#After applying the thinner needle to my syringe and uncapping it

[that-ineffable-devil]

It's t-shot Tuesday, y'all! Woo!

[runpogorun]

I want to talk about Daredevil season 3, episode 4: ‘Blindsided.’

And no, not the incredible one-shot prison fight scene, what I want to discuss is the needle that goes into Matt’s hand immediately before the riot.

There are a couple of things here, that need to be looked at more closely. 

1. The needle itself, and how it penetrates Matt’s hand.

2. Route of administration.

3. The contents of that syringe and the dose Matt receives. 

So here we go.

1. The needle itself, and how it penetrates Matt’s hand.

In my experience, single use hypodermic needles are very, very sharp. They’re pretty easily blunted by such things as being inserted through the rubber bungs in multi-dose vials, or skin. My habit, as a vet, is to change the needle if I’ve drawn out of a couple of vials (because sometimes I administer drugs in combination), or if I think that the animal I’m about to inject will be particularly jumpy.

I treat a range of animals, including cows. Cows have thick hide (after all, we use it for leather) and a new, sharp needle is easy to insert quickly through skin and into the space underneath, with a little speed and force. It becomes much harder when the needle has been used a few times, which is one of the reasons I always use a new needle and strongly encourage my clients to do the same (bacterial contamination is another major reason, but that’s not what we’re discussing here.) The point being, that if I can tap a cow’s rump with the back of my hand a couple of times, then turn my hand over and drive a needle, held between my forefinger and thumb, in the skin up to the hub, it’s going to be easier to do the same in a human. I don’t think I’ve ever injected a human, but I’ve accidentally given myself needle sticks on occasion, and I’m comfortable in my assertion that humans have softer, thinner skin than cattle. Which is why this had me rolling my eyes.

[I.D.: A screenshot from the show, with a syringe and needle centre frame, pointing to the lower left. The tip of the needle is pressing against the palm of Matt’s hand. The barrel of the syringe is filled with clear fluid.]

That's a long needle, and not a particularly large gauge. At a guess, it's 21Gx1". Now, the thing that puzzles me is that the needle is pressing against Matt's hand, and presumably penetrating the skin, but not passing right through his hand. Does he have kevlar pads on his palms, in case of this situation? Very unlikely, and his hands looked normal when he was talking to Michael. Is the needle extremely blunt? If I was planning to attack and dose someone with a sedative, I'd make sure to use a new needle. Has the needle hit the bone? Entirely possible. With the force applied by these two people at this point, I'd expect the needle to pass right through Matt's hand and out the other side, due to its length, unless it's hit bone. Matt's not Luke Cage, so he shouldn't be able to stop the needle going through his hand. It's a good length of needle to go into a thigh or arm or buttock, but not so great for a thinner mass of tissue. 2. Route of administration Generally, we inject either intradermally (within the skin), subcutaneously (SC, into the space between skin and muscle, intramuscularly (IM, into muscle) or intravascularly (IV, into the vein). These different routes are chosen based on product used, volume injected, reactivity, speed of onset and difficulty of administration. For example, if someone is severely dehydrated and needs a litre of fluid, you're going to go IV because you can't squirt a litre into muscle without causing severe damage and pain. You're also going to place a catheter first, because that's going to be easier to manage than a needle. When it comes to sedatives and anaesthetics, route of administration affects time to onset of effect, and sometimes duration of effect. Some things can only be given IV, and some can only be given SC, for safety/ reaction reasons. Morphine given IV works more rapidly than morphine given IM, which in turn is more rapid than morphine given SC. Sometimes when you're injecting IM you'll hit a blood vessel, which can speed up the onset of effect. 

When you inject IM you're adding fluid to a space already occupied by muscle and blood, and usually enclosed by connective tissue. Muscles don't have a great capacity to expand, which is why you get that tight, pumped feeling when you're at the gym and you've been working hard. The size of the muscle you're going into affects the volume you can inject. The muscles in hands are small, and you can't get a lot in them. When the nurse attacks Matt he lifts his hand and strikes, aiming somewhere near Matt's face/ throat. I'm not entirely sure where he's aiming, but it makes for an angle that Matt can block fairly easily. If I was going to try to dose someone quickly with that volume, I'd probably go for their thigh, which is exactly what Matt does to an inmate a few minutes later. 

[I.D. a syringe and uncapped needle lying on a lino floor. The syringe contains clear fluid, and black volume markings can be seen on the barrel. There are some small drops of liquid on the floor by the needle.] The volume the syringe contains when it falls on the floor is approximately 7mL , and that's a 10mL syringe (you can see the volume written on the syringe in the first picture here). We don't know what it started off at, so Matt could have received up to 3mL. Assuming the needle has gone through the skin of Matt's palm (and he does later say that it has), but miraculously not straight through his hand, its tip has ended up either in muscle, under the skin, lodged in bone (owwww!) or in a tendon or tendon sheath (more owww). If it had gone into tendon, Matt would really struggle to do what he does during the rest of the scene, and would probably eventually be forced to seek medical treatment. Tendon injections are really terrible, ask me how I know. So, that aside, being injected into his hand is probably partly why he doesn't receive the full dose. 

3. The contents of the syringe and the dose Matt receives. We know he gets something but we don't know how much or what it is. Whatever it is, it does take the edge off a bit, acts fairly quickly and lasts a little while. The full dose could be 10mL, but I suspect is closer to 8mL. If Matt's around 80kg, that's 1mL/10kg, and he got a 1/8 dose. I'm completely guessing here, because we don't know what he got. But it does affect him. He shows signs of feeling the effects before the clinic door opens, so it's fairly rapid. And when he gets in the cab, 11 minutes later, he does look like he's struggling a bit with consciousness. At that point it's still light, but when we see regain consciousness, about to go into the East River, it's dark. So it's had a relatively prolonged effect. Of course, he's probably physically exhausted as well and could just be plain sleeping by the end of it, which would go some way to explaining why he isn't still very groggy - anaesthetic effects always take a while to wear off and I think it would take a lot of awareness to escape an underwater vehicle. 

[I.D. Matt sitting in the back of a vehicle, dressed in a suit and tie with blood on his shirt. He's not wearing his glasses, and has a concerned expression on his face, and fresh bruising around his right eye. It's dark outside and street lights are visible through the windows.] I've got some theories around what could be in the syringe, probably in combination, but as I said above earlier I'm a vet and some of the things I'm used to using would kill a human. And I don't know that this is the place to talk about that, either. Anyway, that's my thoughts on that scene, which doesn't sit right to me when I watch it. It's a pretty small thing in a season which was overall fantastic.