Q: How long does it take for someone to die if their carotid artery is compressed?
A: The two carotid arteries lie in the front of the neck on either side of the trachea (windpipe) and carry blood from the heart to the brain. They supply 90% or so of the brain’s blood, with the rest coming from the two small vertebral arteries that travel along the spine and over the back-most portion of the brain. The carotids are interconnected in the brain so that in a normal individual compressing a single carotid artery will have little effect. Compressing both can cause a loss of consciousness in 15 to 20 seconds and death in 2 to 4 minutes.
One general rule in medicine is that if the heart stops, the victim will lose consciousness in about 4 seconds if standing, 8 if sitting, and 12 if lying down. This simply reflects the effects of gravity on blood flow. These numbers would also mostly hold true if both carotids were suddenly pressed shut—not easy to do—see below. But, to the brain, the complete interruption of blood flow through carotids would look the same as it would if the heart had stopped. Either way, the brain would receive no blood supply, and the brain needs a continuous supply of blood to function and survive.
Another medical truism is that dizziness, loss of consciousness, and sudden death are simply gradations along the same scale. That is, what makes you dizzy can make you lose consciousness, and what makes you lose consciousness can cause death. One of the things that can do this is compression of the carotid arteries. Brief compression, can cause dizziness, longer compression can cause loss of consciousness, and even a longer period of compression can cause death.
A major variable in play here is how severely the arteries are compressed. If only partially collapsed, the victim might have no problems. Severe and almost complete compression can cause loss of consciousness and death in short order. And anywhere in between. Significant and potentially deadly compression can result from strangulation–either manual or ligature–hanging, or an aggressively applied choke hold.
So, depending upon the nature, force, and duration of the compression, your victim could have no symptoms, become dizzy, lose consciousness, or die. Or could progressively move from one of these to the next. The time required for death could be a couple of minutes or many minutes if the compression is less severe or intermittent. As the victim struggled, he could intermittently release the strangle or choke hold and this would prolong the ordeal.
All these variable means that you can have it almost anyway you want. The killer could overpower the victim, render him unconscious in 20 seconds, and kill him in 2 minutes. Or the struggle could go on for many, many minutes. It’s up to you.
Fritz Strobl MD
July 9, 2011 at 9:11 pm
Nice subject review. I used Carotid Sinus Massage in my novel Presidential Migraines(c) to defeat a foe. When we used to do “direct stick” carotid angiography years ago, we used to compress the opposite carotid to look for contralateral collateralization. Always a concerning time not just for the compression causing decreased flow but knocking off a plaque on either side either with the needle or the compression itself.
J.D.
July 11, 2011 at 6:04 am
If the carotids were stopped up, would that be a factor? As I write this next part, it seems a given—a 70 year-old would require less compression and less time than a 20 something?
D.P. Lyle, MD
July 11, 2011 at 7:02 am
Yes that’s true. The old, young, weak, or sedated have either less muscular necks or a reduced ability to defend themselves and are more susceptible to strangulation and carotid compression.
Fritz Strobl MD
July 14, 2011 at 11:45 am
Generally yes, older patients are more susceptible. I agree with Dr. Lyle. A lot depends on collateralization – read about Circle of Willis. And then, what are you doing to their trachea?
Eloise Hill
July 11, 2011 at 10:12 am
Didn’t know about the 4, 8, 12 second rule—very interesting. I read an article, many years ago, about a jounalist who did an interview with a Vietnam vet who suffered from severe PTSD. At some point in the interview, he became agitated and attempted to strangle the journalist. She barely managed to avoid lapsing into unconciousness and escape but the article stated she suffered chronic “health effects”,with no details. Any idea what those would most likely be?
D.P. Lyle, MD
July 11, 2011 at 10:15 am
The 4, 8, 12 rule is very general and in the end whatever happens, happens. She could have suffered some brain damage for lack of oxygen for a while, or an neck or larynx injury from the trauma, or it could simply be lawyer speak for give me some money. But I wax cynical.
Maria von Ruhtenberg
May 1, 2013 at 5:30 pm
If a person is drunk would it take less time to die from strangulation?
D.P. Lyle, MD
May 2, 2013 at 7:54 am
Not really. Strangulation results in the restricting of blood flow thru the carotid arteries to the brain leading to death. Alcohol in the blood would have no real effect on this situation.
Christopher Valen
May 10, 2013 at 1:10 pm
I have a perpetrator in the new John Santana novel I’m working on who is skilled in judo. Would a properly applied choke hold leave external evidence and/or internal evidence that could be found during an autopsy?
D.P. Lyle, MD
May 10, 2013 at 1:40 pm
Both in most cases. External bruising and perhaps some internal bleeding into what are called the strap muscles of the neck.
Christopher Valen
May 10, 2013 at 2:16 pm
Thanks for the quick reply. I appreciate it.