Please Scroll Down to See Forums Below 
Here is something I found on another board that could be quite useful to people. Credit goes to GYMPHREAK and Blue Bayou of the respective board.
Alright....ive been reading the "injection into vein" thread and i noticed that alot of people are pulling the plunger back to a certain extend. Having been a hematoloy lab tech, and a phlebotomist, i am going to explain the "art" behind the perfect aspiration..
First, you must understand that the blood circulatory system is under pressure at all times within the vessels...so minimal vaccum should cause a draw effect.
Having said that, you must also realize that if you create too big of a vaccum with a syringe inside the needle, you will collapse the vein as you will suck the vein wall right against the bevel of the syringe and that will create a plunger effect.
NOW...since you know the above, now we can start explaining how to aspirate...
What one should do is either just use their finger and flick the plunger or push gently upwards (move the plunger no more than a millimeter) this vaccum draw should create a vaccum effect that you will end up with a fair bit of blood in the syringe already....If you pull to hard and too fast, you will just end up with no blood in the syringe because you created the plunger effect mentioned above...and youll just inject into the blood vessel.
Hope this clarifys how to aspirate...(im still half asleep from work lol...)
Good info GP. You know your stuff. One thing I'd like to add is the speed of injection. INJECT SLOWLY!
Sometimes if you are in or near a pierced vein, no matter what you do that vein will not allow you to draw blood- but may still accept fluid on injection. Its the same way when we start IV's. Very often, you are in the vein, but that vein will not allow you to draw a drop of blood, due to various reasons- collapse, small vein, veinous valves, rarely- even a clot or otherwise incompetent vein distal to the injection site, etc. Before pulling the catheter, we will usually try running fluid first- and what do you know but the IV flows freely into the vein many times! My point is, even if you aspirate properly and dont get blood, you could still be in or near a pierced vein that will accept fluid, so inject slowly.
The primary problem that you would worry about with an oil-based intravenous injection is the oil traveling as a single bolus to block one large branch of the pulmonary circulation and causing a pulmonary embolus from oil. Although this would be extremely rare, it could be fatal. This is much less likely to happen, even if you are in a vein, if you inject slowly.
A heart attack from oil embolism of the coronary arteries would not be a concern with this though, as the oil would not be able to reach that area as a separate constituent, unless there was an anomoly in the patients circulation. The oil would have to pass through the pulmonary capillaries first before reaching the aorta (where the coronary arteries branch off from), and by this time, it would be thoroughly mixed with the blood.
Alright....ive been reading the "injection into vein" thread and i noticed that alot of people are pulling the plunger back to a certain extend. Having been a hematoloy lab tech, and a phlebotomist, i am going to explain the "art" behind the perfect aspiration..
First, you must understand that the blood circulatory system is under pressure at all times within the vessels...so minimal vaccum should cause a draw effect.
Having said that, you must also realize that if you create too big of a vaccum with a syringe inside the needle, you will collapse the vein as you will suck the vein wall right against the bevel of the syringe and that will create a plunger effect.
NOW...since you know the above, now we can start explaining how to aspirate...
What one should do is either just use their finger and flick the plunger or push gently upwards (move the plunger no more than a millimeter) this vaccum draw should create a vaccum effect that you will end up with a fair bit of blood in the syringe already....If you pull to hard and too fast, you will just end up with no blood in the syringe because you created the plunger effect mentioned above...and youll just inject into the blood vessel.
Hope this clarifys how to aspirate...(im still half asleep from work lol...)
Good info GP. You know your stuff. One thing I'd like to add is the speed of injection. INJECT SLOWLY!
Sometimes if you are in or near a pierced vein, no matter what you do that vein will not allow you to draw blood- but may still accept fluid on injection. Its the same way when we start IV's. Very often, you are in the vein, but that vein will not allow you to draw a drop of blood, due to various reasons- collapse, small vein, veinous valves, rarely- even a clot or otherwise incompetent vein distal to the injection site, etc. Before pulling the catheter, we will usually try running fluid first- and what do you know but the IV flows freely into the vein many times! My point is, even if you aspirate properly and dont get blood, you could still be in or near a pierced vein that will accept fluid, so inject slowly.
The primary problem that you would worry about with an oil-based intravenous injection is the oil traveling as a single bolus to block one large branch of the pulmonary circulation and causing a pulmonary embolus from oil. Although this would be extremely rare, it could be fatal. This is much less likely to happen, even if you are in a vein, if you inject slowly.
A heart attack from oil embolism of the coronary arteries would not be a concern with this though, as the oil would not be able to reach that area as a separate constituent, unless there was an anomoly in the patients circulation. The oil would have to pass through the pulmonary capillaries first before reaching the aorta (where the coronary arteries branch off from), and by this time, it would be thoroughly mixed with the blood.
. Thats the point of aspiration.
