Speed is a Silly Question

Imagine one of the most common calls that you will run in EMS – a motor vehicle accident.  Your patient is the restrained driver of a mid-sized sedan who was involved in a frontal impact crash and is complaining of mild dizziness and midline neck pain.  So you take her to the hospital.  After you arrive there, you give your verbal report to the accepting nurse:
“This is the 43 year old restrained driver of a frontal impact crash complaining of dizziness and midline neck pain in a general sense, from about C3 to C7.  She is neurologically intact, was ambulatory prior to my arrival, and remembers the event.  She has a heart rate of 120, a blood pressure of 100/60, and a respiratory rate of…”

“How fast was the crash?” the nurse asks.

“I don’t know, but there was 8-12 inches of frontal damage and the airbags deployed.  The steering wheel, windshield and dash…”

“But how fast was the crash?”

Speed is a dumb question.

There are a few reasons that I feel this way.  First, police don’t take people’s word for the speed of impact.  Why would medical providers?  Police and insurance accident investigators have extensive training in how to estimate the speed of a crash based on skid mark length, road conditions, vehicle damage, passenger injury patterns, and such.  They don't come up with a number by looking at the results for a few seconds.  It makes no sense for me to ask the driver how fast he was going, especially when he is probably worried about what it will do to his insurance rates if he is found to be at fault.

Next, people don’t really know how fast they are going.  For the most part, people kind of just go along with traffic in a way that makes them feel safe.  They certainly don’t realize that a grinder is imminent, take unsuccessful evasive action, and then look at the speedometer right at the time of impact.  When pressed, they quickly try to recall which road they were driving on, try to guess the speed limit on that road, and maybe take off a few miles per hour to decrease the chances of them getting in legal trouble.  Any braking before the crash is not usually included in speed estimates.  Even if it was, it is almost impossible to guess whether their speed went from 55 to 30 at impact or from 55 to 52.  

In addition, the orientation of the impact isn’t included in speed estimates.  What we’re really interested in is the change in velocity.  Hitting a stopped car at an angle and glancing off is completely different than plowing into a bridge abutment at a perpendicular angle.  In the first case, the impact doesn’t take their speed all the way down to zero.  Was what they hit movable?  Were there other factors such as spinning, rollover, or ejection?  What part of the car was hit – there are big differences between taking an impact on the front bumper, getting your hood under a tall vehicle so the impact is on the A-posts, or taking the hit in the driver’s door. 

Finally, the type and age of vehicle matters.  There is a big difference in crashing a 1976 cast iron land yacht and a brand new SUV with all of the modern safety features.  Crumple zones, air bags, and such matter.  Think of really high speed crashes in auto racing – car parts go flying as the race car pirouettes through the infield, but the driver gets out and throws his helmet at the other racer that caused the crash.

Who cares about the reported number?  What if the accident was reported to be a 2 mph crash, but the patient has chest pain, pallor, JVD, and a really narrow pulse pressure indicative of pericardial tamponade?  What if the crash was reported to be 100 mph, but the only damage is that the license plate is sort of bent and the patient is completely uninjured?  The problem is that a 2 mph crash is unlikely to cause severe injury and a 100 mph crash is likely to result in life-threatening injury.  Most crashes we see, though, fall in between where anything can happen.  A person can walk away from a 40 mph crash, or they can be killed.

Quick, what was the speed of this crash?
(Elvert Barnes, Creative Commons)

To me, an accurate description of the crash events and a complete description of the damage to the patient and vehicle is what matters.  The major vehicle factors that should be reported are damage, intrusion, airbags, windshield, steering wheel, and dashboard findings. 

Damage is the amount of external damage.  How deep was the dent?  Where is the damage located on the car?  Is the vehicle drivable?  Could the doors open?  Was heavy extrication required to extricate the patient?  Intrusion, in contrast, is the depth of damage that made it into the passenger compartment (along with its location, etc).  Damage is how the shape of the car changed and intrusion speaks to how the shape of the passenger compartment space changed.  The difference is important, and I hate to hear people mix up the vocabulary. 

Whether or not airbags deployed and their location is important information.  The shape and integrity of the steering wheel, along with any dash damage is important data, as well.  Windshield damage should be reported with any caveats.  By caveats, I mean that a broken windshield can be caused by the airbag, the driver’s hand (as it is blown upwards by the airbag), by the impact itself, or by passenger body parts (read: face) impacting it.  Each of those results in a different mechanism of potential injury and a different index of suspicion. 

Finally, injury patterns on the patient’s body matter.  To say that the airbag deployed and seatbelts were reported to be used is great, but it is also a good idea to point out that the patient’s chest says “DROF”.  Whether or not the patient self-extricated and was ambulatory on scene matters.  So does their position in the car in relation to the impact site.

So I wish that hospital providers focused on the tale that I am trying to tell them, based on all of that damage pattern description.  I think that the importance of speed comes from trauma center requirements, but I don’t know for sure.  There is usually a list of trauma criteria that result in team activations of different levels.  Speed of a car wreck is one of them.  So the hospital is sort-of forced to document the speed findings.  That doesn’t make it any less of a silly question to me.  But there is no need to get into some passive-aggressive pissing contest over it.  I try a few times to point out that I wasn’t there and which road it happened on so they can recall how fast that road moves, but I usually end up estimating that the speed was X mph based on the reported damage/injury patterns.  Move on.