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How To Read A Stab Wound

Most emergency departments do not see much penetrating trauma. But it is helpful to be able to learn as much as possible from the appearance of these piercing injuries when you do see them. This post will describe the basics of reading stab wounds.

Important: This information will allow some basic interpretation of wounds. It will not qualify you as a forensics expert by any means. I do not recommend that you document any of this information in the medical record unless you have specific forensic training. You should only write things like “a wound was noted in the midepigastrium that is 2 cm in length.” Your note can and will be used in a court of law, and if you are wrong there can be significant consequences for the plaintiff or the defendant. This information is for your edification only.

1. What is the length of the wound? This does not necessarily correspond to the width of the blade. Skin stretches as it is cut, so the wound will usually retract to a length that is shorter than the full width of the blade.

2. Is the item sharp on one side or both? This can usually be determined by the appearance of the wound. A linear wound with two sharp ends is generally a two sided knife. A wound with one flat end and one sharp end is usually from a one-sided weapon. The picture below shows a knife wound with one sharp side.

3. Is there a hilt mark? This can usually be detected by looking for bruising around the wound. The picture below shows a knife wound with a hilt mark.

4. What is the angle? If both edges are symmetric, the knife went straight in. If one surface has a tangential appearance, then the knife was angled toward that side. You can approximate the direction of entry by looking at the tangential surface of the wound edge. In this example, the blade is angling upward toward the right.

5. How deep did it go? You have no way of knowing unless you have the blood stained blade in your possession. And yes, it is possible for the wound to go deeper than the length of the knife, since the abdominal wall or other soft tissues can be pushed inwards during the stab.

Why Did The Trauma Team Cut Off My Clothes?

The fifth highest priority taught in the ATLS course is exposure. This generally means getting the patient’s clothes off so any hidden injuries can be identified. Early in my career, I was called to see a patient who had a gunshot to the chest that had been missed because the consulting physician had neglected to cut off her bra. A small caliber wound was found under the elastic strap in her left anterior axillary line after a chest xray showed a bullet in mid-thorax.

The usual trauma activation routine is to cut off the clothes. There are several tips and tricks we use to do this quickly. And a number of commercial products are out there to make it even easier.

But do we really need to cut everyone’s clothes off? I’m not disputing the fact that it’s important to be able to examine every square inch. But do we need to destroy everything our patient is wearing? I once saw a sequined wedding dress cut off (it’s almost as bad as cutting off a down jacket).

The answer is no. The key concept here is patient safety. Can you safely remove the clothing in a less destructive way? For most victims of major blunt trauma, we worry a lot about the spine. Unfortunately, it’s just not possible to allow the patient to wriggle out of their clothes and protect their spine. The same goes for fractures; it may be too uncomfortable to remove clothing because of fracture movement so scissors are required.

Penetrating trauma is a bit different, and in many cases it’s a good idea to try to get the clothing off intact. Once again, if spinal injury is a consideration (gunshots only), the involved clothes should be cut off. A patient with a gunshot to the chest can probably have their pants safely and gently pulled off, but their shirt and coat must be cut.

The police forensic investigators like to have intact clothing, if possible. This is another good reason to try to remove clothing from penetrating injury victims without cutting.

Bottom line: Think before you cut clothes! Major blunt trauma and bad injuries require scissors. Lesser energy blunt injury may allow some pieces of clothing to be removed in the usual method. Most penetrating injury does not require cutting. But if you must (for patient safety), avoid any holes in the fabric so forensics experts can do their job.

How Good Is The Spine Exam In Penetrating Injury?

Examination of the spine in trauma patients is typically not very helpful. We always look for stepoffs. swelling and tenderness, but the correlation with actual injury is poor. A recent paper presented at the American Medical Student Association Annual Convention showed that it actually can be helpful in victims of penetrating injury.

A prospective study of 282 patients was carried out at a Level I Trauma Center, specifically focusing on penetrating trauma. Half had gunshot wounds, and 8% sustained spinal injury with one third left with permanent disability. Stab wounds never led to a spinal cord injury. The most common patterns for cord injury in gunshot wounds was a single shot to the head or neck, or multiple shots to the torso.

The examiners looked for pain, tenderness, deformity and neurologic deficit. They found that the sensitivity was 67%, the specificity was 90%, the positive predictive value was 95% and the negative predictive value was 46%. These numbers are much better than those found during spine examination after blunt trauma. They also determined that prehospital immobilization after penetrating injury would not have helped, which I have also written about here.

Bottom line: A good spine exam in victims of penetrating trauma can accelerate definitive management prior to defining the exact details of the injury with radiographic or MRI imaging. This is particularly helpful in patients who present to non-trauma centers, where imaging or image interpretation may not be readily available.

Reference: American Medical Student Association (AMSA) 60th Annual Convention: Abstract 26: Presented March 11, 2010

Gunshots And CT Scan Of The Abdomen

Abdominal gunshots and CT scanning are usually thought to be mutually exclusive. The usual algorithm generally means a prompt trip to the operating room. But as with many things in the management of trauma, there are always exceptions. The key is to understand when exactly one of those exceptions is warranted.

Exception 1: Did it really enter the abdomen? Gunshots have enough energy that they usually do get inside. However, freaky combinations of trajectory and body habitus do occur. There are three tests that must be passed in order to entertain the possibility that the bullet may not have made it inside your patient: physiology, anatomy, and physical exam. For physiology, the patient must be completely hemodynamically stable. Anatomically, the trajectory must make sense. If the known wounds and angles allow a tangential course make sense, then fine. But if there is a hole in the epigastrium and another next to the spine, you have to assume the bullet went straight through. Finally, the physical exam must be normal. No peritonitis. No generalized guarding. Focal tenderness only in the immediate area of any wounds. If all three of these criteria are passed, then a CT can be obtained to demonstrate the trajectory.

Exception 2: Did it enter an unimportant area of the abdomen? Well, there’s really only one of these, and that’s the area involving the right lobe of the liver and extending posteriorly and lateral to it. If the bullet hole(s) involve only this area, and the three tests above are passed, CT may confirm an injury that can be observed. However, there should only be a minimal amount of free fluid, and no soft tissue changes of any kind adjacent to bowel.

Exception 3: A prompt trauma lap was performed, but you think you need more information afterwards. This is rare. The usual belief is that the eyes of the surgeon provide the gold standard evaluation during a trauma lap. For most low velocity injuries with an easily understood trajectory, this is probably true. However, high velocity injuries, those involving multiple projectiles, or complicated trajectories (side to side) can be challenging for even the most experienced surgeon. Some areas (think retroperitoneum or deep in the pelvis) are tough to visualize completely, especially when there’s blood everywhere. These are also the cases most likely to require damage control surgery, so once the patient has been temporarily closed, warmed and resuscitated, a quick trip to CT may be helful in revealing unexpected shrapnel, unsuspected injuries, or other issues that may change your management. Even a completely unsurprising scan can provide a higher sense of security.

Bottom line: CT of the abdomen and gunshots to that area may actually coexist in some special cases. Make sure the physiology, anatomy and physical exam criteria are passed first. I also make a point of announcing to all trainees that taking these patients to CT is not the norm, and carefully explain the rationale. Finally, apply the concept of the null hypothesis to this situation. Your null hypothesis should state that your patient does not need a CT after gunshot to the abdomen, and you have to work to prove otherwise!

How To: Secure An Endotracheal Tube To… Nothing!

Several decades ago I took care of a patient who posed an interesting challenge. He had been involved in an industrial explosion and had sustained severe trauma to his face. Although he was able to speak and breathe, he had a moderate amount of bleeding and was having some trouble keeping his airway clear.

Everyone frets about getting an airway in patients who have severe facial trauma. However, I find it’s usually easier because the bones and soft tissue move out of your way. That is, as long as you can keep ahead of the bleeding to see your landmarks.

In this case, the intubation was easy. The epiglottis was visible while standing above the patient’s head, so a laryngoscope was practically unnecessary! But now, how do we secure the tube so it won’t fall out? Sure, there are tube-tamer type securing devices available, but what if they are not available to you? Or this happened in the field? Or it was in the 1980’s and it hadn’t been invented, like this case?

The answer is, create your own “skin” to secure the tube to. Take a Kerlix-type stretchable gauze roll and wrap it tightly around their head. Remember, they are sedated already and they can breathe through the tube. This also serves to further slow any bleeding from soft tissue. Once you have “mummified” the head with the gauze roll, tape the tube in place like you normally would, using the surface of the gauze as the “skin.”

Be generous with the tape, because the tube is your patient’s life-line. Now it’s time for the surgeons to surgically stabilize this airway, usually by converting to a tracheostomy.

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