Category Archives: General

How To: Flexion / Extension Views of the Cervical Spine

Clearance of the cervical spine can often be done using clinical criteria alone (see this video at http://youtu.be/NhjF9kDOcjE). If this is not possible, a combination of radiologic and clinical evaluation is usually carried out. 

In some cases, radiographic studies (usually CT) are normal, but there is pain on clinical exam. Our next step is to send the patient to xray for flexion and extension views. This exam is performed by removing the collar while the patient is sitting, so the thoracic and lumbar spines must be clear before ordering this. The patient then gently flexes and extends the neck to their limits of comfort. Images are then obtained at the limits of flexion and extension. The premise is that a normal, awake patient cannot and will not move their neck beyond their comfort level to the point where they could cause themselves neurologic injury. 

It is very important that you look at the images yourself. The radiologist may review the images and will report that “there is no evidence of subluxation at the limits of flexion and extension.” But the patient may have barely moved their neck!

The question is: how much flexion and extension do you need to have to clear the spine?

The answer is not easy to find, and is buried in literature from the 1980s and 90s. According to the EAST guidelines, the ideal amount is 30 degrees from neutral for both flexion and extension. This is not always achievable in elderly patients, so in those cases you must use your judgment. Talk to the patient to find out if they stopped moving their neck forward or backward due to pain, or because they just can’t move it that far.

Trouble signs to look for are:

  • Subluxation of more that 2mm at any level
  • Angulation of more than 11 degrees

Any abnormality should prompt a spine consult.

If the study is not abnormal but the amount of flexion and/or extension is not adequate, there are two options. First, just leave the collar in place and try again in a week or so and try again. This will allow any soft tissue injuries to get better and may allow a successful repeat study. The alternative is a more costly and less well-tolerated MRI.

References:

  1. EAST Practice Guidelines, Identifying Cervical Spine Injuries Following Trauma – Update (2000).
  2. Defining radiographic criteria for flexion-extension studies of the cervical spine. Robert Knopp et al. Ann Emerg Med. 2001 Jul;38(1):31-5.
Print Friendly, PDF & Email

Can Fish-Oil Supplements Speed Recovery From TBI?

Overall, omega-3 fatty acids (O3FA) are thought to be an important and beneficial part of our diet. Recently, the Journal of Neurosurgery published an online paper that looked at the potential benefits of fish oil supplementation on recovery from brain injury.

Originally, axonal damage from TBI was thought to occur at the time of impact. Recent research has shown that the injury is really a progressive event that leads to swelling and axon disconnection during the hours to days after the initial injury. Building on a few animal studies over the past 6 years, a project to look at the effect of omega-3 fatty acid supplementation on brain injury was developed.

The authors performed a controlled study in rats, comparing supplementation with 10 or 40 mg/kg/day of O3FA for 30 days after brain injury with no supplementation. After 30 days, the rats were sacrificed and their brains were examined. The investigators found that a chemical marker of axonal injury (beta amyloid precursor protein) was very significantly decreased in the supplemented animals. The decrease was fairly dramatic and was similar for both doses. 

The actual mechanism by which the protective effect of O3FA was not determined in this study. There is speculation that it may be due to stabilization of brain cell membranes and reduction in the number of reactive oxygen molecules.

This research is very intriguing and appears to have been designed and executed well. The only downside to the work is that the senior investigator is the founder and trustee for the Inflammation Research Foundation. The foundation promotes research on the treatment of diseases with nutritional supplements such as fish oil. The Foundation provided the supplements used in this study. Readers must always be careful when interpreting positive data that is funded or supported by an organization that may benefit from positive results. 

Bottom line: Interesting study, and certainly one that should be followed up with human studies. As far as we know, fish oil supplements are relatively safe, so it should be a little easier to move this work along to human studies. It is not sufficient to recommend adding O3FA to the nutritional regimen of head injured patients yet.

Reference: Omega-3 fatty acid supplementation and reduction of traumatic axonal injury in a rodent head injury model Laboratory investigation. Sears et al. J Neurosurg online July 16, 2010.

Print Friendly, PDF & Email

Performance Improvement for FAST

FAST is an integral component of major trauma evaluation. Unfortunately, although lots of people do them, quality control is not very consistent.

Researchers at the University of Pennsylvania studied how the use of a standard checklist and it’s impact on exam quality. Detection of fluid in any of the standard 4 FAST locations was recorded for every exam performed. No attempts were made to grade the amount of fluid seen. The exam was recorded in video format. 

Reviewers credentialed in FAST later reviewed the study videos in a blinded fashion using a checklist. They were also not aware of any CT or OR findings. The checklist contained grading for quality (poor, fair, good), result (positive, negative, unclear), and initial interpretation (positive, negative) for each of the 4 areas scanned. The study was also graded for its educational value. 

A total of 247 studies were reviewed. All study results were compared with CT (240) or OR (7) results. There 235 true negatives, 6 true positives, 4 false positives and 2 false negatives. Sensitivity was 75%, specificity was 98%, and accuracy was 98%.

Overall, 9% of exams were of good quality, 65% were fair, and 26% were poor. Despite this lack of good quality exams, sensitivity, specificity and accuracy adhered to the usual literature standards. The overall quality in both true and false exams were similar. 

Bottom line: This study reveals that we are doing an “okay” job with FAST exams in trauma patients. However, it also shows that there is room for improvement, and that FAST evaluation should be a part of the Performance Improvement program of any trauma centers that use FAST.

Reference: Performance Improvement for FAST Exam. University of Pennsylvania. Presented at the Eastern Association for the Surgery of Trauma meeting, Poster #24, January 2010.

Print Friendly, PDF & Email

Flying After Pneumothorax

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.
Print Friendly, PDF & Email

To Probe or Not To Probe: Penetrating Wounds

There is considerable variability in the way that penetrating wounds are approached. Some are located over areas of lesser importance (distal extremities) or are so superficial that they obviously don’t fully penetrate the skin.

Unfortunately, some involve high-value structures (much of the neck and torso), or are too small to tell if they penetrate (ice pick injury). How should these injuries be approached?

Too often, someone just probes the wound and makes a pronouncement based on that assessment. Unfortunately, there are major problems with this technique:

  • The tract may be too small to appreciate with a finger or even a cotton-tip swab
  • The tract may be oriented in an unexpected direction, or the soft tissues may have moved after the penetration occurred. In this case, the examiner may not appreciate any significant depth to the wound.
  • Inserting an object may violate a structure that you wish it hadn’t (resulting in a hissing sound after probing a chest wound, or a column of blood after probing the neck)

A better way to approach these wounds is as follows:

  • Is the patient unstable? If so, you know the penetration caused the problem and the patient belongs in the OR.
  • Is there other evidence of deep injury, such as peritonitis with a penetrating abdominal wound? If so, the patient still needs to go to the OR.
  • Do a legitimate local wound exploration. This entails making the hole bigger with a knife, and using surgical instruments and your eyes to find the bottom of the tract. Obviously, there are some parts of the body where this cannot be done, such as the face, but they probably don’t need this kind of workup anyway.

As one of my mentors, John Weigelt, used to say, “Doctor, do you have an eye on the end of your finger?” In general, don’t use anything that doesn’t involve an eyeball in your local wound explorations!

Print Friendly, PDF & Email