Need help with fetal monitoring

jrsmrs · Feb 17, 2010

Beat to beat variability refers to just what it says- the heart rate from one beat to another.

For example, my heart doesn't beat precisely every 0.8 seconds to get to 75 beats/min. There is a variability in that time span from one beat to the next, so it could be 0.59 sec-0.8-0.9-0.85-0.11, etc to end up at my average rate of 75/min. On the monitor, it would show my HR as 102-75-67 etc based on those fictional numbers.

In a baby, the monitor displays this as beats/min on a per-beat basis. So you will see 120-125-122-129-130-128, etc, averaging to a baseline HR of 120-something. These fluctuations are good. You don't want to see a baby whose HR is 120-121-120-120-120-121 etc. No real beat-to beat fluctuation there. The heart is basically beating at the exact same rate consistently, which it shouldn't be doing.

Long term variability are accels/decels that will show up as big spikes or dips on the monitor. So the baby might be going along as I said at 120-125-122-129-130-128, and then starts moving around and you might see a nice jump up to say 140-150 bpm and it will stay up there for a bit before returning back down into the 120s when baby calms down. Same with decels, but the opposite direction- HR might dip down into the 100s or whatever for a bit with a contraction, etc.

Hopefully that helps!

ETA: have you seen a FM strip? It's really very easy to understand if you just see it for yourself. You will see the little squiggles of up and down and then the big jumps and big dips every once in awhile.

bebahloo · Feb 19, 2010

thank you sooo much!! it makes sense now. my book is set up so weird it makes it seem that decelerations, acclerations are completely different but the way you explained it all goes together. thanks again!!