Spinal Dogma Part 3

philips_ct2_pwkt

My last rant for a while.  The patient from scenario 2 is now in the resuscitation room of a trauma center.  He was intubated successfully by the retrieval physician after in line stabilization was removed, changing a grade 4 view to a grade 3a view and allowing blind passage of a bougie.  The collar was then reapplied and the patient transferred to the trauma center uneventfully.  A CT “pan scan” reveals some small cerebral contusions that don’t require operative intervention, some broken ribs and bilateral pulmonary contusions, with a left penumothorax which is drained, a grade 2 liver laceration that can be observed and no other injuries.  The femur fracture is will require fixation at some stage.  The CT of the cervical spine is reported as showing no bony injury, with all soft tissue spaces within normal limits.  You ring your friendly neurosurgical registrar (or perhaps orthopaedic registrar, depending on who does spines where you are) with this news, expecting to be given the go-ahead to take the collar off and relax spinal precautions.  Alas the neurosurgeon tells you that a CT scan isn’t sufficient to rule out a significant injury, and that you should “just keep the collar on” and he’ll review the patient on Monday morning, maybe after an MRI.  It’s currently Friday and the neurosurgeon has obviously never accompanied an intubated patient to the MRI scanner.

 

So here we have the final spinal conundrum.  Now that the collar’s on, it’s very difficult to take off.  So let’s look at the evidence supporting clearing the C-Spine based on CT alone.  Conveniently this was reviewed in  this month’s Annals of Emergency Medicine (and apparently it’s open access – well it was when I downloaded it.)  Kirschner and Seupaul from Indianapolis do what they called a “Systematic Review Snapshot” which I quite liked.  They essentially critique an article that’s been spoken about a bit lately – a systematic review and meta-analysis of the research comparing CT clearance with clinical clearance (it also seems to be freely available).  They note that the research is mostly observational (and therefor prone to bias).  The meta analysis that they discussed included 14,327 patients.  Of these 14,327 patients with a negative CT scan, 7 had a clinically significant injury, 3 of which were unstable. Thats 0.02%.  Let me say that again. 3 out more than 14,000 patients had an unstable injury.  This gives CT a sensitivity and specificity of 99.9%.  I don’t know of any other test that has a sensitivity and a specificity that high.   The authors of the original meta-analysis pit it even more succinctly – Clearance based on CT alone will result in one missed injury every 14 years in a moderately busy trauma centre, compared with hundreds of complications from prolonged immobilisation. Yet the reviewers in the Annals come to a vague and safe conclusion that CT “may reliably exclude unstable injuries” in obtunded patients.  May?  Well in their defence, the reviewers didn’t think very highly of the papers that went into the meta-analysis, commenting on flawed study designed and a high degree of heterogeneity.  They do, however, point out that the soft tissue injuries found on MRI are often of uncertain clinical significance, and there can be lots of false positives on MRI.

 

So where does this leave us? Is 99.9% sensitive and specific good enough?  Or is paraplegia such a devastating complication that we need a test that’s 100% specific (I would argue that clinical examination certainly isn’t).  What about the complications of leaving the collar on?  Bedsores, airway compromise, possibly increased VAP rates through being supine. The list goes on.  I’ll be willing to bet that the rate of serious complications from keeping an ICU patient in a collar is > 0.02%.  So does that put the risk benefit ratio in favour of taking the collar off?

 

As devastating as the possibility of paraplegia may be, people seem to lose sight of the fact that spinal immobilization in an intubated patient carries a not-insignificant harm.  Bedsores cause sepsis which kills.  What if the patient is ready to be extubated before the spine in cleared?  Do you keep them intubated until then, increased the risks associated with prolonged intubation? Or do you extubate them in a supine or reverse Trendellenburg position, with all the risks that brings? Is our lack of trust in a very large, but possibly not very good, meta-analysis just a convenient way for us to say that we don’t want to risk a less than 0.02% chance of missing a ligamentous injury that may or may not cause future harm to the patient while blissfully ignoring the very real risks of lying flat on you back in a collar in the ICU.  I encourage you all to make up your own minds by reading at least the short review in the Annals, if not the full paper from the Journal of Neurosurgery.

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4 Responses to Spinal Dogma Part 3

  1. Kannan says:

    What about Philadelphia collar? Why not change to it ?

  2. Sean Scott says:

    I have taken the collar off on the basis of a normal CT. The caviate to this is that it must by 100% normal. I remember a case with a small spinous process # who hade collar removed based on CT alone. Unfortunately when extubated awake and mobilizing…

    …His head fell off

    Significant cord injury. Required reintubation. Long ICU stay. Rehab an overall bad outcome. If the collar had been left on and we waited to “clinically” clear the C-spine, I wonder if midline tenderness would have alerted us to the need fror MRI.

    Of course an N=1 with this sort of outcome was more than enough to change hospital policy. Now every obtunded patient needs a MRI before they are cleared. However in other settings I still clear on a 100% normal CT C-spine.

  3. Pingback: The Death of the Cervical Collar? | AmboFOAM

  4. Pingback: Collier cervical | thoracotomie

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