Video March 9, 2011 The Trauma Pro Leave a comment

http://video.ted.com/assets/player/swf/EmbedPlayer.swf

Printing A Whole Kidney?

And so it begins. I wrote recently about using a special version of a 3D printer to print a skin graft (read it here). I also speculated that we could be seeing 3D printers that could eventually print entire organs at some point. Well, leave it to Wake Forest again.

They demonstrated the concept of printing an organ at the 2011 TED Conference (Technology, Entertainment, Design) last week in Long Beach. Now, this was not a working organ, just a concept demo of sample tissue. Nonetheless, this is a preview of things to come. Imagine when we can print up a new kidney to replace the shattered one in the pan on the back table of the OR.

Check out this fascinating video!

(Source: http://video.ted.com/)

General

Gallery March 7, 2011 The Trauma Pro Leave a comment

Dry Seal Chest Tube Suction Systems

The original chest tube collection system traditionally consisted of three chambers. The picture above shows the classic three bottle system (which I actually remember using during residency). On the left is the suction control bottle that determines how much suction is applied to the patient. The middle bottle provides one way flow of air out of the patient, the so-called water seal bottle. Finally, the right bottle collects any fluid from the pleural space.

Collection systems used in hospitals are much more tidy than this, wrapping all three into one modular unit. However, if you look closely you can identify parts of the system that correspond to each of the bottles.

The problem with the older systems is that they typically require water in the “water-seal” chamber to maintain one-way flow out of the patient. If this chamber is compromised by knocking the system over (see this post), air may be able to enter the patient’s chest, giving them a big pneumothorax.

Management of chest tube collection systems by EMS is tough. It’s very easy to tip the system during air or ground ambulance runs, putting the patient at risk. Some manufacturers have developed so called “dry-seal” systems that use a mechanical one-way valve to avoid this problem.

I have not been able to use one of these systems yet. Here is my take on the pros and cons:

Pro – immune to tip-over and malfunction of the water-seal chamber
Con – more difficult to detect an air leak. Current models require either injection of a small quantity of water, tipping the system, or converting to a water-seal system.
Con – no literature regarding safety of this relatively new technology

Bottom line: Looks like a great idea to me, especially for EMS use. Once they get to the hospital, the unit can be changed to a water-seal system or a larger dry-seal system with the water injection port inthe dry-seal chamber.

General

Enoxaparin And Pregnancy

March 4, 2011 The Trauma Pro Leave a comment

Lovenox

Pregnant women get seriously injured, too. And pregnancy is an independent risk factor for deep venous thrombosis. We reflexively start at-risk patients on prophylactic agents for DVT, the most common being enoxaparin. But is it safe to give enoxaparin during pregnancy?

Studies have looked at drug levels in cord blood when the mother is receiving enoxaparin, and none has been found. No specific bleeding complications have been identified, either. So from the baby’s standpoint, administration is probably safe.

However, there are two other issues to consider. In a study looking at the use of enoxaparin for prophylaxis in women with a mechanical heart valve, 2 of 8 women (and their babies) died. Both suffered from clots that developed and blocked the valves. Most likely, the standard dose of enoxaparin was insufficient, so monitoring of anti-Factor Xa levels must be done.

The other problem lies in the multi-dose vial of Lovenox (Sanofi-Aventis). Each 100mg vial contains 45mg of benzyl alcohol, which has been associated with a fatal “gasping syndrome” in premature infants. The individual dose syringes do not have this preservative.

Bottom line: It is probably safe to give enoxaparin to pregnant women after trauma. However, it is unclear if the dose needs to be increased to achieve adequate prophylaxis. Only consider using this medication after consultation with the patient’s obstetrician, and use only the individual dose syringes. Otherwise fall back to standard subcutaneous non-fractionated heparin (even though it is a Category C drug by FDA; it is still considered the anticoagulant of choice during pregnancy).

General

Q&A: Is Undertriage Bad?

March 3, 2011 The Trauma Pro Leave a comment

After my discourses on under- and over-triage in the last week, I received an interesting question from a reader: although undertriage seems bad from a theoretical standpoint, are there any objective negative consequences?

As you might imagine, there is little literature on this topic. The incidence is low, so it’s tough to design a study with enough power to come to any solid conclusions. There are two studies that I can cite that shed as much light on the subject as possible.

The first looks at system undertriage at the EMS level. A Canadian study looked at patients with severe injuries (identified by ISS>15 after admission) who were taken to trauma centers (correct triage) vs non-trauma centers (undertriage). After solid statistical analysis of over 11,000 patients, they found that mortality in the undertriage group was 24% higher than the correctly triaged patients.

A second study looked at undertriage in one trauma center (1,424 patients) using their standard triage criteria, not ISS. The undertriage group had a significantly lower ISS (17 vs 25). The correctly triaged patients were more frequently intubated in the ED, more likely to be admitted to the ICU, and had longer ICU and hospital stays. Mortality was not significantly different. The problem with this study is that most of the undertriage group probably did not need a trauma activation, based on their lower ISS. The higher ISS patients (who met triage criteria) needed an airway earlier and required critical care more often. These data show that the institution probably needs to adjust its triage criteria!

Bottom line: The Canadian study shows the danger of undertriage prior to reaching definitive care. There is no good literature that illustrates its danger once the patient is at a trauma center. But there is support for the converse idea that appropriately triaged patients get definitive management sooner (airway, critical care). Any takers for designing the study to answer this question?

References:

Survival of the fittest: the hidden cost of undertriage of major trauma. J Amer Col Surgeons, 211:804-811, Dec 2010.
Outcome assessment of blunt trauma patients who are undertriaged. Surgery 148(2): 239-245, Aug 2010.

General

Undertriage Revisited

March 2, 2011 The Trauma Pro Leave a comment

I’ve updated my original post on trauma undertriage when activating your trauma team. The initial post gave a general approach that was reasonably accurate as long as the number of missed activations was low. Here’s the new and improved version!

Trauma centers look at over- and undertriage rates as part of their performance improvement programs. Both are undesirable for a number of reasons. I’ll focus on undertriage today, why it happens and what can be done about it.

Undertriage in trauma care refers to the situation where a patient who meets criteria for a trauma activation does not get one. First, calculate your “magic number”, the number of patients who should have been trauma activations.

If you track the exact triage criteria met at your hospital, it is calculated as follows:

Magic Number = (Number of ED trauma patients who met activation criteria
but were not trauma activations)

If you don’t track the triage criteria, you can use ISS>15 as a surrogate to identify those patients who had severe enough injuries that should have triggered an activation. This is not as accurate, because you can’t know the ISS when the patient comes in, but it will do in a pinch. In that case, the magic number is:

Magic Number = (Number of ED trauma patients with ISS>15
but were not trauma activations)

Your undertriage rate is then calculated as follows

   Magic Number
   ———————————————————– x 100
   (Total number of trauma activations) + Magic Number

Undertriage is bad because patients who have serious injuries are not met by the full trauma team, and would benefit from the extra manpower and speed possible with an activation.

The most common causes for undertriage are:

Failure to apply activation criteria
Criteria are too numerous or confusing
Injuries or mechanism information is missed or underappreciated

Undertriage rates can range from 0% to infinity (if you never activate your trauma team). A general rule is to try to keep it below 5%.

If your overtriage rate is climbing past the 5% threshold, identify every patient who meets the ISS criterion and do a complete ED flow review as concurrently as possible. Look at their injuries/mechanism and your criteria. If the criteria are not on your activation list, consider adding them. If the criterion is there, then look at the process by which the activation gets called. Typically the ED physicians and nurses will be able to clarify the problem and help you get it solved.

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