spine tenderness is present if the patient complains of pain on palpation of the posterior midline neck from the nuchal ridge to the prominence of the first thoracic vertebra, or if the patient evinces pain with direct palpation of any cervical spinous process.
2. Patients should be considered intoxicated if they have either of the following: a) a recent history by the patient or an observer of intoxication or intoxicating ingestion; or b) evidence of intoxication on physical examination such as odor of alcohol, slurred speech, ataxia, dysmetria or other cerebellar findings, or any behavior consistent with intoxication. Patients may also be considered to be intoxicated if tests of bodily secretions are positive for drugs (including but not limited to alcohol) that affect level of alertness.
3. An altered level of alertness can include any of the following: a) Glasgow Coma Scale score of 14 or less; b) disorientation to person, place, time, or events; c) inability to remember 3 objects at 5 minutes; d) delayed or inappropriate response to external stimuli; or, e) other.
4. Any focal neurologic complaint (by history) or finding (on motor or sensory
   examination).
5. No precise definition for distracting painful injury is possible. This includes any condition thought by the clinician to be producing pain sufficient to distract the patient from a second (neck) injury. Examples may include, but are not limited to: a) any long bone fracture; b) a visceral injury requiring surgical consultation; c) a large laceration, degloving injury, or crush injury; d) large burns: or e) any other injury producing acute functional impairment. Physicians may also classify any injury as distracting if it is thought to have the potential to impair the patient’s ability to appreciate other injuries.

See how this can easily be converted in to a prehospital guideline? Of coarse you can, I already showed it to you.

It only makes sense that the same criteria that physicians use in their assessment to clear a cervical spine be used by EMTs/paramedics. If it can be taught to a doctor, why not us? We have all seen physicians take the cervical collars, that we have applied, off the patients that we bring in. This criteria has been questioned and compared to other studies such as the Canadian method, and I will go over a retrospective comparison of these two methods in my next post on this topic.

Click here for the Michigan protocol that I mentioned in my last post on this topic. Even though they implement some of the same assessments as NEXUS, they do not cite them as a reference. Their protocol includes a rule in method. If any of the specified findings are present, they are to immobilize.

Click here for the 2002 version of Maine's spinal clearance protocol. They appear to have included all of the NEXUS criteria and then some. They claim to have an increased sensitivity of spinal assessment:

An additional Maine EMS 2002 Spine Assessment Protocol departure from the NEXUS investigation is the direction to immobilize patients for a complaint of neck pain as well as any tenderness present in the prehospital spine assessment. This change is purposefully meant to provide an added level of concern for spine injury by increasing the “sensitivity” of the spine assessment protocol. This direction should also serve as a means for decreasing the disagreement potential between providers’ (both in and out of the hospital) assessment of individual patients.

While the NEXUS investigation applies solely to the cervical spine, large scale clinical trials evaluating clinical decision rules for thoracic, lumbar, or sacral spine injuries have yet to be performed. As a consequence, care of the entire spine generally follows cervical spine assessment and treatment principles.

The prehospital assessment of tenderness should include, but not be limited to, the palpation of the posterior midline spine. While NEXUS has emphasized the sole importance of posterior, midline spine tenderness in cervical spine assessment, the Maine EMS 2002 Spine Assessment Protocol includes consideration of any areas of spine tenderness as a means for immobilization. This decision represents another adaptation of the NEXUS rules in an attempt to improve the instrument’s sensitivity for any spine injury as well as decreasing medical provider disagreement potential.

Finally, we have found research that was done on a large enough scale to be considered conclusive evidence to support a prehospital cervical spine clearance protocol. In fact, it is currently being used by many prehospital clinicians already. So why isn't it universally accepted?

As I stated, in the next post on this topic I will go over the comparison between NEXUS and the Canadian method. Maybe we haven't reached the final answer.

[1]Hoffman JR, Wolfson AB, Todd K, Mower WR: Selective cervical spine radiography in blunt trauma: methodology of the National Emergency X-Radiography Utilization Study (NEXUS). Annals of Emergency Medicine 2001.