All posts by TheTraumaPro

How To Remember Those “Classes of Hemorrhage”

The Advanced Trauma Life Support course lists “classes of hemorrhage”, and various other sources list a similar classification for shock. I’ve not been able to pinpoint where these concepts came from, exactly. But I am sure of one thing: you will be tested on it at some point in your lifetime.

Here’s the table used by the ATLS course:

classes_of_shock

The question you will always be asked is:

What class of hemorrhage (or what % of blood volume loss) is the first to demonstrate systolic hypotension?

This is important because prehospital providers and those in the ED typically rely on systolic blood pressure to figure out if their patient is in trouble.

The answer is Class III, or 30-40%. But how do you remember the damn percentages?

multiscore-maxi1

It’s easy! The numbers are all tennis scores. Here’s how to remember them:

Class I up to 15% Love – 15
Class II 15-30% 15 – 30
Class III 30-40 30 – 40
Class IV >40% Game (almost) over!

Bottom line: Never miss that question again!

Can Prehospital Providers Accurately Estimate Blood Loss? Part 2

I’ve previously written about the difficulties estimating how much blood is on the ground at the trauma scene. In general, EMS providers underestimated blood loss 87% of the time. The experience level of the medic was of no help, and the accuracy actually got worse with larger amounts of blood lost!

A group in Hong Kong developed a color coded chart (nomogram) to assist with estimation of blood loss at the scene. It translated the area of blood on a non-absorbent surface to the volume lost. A convenience study was designed to judge the accuracy that  could be achieved using the nomogram. Sixty one providers were selected, and estimated the size of four pools of blood, both before and after a 2 minute training session on the nomogram.

Here’s what it looks like:

Note the areas across the bottom. In addition to colored square areas, the orange block is a quick estimate of the size of a piece of paper (A4 size since they’re in Hong Kong!)

Here are the factoids:

  • The 61 subjects had an average of 3 years of experience
  • Four scenarios were presented to each: 180ml, 470ml, 940ml, and 1550ml. These did not correspond exactly to any of the color blocks.
  • Before nomogram use, underestimation of blood loss increased as the pool of blood was larger, similar to the previous study
  • There was a significant increase in accuracy for all 4 scenarios using the nomogram, and underestimation was significantly better for all but the 940ml group
  • Median percentage of error was 43% before nomogram training, vs only 23% after. This was highly significant.

Bottom line: This is a really cool idea, and can make estimation of field blood loss more accurate. All the medic needs to do is know the length of their shoe and the width of their hand in cm. They can then estimate the length and width of the pool of blood and refer to the chart . Extrapolation between colors is very simple, just look at the line. The only drawback I can see occurs when the blood is on an irregular or more absorbent surface (grass, inside of a car). 

Related posts:

Reference:  Improvement of blood loss volume estimation by paramedics using a pictorial nomogram: a developmental study. Injury article in press Oct 2017.

What Is: Bucket Handle Injury Of The Intestine

A bucket handle injury is a type of mesenteric injury of the intestine. The intestine itself separates from the mesentery, leaving a devascularized segment of bowel that looks like the handle on a bucket (get it?).

These injuries can occur after blunt trauma to the abdomen. The force required is rather extreme, so the usual mechanism is motor vehicle crash. In theory, it could occur after a fall from a significant height, and I have seen one case from a wood fragment that was hurled at the abdomen by a malfunctioning lathe.

The mechanics of this injury are related to fixed vs mobile structures in the abdomen. Injuries tend to occur adjacent to areas of the intestine that are fixed, such as the cecum, ligament of Treitz, colonic flexures and rectum. During sudden deceleration, portions of the intestine adjacent to these areas continue to move, pulling on the nearby attachments. This causes the intestine itself to pull off of its mesentery.

Source: personal archive. Not treated at Regions Hospital

The picture above shows multiple bucket handle injuries in one patient. There are 3 injuries in the small bowel, and one involving the entire transverse colon. Note the obviously devascularized segment at the bottom center of the photo.

The terminal ileum is the most common site for bucket handle tears. Proximal jejunum, transverse colon, and sigmoid colon are other possible areas. In my experience, the driver is more likely to sustain an injury to the terminal ileum, and the front passenger to the sigmoid. I think this is due to the location of the buckle, but it’s just my own observation.

Always think about the possibility of this injury in patients with very high speed decelerationSeat belt marks have a particularly high association with this injury. If your patient has an abnormal exam in the right lower quadrant, or if the CT shows unusual changes there (“dirty” mesenteric fat, thickened bowel wall, extravasation), I recommend a trip to the OR. In these cases, an injury will nearly always be present. And since the affected intestine may take a few days to die and leak, look for an unexplained rise in WBC beginning on hospital day 2.

Related posts:

Stuff You Sterilize Other Stuff With May Not Be Sterile??

When one works in the trauma field, or medicine in general, we deal with the need for sterility all the time. We use equipment and devices that are sterile, and we administer drugs and fluids that are sterile. In surgery, we create sterile fields in which to use this sterile stuff.

In the past few years, we’ve come to the realization that the sterility we take for granted may not always be the case. There have been several cases of contaminated implanted hardware. And a few years ago, supposedly sterile injectable steroids were found to be contaminated with fungus, leading to several fatal cases of meningitis.

An article in the New England Journal of Medicine brings a bizarre problem to light: microbial stowaways in the topical products we use to sterilize things. Most drugs and infused fluids are prepared under sterile conditions. However, due to the antimicrobial activity of topical antiseptics, there is no requirement in the US that they be prepared in this way.

A number of cases of contamination have been reported over the years:

  • Iodophor – contamination with Buckholderia and Pseudomonas occurred during manufacture, leading to dialysis catheter infection and peritonitis
  • Chlorhexidine – contaminated with Serratia, Buckholderia and Ralstonia by end users, leading to wound infections, catheter infections, and death
  • Benzalkonium chloride – contaminated with Buckholderia and Mycobacteria by end users, causing septic arthritis and injection site infections

Bottom line: Nothing is sacred! This problem is scarier than you think, because our most basic assumptions about these products makes it nearly impossible for us to consider them when tracking down infection sources. Furthermore, they are so uncommon that they frequently may go undetected. The one telltale sign is the presence of infection from weird bacteria. If you encounter these bugs, consider this uncommon cause. Regulatory agencies need to get on this and mandate better manufacturing practices for topical antiseptics.

Reference: Microbial stowaways in topical antiseptic products. NEJM 367:2170-2173, Dec 6 2012.

How Long Does It Take EMS To Respond?

How long does it take for EMS to get to the scene of an emergency? That’s a loaded question, because there are many, many factors that can impact this timing. If you look at the existing literature, there are few, if any, articles that have actually looked at this successfully.

A group from Aurora, IL and Wake Forest reviewed EMS records from across the country, spanning 485 agencies over a one year period. Only 911 responses were reviewed, and outliers with arrival times of more than 2 hours and transport times of 3 hours were excluded. Over 1.7 million records were analyzed, and 625 were excluded for this reason.

Here are the factoids:

  • In 71% of cases, the patient was transported to a hospital. In one quarter of cases, they were evaluated but not transported. 1% were dead on arrival, and in 2% no patient was found at the scene (!)
  • 4% of patients were transported in rural zip codes, 88% in suburban ones, and 8% from urban locations
  • Overall response time averaged 7 minutes
  • Median response times were 13 minutes for rural locations, and 6 minutes for both suburban and urban locations
  • Nearly 1 in 10 patients waited 30 minutes for EMS response in rural locations

Bottom line: There is an obvious difference in EMS response times between rural and urban/suburban locations. And there are many potential reasons for this, including a larger geographic area to be covered, volunteer vs paid squads, etc. Many of these factors are difficult, if not impossible to change. The simple fact that it takes longer to reach these patients increases their potential morbidity and mortality. Remember, time is of the essence in trauma. The patient is bleeding to death until proven otherwise. It is far easier and cost-effective to equip bystanders with the skills to assist those in need (basic first aid, CPR, Stop the Bleed, etc) while waiting for EMS to arrive.