Category: Research Methods

ABG collection Part 2

by Drvinnyt, posted in Graduate School, Methods, Research Methods, Thesis

Preparation for my study begins at 7am, for the subject usually arrives at 8:30/9pm and lots of stuff needs to be done.

For blood collection we need to heparinize the syringes to prevent clotting in the samples. A little bit about heparin: Anticoagulants – How It Works

Anticoagulants are complex organic or synthetic compounds, often carbohydrates, that help prevent the clotting or coagulation of blood. The most widely used of these is heparin, which blocks the formation of thromboplastin, an important clotting factor in the blood. Most anticoagulants are used for treating existing thromboses (clots that form in blood vessels) to prevent further clotting. Oral anticoagulants, such as warfarin and dicumarol, are effective treatments for venous thromboembolisms (a blockage in a vein caused by a clot), but heparin is usually prescribed for treating the more dangerous arterial thrombosis.
In this case, this heparin was derived from porcine intestinal mucosa, and we plan to give little to none of it to our subject, again just for sample quality purposes.
The back room, dubbed the post-doc room, has been partially converted to become a psuedo-clean room. This is where the sterile prep will happen, where the arterial lines will be inserted and eventually removed. Prior to the study we had the floors stripped and cleaned, and after every study I wipe down ALL surfaces with antiseptic (Lysol)
 

Everything all setup… except for our subject, who forgot their shoes at home…

I should say from here on out there will be less pictures, as more pressing matters were at hand. Any pictures with the subject included will be blurred to protect their confidentiality.

The blue luer-lock 3-way stopcocks were assembled on the 3ml syringes, and then heparin was flushed in and out of each, making sure no air-bubbles remained in the syringe. Why might bubbles be a problem?
Well, since our primary measures involve arterial pressures of O2 and CO2, introduction of an atmospheric air bubble would increase PaO2 and decrease PaCO2, since PatmO2 ~ 150 torr, and Patm CO2 is nearly 0.
In the next post I will talk about Arterial-Alveolar Oxygen Difference, how and why it increases with exercise, and how we measured the above using these blood samples.
Til’ next time!

Collecting arterial blood samples during exercise, Part 1

by Drvinnyt, posted in Graduate School, Research Methods, Thesis

My apologies for the long absence of blog entries. Update on the study, we have finished collecting data on 6 subjects, and we believe that will be enough to show significant differences in the various measures we are collecting (more on that later). Disclaimer: Please note that all of these procedures were done under the supervision of highly trained professionals and arterial lines must be placed by a board licensed physician. All information included on this blog is for your information only, and is not intended to be an instructional guide.

Here’s a blog entry with some exercise physiology content in it for you…. This is compiled Arterial Blood Gas data from the subjects who have participated in our studies. ABG collection is fairly simple if it is a single sample, requiring a bit of local anesthetic and usually a fine (25ga) needle and 3ml syringe, or larger if needed. The problem with this:

1) We aren’t doing just 1 ABG collection, we are doing 16.
2) We are collecting during exercise, and sticking our subject with a needle 16 times while they are riding at their ventilatory threshold will be challenging and exasperating to both subject and physician
3) Since exercise increases core temperature, pressures of Oxygen and Carbon Dioxide will fluctuate. (Remember PV=nRT from physics and chem)

So the answer is to cannulate the artery (radial artery) so we can have unobstructed and frequent access to the arterial blood. To answer the temperature issue, we place a sterile temperature probe inside a piece of extensioin tubing, and it will record temperature while the blood flows past it during collection. Other data we can collect by using a radial artery catheter: direct arterial pressure measurement and direct heart rate measurement.

The procedure itself is substantially more complicated than placing an intravenous line (IV), and requires quite a bit of sterile setup and equipment. Directly from my checklist:


Exercise-SVI Study
Arterial Catheter Supplies

General prep (Set up night before):
1% lidocaine
4×4 sterile gauze (1 pack)
4×4 non-sterile gauze
Betadine pads (6)
Alcohol pads (9)
16G needle
18G needle
25G needle
Non-sterile gloves –large for Peter, Box of medium
3M micropore tape
3M bandage wrap
5 mL syringe (1 slip-tip)
10 mL syringe (3 luer-lock)
Tourniquet
Atropine sulfate – 1 mL
0.5 mL syringe
Double male luer-lock connector (1)
Razor
Bandaids (3)
BioZ electrodes
Digital thermometer + covers
Stopwatch
Extra chux to go under patient’s arm
Biohazard trash and Sharps containers
Temp Probe and box
Extension tubing with hub for probe

 

Check Crash Kit: Advanced Cardiac Life Support

 

 

 

 

 

 

Arterial line:
20G BD angiocath (2)
500 mL saline (1)
3-way stopcocks (2 white locking w/ swivel male)
6” extension tubing (Included with Transpac IV Monitoring kit)

 

 

 

 

For sample collection:
3 mL syringes – luer-lock (17)
3-way stopcock (17)
Sterile gloves – Vince size 8

Sterile field
10 mL syringe – slip
Heparin
16G needle
Labeling supplies (masking tape and sharpie)

This is it for now, will post the setup procedure next time!

-Vince

Back to the Grind!

by Drvinnyt, posted in Graduate School, Research Methods, Thesis

So I’m back in SD. And a ton of work to do before we start data collection on Aug 20th. I haven’t updated very much on the progression of my thesis, but here is where I stand.

We’ve conducted VO2Max tests on 8 Subjects, 6 Males, and 2 Females. I’ve had to drop 3 of them for various reasons. But here are the data on the 5 subjects I’ve got scheduled so far…. Take note of the category 1 cyclist weighing 137.3 lbs and putting out 453 watts!

Next week is the fun part. Because there are at least 12 people who will be involved in the collection of data, Kim suggested that I put together a visual timeline to organize people, and to distribute this so everyone knows exactly where they are supposed to be and what they are doing. Well, 3 hours later and 4 revisions yield this: The master blueprint 😛 Anyways, back to more work.