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Sunday, August 24, 2008

Ventilator protocol: Setting up pt. on ventilator; and some information about EtCO2 monitoring

As I've been writing about the past few posts, we have a so-so Ventilator protocol here at Shoreline, and we are currently in the process of updating it.

Just for the record here, the ventilators we use are the Servo 300A and the Servo i.

While the majority of the protocol is actually an extubation protocol, we also have the ability to wean FiO2 to maintain an SpO2 of 92%. Which is nice, because before we used to have to sit on an SpO2 of 100 on a specified FiO2 all night long. Now I can wean it down as low as necessary.

This has got to be better for the patient, considering the hazards of oxygen therapy.

So, basically, when setting up a ventilator, we can pretty much determine the most appropriate respitatory rate, FiO2 and tidal volume for the patient based on the protocol, as opposed to just making up numbers.

Here are the initial vent settings per protocol:
  1. FiO2: 40%, and increase to main SpO2 >92% (or as specified by physician).
  2. VT: 6-10 ml/kg IBW (for Acute Lung Injury or ARDS use 6 ml/kg IBW)
  3. PRVC: 10-14 BPM

  4. PEEP: 5

  5. ABG within 30 minutes post set-up

  6. Automode: per RT discretion

  7. Maintain cuff pressure >20

  8. Suction and send sputum to lab

  9. Perform oral care Q2 hours

  10. elevate head of bed 40 degrees
There's a little more than just ventilator settings there, so allow me to explain.

First, our doctor who is championing the protocol has decided that lower tidal volumes are safer for patients than the 10-15cc/kg IBW that is taught in RT school. Actually, people with normal lungs may use 10-15cc/kg IBW, but it's better to be on the safe side with lower tidal volumes.

Likewise, studies have shown lower tidal volumes to be equally effective ventilation.

As per another hospital's ventilator protocol: "Recent literature has shown tidal volumes in the range of 7-10 cc/kg to be effective in ventilation while reducing the risk of barotrauma."

So, the going trend is to start low and increase as indicated, based on ETCO2 (see below) and SpO2 or ABG.

PEEP of 5 is a good place to start, and increase as indicated or as directed by a physician. I discussed PEEP studies a few days ago.

Along with an ABG, an X-Ray should be completed within 30 minutes. Soft wrist restraints as needed, Ativan as needed, NG, etc. are also included in the protocol.

While this is not a ventilator weaning protocol per se, the ability of the RT to turn on automode allows us to basically switch the patient over from PRVC to volume support. In VS, the patient determines his own flow and pressure support.

For the most part, in the aspect, we RTs are allowed to change modes, so long as the mode we choose to change it to is VS. The funny thing is, I think a lot of doctors have little understanding of automode, as even while the patient may have been in Volume Support for three days, some of our doctors continue to order for rate and tidal volume changes thinking that's what the patient will get.

Now this is fine, so long as they understand the changes are in order to maintain a minute ventilation, as opposed to guaranteeing the preset rate and tidal volume.

It can be safe to say that once the patient switches himself to volume support, he has taken the first step in the weaning process.

Basically, the pressure support in volume suport mode can be measured by subtracting static pressure from peak pressure. If PIP is 20 and static is 15, then the pressure support the patient is drawing in is 5, which is actually a good number. Anything under 10 is good. If a patient is sucking in more than 10, then you may be safe to assume the patient is not weanable.

Automode is nice for the patient, because as he wakes up, he is able to actually control the vent, instead of the vent controlling the patient. This was a big selling point for us in choosing to purchase the Servo vents.

When I explain the ventilator to nurses and patients, I tell them that it is "state of the art life support technology, and it actually has a brain that senses when the patient is ready to breath on his own."

And, when the patient stops breathing on his own, the vent will automatically switch back to the PRVC mode. And then back to VS after the patient takes three consecutive spontaneous breaths.

I wouldn't always turn the automode on. If the patient had a cardiac event, or if the patient is not breathing effectively on his own, I would keep the patient in PRVC.

Basically, once the patient is in automode, and stays there, the weaning process is started. The initial vent settings are assuring the patient maintains the desired minute ventilation, but otherwise determining his own settings.

While in school we were taught that the cuff pressure should always be maintained at less than 20 to make sure the circulation to the arteries are not cut off. However, with new research, it has been learned that most patients are intubated for such a short period of time now, that this is less of a concern.

As I've written about before on this blog, the average stay on a ventilator has significanly decreased since the advent of microprosessor ventilators that allow the patient to control the vent instead of the other way around.

So, now we want the cuff pressure to be >20. The reason here is we want to prevent VAP. Also, to prevent Ventilator Acquired Pneumonia (VAP), we make sure that we clean the oral cavity as often as possible. Our protocol recommends Q2 hours. Usually this job is shared between RTs and RNs.

Then, so we can prove later that the patient had pneumonia prior to being placed on the vent, or to prove that we caused it later on, we obtain a sputum as soon as possible and send it to the lab.

Also, we want to make sure the head of bed is elevated to protect the airway, and prevent aspiration, which is another VAP preventative measure.

Ultimately, however, "the guidelines listed above should be considered a starting point for most patients. Adjustments to rate, tidal volume, or inspiratory time should be made according to disease process or as changes in the patient's condition warrants. Closely monitor BP, HR, RR, EtCO2 (as needed), SpO2, and breath sounds for changes in patient status."

Shorter inspiratory times and longer expiratory times may be indicated for some asthma and COPD patients to prevent air trapping.

EtCO2 should be monitored on all ventilator patients. A normal EtCO2 is 40, however the EtCO2 should be coordinated with the ABG so it can be monitored instead of doing ABGs.

There are some conditions that may alter EtCO2 and cause it to read lower than the actual ABG due to shunting. These include:

  1. Asthma

  2. COPD

  3. Severe Pneumonia

  4. ARDS

  5. Chest trauma

  6. pulmonary embolism

  7. decreased cardiac output

This is progress based on the latest studies. If you guys think our data is wrong, or if you have new information to add here, please feel free to respond. We RT are continuously trying to stay up to date, or to stay ahead of the curve.


Anonymous said...

I'm actually surprised that FIO2 titration is not up to the RT. Our pulmonologists always encourage us to wean the O2 as long as the SPO2 holds 92%<. The only doc who says otherwise is this one trauma surgeon we have, he prefers fixed FIO2s at 40% on the neuro traumas. It used to be at 60%, but somebody reminded him of the dangers of O2 toxicity.

On vent settings, our only other protocol is add PEEP+5 unless hemodynamically unstable, since ER docs and post op patients don't usually come with PEEP added. Talk about having basilar atelectasis on the CXR...

Rate, tidal volume and PEEP >5 are up to the physician's discretion. They are always open to suggestion and depending upon the therapist, they will order what you, the RT, thinks what might be beneficial to the patient.

Weaning trials and SBT's, now that's a completely different scenario...

Glenna said...

Sounds like you guys are on your way to a nice protocol. I am lucky at my hospital that those who started 10 years before me worked long and hard with our pulmonology group to set our protocols several years ago. It's such a nice workign relationship now that we have primary responsibility for running our vents. The pulmos never even give us starting or stopping settings. They just say "Vent per protocol; wean to extubate" and that's usually the only order we get unless we ask for help. Not that the pulmos don't read our charts or discuss and suggest with us, just that they trust us because we've proven over the years that we can do it. I'm very grateful to have that trust and that freedom because there are times on night shift where it's really convenient to be able to shift into Bivent when a patient needs it or do recruitment maneuvers or whatever is called for. As to Peep we and our pulmos are very pro Peep and we start out at 10-12 (or more if needed) and wean from there. Our favorite mode is Pressure Control with Automode unless, like you said, there's a reason the patient shouldn't be in Automode because that and weaning that pressure support (rather than the volume support of PRVC) is the quickest way to tell if someone's ready for transition.

We're also lucky to have a very aggressive Non-invasive protocol. Most of our docs will try BiPap before vent if at all possible and I've seen a lot of patients come back from pH's a lot lower than what we were taught in school for automatic intubation. It's really a beautiful thing to see when a mask and aggressive settings can save someone from a tube.

Freadom said...

We do not have a vent management protocol like you describe as of yet, but that's what we plan on working on next. I'm not quite sure if our doctors are ready to let us have that much control. Howver, it's possible.

Our doctors too like to use BiPAP to try to prevent the need for a vent. I've seen BiPAP work on pHs as low as 6.9 and CO2s as high as 116. Like you say, unlike what we learn in school, being out of the normal ranges doesn't guarantee a vent anymore.

Glenna said...

You guys will get there as far as your protocols. I'm really enjoying watching you go through these changes since I came along after my co-workers who've been at our hospital for a decade longer already fought "the good fight" that allows me the freedom to do my job and really THINK on the job. I think it's a fabulous thing to see that your docs are even willing to work with you all on it.

Don't let the hiccups get to you, though. I've heard horror stories about how some of our surgeons went head to head with our pulmos trying to NOT give us those protocols but after a couple of years of us proving over and over again that we can take care of their patients BETTER, now they trust us.

It's a great feeling to have the docs tell the nurses "put the RT on the line....what do you think we should do?" I mean, that is such a vote of confidence that it makes me work harder to be the best damn RT I can.

Hang in there. You guys are going through an incredibly wonderful growth process right now and I'm jealous that you get to be a part of it!

Freadom said...

You know what, it is cool to be part of it, even if my job has basically been on the writing and designing end of it.

The next step is going to be to incorporate an RT Consult. Now achieving that will be the ultimate dr. RT relationship.

Yes, I agree with you, there is no better feeling when the dr. says, "Get RT on the line."

It's progress like this that makes it all seem worthwile all the extra research we have been doing around here. We RTs are privy to so much knowledge from our excellent RT schooling, and from experience on the job, it would be a true shame (crime) not to tap into it.

Glenna said...

I agree. That is the kind of progess that makes it all worth it. We do learn so much that I love being able to be a real advocate for my patients. Hey, if I wanted to be an M.D., I would have gone to medical school. I LIKE being an RT and doing my job and I love it when they step back and let me do what I was trained to do. You know what I mean?

Glenna said...

Oops, I think I forgot to say that you'll find that the rest of the areas of the job will get easier as those protocols are put into place and prove effective. We have the same kind of BiPap protocols. We do have to have a doc order, but again, they never specify anything more than "BiPap as needed" and a lot of the docs if they think there might be a respiratory problem down the road will write in the original orders "RT to Assess/Treat; standing BiPap order IF needed." Talk about saving time. Because of the success in critical care it's also opened up our Assess/Treat protocols so that we can order the ABG's and stat CXR on the floors if needed so we have that info in hand when we call the doc in the middle of the night to discuss metabolic, BiPap, or Intubation intervention.

It makes our life easier and their lives easier. I think your docs will find that they really like having you guys there more "on their side" than ever before. And you'll find that it's seriously morale boosting. :-)

Freadom said...

I wrote once (click here) about the irony of being to do whatever we want to do with BiPAP, yet when it comes to the vent we have limitations. It good to know how well protocols work at other hospitals. I often use testimonials like yours as good material to try to convince people around here. Thanks.

Glenna said...

I agree with you that if you can run a BiPap effectively, then you can run a basic vent. It's only really different to the docs. They are both ventilation, the only differences are the machine to patient interface (mask/tube) and that the vent has more tools to use, mean more bells and whistles.

By the way, we use the same vents. We use Servos too, only we use exclusively "i"s, along with oscillators, and then we run jets in the NICU as well as the other two vents.

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