MTP Activation Criteria For Pediatric Patients

Early resuscitation, particularly with blood products in patients with hemorrhage, is literally a lifesaver.  As each minute ticks by, survival slowly diminishes. To facilitate this, massive transfusion protocols (MTP) have been designed to rapidly deliver sizable quantities of blood products to the trauma resuscitation bay.

One of the recurring issues I see at trauma centers is the lack of a reliable way of activating the MTP. Many centers publish what I consider “psychic criteria.” These promote criteria that involve the amount of blood loss over four or twenty-four hours. Who even knows?

Delays in activating the MTP frequently occur because no one thinks about it when a critically injured patient arrives. All of the trauma professionals are busy with the patient and are rudely surprised when they ask for the first unit of blood.

Objective MTP activation criteria have been developed and are well-supported by the literature. The ABC score and the shock index are two of the more common methods. Both are based on observations made upon patient arrival (and possibly before if a prehospital report is received).

The ABC score uses four criteria:

  • Heart rate > 120
  • Systolic blood pressure < 90
  • FAST positive
  • Penetrating mechanism

If any two of these are present, there is a 50% chance that massive transfusion is warranted.

The Shock Index (SI) uses the initial vital signs to perform a quick and dirty calculation by dividing the heart rate by the systolic blood pressure.  A score greater than or equal to one predicts at least a 2x higher need for blood. Of the two, SI is more easily calculated and gives a marginally more accurate result.

But what about children? The ABC score was evaluated in pediatric patients and was found to be much less sensitive than in adults. Combining the ABC score with an age-adjusted Shock Index improved the accuracy only slightly. This was named the ABC-S score.

Several adult and pediatric trauma centers in the Denver area collaborated to test a new score using the ABC-S score in combination with serum lactate and base deficit. This was termed the ABC-D score. Clever.

Here are the factoids:

  • A retrospective review of patients aged 1-18 from a single trauma registry who had received a blood transfusion during their initial care
  • The study included 211 children, of whom 66 required massive transfusion
  • The three methods listed above were compared, and the ABC-D score was found to be the most predictive of MTP
  • ABC-D was 77% sensitive and 79% specific
  • The authors showed that the accuracy and balance between sensitivity and specificity improved for each point increase in the ABC-D score.
  • They concluded that ABC-D may be a useful tool to expedite the delivery of blood products during a trauma resuscitation.

Bottom line: Hmm. The system that they developed and the analysis of their experience appears to be sound. But unfortunately, it fails the practicality test. Here’s the sticking point. How long does it take to obtain that initial blood specimen, send it to your lab, and then return stat results to your trauma bay? Once you receive the results, you then activate the MTP and wait another 5-10 minutes for the first cooler to arrive!

That’s an awful long time to wait for blood while you watch a child hemorrhaging in front of you. So what to do? For now, use one of the existing systems to make a rapid decision. And always err on the side of activation. You can always send the blood back if you don’t need it!

Reference:  The ABC-D score improves the sensitivity in predicting need for massive transfusion in pediatric trauma patients. J Pediatr Surg. 2020 Feb;55(2):331-334. doi: 10.1016/j.jpedsurg.2019.10.008. Epub 2019 Nov 1. PMID: 31718872.

Updated: How To Detect Bucket Handle Injuries With CT

A bucket-handle injury is a relatively uncommon complication of blunt trauma to the abdomen. It only occurs in a few percent of patients, but is much more likely if they have a seat belt sign.  The basic pathology is that the bowel mesentery (small bowel of sigmoid colon) gets pulled away from the intestinal wall.

This injury is problematic because it may take a few days for the bowel itself to die and perforate. Patients with no other injuries could potentially be discharged from the hospital before they become overtly symptomatic, leading to delayed treatment.

Here’s an image from my personal collection with not one, but four bucket-handle injuries.

Typical patients with suspected blunt intestinal injury are observed with good serial exams and a daily WBC count. If this begins to rise after 24 hours, there is a reasonable chance that this injury is present.

CT scan has not really been that reliable in past studies. There may be some “dirty mesentery”, which is contused and has a hematoma within it. But without a more convincing exam, it is difficult to convince yourself to operate immediately on these patients.

A paper was published by a group of radiologists at Duke University. It appears to be a case report disguised as a descriptive paper. It looks like they picked a few known bucket-handle injuries from their institution and back-correlated them with CT findings.

The authors called out the usual culprits:

  • Fluid between loops of bowel
  • Active bleeding in the mesentery
  • Bowel wall perfusion defects

But they also noted that traumatic abdominal wall hernias were highly associated with seat belt sign as well. These are rare, but should bring intestinal injury to mind when seen.

With newer scanners, radiologists are better able to detect subtle areas of hypoperfusion as well. This is a fairly good indicator of injury, especially when adjacent bowel appears normally perfused. Here are two examples. The black arrows denote active extravasation, and the white ones an area of hypoperfusion.

The authors add bowel wall hypoperfusion as another finding that may point to a bucket-handle type injury.

A recent paper demonstrates the value of the current generation of high-quality scanners. A collection of California and Denver centers implemented a multicenter, prospective, observational study of patients with seat belt signs. The developed a list of positive findings, which included:

  • abdominal wall soft tissue contusion (radiographic seat belt sign)
  • free peritoneal fluid
  • bowel wall thickening
  • mesenteric stranding
  • mesenteric hematoma
  • bowel dilation
  • pneumatosis
  • pneumoperitoneum

A total of 754 patients with visible seat belt sign were enrolled and all went to CT scan. Any of the findings listed above were associated with a statistically significant likelihood of hollow viscus injury. The highest likelihood was associated with:

  • free peritoneal fluid – 42x more likely
  • bowel dilation – 21x
  • free fluid with no solid organ injury – 20x
  • bowel wall thickening – 19x
  • radiographic seat belt sign – 3x

Any of the radiographic findings strongly suggested that an injury could be present. However, if none were present, it was very unlikely that there were any significant injuries. The authors suggested that if such patients had no other injuries requiring hospitalization, they could potentially be discharged home. However, those patients should be counseled to return for evaluation immediately if they have any change in their abdominal or systemic status.

Bottom line: Some patients with a visible seat belt sign might be eligible for discharge from the ED if they have a totally negative abdominal CT and no other injuries requiring hospitalization. If they have any finding, they should be admitted for observation.

If your patient has an unconcerning exam and any of the findings listed above, perform serial exams and get a WBC the next morning. If the exam worsens, operate. If the WBC rises, consider laparoscopy to see if you need to make a bigger incision. And if you see any evidence of hypoperfused bowel, consider laparoscopy right away. 

References:

  • Excluding Hollow Viscus Injury for Abdominal Seat Belt Sign Using Computed Tomography. JAMA Surg. 2022 Sep 1;157(9):771-778. doi: 10.1001/jamasurg.2022.2770. PMID: 35830194; PMCID: PMC9280606.
  • CT findings of traumatic bucket-handle mesenteric injuries. Am J Radiol 209:W360-@364, 2017.
  • Multidetector CT of blunt abdominal trauma. Radiology 265(3):678–693, 2012.

Prehospital: What’s The Best Chest Seal For Sucking Chest Wounds?

The treatment of a “sucking chest wound” in the field has typically been with application of some type of occlusive dressing. Many times, a generic adhesive dressing is applied, typically the same kind used to cover IV sites. This is quick, easy, cheap, and readily available in the ambulance. But there is a danger that this could result in development of tension pneumothorax, because the dressing not only keeps air from getting in but also keeps any buildup of pneumothorax from getting out.

To avoid this, a number of vented products have been developed and approved by the US Food and Drug Administration (FDA). These devices have some sort of system to allow drainage of accumulating air or blood, typically a one-way valve or drainage channels. They also need to stick well to a chest wall, which may have blood or other fluids that might disrupt the seal completely.

The US Army has a strong interest in making sure the products they use for this purpose work exactly as promised. The US Army Institute of Surgical Research examined 5 currently FDA-approved products to determine their ability to adhere to bleeding chest wounds, and to drain accumulating air and/or blood from the pleural space. They developed an open chest wound with active bleeding in a swine model.

An open hemopneumothorax was created by infusing air and blood, the animal was stabilized, then additional aliquots of air and blood were infused to simulate ongoing bleeding and air buildup. The image below shows the 5 products used and the animal setup:

Here are the factoids:

  • Creation of the open hemopneumothorax caused the intrapleural pressure to move toward atmospheric pressure as expected, resulting in labored breathing and reduced O2 saturation
  • Sealing the wound with any of the chest seal products corrected all of the problems just noted
  • Chest seals with one way valves did not evacuate blood efficiently (Bolin and SAM). The dressings either detached due to pooled blood, or the vent system clogged from blood clot.
  • Seals with laminar channels for drainage (see the pig picture above) allowed easy escape of blood and air
  • Success rates were 100% for Sentinel and Russell, 67% for HyFin, 25% for SAM, and 0% for Bolin

Bottom line: Prehospital providers need to be familiar with the products they use to cover open chest wounds. Totally occlusive dressings can result in development of a tension pneumothorax if there is an ongoing air leak from the lung. Vented chest seals are preferable for these injuries. Just be aware that vented seals with drainage channels perform much better than those that rely on a one-way valve.

Reference: Do vented chest seals differ in efficacy? An experimental
evaluation using a swine hemopneumothorax model. J Trauma 83(1):182-189, 2017.