Cpap

preemieRNkate, RN · Jun 20, 2008

What do you mean? How it works?

elizabells, BSN, RN · Jun 20, 2008

And do you use bubble or vent? Those are two fairly different things. I'm more qualified to speak about bubble than vent.

Dachsielover · Jun 20, 2008

Thanks guys for responding. I would like to know the difference between vent and bubble cpap. Also, how does "back up rate" fit into everything. I wanted to ask my preceptor, but we were extremely busy. Thanks.

wee one rn · Jun 25, 2008

Here's how I've always thought of CPAP, I've worked mainly with the 'vent' CPAP and a little bit with the bubble.

The main purpose is to provide a continuous flow of air that causes some pressure in the lungs to help keep the alveoli from collapsing as the baby breathes. The higher the PEEP, the more pressure in the lungs. So, a baby is on a CPAP of 5, which means you will see on your vent a set PEEP of 5. Usually I've seen PEEPs set from 4-6 depending on how bad the baby's lungs are.

Now, back-up rates. Sometimes, the baby is still having apneas and needs a little bit more stim to help them remember to breath, or maybe there is a little bit of collapse and they need slightly higher pressures. I've seen this done in a couple of different ways.

#1- the rate is set to 10 and pressures are 8/5. This means that the baby is getting a PEEP of 5 all the time, and 10 times a minute the PEEP is increased to 8 for a short period of time. (I have no idea how long, I'll have to check with my RT next time I work, or maybe one of the other nurses can fill that in) This will help to expand the lungs a little more and for some babies that extra flow and pressure is enough to help remind them to breath more regularly. Theoretically, that small increase in PEEP isn't enough to force the baby to take a breath. I've seen backup rates generally set from 5-25.

#2- The other way that I have seen backup rates set is more similar to a PIP on a vent for an intubated baby with pressures of 15-20 which will actually cause the baby to take a breath, not simply increase the PEEP. In this case, the babies also generally have pressure support on so that when the vent senses that the baby is taking a breath, the pressure will increase from the PEEP to whatever the pressure support is.

IE- Rate-20, PIP-18, PEEP-6, Pressure Support-10. So, this baby will always have a pressure of 6, 20 times a minute the vent will force him to take a breath and give him a pressure of 18(PIP) and for every breath above the 20/minute, the vent will sense the breath and help him with it by giving the pressure support of 10.

The bubble CPAP I can't explain the details of, but basically the baby is getting a continuous PEEP of whatever you set it to, I've only seen it set at 5 or 6.

Whew! That was a lot and I just got home from a night shift so I hope that it made sense and helped! If anyone else can expand or clarify please do, hopefully someone can explain the theory behind why the bubble is better than the straight flow of mechanical CPAP.

SteveNNP, MSN, NP · Jun 25, 2008

With vent cpap, the circuit tubing is connected to a ventilator, which provides a constant flow of gases at a set peep. with NIMV/IMV CPAP, the vent gives a "breath" through the prongs at a set rate, usually 20 or something, depending on the baby's gas. The PIP is usually set higher than on an intubated baby, due to air leaking around the prongs. You adjust the set PIP to get an average measured PIP. Eg. you set it at a PIP of 22 to get a measured PIP of 18.

Bubble CPAP involves a bottle (we use 0.4% acetic acid solution) with the expiratory circuit tubing (blue) suspended to a depth of 5cm for a peep of 5. The inspiratory tubing is connected to a heater/humidifier and a flowmeter (usually set at 6 lpm.) when the prongs properly seal, the bottle bubbles, creating a theoretical "oscillator" like effect in the lungs while maintaining distending pressures of 5mmHg.

The success of these therapies depends highly on nurses. You have to constantly maintain a good seal, protect the septum, and keep their airway open, and free of secretions. You also have to get the air out of their stomach. With bubble CPAP, we have a success rate of around 45% with 23-24 weekers not ever having to be intubated here.