# 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.

# Can Prehospital Providers Accurately Estimate Blood Loss?

EMS providers are the trauma professional’s eyes and ears when providing transportation from the scene of an accident. We rely on their assessment of the mechanism of injury and the amount of blood lost. We tend to believe in the accuracy of those assessments.

A study was carried out that tested EMS personnel on their ability to accurately estimate specific amounts of blood that were left at a simulated accident scene. The blood volumes tested were 500cc, 1000cc, 1500cc and 2100cc. A total of 92 professionals participated, and there was an even split into basic EMTs (34%), intermediate/critical care EMTs (33%) and paramedics (31%). Experience levels were as follows: 0-5 years 43%, 6-10 years 30%, >10 years 31%.

The results were as follows:

• 87% underestimated the quantity of blood
• 9% overestimated
• 4% guessed the exact amount
• Experience or credentialing level did not matter

Only 8% of the subjects were within 20% of the actual volume, and an additional 19% were within 50%. In general, most medics underestimated the amount of blood lost, and their guesses were worse with higher volumes. The median guess for the 2100cc loss group was only 700cc!

Bottom line: Visual estimates of blood loss are extremely inaccurate, and are most likely  underestimates. Physicians in the ED should rely on exam and physiology to help determine the amount of blood loss. For safe measure, multiply the reported blood loss of the EMT or paramedic by 2 or 3 to get a realistic number.

Reference: Patton et al. Accuracy of Estimation of External Blood Loss by EMS Personnel. J Trauma 50(5), 914, 2001.

# 5 Guidelines For Diaphragmatic Injury

Today’s post is another review of some of the practice guidelines published by the Eastern Association for the Surgery of Trauma (EAST).  This one covers the evaluation and management of diaphragmatic injury.

Diaphragm injury is a troublesome one to diagnose. It is essentially an elliptical sheet of muscle that is doubly-curved, so it does not lend itself well to diagnosis by axial imaging. Addition of sagittal and coronal reconstructions to a thoraco-abdominal CT has been helpful, but still has a far from perfect diagnostic record.

From an evaluation standpoint, there are several possibilities:

• Observation – not generally recommended. It is usually combined with imaging such as chest x-ray to see if interval changes occur that would indicate the injury.
• Chest x-ray – this is not often diagnostic, but when herniation of abdominal contents is obvious the patient most assuredly has an operative problem.
• Thoraco-abdominal CT scan – this technology keeps getting better, especially with thinner cuts and different planes of reconstruction. Sometimes even subtle injuries can be detected. But this exam is still imperfect.
• Laparoscopy or thoracoscopy – this technique yields excellent accuracy when the injury is in an area that can be viewed from the operative entry point chosen.
• Laparotomy or thoracotomy – this is the ultimate choice and should be nearly 100% accurate. It is almost the most invasive and has more potential associated complications.

EAST reviewed a large body of literature and selected 56 pertinent papers for their quality and design. They critically reviewed them and applied a standard methodology to answer several questions.

Here are the questions with the recommendations from EAST, along with my comments:

• Should laparoscopy or CT be used to evaluate left-sided thoraco-abdominal stab wounds? First, these patients must be hemodynamically stable and not have peritonitis. If either is present, there is no further need for diagnosis; a therapeutic procedure must be performed.
Left sided diaphragm injuries from stabs are evil. The hole is small, and since the pressure within the abdomen is greater that the chest, things always try to wiggle their way through this small hole. It can remain asymptomatic if the wiggler is just a piece of fat, but can be catastrophic if a bit of the stomach or colon pushes through and becomes strangulated. Furthermore, these holes enlarge over time, so more and more stuff can push up into the chest.
EAST recommends the use of laparoscopy for evaluation to decrease the incidence of missed injury. However, if the injury is in a less accessible location (posterior), the patient has body habitus issues, or adhesions from previous surgery may lead to incomplete evaluation, laparotomy should be strongly considered.
• Should operative or nonoperative management be used to evaluate right-sided thoraco-abdominal penetrating wounds? Note that this is different than the last question. All penetrating injuries are included (stabs and gunshots), and this one is for management, not evaluation. And the same caveats regarding hemodynamic stability and peritonitis apply. It applies to both stabs and gunshots.
Unlike left-sided injuries, right-sided ones are much more benign. The liver keeps anything from pushing up through small holes, and they do not tend to enlarge over time due to this protection. For that reason, EAST recommends nonoperative management to reduce mortality and morbidity related to operation.
• Should stable patients with acute diaphragm injury undergo repair via an abdominal or thoracic approach? This question applies to any diaphragm injury that requires operation, such as right-sided penetrating injury or any blunt injury. EAST recommends an approach from the abdomen to reduce morbidity and mortality. Since abdominal injury frequently occurs in these cases, an approach from the chest limits the ability to identify and repair abdominal injuries. Otherwise, you may find yourself doing a laparotomy in addition to the thoracotomy.
• Should patients with delayed visceral herniation through a diaphragm injury undergo repair via an abdominal or thoracic approach?  For years, the preferred approach for delayed presentations has been through the chest because the injury is easier to appreciate and repair.  However, if ischemic or gangrenous viscera are present, it will be more difficult to manage and repair from the chest. EAST does not make a specific recommendation for this question and suggests the surgical approach be determined on a case by case basis.
• Should patients with an acute diaphragm injury from penetrating injury without concern for other intra-abdominal injuries undergo open or laparoscopic repair? The quality and quantity of data addressing this question were very low, but EAST recommends laparoscopy for repair of these injuries to reduce morbidity and mortality. This includes blunt injuries, which tend to be larger. There were some conversions to an open procedure, especially in the blunt cases. The usual caveats on exposure, injury location, body habitus and previous surgery apply.

Reference: Evaluation and management of traumatic diaphragmatic injuries: A Practice Management Guideline from the Eastern Association for the Surgery of Trauma. J Trauma 85(1):198-207.

# 4 Guidelines For the Management Of Bladder Injury

The Eastern Association for the Surgery of Trauma (EAST) has been at the forefront of trauma practice guideline dissemination for decades. They recently published a set of recommendations for managing patients with bladder injury. These injuries are not commonly encountered by trauma professionals, and I thought a refresher on current thinking on their management was in order.

Using the usual methodology, the trauma literature was scanned for papers dealing with this topic. After screening for quality, the field was narrowed to 17 papers which were used to formulate the published recommendations. These cover imaging and management questions that frequently come up during the evaluation of these patients.

Following are the questions raised, the EAST recommendations, and my commentary about them:

• In patients with intraperitoneal bladder rupture from blunt trauma, should operative or nonoperative management be used to decrease complications? Another silly question? In general, intraperitoneal bladder ruptures do not heal on their own, so urine continues to bathe the peritoneal cavity until the injury is fixed. The review article recommended that operative repair be performed in all of these cases.
• In patients with extraperitoneal bladder rupture from blunt trauma, should operative or nonoperative management be used to decrease complications? Patients with a simple extraperitoneal bladder injury should undergo nonoperative management. These injuries usually heal and seal within about 10 days. However, patients with this type of bladder injury that is more complicated (bone spicules piercing the bladder, concomitant vaginal or rectal injury, bladder neck injury) should undergo operative repair in order to decrease the complication rate. One additional group that should be repaired: patients with pubic diastasis that will require operative fixation. The bladder should be repaired at the time of the orthopedic procedure to avoid bathing the new hardware in urine.
• In patients who have undergone operative or nonoperative management of bladder injury, should bladder closure be assessed with cystogram or not? This one depends on the type and complexity of injury. For simple intraperitoneal bladder injuries that were operatively repaired, no followup cystogram is required. More complex repairs should be evaluated by cystogram before removing the urinary catheter. Finally, simple extraperitoneal injuries should also have a cystogram obtained before removing the catheter. My magic number for obtaining followup studies is 10 days. There is no real science behind this, and no one has systematically looked at 5 vs 7 vs 10 vs 14 days. This one is based only on personal experience.

And by the way, most simple bladder injuries (both intra- and extra-peritoneal) can be easily repaired using two layers by your friendly neighborhood trauma surgeon. More complex injuries are generally best left to the urologist.

Reference: Management of blunt force bladder injuries: A practice management guideline from the Eastern Association for the Surgery of Trauma. J Trauma 86(2):326-336, 2019.

# Coming Soon! New Site For Trauma PI!

One of the most common requests I get is to provide more detailed content on Trauma Performance Improvement! To that end I am putting together a collection of print and video content on a new website that will address the things you really want to hear about but can’t find anywhere else.

Here’s a sample listing of some of the topics that will be covered:

 Writing a good PI plan Loop closure – basic to advanced Involving your TMD PRQ preparation Creating workable practice guidelines Crafting a Massive Transfusion Protocol that works for you How to calculate your optimal number of trauma registrars Preparing for your site survey How to read your TQIP report What is OPPE and how do I do it? Integrating PI with your registry How to interpret the Orange Book

If you want to be one of the first to get access to this content, please fill out the form by clicking here. Your name will be placed on my early bird e-mail list. I’ll provide regular updates on the opening date, and solicit your ideas on specific content you would like to see.

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