Using Shock Index to Identify Risk for Massive Transfusion

January 24, 2010 The Trauma Pro Leave a comment

This paper was presented at the 23rd Annual Scientific Assembly of the Eastern Association for the Surgery of Trauma.

Frequently, the need for massive transfusion in major trauma patients is apparent as soon as they arrive in the emergency department. Occasionally, the trauma team is surprised when an apparently stable patient catastrophically drops their pressure. This paper attempts to identify an easily calculated parameter to help predict those surprises before they happen.

The shock index (SI) is defined as the heart rate divided by the systolic blood pressure (HR/SBP). Normal values range from 0.5 to 0.7. The authors looked at all blunt trauma victims at their trauma center over a 9 year period who entered the ED with a SBP > 90. There were 8111 of these patients who met these criteria, and 276 required massive transfusion (3.4%), which they defined as 10 or more units of packed cells in 24 hours.

Analysis of their data showed that the risk for massive transfusion doubled with a SI > 0.9, quintupled for SI > 1.1, and was 7 times higher for SI > 1.3. There was some criticism for using only blunt trauma patients and for the authors’ definition of massive transfusion, but their data appeared to be sound.

The bottom line: the easily calculated Shock Index (HR/SBP) reliably predicts the need for massive transfusion in blunt trauma patients. It is probably valid for penetrating injury as well, but this was not addressed in the current paper.

Reference: Identifying Risk for Massive Transfusion in the Relatively Normotensive Patient: Utility of the Prehospital Shock Index. Vandromme, Griffin, Kerby, McGwin, Rue, Weinberg. University of Alabama at Birmingham.

General

WR U TXTING B4 U CRASHED?

January 23, 2010 The Trauma Pro Leave a comment

This interesting paper was presented at the 23rd Annual Scientific Assembly of EAST. The authors studied attitudes and behaviors regarding texting among college students. They performed an anonymous internet survey of 426 freshmen looking at a number of indicators. The specific items and results are as follows:

Average age of cell phone use: 14
Average age of first texting: 15
73% have texted while driving but
- 53% do not believe they can safely text while driving and
- 60% feel texting while driving should be illegal
- Only 63% would abide by the law if it were passed
92% feel texting is less safe than talking on the cell phone
84% have ridden with drivers who text

A lot of psychological subterfuge goes on in the minds of these young adults as they consider whether to text while driving or not. They weigh the use of fear control (rationalization) versus danger control (behavior change), and frequently rationalization wins out as the majority continue to engage in this risky behavior.

Education and awareness are needed to try to change behaviors, but will probably not be sufficient. Another study at this meeting compared cell phone use in two adjacent states, one where it was not legal and the other where it was. Cell phone use in the unrestricted state was over 6% vs 2% in the restricted state. Education programs, coupled with laws making texting illegal are a good combination, but more work will need to be done. Cell phone apps are in development that shut down talk and text functions when they are moving at automobile speeds. More innovative solutions like this will certainly be required.

General

How Do I Clear the Pediatric Cervical Spine?

January 22, 2010 The Trauma Pro Leave a comment

There is quite a bit of controversy surrounding clearing the cervical spine in children. The trauma and emergency medicine literature have few high quality studies to base recommendations on. However, a few very good studies have been carried out that did include children, and they are the basis for this suggested method for clearance.

There are a few key concepts that must be understood before approaching spine clearance in this patient group.

Clinical clearance is key! The majority of children’s cervical spines can be cleared clinically
Limit routine radiographic evaluation, especially by CT. The head and neck is packed with glandular tissue that is sensitive to radiation, especially in early childhood.
If radiographs are required, be sure to have them read by a radiologist who routinely reads pediatric images. There are many nuances in ossification and bony positioning that may falsely lead to injury diagnoses.
Memorize the NEXUS criteria. This study included enough children to allow treatment recommendations to be validated. They are:
- Midline cervical tenderness
- Focal neurologic deficit
- Altered level of consciousness
- Evidence of intoxication
- Painful distracting injury

The first step is to determine whether the child is eligible to be clinically cleared. They must be able to verbalize and cooperate with your exam. They may not have a developmental delay, since this may interfere their ability to cooperate with your exam. Frequently, younger children are apprehensive around doctors, and I recommend that you have a parent perform appropriate parts of the exam under your verbal guidance.

Next, evaluate to see if any of the NEXUS critieria are met. The distracting injury criterion is the most difficult to assess. This is a judgment call, but if the child is aware of multiple potentially painful areas, then a distracting injury is probably not present.

If no NEXUS criteria are met, the spine is cleared and should be documented as such. If any are present, a lateral cervical spine xray should be ordered. If the child is >8 years old, a plain odontoid xray should also be obtained. If all are normal, the spine is cleared and should be documented. Children 8 or younger do not have an odontoid that visualizes well. In such cases, a CT from occiput to the base of C2 should be obtained, with appropriate shielding in place.

If, at any point, an abnormality is encountered, expert consultation must be sought in order to safely clear the cervical spine and remove any stabilization.

General

Factors Predicting Failure of Observation of Occult Pneumothorax

January 20, 2010 The Trauma Pro Leave a comment

An occult pneumothorax is defined as one that is seen on CT scan, but not on plain chest x-ray. It is a common finding in blunt trauma that is evaluated using CT 2-12% of scans), but there is no consensus on management. It is recognized that some of these progress and require insertion of a chest tube, while many can be observed safely. The authors try to define what factors predict the need for chest tube management.

The authors reviewed their experience over a 3 year period, and identified 642 patients (10% of their registry entries) with a pneumothorax. 283 were occult, and 98 ultimately received a chest tube.

They found that age>35, ISS>24, more than 4 rib fractures, and need for positive pressure ventilation increased the risk for chest tube insertion. These seem to make sense, but there was one significant limitation in this study: there were no standard indications for a chest tube insertion among the surgeons involved with these patients. There was significant variability, so the actual need for tube insertion was probably less than reported.

An audience member related one anecdotal factor for chest tube as well: a heavy smoking history. This makes intuitive sense, but not everything that makes sense is borne out by research.

At Regions, we define an occult pneumothorax the same way these authors did. We routinely get a delayed chest xray 6 hours later. If there is still no visible pneumothorax, we stop looking. If it is visible, we will obtain periodic (q12-24 hrs) xrays until it stabilizes or grows to a size that demands tube or pigtail insertion.

Given the data conveyed in this paper, we will consider watching a bit longer than 6 hours in patients at higher risk.

Reference: Factors Predicting Failed Observation of Occult Pneumothorax in Blunt Trauma. Selander, Minshall, couillard, Leon. Medical University of South Carolina.

Presented at the 23rd Annual Scientific Assembly of the Eastern Association for the Surgery of Trauma

General

Can a Normal CT Scan Alone Clear the Cervical Spine in Obtunded Trauma Patients?

January 20, 2010 The Trauma Pro Leave a comment

This is the first in a series of articles on interesting abstracts presented at the 23rd Annual Scientific Assembly of the Eastern Association for the Surgery of Trauma in Phoenix, Arizona.

C-spine clearance in obtunded trauma patients has been problematic for some time. The options have been:

CT plus MRI. This is probably only valid for the first 72 hours after injury, and entails some risk in placing a critically ill patient inside the MRI for 30 minutes or more.
CT plus flexion/extension images under fluoroscopy. These are generally only performed by a few brave souls.
Leave the collar on until a clinical exam can be performed. This frequently leads to significant skin breakdown problems.

The authors have been reviewing their experience with using CT scan alone. In this paper, they used this technique in patients who met the following criteria:

Obtunded
Blunt trauma
CT normal, as read by a neuroradiologist
Moving all extremities

They studied 197 patients, and found no injuries in all surviving patients (11% were lost to followup). One deceased patient had a stable ligamentous injury without spine fracture seen at autopsy. Using this technique resulted in a decrease in the average number of days to spine clearance from 7.5 to 3.3 days, a decrease in skin breakdown from 5% to 0.5%. A decreased length of stay from 23.4 to 13.8 days was also seen, but this could not be attributed to the collar.

Very intriguing! However, the fear of SCIWORA is high in all who clear c-spines. The rarity of this catastrophic problem means that no existing study has the statistical power to show that this type of clearance is safe.

Bottom line: We all need to decide “How many missed injuries is okay?” We will never be able to absolutely clear 100.000% of c-spines by xray alone, or even by adding a clinical exam. This study provides support for one technique, but eventually a catastrophic injury will occur. Who will decide what constitutes an acceptable complication and with what frequency they will occur?

Reference: A Normal CT Alone May Clear the Cervical Spine in Obtunded Blunt Trauma Patients with Gross Extremity Movement – A Prospective Evaluation of a Revised Protocol. Leukhardt, Como, Anderson, Wilczewski, Samia, Claridge. MetroHealth Medical Center, Cleveland, OH.

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