All posts by TheTraumaPro

The Rise And Fall Of MAST Trousers

Remember MAST Trousers (Military Anti-Shock Trousers)? They were a staple of prehospital care starting in the 1970s and lasting through the turn of the century. But what happened after that? They seem to have disappeared. I recently received a question on the topic recently and wanted to share the real story with you readers.

The basic MAST trouser consists of three inflatable compartments: two legs and one covering the abdomen and pelvis. Each can be inflated or deflated separately. The basic concept was first described by a surgeon who wanted to increase blood pressure during neurosurgical procedures in the early 1900s. The US military embraced the concept during the Vietnam war, using it to augment systolic pressure in servicemen in shock.

Military surgeons migrated this device into civilian prehospital care during the mid-1970s, and the American College of Surgeons Committee on Trauma listed this device as essential on all ambulances in 1977. MAST trousers then came into widespread use throughout the 1980s and 1990s.

Early research in the 1970s suggested that this device could provide up to a 20% boost in volume to the upper part of the body when applied. But as occurs with so many new toys, additional research demonstrated that this auto-transfusion effect was actually only about 5% of blood volume. Some significant complications also came to light as lower extremity ischemia and compartment syndromes were described. Ben Taub Hospital published a study in 1987 which showed no improvement in mortality in patients with penetrating injury.

At the end of the century, support for MAST started to dry up. The NAEMSP published a position paper limiting use to ruptured abdominal aortic aneurysms and pelvic fractures with hypotension. The final straw was a review by the Cochrane Collaboration in 2000 that confirmed no reduction in mortality with MAST use.

Although a few older textbooks may still mention MAST trousers, they are no longer the standard of care. There are no longer any accepted indications for their use, and the few trousers that remain are gathering cobwebs in some corner of the trauma basement.

Reference: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan.

How To: The Serial Abdominal Exam

How often have you seen this in an admitting history and physical exam note? “Admit for observation; serial abdominal exams.” We say it so often it almost doesn’t mean anything. And during your training, did anyone really teach you how to do it? For most trauma professionals, I believe the answer is no.

Yet the serial abdominal exam is a key part of the management of many clinical issues, for both trauma patients as well as those with acute care surgical problems.

Here are the key points:

  • Establish a baseline. As an examiner, you need to be able to determine if your patient is getting worse. So you need to do an initial exam as a basis for comparisons.
  • Pay attention to analgesics. Make sure you know what was given last, and when. You do not need to withhold pain medications. They will reduce pain, but not eliminate it. You just need enough information to determine if the exam is getting worse with the same amount of medication on board.
  • Perform regular exams. It’s one thing to write down that serial exams will be done, but someone actually has to do them. How often? Consider how quickly your patient’s status could change, given the clinical possibilities you have in mind. In general, every 4 hours should be sufficient. Every shift is not. And be thorough!
  • Document, document, document. A new progress note should be written, dated and timed, every time you see your patient. Leave a detailed description of how the patient looks, vital signs, pertinent labs, and of course, exact details of the physical exam.
  • Practice good handoffs. Yes, we understand that you won’t be able to see the patient shift after shift. So when it’s time to handoff, bring the person relieving you and do the exam with them. You can describe the pertinent history, the exam to date, the analgesic history, and allow them to establish a baseline that matches yours. And of course, make sure they can contact you if there are any questions.

Cool EMS Stuff: The Backboard Washer!

Backboards are made to get messy. And every time your friendly EMS provider brings you a patient, they invariably have to swab it down to give the next patient a reasonably sanitary surface to lie on. But sometimes the boards get downright nasty and the cleanup job is a major production.

Enter… the backboard washer. I recently saw one of these for the first time at a Level III hospital in Ohio. Fascinating! Pop the board inside and seven minutes later it’s clean. And I mean really squeaky clean. You may think it looks clean and a good hand wash, but just take a look at the effluent water coming out of this washer!

These units use standard 100V 20A power and only require a hot water hookup and a drain. They can wash two boards at once.

Hospitals in the know need to locate one of these next to a work area for completing paperwork and some free food. What could be better?

Reference: Aqua Phase A-8000 spec sheet. Click to download.

Complications After Single-Look Laparotomy

Damage control laparotomy (DCL) has been around now for over 25 years. Many, many papers have been written on its benefits, and the decreased mortality for abdominal trauma specifically. In fact, its use has been generalized to trauma for all other body cavities as well.

However, with this improved mortality came an increase in complications. Incisional hernias remain common, as do episodes of delayed small bowel obstruction. Much of the emphasis in traumatic damage control surgery has now shifted to finding ways to close wounds more quickly and reduce the overall complication rate.

In contrast to damage control laparotomy, much less is known about the potential complications associated with the single-look trauma laparotomy.

This procedure is carried out more frequently than DCL, but we have spent less time studying outcomes and risk factors for complications in this group of patients.

The surgery group at Scripps Mercy Hospital in San Diego conducted a statewide retrospective review of a hospital discharge database of adult trauma patients over an eight-year period. Patients with multiple laparotomies were excluded, as it was assumed that these were damage control patients.

The primary outcomes studied were surgical complications, including bowel obstruction, hernia, fistula, wound infection or dehiscence, and evisceration. Complications were recorded during the initial admission, and during any readmissions in the study period.

Here are the factoids:

  • Over 3700 patients were identified as undergoing trauma laparotomy during the study period
  • About 2100 were left for review after excluding those with multiple laparotomies (DCL) or an unclear trauma mechanism
  • 80% of patients were male and 60% had a penetrating mechanism
  • One third of patients were readmitted for a surgery-related complication: SBO 18%, hernia 12%, infection 9%
  • Median time to readmission was about 4 months (range 1 week to 1.5 years)
  • Patients with blunt injury tended to present with complications earlier (6 days) than penetrating injuries (6 weeks)

Bottom line: This paper is unique in that it is one of the few that was able to follow a large patient population for complications occurring both during and after the initial admission. The overall complication rate was surprisingly high (33%), which is similar to that seen after emergency surgery.

Knowing all of this, what should we do? To date, we have not come close to solving the problems of postop adhesive small bowel obstruction, wound infection, and incisional hernia in any surgical population. However, this work points out the importance of counseling our patients about the potential for complications, how to recognize them, and when to present for evaluation and treatment.

Reference: Outcomes after single-look trauma laparotomy: A large population-based study. J Trauma 86(4):565-572, 2019.

Trauma And The Gut Microbiome

This is a follow-on post from one published last week (gut microbiome changes in rats due to trauma). Click here to read it.

One of the newest frontiers in health-related research recognizes the importance of the human microbiome. This term describes the collection of all genomes from the microorganisms found in a particular environment, such as in, on, or around a human. The term microbiota refers to the specific bacteria, viruses, and fungi that colonize the areas within this environment.

Within the last decade or so, we have just begun to appreciate the importance of the microorganisms that live within us. From a purely numerical standpoint, there are 10 times as many of them as there are our own human cells. However, since they are so small in comparison, we can’t really appreciate the huge number of “other” cells in and on us.

These tiny cohabitants provide many, many functions that are important to our health and well-being. They protect us from pathogenic organisms, help digest our food, fine-tune our immune system, and synthesize proteins, amino acids, and vitamins that are essential to our health. And much more!

The usual microbiota can be disrupted by disease, poor diet, stress, and even a single dose of antibiotics. With each new research paper, we recognize new functions for and disruptors of our microbiota.

The surgery groups at two San Antonio hospitals, UT Health and the US Army Institute of Surgical Research, recognize the importance of the gut microbiota, building upon prior work demonstrating changes within it in the presence of trauma and burn injury.

The authors performed a prospective, observational cohort study of severely injured patients over a two-year period. They attempted to characterize differences in the microbiota between trauma patients and to identify changes in these communities over time.

A rectal swab was obtained from each patient shortly after admission and the microbial DNA present was identified. This was repeated regularly throughout the hospital stay.

Here are the factoids:

  • 72 patients and 13 healthy controls were enrolled
  • Patients were severely injured with a mean ISS of 21; an average of 6 units of blood products were given in the first 24 hours
  • Only one fourth of the injured patients had a microbiome similar to the healthy controls
  • These 26% received significantly more blood products than the dissimilar patients (14 units vs 3)
  • There were significant decreases in the numbers and ratios of normal gut bacteria and increases in the numbers of pathogenic bacteria. These changes increased with time in hospital

Bottom line: Yes, this is new and bizarre territory. It appears that shock, hypoxia, medications (and not just antibiotics), surgical intervention, and poor nutrition can adversely affect the microflora in our gut. Conversely, early transfusion seems to ameliorate this effect to some degree.

At this point in time, there is nothing you can do with this knowledge. Just be aware that everything you routinely do to your patients can change their microbiota, and this may in turn have unexpected effects on their health and recovery. I anticipate seeing many more papers like this one in the near future.

Reference: A prospective study in severely injured patients reveals an altered gut microbiome is associated with transfusion volume. J Trauma 86(4):573-582, 2019.