Intravenous Catheter / Infusion needle in Dorsal [Hand or Foot] Vein to measure   which can cause them to relax or tighten. 8 times
These two tests are always done back-to-back: hand one day, foot the next.  As if the study description above isn't doomsday enough, they actually strap us to the beds for this one, because it's tremendously important that you DO NOT MOVE.  We are wheeled into a dimly lit room full of equipment, then wrapped with Velcro straps, which are secured to keep us in one spot.  

The crossing guard fashion statement

One member of the team will use a needle to insert a small plastic tube through the skin, and into a blood vessel.  I'm fairly lucky in that it usually only takes one quick jab to find a prominent vein.  The back of the hand doesn't feel much different from a blood draw from the inner arm or forearm, and none of those yield more than a trifling sting.  

However, the needle stick atop the foot HURTS LIKE A WORD I CAN'T TYPE if I want to hang on to my PG-13 rating here.  On the first try, blood spurted out of my foot and then the vein closed entirely so they had to puncture me twice.  By the second insert attempt, I was gripping the bed, barking: "WHOA, how about them Red Wings, huh!?"  Anything for a distraction.  It helps if someone keeps talking to you while the tube is adjusted, because it smarts for a few minutes.

Ouch ouch ow ow ow ow ow... 

After the tubes are taped, they raise the arm or leg off the bed in a ramp and position pillows and towels all around.  Wraparound cuffs (see the blue canvas + tube above) are placed on the leg and upper arm, which are use throughout the procedure to measure blood pressure or constrict as needed for whatever they are testing at the time.  

Electrodes attached to wires are placed on the chest and stomach so that heart rate and rhythms may be observed throughout the duration of the procedures. Also, a transducer is held over the particular vein in a metal clamp, so they can gather stable images in 2-D and 3-D ultrasound.

Michael's snazzy shirt says "NASA JSC Cardiovascular Laboratory"

Several medications that cause blood vessels relax or tighten are infused, alone or in varied combinations, through the plastic tube.  They are experimenting with:
  • Nitroglycerin
  • Ketorolac
  • Phenylephrine
  • Isoproterenol
  • Acetlycholine
  • NG-Monomethly-L-Arginine ("L-NMMA")

The amount that the blood vessel opens or closes in response to the counter-measure medications are determined and recorded by the ongoing ultrasound. The amounts of the meds are extremely small only cause effects on the blood vessel in the area where it is given. 

After we are initially clamped in, we subjects usually tune out and just try to stay as still as possible while the science teams do their work.  A laptop is leaned over our field of view, and we bring DVDs to watch over the 3-to-5 hour duration.

Pretty spine-tingling, huh?  You can see why they do more of this on the ground than in the space station!  By the time these are over, every part of the body is stiff, and sometimes it's a challenge just to stay awake.  When you get your hand or foot back, it tingles for awhile, and sometimes the IV stings a bit more coming out than it did going in.  Did I mention no food or water?  But they feed you within minutes of exit... then you can return to your busy and rewarding day of... lying down someplace else ;)