Category Archives: General

General

EAST 2016: Measuring Volume Status Using Jugular Ultrasound

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We’re getting pretty handy using ultrasound at
the bedside to tell us some interesting things. It started with FAST exams in
the ED. Then we added a few views and came up with the Extended FAST, which was
helpful in showing potential chest pathology.

Ultrasound made its way into other areas of the
hospital, and is now used routinely to place IV lines, arterial lines, and
central venous catheters. I’ve previously written about using ultrasound to
evaluate volume status by imaging the IVC in the abdomen. And now, the group at
Shock Trauma in Baltimore is trying to reach even further.

They are now using IVC variations and cardiac
stroke volume variations to assist in volume assessment in critically ill
patients. These studies have a learning curve, especially the stroke volume
calculations. They performed a study that evaluated another possible window
into the patient’s volume status, the positional internal jugular change.

The diameter of the IJ was evaluated while the patient
was flat, and again when the head was elevated to 90 degrees. A fluid bolus was
given, and the positional change in diameter was measured again. The results
were then correlated with changes in measured stroke volume of at least 10%.

Here are the factoids:

  • This prospective, observational study involved 159 patients over 1.5
    years
  • Positional IJ diameter change was much better than IVC diameter changes
    (receiver operating characteristic areas of 0.93 vs 0.67)
  • The authors tried to use the stroke volume variation during passive leg
    raise (odd, but doesn’t involve sitting the patient up), and concluded they
    could not accurately assess it. This arm of the study was abandoned.

Bottom
line: Leave it to the folks at Shock Trauma to come up with more weird yet interesting
stuff. This is very preliminary data, and their analysis is ongoing. Any
application of this study will be somewhat limited, since many patients are not
allowed to sit up due to their injuries or baseline hemodynamic status. We will
see where this technique
ends up: in our armamentarium, or in the trash heap.

Go for the
jugular: assessing volume responsiveness in critically ill surgical patients.
EAST 2016 Oral abstract #32.

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General

EAST 2016: How Long Does VTE Risk Last In TBI?

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Most trauma patients
are considered to be at some risk for deep venous thrombosis (DVT) and/or
venous thromboembolism (VTE) during their hospital stay. Trauma professionals
go to great lengths to screen for, prophylax against, and treat these problems.
One of the tougher questions is, how long do we need to worry about it? For
fractures, we know that the risk can persist for months. But what about head
injury?

A group at Brigham
and Women’s Hospital did a large database study looking at the VTE risk in adults
who sustained significant head injury, with only minor injuries to other body
regions. They tried to tease out the risk factors using multivariate regression
models.

Here are the
factoids:

  • Patients were only included if their AIS Head
    was >3, and all other AIS were <3
  • Of the over 50,000 patients in the study,
    overall incidence of VTE was 1.3% during the hospital stay, and 2.8% overall
    within 1 year     of injury
  • Risk factors for VTE after discharge included
    age > 64 (3x), discharge to a skilled nursing facility (3x), and prolonged
    hospital length of stay     (2x)
image

Incidence of VTE over time

Bottom line: View this paper as a glimpse of a potential unexpected
issue. The risk of VTE persists for quite some time after head injury (and
probably in most other risky injuries like spine and pelvic fractures. The
three risk factors identified seem to identify a group of more seriously
injured patients who do not return to their baseline soon after injury. We may
need to consider a longer period of screening in select patients, but I believe
further work needs to be done to help figure out exactly who they are.

Reference: How long should we fear? Long-term risk of
venous thromboembolism in patients with traumatic brain injury. EAST 2016 Oral
abstract #28.

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General

EAST 2016: Lower Mortality In Patients Taking Newer Oral Anticoagulants vs Warfarin

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How not to write your abstract! The full title is this:

Trauma Patients on New Oral Anticoagulation Agents Have Lower Mortality Than Warfarin

Now let’s look at what it really says. This was a retrospective trauma registry review from a single Level I trauma center. Over a 14 month period, 275 of 1994 admitted patients were on anticoagulants.

Here are the (misleading) factoids and my comments:

  • Patients on warfarin had a higher mortality (13%) than those on new oral agents (NOA) (6%). (I can’t duplicate the statistical significance calculation)
  • Patients taking any anticoagulant were admitted to an ICU more often (44-50% vs 36%). (Duh! This just shows their usual practice, nothing new)
  • Patients on warfarin were more statistically likely to receive prothrombin complex concentrate. (Double duh! Because it doesn’t work for NOAs?)
  • The authors pointed out a trend toward more NOA use in this graph. (Really? It goes from 11 to 14 with wide monthly variations!)
image

Bottom line: This is why it’s so important to read the entire abstract and think about the stats. And ultimately, it’s even more important to read the whole paper! They don’t always say what you think they say!

Reference: Trauma patients on new oral anti-coagulation agents have lower mortality than those on warfarin. EAST 2016 Oral abstract #24.

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General

EAST 2016: Scene Time And Mortality

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The old “scoop and run” vs “stay and play” debate has gone on for years. It would seem to be intuitive that trauma patients, who should be assumed to be bleeding to death, would do better with shorter prehospital times and quicker transport to definitive care. 

However, several studies have not shown worse outcomes in the “stay and play” patients. Once again, mortality is a very crude indicator of “worse” outcomes, and may not be a good enough measure. Nonetheless, the debate continues to rage. A group at the University of Pittsburgh used the Pennsylvania Trauma Registry to review a huge number of EMS transports, looking at mortality as the measure of interest.

Recognizing that total prehospital time can be influenced by delays in specific phases (response, scene, or transport), they analyzed the impact of problems in each. If one particular phase represented more that 50% of the total prehospital time, it was considered a delay. Logistical regression was used to match patients to try to control for any confounding issues.

Here are the factoids:

  • Over 164,000 records with prehospital times were reviewed over a 14 year period.
  • There was a statistically significant increase in mortality if the scene time phase was prolonged.
  • No differences in mortality were noted with longer response or transport times.
  • Prolonged extrication and intubation had a tendency to prolong scene time, and were independently associated with higher mortality.
  • Lengthy scene time without extrication or intubation was not associated with higher mortality.

Bottom line: This registry-based study has helped us to slice and dice the prehospital time issue a little bit better. As with other studies, the times themselves may not necessarily be the problem. It’s what is causing the delay that matters. Extrication and intubation tend to indicate sicker trauma patients, but they are also somewhat unavoidable. Prehospital trauma professionals will need to focus on tools and exercises that save time during these critical interventions.

Reference: Not all prehospital time is equal: influence of scene time on mortality. EAST 2016 Oral abstract #9, resident research competition.

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General

EAST 2016: (F)utility of CPR In Hemorrhagic Shock

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Ahh, another (f)utility study. Does it work, or doesn’t it? And yes, I know. It’s another animal study. But it may give us a glimpse of where we are really going with this. 

A team at the University of Tennessee – Knoxville devised a dog experiment to study how well performing CPR works in critically hypovolemic animals. They used three groups of dogs that received a severe shock insult: hemorrhage until loss of pulse, then waiting for 30 minutes in that pulseless state. At that point, one of three interventions was performed for 20 minutes.

One group received CPR only, another group underwent CPR plus fluid administration, and the last group got fluids only. 

Here are the factoids:

  • The insult to all three groups was similar.
  • Vital signs and lab studies were similar in the CPR+fluid and fluid only groups.
  • The CPR only group had significantly lower mean arterial pressures and higher pulse rates than the other CPR+fluid and fluid only groups.
  • Ejection fraction was lower in the CPR only group, and it also had a higher incidence of end organ damage. 
  • Two of the six dogs in the CPR only group died before the end of the study.

Bottom line: Tread with caution here. It makes sense that pounding on an empty tank won’t do much. But this study doesn’t exactly prove this. Only the vital signs measurements were significantly different. All other results are just trends in this very small study. And finally, dogs are (obviously) different than people, in their physiology and their chest wall shape. This can certainly make a difference, and does not mean that we should abandon CPR in humans in hemorrhagic shock.

Reference: Utility of CPR in hemorrhagic shock, a dog model. EAST 2016 Oral abstract #8, resident research competition.

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