Monthly Archives: July 2013

General

The Prehospital “Nonstandard Patient Position” Sign

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Prehospital providers follow protocols for securing and transporting trauma patients. These may include cervical spine stabilization and short or long backboards. Every once in a while they can’t follow protocol, and in my experience it usually means that something is very wrong. 

There are three typical problems leading to nonstandard transport positions:

  • Occult airway injury – These patients have either blunt injury to the neck, smoke inhalation, or penetrating injury to the submandibular area. They tend to have problems protecting their own airway when they are supine, so they insist on being transported in an upright position.
  • Impalement – Since the general rule is to leave foreign objects in place to avoid potential bleeding, the patient is positioned in an odd way to accommodate both them and the impaling object. 
  • Life-threatening bleeding – Patients with exsanguinating hemorrhage who are awake tend to insist on transport in certain positions. Most with serious chest hemorrhage complain that they can’t breathe and want to sit upright. Those with severe pelvic fractures complain of pelvic or back pain and may prefer lying on their side during transport.

Bottom line: If prehospital providers bring a trauma patient to you in a non-supine position, be very afraid. If not done already, activate your trauma team. Talk to the medics to find out why they had to use a nonstandard position. Then rapidly assess the patient to rule out life-threatening issues.


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General

Don’t Get Lateral View Chest Xrays to Diagnose Pneumothorax

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Pneumothorax is typically diagnosed radiographically. Significant pneumothoraces show up on chest xray, and even small ones can be demonstrated with CT.

Typically, a known pneumothorax is followed with serial chest xrays. If patient condition permits, these should be performed using the classic technique (upright, PA, tube 72" away). Unfortunately, physicians are used to ordering the chest xray as a bundle of both the PA and lateral views. 

The lateral chest xray adds absolutely no useful information. The shoulder structures are in the way, and they obstruct a clear view of the lung apices, which is where the money is for detecting a simple pneumothorax. The xray below is of a patient with a small apical pneumothorax. There is no evidence of it on this lateral view.

Bottom line: only order PA views (or AP views in patients who can’t stand up) to follow simple pneumothoraces. Don’t fall into the trap of automatically ordering the lateral view as well!

Lateral chest xray

General

Crowdsourcing Medical Research

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Medical resource is hard to do. It’s tough to come up with an idea no one has explored, design the study, accumulate subjects (for clinical research), analyze it, and then write a good paper. You’re probably familiar with my lamentations over all of the small,retrospective studies that seem to dominate the medical literature.

Crowdsourcing takes advantage of the “human computing power” of ordinary people all around us. Some of you may remember the protein folding computer game that was distributed for free about 10 years ago, allowing everyone to try their hand at designing protein configurations. Turns out, masses of regular people are better than computers for doing this kind of stuff. And the results were impressive. Or look at the power of Amazon’s Mechanical Turk, a crowdsourcing platform for a variety of tasks. Or KickStarter for funding projects that would have a tough time getting money on their own.

Researchers at Penn used crowdsourcing in a study to map the locations of all automated external defibrillators in Philadelphia. They called it the MyHeartMap challenge. The crowd quickly identified and catalogued over 1400 of them. They are now using crowdsourcing to perform literature sources to collect and analyze health-related studies using free medical literature search sites.

The crowd does best on studies involving problem solving, data processing, monitoring and surveying. The downside is that there is built-in variability when using the crowd, which can make it difficult to replicate and confirm validity. But the sheer numbers that can be accumulated are far larger than what can be expected using traditional research methods.

Bottom line: Crowdsourced research has significant potential to accelerate and improve the quality of medical research (and in other fields as well). Anyone engaged in research needs to look at their own projects to determine if any of them can be improved using crowdsourcing. Look at what crowds are good at (solving problems, observing and reporting), and use them to bolster and improve our knowledge base.

Reference: Crowdsourcing – Harnessing the masses to advance health and medicine, a systematic review. J General Int Med DOI: 10.1007/s11606-013-2536-8, 2013.

General

Motorcycle Helmet Type Makes A Difference

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It’s well established that motorcycles helmets make a difference during a crash. EAST has developed an evidence based review that provides recommendations regarding helmet use. Click here to see them. Unfortunately, many states don’t have helmet laws, and several have been persuaded to repeal perfectly good ones.

Although there is strong literature support for helmet use, the specific type of helmet (full-face vs all others) has not been prospectively studied. Helmets that are not full-face (FF) do not cover areas that protect lower parts of the brain and the upper brainstem.

A group in Baltimore did a one year prospective study on the effect of helmet type on craniofacial injury. They treated 176 motorcycle crash victims during that time, and were able to identify the helmet type in 151. A total of 84 wore FF helmets, and 67 wore other types. Here are the interesting findings:

  • Facial fractures occurred in 16% of patients. Only 7% of FF helmeted patients had these fractures vs 27% wearing other helmets.
  • Skull fractures were found in 6%, with only 1% in FF helmet wearers vs 11% in other helmet types
  • Mortality decreased from 7.5% to 4.8% (36% reduction) in the FF helmeted patients (not statistically significant)
  • Cervical spine fractures decreased 20% from 11.9% to 8.5% in the helmeted group (also not significant)

Bottom line: Choosing a motorcycle helmet carefully is important. Remember, motorcyclists are far less protected than automobile drivers. Improving protection has definitively been shown to decrease injuries of nearly all types. Although it certainly is patient choice as to what they wear and if they ride, it can make a big difference to them (and society) if they ignore these recommendations.

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Reference: Choice of motorcycle helmet makes a difference: a prospective observational study. J Trauma 75(1):88-91, 2013.

General

Identifying Bowel and Mesenteric Injury by CT

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CT scan is an invaluable tool for evaluating blunt abdominal trauma. Although it is very good at detecting solid organ injury, it is not so great with intestinal and mesenteric injuries. Older studies have suggested that CT can detect mesenteric injuries if done right, but a newly published study has shown good accuracy with a few imaging tweaks.

A Taiwanese study looked at a series of prospectively studied victims of blunt abdominal trauma. Patients with abdominal pain or a positive FAST were entrolled (total 106). IV contrast was given, and scans during the arterial, portal, and equilibrium contrast phases were performed using a multidetector scanner. Images were read in a blinded fashion.

A total of 13 of 23 patients who underwent laparotomy were found to have a bowel or mesenteric injury. Five had bowel injury, 4 had mesenteric hemorrhage, and 4 had both. Mesenteric contrast extravasation was seen in 7 patients, and this correlated with mesenteric bleeding at laparotomy.

The authors found that the following signs on CT scan indicated injury:

  • Full or partial thickness change in bowel wall appearance
  • Increased mesenteric density
  • Free fluid without solid organ injury

Bottom line: This study shows that CT scan can detect bowel and mesenteric injury reliably if you scan the patient 3 times! This seems like over-radiation and overkill. A more intelligent way to approach this would be to perform a normal trauma abdominal scan. If a suspicious area of mesenteric or bowel thickening is seen, then a limited rescan through the affected area only for equilibrium phase images may be warranted. If actual contrast extrvasation is seen, no further scanning is needed. A quick trip to the OR is in order. And higher risk patients (e.g. seat belt sign) should have a lower threshold for diagnosis!

Reference: Contrast-enhanced multiphasic computed tomography for identifying life-threatening mesenteric hemorrhage and transmural bowel injuries. J Trauma 71(3):543-548, 2011.