DRHOOK- The vapors: Blame the Vagus nerve for fainting

the handsome doctor John Hong of Charlottesville

Choir performances were always nerve-wracking for me when I was growing up, but in ninth grade we actually had something fun to do in a performance. We clapped our hands and stomped our feet, like a choo-choo-zam-bing! The risers were shaking as we did that, and suddenly the girl in front of me was down... as in down for the count!

I looked at our choir director. He stood there for a few seconds, and then walked over to our damsel in distress. She was sweaty, groggy, but evidenced no seizure-like activity (such as rigidity followed by shakes). 

He said, "Yep, she fainted!" So some folks carried her off the stage as the audience booed (kidding about the last part). 

What gives people the "vapors"?

Vasovagal syncope is the medical term for fainting– it relates to the nervous system's effect on the cardiovascular system. Huh? 

The Vagus nerve is part of the parasympathetic system. Basically it "relaxes" the cardiovascular system by slowing down the heart and easing pressure on the arteries. It's the most common reason for fainting. Everyone's heard about 300-pound football players who faint at the sight of a needle.

Prolonged standing, heat exposure, pain, and fear can all trigger vasovagal syncope. Usually before swooning, the person might feel like he's going to vomit. Also sweating and becoming pale are signs the vagal tone is up and ready. In the best situation, as the person is starting to faint, she realizes it and sits or lies down. Unconsciousness is pretty short lived, and upon awakening, the person is usually groggy.

Senior citizens who experience vasovagal syncope are more likely to have neurological or cardiovascular disease or may be taking medicines that make it easier for the blood pressure to drop faster than Enron stocks.

Hot under the collar? Well, in our neck lies the carotid sinus– a receptor on the carotid artery that senses pressure. When pressure increases, the carotid sinus slows the heart rate to lower the blood pressure, which can lead to a vasovagal episode.

Have you ever noticed if you're dehydrated and squatting down for a while, standing up makes you feel like you're going to keel over? That's because squatting pushes the blood up the body and stimulates the carotid sinus... lowering the blood pressure and heart rate. So when people stand up quickly and the blood pressure can't increase in time– "Oooh, will someone please catch me?"

I'm sure you know of one person who has fainted after using the bathroom. Urinating can stimulate the parasympathetic system! Maybe that's the origin of being "pissed off." 

Straining (called Valsalva) increases the pressure in the carotid bulb. So things like pooping, sneezing, coughing, weight lifting, and playing a brass instrument can causes a person to faint.

Swallowing can precipitate syncope— maybe that's why it can be really hard to swallow the truth. After eating, the parasympathetic system really kicks in, as well as blood flow to the GI system, so maybe that's a reason we aren't supposed to swim right after eating).

Susan Boyle didn't vasovagal during her amazing performance on Britain's Got Talent. She almost made the world, though, including this new fan. Wow, I wish there were a talent show for doctors, like "Doctor's Got Diagnosis– and Talent." I'd sing for Simon Cowell while doing a stress test on him– so he'd be too out of breath to say, "That was so karaoke."


Dr. Hook cracks a joke or two, but he's a renowned physician with a local practice and an interesting website, drjohnhong.com. Email him with your questions.