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:
- FiO2: 40%, and increase to main SpO2 >92% (or as specified by physician).
- VT: 6-10 ml/kg IBW (for Acute Lung Injury or ARDS use 6 ml/kg IBW)
- PRVC: 10-14 BPM
- PEEP: 5
- ABG within 30 minutes post set-up
- Automode: per RT discretion
- Maintain cuff pressure >20
- Suction and send sputum to lab
- Perform oral care Q2 hours
- elevate head of bed 40 degrees
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:
- Severe Pneumonia
- Chest trauma
- pulmonary embolism
- 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.