What impact does an AR-15 rifle wound have?
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(CNN) --
One of the most memorable lectures during my first year of medical school at the University of Michigan was given by Dr. Julian "Buz" Hoff.
He was chair of Neurosurgery and teacher in teaching Natural History of Brain Diseases.
We learned about brain tumors, vascular diseases, and trauma.
Hoff had a way of explaining things that really made us learn them, and that was particularly clear in his talk called "GSW."
Anyone who works in a hospital probably knows that the acronym GSW stands for
gunshot wound
, and the way Hoff wanted us to learn the subject was to see the impact firsthand.
So, on the last day of his class, we went to an outdoor shooting range in Ann Arbor for our GSW conference.
There were pistols there, as well as rifles.
In the distance, I saw several watermelons on top of old barrels that would serve as targets.
After putting on his earplugs and safety glasses, Hoff shot a watermelon with a pistol.
I saw the bullet hit the watermelon, but I wasn't sure I saw the bullet come out.
The watermelon was then brought to us for inspection.
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The first thing we noticed, he told us: There was an obvious entry and exit "wound" and they were about the same size.
We could see green skin folding in on itself around the entry wound and tissue beveling outward around the exit.
After we opened the watermelon, he noted that the bullet seemed to have followed a fairly predictable path, a bullet-sized straight line through the body of the watermelon.
Then came the same demonstration with a rifle.
This time, I saw the watermelon shudder when he hit it, and I immediately saw a significant amount of red tissue fly out the back.
Upon inspection, the first thing I noticed was how much larger the exit wound was compared to the entrance.
And after the watermelon was cut open, the purpose of the demo became clear: instead of a predictable linear track, the watermelon appeared to have been cored and what was left was shredded.
He explained that it was a phenomenon known as cavitation, which is exactly what it sounds like: the bullet doesn't just travel through the body, but creates a large cavity inside it.
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The message was clear: I want you to imagine if it had been a human body.
Just as the images of black lungs had left an indelible impression of smoking on all medical students, Hoff had done the same with me for the gunshot wounds.
I was reflecting on that demonstration recently when I operated on a patient with a gunshot wound to the head.
It was a gunshot injury and we were able to quickly control the bleeding and relieve pressure on the brain.
The patient spent a day in the ICU for observation and was discharged a few days later.
If it had been a rifle wound, there was almost no chance he would have survived.
With guns front and center in the news in recent weeks, I wanted to share what I've learned over the years about what bullets do to the human body and the challenge it poses for surgeons to repair the damage.
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Weapons that do the most damage
Nearly 30 years after my medical school shooting range demonstration, Dr. Ernest E. Moore, trauma surgeon and director of Trauma Research at the Shock Trauma Center that bears his name at Denver Health, is also using the example. watermelon to draw a comparison between different firearms.
"I often use the analogy that injuring the liver [with a semi-automatic rifle] would be akin to just picking up a watermelon and dropping it on concrete. It's amazing the amount of energy delivered...By comparison, a 9mm gun would punch a hole through the liver. So you'd have a sizable hole, but if you don't hit a major blood vessel, it's a pretty tolerable injury. In fact, we in civil trauma often manage to treat a 9-millimeter liver injury without an operation , whereas a patient with an assault rifle would be dead in 20 minutes without surgery," he said.
Other human tissues in the body react differently.
"If you hit a bone with an AR-15, like your femur in your leg, it would literally break into multiple fragments that would serve as secondary missiles. Whereas... we've seen 9 millimeters that will actually punch a hole all the way through the femur," said.
(An AR-15 is a lightweight, semi-automatic, i.e. self-loading rifle, made by Colt; other gun manufacturers make similar style rifles.)
Moore also mentions cavitation as a way to visualize what is happening in the body.
He describes cavitation "as the result of rapid expansion of the tissues surrounding the bullet's trajectory... In essence, instead of a virtual drill hole with a 9-millimeter, the injury trajectory in the tissue with an AR-15 rifle will be six inches wide. And the path beyond is even wider, but the fabric recedes into it," Moore said.
He further pointed out that inelastic tissue, such as the liver, heart and brain, are the most vulnerable to this type of energy.
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While the US Department of Justice notes that 77.2% of mass shootings, which count as four or more deaths not including the shooter, involve handguns, many of the highest-profile incidents involve assault rifles. involved.
For example, the 2012 Sandy Hook Elementary School shooting in Newtown, Connecticut;
the shooting at Orlando's Pulse nightclub in 2016;
the 2017 shooting at a music festival in Las Vegas;
and the 2018 shooting at Marjory Stoneman Douglas High School in Parkland, Florida, just to name a few.
And more recently, the shooting at Robb Elementary School in Uvalde, Texas.
This type of rifle releases a lot of power, said Moore who, in addition to being a trauma surgeon since 1976 (and operated on some of the Columbine massacre survivors), co-edited a major textbook on trauma surgery, authored more of 1,700 scientific articles and was a long-time editor of the Journal of Trauma and Acute Care Surgery.
"The capacity of tissue damage is reflected in the so-called kinetic energy. And the kinetic energy, simply put, is the mass or the weight of the bullet multiplied by the speed squared. So the speed, the speed of the bullet that comes out of the gun, it's really its main effectiveness," he said.
Moore said a 9-millimeter handgun has a muzzle energy — the kinetic energy of a bullet as it leaves the muzzle of the gun — of about 400 foot-pounds of force.
For a rifle like the AR-15, that number is 1,300.
"So you have a huge increase in the amount of energy imparted by the weapon," he explained.
He said the size of the bullet has less to do with the damage it causes.
"I think there are some misconceptions with...rifles. A lot of people say, 'Oh, they're big bullets.' They're actually small bullets, oddly enough, they're even smaller than a lot of guns. So the actual bullet that's discharge from an AR-15, for example, is half the size of the 9-millimeter bullet. The difference is the…velocity," he said.
And, if that rifle is a semi-automatic weapon, the weapon can be fired repeatedly, without manual reloading, simply by pulling the trigger.
In Uvalde, hundreds of bullets were fired into classrooms in the first four minutes, according to Texas Department of Public Safety Director Steven McCraw.
Moore, who grew up in a family of hunters, owns firearms and is an avid hunter, has been outspoken in his opposition to civilians owning AR-15-style semi-automatic weapons and does not own any.
“The rifle that our military uses to fight our enemies is the same rifle that we allow civilians access to and we can create these mass shootings,” he said.
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An Emmett Till Moment
During my training in neurosurgery and the first years of my career, I did not encounter these types of injuries.
That's because between 1994 and 2004 certain semi-automatic firearms were banned.
In fact, it was in 2003, while I was covering the war in Iraq, that I first saw the damage these weapons do to the human body, not just a watermelon.
It was integrated with Devil Docs, the Navy medical team that provides frontline medical care to Marines.
There are things my cameraman Mark Biello and I saw on the battlefield that we still have a hard time talking about.
It's still hard to even write about them.
Limbs severed from the body and injuries so horrible I thought they must have been caused by a bomb or improvised explosive device.
I never imagined that just a couple of years later, I would see the same type of injuries in cities across the US, including my own, Atlanta.
Those are the days when I come home from the hospital simply unable to speak, let alone describe what I had just witnessed.
Still, as you may have read after the Uvalde tragedy, some people are now raising the question of whether we should have an "Emmett Till moment."
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Emmett Till was a 14-year-old black teenager who was kidnapped and violently murdered in 1955 by white racists in Mississippi after a white woman accused him of whistling at her.
Till's mother took the unusual step of holding an open-casket funeral and allowed a Jet magazine photographer to photograph her son's disfigured and unrecognizable face to show the country the aftermath of racial violence.
Many see that moment as a turning point in the country's collective support for the Civil Rights Movement.
Many of my colleagues have urged me to further describe the horrific injuries I have seen over the last nearly 20 years as a neurotrauma surgeon.
The truth is that I am not sure that the United States is ready to see that.
More importantly, it's not a decision anyone can make unless it's her loss and her story to tell, like Emmett Till's mom.
public health emergency
Louis Klarevas, Research Professor at Columbia University and author of the 2016 book "Rampage Nation," credits the 10-year federal assault weapons ban between 1994 and 2004 with significantly reducing the number of shooting incidents. mass injuries and fatalities (which he defined as injuring or killing six or more people) before recovering to even higher levels after the ban expired.
In 2020, there were an estimated 20 million AR-15-style guns in circulation in the United States, according to the National Shooting Sports Foundation.
Between 1990 and 1999, during the decade that I traveled to that shooting range with Hoff, mass shootings claimed an average of 21 lives per year;
from 2012 to 2021, that average had risen to 51, according to the Violence Project.
This organization defines a mass shooting as four or more people in a public place who are killed with firearms, without any underlying criminal activity, excluding the attacker.
(CNN defines mass shootings as those in which four or more people, not counting the shooter, are injured or shot dead during an event.)
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Federal data on the overall impact of gun violence is lacking.
Even getting the basic numbers can be a challenge, as I learned writing this article.
While the US Centers for Disease Control and Prevention (CDC) has data for covid-19 and even monkeypox, gun violence remains an enigma for the community of public health.
That's due in large part to the Dickey amendment that, in 1996, made it financially challenging and potentially punitive for the CDC to conduct or fund gun violence research if it were used in any way to further gun control. weapons.
Even today, it is organizations like the Gun Violence Archive, an independent data collection and research group that compiles information on gun violence from more than 7,500 sources daily, and not the CDC, that provides some of the up-to-date data and statistics. on gun violence and deaths on a daily basis.
The rise in gun violence is something that Dr. Bellal Joseph has seen firsthand.
He is the chief of the Division of Trauma, Surgical Critical Care, Burns and Critical Care Surgery at Banner University Medical Center at the University of Arizona.
"I can tell you from our own data, but also from a national perspective, there is no question that ... every trauma center in the country is seeing an unprecedented number of traumas," he said, referring to "violent trauma: more shootings, more victims".
"Mass shootings are more common in trauma centers than people really think," Joseph said.
"It often takes a high [profile] school shooting to activate the media, but it actually happens a lot more than we think, unfortunately."
Joseph, who in 2011 helped treat nine of the survivors of the mass shooting that targeted US House Representative Gabrielle Giffords, like any other surgeon we have spoken with, emphasizes that the injuries of AR-15 type semi-automatic rifles are not like other wounds.
"When you see ... victims of AR assault rifle assaults, what you're seeing is a violent crime against others," he said.
Stalemate in the face of rising violence
According to an analysis by the Institute for Health Metrics and Evaluation, the US ranks first in firearm homicides per capita among high-income countries of more than 10 million;
that's an age-adjusted rate 13 times that of France and 23 times that of Australia.
And, according to the CDC, the most recent data shows that firearms were the leading cause of death for children and teens up to age 19 in 2020, claiming more than 4,300 lives.
That was an increase of nearly 30% from 2019.
The deaths are only a small fraction of those affected.
The lives of those injured, the victims' families, friends and the wider community are forever shattered.
And if you need a reason to look beyond the human cost of gun violence, there's also the cost to society: According to a February 2021 report by Everytown Research and Policy, it's estimated at $280 billion a year, which includes medical, criminal justice and other expenses.
The American College of Surgeons, the professional organization that represents people who see these types of injuries too often, has called for tighter gun control and more sensible rules.
In 2018, the ACS Firearms Strategy Working Group published 13 recommendations that include items such as regulation of heavy firearms, more safety training, and greater recognition of mental health issues.
But the bipartisan legislation currently being considered in the House of Representatives falls short of these recommendations.
"There has to be some research and training," Joseph said, especially when it comes to weapons like AR-15-style semi-automatic rifles.
He pointed out that in order to be allowed to drive, a person needs many hours of training and practice to pass an exam and obtain a license: "nobody gets in a car and just drives."
As for objections that "government can't tell us what to do," says Moore, yes, citizens have rights, but they are not unlimited.
"We don't drive tanks down the street. We don't throw a grenade into parks... We need to have rational thinking," he said.
The same kind of rational thinking that Hoff impressed us with so many years ago at a shooting range in Ann Arbor, Michigan.
-- CNN's Andrea Kane contributed to this report.
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