Polite Dissent

Manhunter #11 “Manhunted, part 2: Chasing the Dragon”
Marc Andreyko, writer
Diego Olmos, penciler

Manhunter Kirk Depaul is lured into a fight with a villain named Dumas. At a key point in the fight, Dumas stabs Depaul in the arm with a syringe.

DEPAUL: A hypodermic? Filled with what? Succinyl chloride? Arsenic? Cyanide? It’ll take more than any of that to kill me! Or didn’t you know that I have a healing factor?
DUMAS: Oh, I knew…that’s whay I injected you with an air bubble. The massive stroke you’re having right now should kill you — albeit painfully — in a few minutes.

The question before us today is whether a syringe-full of air injected into the arm could cause a stroke. The answer: very, very doubtful.

First, it’s unlikely that Dumas would be able to inject the air directly into a blood vessel. He’s just blindly stabbing the syringe into the upper arm — and through Depaul’s shirt, at that. It can be tricky to find a blood vessel even when you’re looking for one (as anyone who’s given blood knows), so the odds of Dumas finding one while stabbing blindly during a fight is very low. In addition, Dumas is pushing the syringe straight in – so even if he does find a blood vessel, he’ll probably go right through it and into the muscle.

Dumas will most likely just inject the air into the arm muscles. It’ll be painful for Depaul, but not deadly, and it wouldn’t lead to a stroke.

There’s a small chance that Dumas could inject the air into an artery. Even this wouldn’t cause a stroke. The air bubble would travel with the blood flow down the arm, but become trapped as the arteries get narrower and narrower. Depaul would end up with a blocked artery in the arm, stopping the blood flow from reaching a finger or two, or maybe even the entire hand. This would be extremely painful and render the hand useless, but it wouldn’t be deadly.

It’s also possible that Dumas might manage to inject the air into a vein. In this case, the air bubble would travel with the blood flow back to the right side of the heart and then out into the lungs. The air bubble would become trapped and block the pulmonary circulation. This is a type of pulmonary embolus, which is very painful and quite often deadly.

None of these situations would lead to a stroke in Depaul. That’s not to say that air bubbles can’t cause strokes: there are some very rare and specific circumstances where an air bubble can lead to a stroke. Air injected directly into the carotid artery would cause a stroke. Additionally, just like in a glass of soda, air bubbles have a tendency to rise. In the body, the flow of the blood keeps most bubbles from rising. Studies on SCUBA divers suggest that small bubbles (think soda again) have the greatest chance to fight the current and rise up to the brain and cause a series of small strokes. At the opposite extreme, a large air bubble can entirely block the pulmonary circulation, which would cause the blood to back up and increase the pressure on the right side of the heart. If the pressure builds up enough, and if a person has a small hole between the two sides of their heart, then this increased pressure can send the air bubble from the right side of the heart to the left side of the heart and then into the arterial circulation and the brain. Bear in mind that holes in the heart like this are uncommon and this situation requires an air bubble of at least 50cc.

Dumas would have been better off using poison.

Final thoughts:

• It looks like Dumas is using a 20cc syringe.
• Succinyl Choline is a paralyzing agent. Arsenic and Cyanide are both infamous (and deadly) poisons.
• There are no pain sensors within the brain, so despite what Dumas says, strokes aren’t painful.
• If Depaul is having a stroke, why is he clutching his chest?
• I suspect that Dumas managed to inject the air bubble into a vein, which led to Depaul developing a large pulmonary embolus. The art supports this, with Depaul clearly grabbing his chest in pain.
• Here’s a nice page for teenagers that deals with air bubbles in the blood.