Monthly Archives: January 2016

Philosophy

The Sixth Law Of Trauma

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Here’s another one. I’ve seen the clinical problems and poor outcomes that can arise from ignoring it many times over the years.

You’ve ordered a CT or a conventional x-ray image. The result comes back in your EMR. You take a quick glance at the summary at the bottom of the report. No abnormal findings are listed. So now, in your own mind and in any sign-outs that you provide, the image is normal.

Here’s the rub. Saying something is not abnormal doesn’t necessarily mean that it’s normal. Hence the sixth law:

Always look at the image yourself.

Sometimes, the radiologist misses key findings on the image. Sometimes they see them and make a note of them in the body of the report. But they don’t get the clinical significance and don’t mention it in the summary (which is the only thing you looked at, remember?).

Bottom line: Always make a point to pull up the actual images and take a look. You have the full clinical picture, so you may appreciate findings that the radiologist may not. Sure, you may not have much experience or skill reading more sophisticated studies, but how do you think you develop that? Read it yourself!

Other Laws of Trauma:

General

Flying After Pneumothorax

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This question just keeps on coming up!

Patients who have sustained a traumatic pneumothorax occasionally ask how soon they can fly in an airplane after they are discharged. What’s the right answer?

The basic problem has to do with Boyle’s Law (remember that from high school?). The volume of a gas varies inversely with the barometric pressure. So the lower the pressure, the larger a volume of gas becomes. Most of us hang out pretty close to sea level, so this is not an issue.

However, flying in a commercial airliner is different. Even though the aircraft may cruise at 30,000+ feet, the inside of the cabin remains considerably lower though not at sea level. Typically, the cabin altitude goes up to about 8,000 to 9,000 feet. Using Boyle’s law, any volume of gas (say, a pneumothorax in your chest), will increase by about a third on a commercial flight.

The physiologic effect of this increase depends upon the patient. If they are young and fit, they may never know anything is happening. But if they are elderly and/or have a limited pulmonary reserve, it may compromise enough lung function to make them symptomatic.

Commercial guidelines for travel after pneumothorax range from 2-6 weeks. The Aerospace Medical Association published guidelines that state that 2-3 weeks is acceptable. The Orlando Regional Medical Center reviewed the literature and devised a practice guideline that has a single Level 2 recommendation that commercial air travel is safe 2 weeks after resolution of the pneumothorax, and that a chest xray should be obtained immediately prior to travel to confirm resolution.

Bottom line: Patients can safely travel on commercial aircraft 2 weeks after resolution of pneumothorax. Ideally, a chest xray should be obtained shortly before travel to confirm that it is gone. Helicopter travel is okay at any time, since they typically fly at 1,500 feet or less.

References:

  • Practice Guideline, Orlando Regional Medical Center. Air travel following traumatic pneumothorax. October 2009.
  • Medical Guidelines for Airline Travel, 2nd edition. Aerospace Medical Association. Aviation, Space, and Environmental Medicine 74(5) Section II Supplement, May 2003.
General

Dysphagia and Cervical Spine Injury

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Cervical spine injury presents a host of problems, but one of the least appreciated ones is dysphagia. Many clinicians don’t even think of it, but it is a relatively common problem, especially in the elderly. Swallowing difficulties may arise for several reasons:

  • Prevertebral soft tissue swelling may occur with high cervical spine injuries, leading to changes in the architecture of the posterior pharynx
  • Rigid cervical collars, such as the Miami J and Aspen, and halo vests all force the neck into a neutral position. Elderly patients may have a natural kyphosis, and this change in positioning may interfere with swallowing. Try extending your neck by about 30 degrees and see how much more difficult it is to swallow.
  • Patients with cervical fractures more commonly need a tracheostomy for ventilatory support and/or have a head injury, and these are well known culprits in dysphagia

Normal soft tissue (<6mm at C2, <22mm at C6)

A study in the Jan 2011 Journal of Trauma outlined the dysphagia problem seen with placement of a halo vest. They studied a series of 79 of their patients who were treated with a halo. A full 66% had problems with their swallowing evaluation. This problem was associated with a significantly longer ICU stay and a somewhat longer overall hospital stay.

Bottom line: Suspect dysphagia in all patients with cervical fractures, especially the elderly. We don’t use halo vests very often any more, but cervical collars can exacerbate the problem by keeping the neck in an unaccustomed position. Carry out a formal swallowing evaluation, and adjust the collar (or halo) if appropriate.

Reference: Swallowing dysfunction in trauma patients with cervical spine fractures treated with halo-vest fixation. J Trauma 70(1):46-50, 2011.

General

What Percent Pneumothorax Is It?

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Frequently, radiologists and trauma professionals are coerced into describing the size of a pneumothorax seen on chest xray in percentage terms. They may something like “the patient has a 30% pneumothorax.”

The truth is that one cannot estimate a 3D volume based on a 2D study like a conventional chest xray. Everyone has seen the patient who has no or a minimal pneumothorax on a supine chest xray, only to discover one of significant size with CT scan.

Very few centers have the software that can determine the percentage of chest volume taken up with air. There are only two percentages that can be determined by viewing a regular chest xray: 0% and 100%. Obviously, 0% means no visible pneumothorax, and 100% means complete collapse. Even 100% doesn’t really look like 100% because the completely collapsed lung takes up some space. See the xray at the top for a 100% pneumothorax.

If you line up 10 trauma professionals and show them a chest xray with a pneumothorax, you will get 10 different estimates of their size. And there aren’t any guidelines as to what size demands chest tube insertion and what size can be watched.

The solution is to be as quantitative as possible. Describe the pneumothorax in terms of the maximum distance the edge of the lung is from the inside of the chest wall, and which intercostal space the pneumothorax extends to. So instead of saying “the patient has a 25% pneumo,” say “the pneumothorax is 1 cm wide and extends from the apex to the fifth intercostal space on an upright film.”

General

EAST 2016: Pain And Tourniquet Efficacy

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Ischemia hurts. And tourniquets induce ischemia
on purpose. So logically, tourniquet application should hurt. In a hospital
setting, Doppler ultrasound is used to confirm loss of arterial inflow to the
extremity. In the field, the usual end point is cessation of bleeding. The idea
is to stop tightening the moment that bleeding stops. Unfortunately, this is
not very exact. So the next question is, can pain after tourniquet application
be used to predict how well it is working?

The group at Cook County in Chicago measured
pressures, arterial occlusion, and pain in various extremities in a group of
healthy volunteers (!!). Fortunately for them, complete occlusion was only
maintained for a minute.

Here are the factoids:

  • Three tourniquet systems were used: an
    in-hospital pneumatic tourniquet, the CAT™, and the SWAT™
  • Readings were taken on left and right upper
    arms, the forearms, legs, and the right thigh
  • Using a pain scale of 0-10, tourniquet
    application did not generally induce severe pain
  • Pain scores were 1-3 in the upper arms and forearms,
    3-4 in the thigh, and 2-3 in the leg

Bottom
line: Strangely enough, tourniquet application did not produce severe pain in
any of the subjects. Thigh application tended to be more painful. But,
generally speaking, pain cannot be used as an indicator of effective
application. In the field, cessation of bleeding is the best indicator. And in
the hospital, Doppler ultrasound confirmation should be the standard. In any
case, if the patient is experiencing undue pain after application, check the tourniquet and its positioning.
Something else might be wrong!

Reference:
Pain is an accurate predictor of tourniquet efficacy. EAST 2016 Poster abstract
#23.