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Patient Safety Tip
of the Week
April 20, 2021
Taser “Slip and Capture
Error” Again!
In the midst of a trial of a police officer
in the death of an unarmed African-American man in Minneapolis, 10 miles away
there was another incident in which a young African-American man was fatally
shot by a police officer during a traffic stop. In the latter incident, the
police officer apparently intended to use a taser on the man but instead fired
her gun, killing the man. “How could that happen?” you ask. It’s not the first
time this has happened. In fact, it has happened multiple times. Our
April 21, 2015 Patient Safety Tip of the Week “Slip and Capture Errors” noted at least 8 prior instances where
police intending to use tasers, instead pulled out their guns and shot someone.
It is the classic example of what is known as a “slip and capture” error.
The police stopped the
man for a suspected traffic violation but found there was an outstanding arrest
warrant on him. When he got back into his vehicle against the commands of the
police officers, one officer aimed a weapon at him and shouted “Taser! Taser!
Taser!” (Bogel-Burroughs
2021, Broaddus
2021, Navratil 2021). She fired one round, and the man
groaned in pain. “Holy shit, I just shot him,” the officer can be heard
shouting. The man drove off in the car but crashed a couple blocks away and was
pronounced dead at the scene.
A nearly identical
incident occurred in 2018 in Kansas (Robertson 2019). A police officer thought she had her Taser
in her hand as she watched an unarmed man beating a fellow officer. What she
fired, however, was her gun — by mistake. “Oh s---, I shot him,” she shouted.
During legal proceedings, she explained her brain immediately went ‘you need to
tase this guy, you got to tase, you got to tase him” and she shouted “Taser!
Taser! Taser!” She fired what was in her hand, and the assaulter shouted in
pain — which would have been normal when hit with a Taser. But the officer said
she was stunned that she didn’t see the wires of a Taser gun strike. At this
point she realized she had pulled her gun and shot the assaulter by mistake,
instead of pulling her Taser. She exclaimed aloud, “Oh s---, I shot him.”
We wrote our April 21,
2015 Patient Safety Tip of the Week “Slip and Capture Errors” after a volunteer police deputy fatally
shot a man, thinking he was firing his taser, not his gun (Yan
2015). In 2009 a very similar shooting occurred on the Oakland BART
system when the officer fired his gun rather than the intended taser (Force
Science Institute 2010). At that time, retired Capt. Greg Meyer
noted there were at least 6 similar incidents prior to that 2009 shooting (Meyer
2010). So, when we did our 2015 column, there were at least 8 similar
incidents where a police officer inadvertently shot someone, mistakenly
thinking they were using a taser and not their gun. After the recent Minnesota shooting,
media reports put the number of similar incidents as high as 18 (Elinson 2021). One article actually lists 16 of the prior
incidents (Ciavaglia 2021).
Sure sounds like a system problem to
us! It’s reminiscent of concentrated potassium chloride issues in healthcare in
the past. Multiple incidents occurred disseminated both in time and location,
so it took years for us to see a pattern and look for root causes and,
ultimately, solutions.
So, this is a patient safety column, not a
crime column. Why are we discussing this at all? We discuss it because these
are instances of a human factors concept, the “slip and capture error”,
and we need to understand why they occur because similar errors can occur in
healthcare. We gave many examples in our April 21, 2015 Patient Safety Tip of
the Week “Slip
and Capture Errors” and such are well worth
reiterating.
But the capture error is not a new concept.
In fact, for years when we are teaching patient safety to medical students,
residents, or other healthcare workers and tell them mistakes are inevitable we
give them a classic example: “It’s Sunday morning. You intend to go to the grocery
store. But you find yourself in your car on the route to your usual
workplace/school, instead of the route to the grocery store.” (Usually about
two thirds of the audience raises their hands when we ask if that has happened
to any of them!) That happens to be a classic capture error. The more practiced
activity “captured” the intended but less familiar activity.
Usually there are “enabling” factors that
contribute to the occurrence of “capture” errors. These include stressful
situations, emergencies, distractions or interruptions and others.
So, what are some healthcare examples of “capture” errors?
A nurse or physician, confronted with a new version of a device (eg. ventilator, infusion pump, dialysis machine,
etc.), programs in the sequence of keystrokes or dial manipulations he/she used
on the old device even though he/she has been inserviced
on the new device.
A somewhat similar error may have occurred in
the fatal NMBA incident we described in our Patient Safety Tips of the Week for
December 11, 2018 “Another
NMBA Accident” and
February 12, 2019 “From
Tragedy to Travesty of Justice”. In that case, a nurse was attempting to retrieve Versed from an automated
dispensing cabinet (ADC). She recalled talking to an orientee about something
unrelated while entering the first two letters “VE” into the ADC. The first
medication on the list was chosen. The nurse did not recognize that the
medication chosen was vecuronium, not Versed. The nurse looked at the back of
the vial to see how to reconstitute the medication but did not recheck the name
of the medication on the vial. Ultimately the fatal dose of the paralyzing
agent vecuronium was administered to a patient.
In our April 21, 2015 Patient Safety Tip of
the Week “Slip
and Capture Errors” we also noted an example
where we might incorrectly choose an order set for order set for DKA (diabetic
ketoacidosis), which gets used very often, rather than the intended order set
for nonketotic hyperosmotic state, which is used much less frequently.
There is probably also some relationship or
at least overlap of “capture” errors with another human factors concept: inattentional blindness (ISMP 2009). In
the latter, which is really a sort of confirmation bias, we tend to see what we
expect to see rather than what we actually see. This is often a contributing
factor in incidents where medications are drawn up from the wrong vials.
Another interesting thought: technology may cause some “capture” errors.
Autotext or automatic completion of phrases by a word
processor or smart phone may lead to such errors. We’ve noted several times
that every time we type “EHR” (for electronic health record), our word
processor converts it to “HER” and we might miss that on proof-reading. Or our
smart phone automatically inserts one email address when we really intended a
different one. These examples really meet the definition of a “capture” error
in that two actions start with the same sequence of steps and one that is far
more familiar than the other (at least far more familiar to the computer!)
takes over for the intended action. You can bet that there will be analogies
with healthcare technologies.
Capture errors have long been described by
human factors pioneers like James Reason and Don Norman. How about some
everyday examples of “capture” errors?
James Reason, widely known as the father of
human factors research, provides numerous examples (Reason 1990):
- After
a decision to reduce sugar consumption, someone finds himself sprinkling
sugar on cornflakes the very next morning.
- After
food is moved to new refrigerator, someone finds himself opening the old
refrigerator to look for food.
- After
moving to a new home, some starts a letter with previous home address.
- Someone
intends to stop at a store on the way home but drove past the store
without stopping.
- Someone
wants to put milk in a cup but puts it back in the refrigerator before
putting any in the cup.
- Someone
takes off their socks when they only meant to take off their shoes.
Don Norman (see our November 6, 2007 Patient
Safety Tip of the Week “Don Norman Does It Again!”) in
his two great books on human factors and design of things (Norman 1988, Norman 2009) has
some great examples:
- A
person who frequently plays cards is counting pages at a copy machine and
counts 1-2-3-4-5-6-7-8-9-10-J-Q-K-A!
- A
person playing a song on an instrument finds himself switching to a more
familiar song.
- A
person goes to the bedroom to change for dinner and finds himself going to
bed.
- Someone
finishes typing his thoughts on the word processor and turns it off
without saving.
Did you ever rent a car on a trip and turn on
the windshield wipers instead of the lights because the control knobs were
reversed from the car you usually drive?
In the taser/gun incidents, use of the taser
is the relatively unfamiliar action and use of the gun is the more familiar and
well-practiced action. Even if the officer has never fired his/her gun on duty,
they all spend considerable time on the shooting range so have practiced use of
the gun frequently. But we suspect most have practiced using the taser much
less frequently and probably never practiced under stressful conditions.
As Don Norman would tell us, design of
systems significantly impacts on how humans use those systems. Design of the
taser and its holster likely contributed to each of the incidents. In many of
the previous taser/gun mistakes the taser had apparently been drawn by the
“strong” (dominant) hand, though the location of the taser holster was variable
(Meyer 2010).
One of the recommendations made by the Forensic Science Institute after the
BART case was use “weak-side, weak-hand-draw” taser holsters to minimize the
chance of unintentionally drawing one’s gun rather than the taser. It’s not
known how the officer in the current Minnesota incident was wearing her weapons
and holsters at the time of the shooting. Apparently, the policy was that the
tasers were to be holstered on the nondominant side. But, even then, there is a
problem. The video of the incident shows another officer wearing the taser holster
on the nondominant side but the butt of the taser was positioned such that the
officer could easily “cross-draw” the taser with his dominant hand (Hubler 2021). An
article in USA Today (Loehrke 2021) has
a good graphic showing not only holstering but also all the other equipment police
officers typically carry on their belts.
And it’s clear it is not enough to just
receive some education/training on use of the taser. Taser use must be
practiced just as often (perhaps even more often) than practicing gun use and
done under conditions closely simulating those in which a taser is likely to be
needed.
Our take – the taser looks like a gun and has
a trigger like a gun! So, it’s no surprise that, in the heat of an emergent
situation, someone will pull that trigger. If nothing is done, it is inevitable
there will be another inadvertent shooting after mistaking a gun for a taser. The
solution should be to redesign tasers so they have a different shape and
have an activation mechanism that is different than a gun-style trigger. Maybe
add some sort of audible signal that appears when the taser is unholstered. Is
that too much to ask? Just be careful the redesign does not have its own
unintended consequences (like tasing oneself!).
References:
Bogel-Burroughs N, Bosman J. Minnesota Officer Who Shot Daunte Wright
Meant to Fire Taser, Chief Says. New York Times 2021; April 12, 2021
https://www.nytimes.com/2021/04/12/us/brooklyn-center-police-shooting-minnesota.html
Broaddus
A, Yan H, Allen K, Silverman H, Minnesota officer shouted 'Taser!' but fired a
gun instead, fatally shooting a man at a traffic stop, police say. CNN 2021; April
12, 2021
https://www.cnn.com/2021/04/12/us/brooklyn-center-minnesota-police-shooting/index.html
Navratil L, Montemayor S, Mannix A. Chief: Officer meant to use
Taser, not firearm, on Daunte Wright. Minneapolis Star Tribune 2021; April 13,
2021
Robertson J. A Lawrence police officer meant
to use a Taser. She shot a man by mistake.
The Kansas City Star 2019; September 06, 2018
Updated March 26, 2019
https://www.kansascity.com/news/local/crime/article217924280.html
Yan H. How easy is it to confuse a gun for a
Taser? CNN 2015; April 14, 2015
http://www.cnn.com/2015/04/14/us/taser-gun-confusion/index.html
Force Science Institute. Force Science
explains "slips-and-capture errors" and other psychological phenomena
that drove the fateful BART shooting. PoliceOne.com July 22, 2010
Meyer G. The BART shooting tragedy: Lessons
to be learned. PoliceOne.com July 12, 2010
http://www.policeone.com/legal/articles/2095072-The-BART-shooting-tragedy-Lessons-to-be-learned
Elinson Z.
Kim Potter mistook her gun for a Taser, police say: How often does that happen?
Fox News 2021; April 13, 2021
Ciavaglia J. How
could a gun be mistaken for a Taser? There have been at least 16 incidents of
'weapon confusion' since 2001. USA Today 2021; April 13, 2021
ISMP (Institute for Safe Medication Practices).
Inattentional blindness: What captures your attention? ISMP Medication Safety Alert Acute Care
Edition 2009; February 26, 2009
http://www.ismp.org/newsletters/acutecare/articles/20090226.asp
Reason J. Human Error. Cambridge: Cambridge
University Press. 1990. p. 68
Norman D. The Psychology of Everyday Things. New
York: Doubleday. 1988. P. 107
Norman D. The Design of Future Things. New
York: Basic Books. 2009. P. 107
Hubler S, White J.
How Could an Officer Mistake a Gun for a Taser? New York Times 2021; April 13,
2021
Loehrke J, Padilla
R, Petras G. Aftermath of fatal shooting: How can a
handgun be mistaken for a Taser? USA Today 2021; April 14, 2021
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