Technology. Gotta love it.
NICU nursing is very much about the technology. We have a machine for just about everything. OK, nobody has perfected the baby-butt-patter yet, but pretty much everything else.
I've been a NICU nurse for over 25 years, so I've seen lots of changes in the technology. IV technology, for example. When I started in NICU, nearly all the IV's were started in the scalp with a steel needle called a butterfly. It has little plastic "wings" to help stabilize it, hence the name. Now, we almost always use a tiny flexible catheter. It has a stylet (special hollow needle) in the center, but we take that out once the catheter is in place.
Scalp veins are still the largest, most stable veins in a newborn, but if the baby has hair, you end up shaving and that's disturbing to the parents.
Also disturbing to the parents is the thought that the baby could be injured by the catheter. They know we use a needle to place it, and some of them either forget or don't know that the needle comes out and only a flexible tube is in place. More than once, I've been asked about the risk of "that needle" getting into the baby's brain. That wasn't a problem when we DID use needles, and it certainly isn't a risk with the catheters. Scalp vein placements don't bother the babies, but they do bother parents, so we try to avoid them if possible.
New babies who are seriously ill or very tiny may have a conventional IV, but they will also have some sort of central venous catheter as well. The easiest to place are the umbilical catheters. It's not exactly a simple matter, but when things go well, it's possible to have a catheter placed in the umbilical vein and one of the 2 umbilical arteries fairly quickly. Those give central venous and arterial access without making any incisions or even puncturing the skin.
We use the umbilical arterial catheter(UAC) to measure blood pressure and to take blood samples to measure oxygen and carbon dioxide content in the blood as well as acid-base balance. We also get the majority of our blood counts and blood chemistry samples from the arterial line.
The umbilical venous catheters (UVC) are used primarily to provide fluid and high calorie IV feedings. One of the most important advances for the UVCs is the double-lumen catheter. It has 2 separate tracks and that allows us to give 2 totally different fluids at the same time. When there isn't a UAC, we can get blood samples from the UVC, but this is much less common. UAC and UVC have been around NICU's longer than I have, but the technology has been upgraded.
Another huge step forward was the development of the neonatal-sized PICC - percutaneously inserted central catheter. This is a longer, flexible catheter placed through a fairly large peripheral vein. It is long enough to reach the large blood vessels in the chest that flow into the heart. It can be left in place for weeks, unlike the conventional IV catheters which usually have to be replaced after a few days (when we're lucky). Those come in single-lumen and double-lumen catheters as well. The physician or nurse practitioner decides based on the length of time the baby is likely to need the PICC and the reason she needs it.