Why cannot give IV medication via artery?

Pets to People · Jun 8, 2012

Backtoyou2011 said:
To the question about running tpn into a UAC, this is something that we will not do in our NICU unless in an emergency where no other access is available.
In terms of a neonates circulation, in an ideal situation it is not different from an adults. The uac is no different than a central artline in an adult except where its inserted. The umbilical arteries are connected to the descending aorta. The catheter in a UAC ideally ends in the high position in the aorta between t6 or t9 or the low position at around L4 in the descending aorta.
Once a child is born they no longer have fetal circulation because you change the pressure of the whole system when you cut the umbilical cord from the placenta and kiddo takes their first breaths ,it makes the path of least resistance through the lungs and not to bypass then through the ductus or foramen ovale. So in response to neonates having fetal circulation the answer is technically no because there is no placenta providing oxygen, their lungs are. So the aorta is carrying (in an ideal situation) oxygenated blood from the lungs ( provided they are working well) away from the heart just like in an adult.
Where a premature infants circulation might differ is that the may have patent ductus or a foramen oval or many other heart defects that causes shunting of blood similar to fetal circulation or immature lungs that lower the oxygenation of the blood within the artery. But in terms of running meds into the aorta of a neonate, not the best route due to the same reasons listed by many other posters. Also UACS aren't used for more than 7 days at a time so you really wouldn't want to be relying on it for any long term infusions.

Thank you for clearing that up! I understand that fetal circulation/cutting the cord/change of pressure and all that jazz, but I was thinking that if fluids and other substances were still being infused through the cord then the change of pressure with the cutting of the cord would not have happened and thus fetal circulation would stay intact.

So let me think here...you would give anything via the umbilical artery because that is flowing out of the cord away from the body, the med would be given via the umbilical vein which is headed to the liver and vena cava thus it will be filtered and reach general circulation?

Backtoyou2011 · Jun 9, 2012

Correct, kind of. Once you separate babe from mom the umbilical arteries are no longer connected to the umbilical vein ( no placenta anymore).

So a Med infused into the Cather will distribute via the descending aorta. I think what maybe confusing you is the difference between a UAc and a UVC. To be clear an umbilical arterial catheter is separate from an umbilical venous catheter. So if a baby were to have both (not likely but for explanation sake) we'd have fluids going through the UVC because you're right it circulates meds better an it's safer. The uac would be hooked to a transducer and only be used for abgs and other labs and monitoring pressure. Hope I made sense kind of tired, lol!