Category Archives: General

The Electronic Trauma Flow Sheet: What Does(n’t) Work – Part 1

There are two major problem areas using an electronic trauma flow sheet (eTFS): the front end and the back end. Today, I’ll discuss the front end data entry problems.

Trauma activations are very data intensive events. Beginning prior to patient arrival, there are registration activities so the electronic health record (EHR) can begin accepting other information about the patient. Once they arrive, there is a continuous stream of information regarding observations, actions, results, medications, fluid, blood, and much more. All of these occur during a relatively brief period of time. Some are simultaneous.

This stream of information continues after the patient leaves the trauma bay for CT, imaging, interventional radiology, operating room, ICU, or ward bed. The flow sheet scribe is charged with recording all of this information as contemporaneously as possible. This ensures accuracy of the data, particularly with events that occurred at the same time.

But there is a major difference in input between the paper trauma flow sheet and the eTFS. The paper sheet is typically a three or four page form that is laid out in front of the scribe. All of the data blocks are readily visible, and are grouped in logical clusters: prehospital information here, primary survey data there, procedures in that one, vitals and narrative there.

Unfortunately, it’s not so simple with the eTFS. The scribe can view whatever content fits on a single screen. And it is just not possible to display all of the needed info on that one screen. The software developers addressed this problem by creating multiple screens that can be accessed by clicking on various tabs or buttons. The problem is that the human cannot see where the blocks are and must be very familiar with the tabs and buttons. And to make it worse, they must shift between mouse click and keyboard to move between them and record data.

This results in a stream of input that can’t be recorded quickly enough to stay current. It is very common to see a “cheat sheet” next to the input terminal so the scribe can add quick handwritten notes when they get behind. This information is entered later, but as you may imagine, accuracy suffers. It is very common to see events or results that do not fit the timeline. Once this occurs, the entire record is suspect and will not represent the true flow of the resuscitation. And what about events that occur during patient transport, between computer workstations?

The difficulty of entering trauma resuscitation information in true real time results in a Garbage In situation. Tomorrow, I’ll continue with problems on the back end that can result in Garbage Out.


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Trauma Mythbusters: Removing Bullets With Metal Instruments

I’ve heard this time and time again over the years. Don’t remove a bullet using metal forceps or a hemostat. Don’t drop it into a metal pan. Have you heard these, too? Is it true?

The idea is that rifling marks on the bullet that would help match it to a particular weapon may be damaged through mishandling, interfering with any criminal investigation.

So I decided to go to a reputable source. I asked a local police firearms and munitions expert the question. The result:

Myth busted! The amount of damage to the bullet due to handling with metal instruments is negligible and will not interfere with an investigation. Many of the bullets used in crimes are jacketed with copper or other metals, which are resistant to damage anyway. The surgeon would have to make an intentional effort to damage the bullet enough to interfere with a ballistics investigation. And I don’t recommend that anyway!

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Where Did The Hypodermic Needle Gauge System Come From?

Yesterday, I wrote about one of the weirder measurement systems in medicine, the French (or Charrière) system for catheter sizes. Today, I’ll deal with another arcane system, the gauge system for hypodermic needles.

I’ve always wondered how this worked. Lower numbers somehow indicate bigger needles. And to make it more confusing, there are two conflicting gauge systems, the Birmingham Wire Gauge (aka the Stubs Iron Wire Gauge) and the Stubs Steel Wire Gauge. Confusing, right? And these two are actually a little different.

Hypodermic needle sizes are based on the Birmingham gauge system (G).  The Gauge indicates the outer diameter (OD) of the wire used to make the needle, but is inversely related to it. And to top it off, there is no real mathematical formula that relates gauge to the OD. If you are that interested, you have to consult a printed table.

Needle gauge ranges from 7G (4.57mm OD) to 34G (0.18mm OD). There is also little correlation of the inner diameter to gauge, as the wall thickness decreases as the OD of the needle decreases. As an interesting tidbit, there is an International Standards Organization (ISO) standard for single-use needles that determines the color coding of the hub. I always wondered who thought those up!

Okay, so needle gauge is based on the size of the wire used to make them. What about IV catheters? Just to make it more confusing,  IV catheter size indicates the size of the needle used to insert them. So an 18G IV catheter has an inner diameter that is almost identical to the OD of its needle. The outside diameter of the catheter will be a tiny bit bigger. Got it?!

So there you have it. Amaze your friends with your arcane knowledge about tubes and needles and catheters!

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Where Did The French Tube Size System Come From?

Medicine sure has some weird measurement systems. Besides the more standardized units like microliters, milligrams, and International Units, we’ve got some odd stuff like French (tubes) and gauge (needles). When dealing with tubes and catheters, the size is usually specified in French units.

Where did the French system come from? It was introduced by a Swiss-born gentleman named Joseph-Frédéric-Benoît Charrière. He moved to Paris and was apprenticed to a knife maker. At the age of 17, he founded a  company that manufactured surgical instruments. His company developed and improved a number of surgical instruments, including hypodermic needles and various catheters.

Charrière introduced the system for describing catheters based on their outer diameter (OD).  It was actually named after him, and in France one will occasionally see catheters described in Ch units. Unfortunately, we Americans had a hard time pronouncing his name, and changed it to the French system (Fr).

So what’s the translation? The Ch or Fr number is the outer diameter of a catheter in millimeters multiplied by 3. It is not the outer circumference in millimeters, and the use of pi is not involved. So a big chest tube (36 Fr) has an OD of 12 mm, and a bigger chest tube (40 Fr) has an OD of 13.33 mm.

Tomorrow: Where did the needle gauge size come from?

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