Tag Archives: Penetrating trauma

How To Evaluate A Stab To The Diaphragm – Part 1

Penetrating injury to the diaphragm, and specifically stab wounds, have been notoriously hard to diagnose since just about forever. Way back in the day (before CT), we tried all kinds of interesting things to help figure out if the patient had a real injury. Of course, we could just go to the OR and lap the patient (laparoscopy did not exist then). But the negative lap rate was significant, so we tried a host of less invasive techniques. 

Remember diagnostic peritoneal lavage? Yeah, we tried that. The problem was that the threshold for red cells per cubic mm was not well defined. Some would supplement this technique with a chest tube to see if lavage fluid would drain out. And one paper described instilling nuclear medicine tracer into the abdomen and sitting the patient under a gamma camera for a few hours to see if any ended up in the chest. Groan!

We thought that CT would save us. Unfortunately, resolution was terrible in the early years. If you could actually see the injury on CT, it was probably because a large piece of stomach or colon had already fallen through it. But as detectors multiplied and resolution improved, we could begin to see some smaller defects. But we still missed a few. And the problem is that left-sided diaphragmatic holes slowly enlarge over time (years), until the stomach or colon falls through it. (See below)

A group of radiologists and surgeons in a Turkish trauma hospital recently published a modest series of patients with left-sided diaphragm injuries evaluated by CT. They looked at about 5 years of their experience in a group of patient who were at risk for the injury due to a thoraco-abdominal stab wound. Unstable patients were immediately taken to OR. All of the remaining patients underwent an initial CT scan, followed by diagnostic laparoscopy after 48 hours if they remained symptom free.

Here are the factoids:

  • A total of 43 stable patients with a left thoraco-abdominal stab were evaluated
  • 30 patients had a normal CT, and 13 had the appearance of an injury
  • Of those who were CT positive, only 9 of 13 (69%) actually had the injury at operation
  • Two of the 30 (7%) who were CT negative were found to have a diaphragm injury during followup laparoscopy
  • So in the author’s hands, there was 82% sensitivity, 88% specificity, a positive predictive value of only  69%, and a negative predictive value of 93%

Bottom line: The authors somehow looked at the numbers and concluded that CT is valuable for detecting left diaphragm injury. Huh? They missed 7% of injuries, only finding them later at laparoscopy. And they had a 31% negative laparotomy rate. 

Now, it could be that the authors were using crappy equipment. Nowhere in their paper do they state how many detectors, or what technique was used. Since it took place over a 5 year period, it is quite possible that the earlier years of the study used equipment now considered to be out of date, or that there was no standardized technique.

CT may not yet be ready for prime time. But it can be a valuable tool. Tune in tomorrow for some tips on how and when to look for this insidious injury.

Related post:

Reference: Evaluation of diaphragm in penetrating left thoracoabdominal
stab injuries: The role of multislice computed tomography. Injury 46:1734-1737, 2015.

What Is: An “Egg Timer Injury”?

Most patients with major traumatic injuries are handled in a very systematic way by both EMS and trauma centers. We have routines and protocols designed to provide rapid, quality care to these individuals. But over the years, I’ve begun to appreciate the fact that there is a very small subset of these patients who are different.

I term these patients as having an “egg timer injury”. These are patients who have only a certain number of minutes to live. This fact requires us to change the usual way we do things in order to save their lives or limbs. The usual routine may be too slow.

And unfortunately, no one can tell us exactly how many minutes are left on the timer. We only know that it’s ticking. Here are some examples of such  injuries:

  • Pericardial tamponade
  • Penetrating injury to the torso with profound hypotension
  • Orbital compartment syndrome

In each case, speed is of the essence. What can we do to decrease the time to definitive intervention? For prehospital providers, you may need to bypass a closer hospital that might not have the necessary resources at a particular time of day. Once at the hospital, the patient may need to bypass the emergency department and proceed straight to the OR. Or you may need to do a lateral canthotomy yourself, rather than waiting for an ophthalmologist to drive in only to have the patient lose their vision because of the  delay.

Bottom line: Remember that protocols are not necessarily etched in stone. They will cover 99.9% of cases you see. But that remaining 0.1%, the patients with the “egg timer injury”, will require you to think through what you know about the patient at the time, and make decisions about their care that may have a huge outcome on their life or livelihood. And as always, if you find that you must do things differently in the best interest of your patient, be sure to document what you knew and your thought processes thoroughly so you explain and/or justify your decision-making when you are invariably asked.

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!

Managing Penetrating Injuries: Some Practical Tips

Although penetrating injuries are a relatively uncommon mechanism at most trauma centers, they are more likely than not to injure deeper structures. Key decisions need to be made quickly during the initial evaluation in order to provide the best care.

Here are some practical tips:

  • Penetrating injuries to just about anything but the extremities should activate your trauma team.
  • If your patient is hypotensive, they will need to go to the OR. You can certainly start infusing some fluid or blood, but a lot leaked out before they got to you, indicating that the leak needs to be surgically fixed. No exceptions.
  • All hypotensive patients require activation of your massive transfusion protocol and consideration of giving tranexamic acid (TXA).
  • If your patient is normotensive, you have the luxury of evaluating them more thoroughly. But don’t lose your sense of urgency. Assume they are dying until you prove otherwise.
  • Complete your secondary survey. Don’t skimp on the exam and always look at the back. If your patient ends up on an OR table, it may be the only time you get to look at it for quite some time.
  • Get a single x-ray of the affected area, even if you need to go to the OR quickly. This can help plan your operation, and may drive you to explore areas you had not considered.
  • Before shooting the x-ray, mark any and all entry and exit points. This will help to predict the trajectory and any injured structures.
  • Use small markers, but not too small. Most radiology departments have small arrows, which are ideal. Dots are too small and may not show up well on plain images. But be aware that some markers may be too dense for CT, causing artifacts that may obscure pathology.
  • Watch out for your own safety! Somebody was trying to kill your patient, and they may show up at your hospital to try to finish the job. Make sure your ED and inpatient areas take appropriate security precautions.

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.