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Monday, February 23, 2015

Ventilators Explained Extremely Easy

Ventilator, student nurse, nurse, ICU, ARDS, vent, peep, lungs, simv, assist control, endotracheal tube, breathing tube, code blue, hospital, respiratory therapist, doctor

Ventilators Explained Extremely Easy

I don't think I'm alone when I say I have no freaking clue what PEEP, SIMV, AC, IMV, FiO2, etc means when I'm getting report.... I do now. So don't flip. 

But I remember what it was like when I had my first patient on a ventilator. What are all those settings? We had only had a one hour lecture on this stuff, once. Oh god! I'm so lost!!

Breathe easy {pun intended} I'm going to try to make this as pain free as possible.

Ventilator Settings

Ok here's some vocab so you'll understand the settings on the machine. Also, as the nurse, you're probably not adjusting anything on the machine except the silence button or 100% O2 because you're about to suction the patient. Respiratory Therapists and physicians should be the ones messing around with these machines. But I like to know EVERYTHING, so therefore, this post was born.

  • PEEP- Positive-End Expiratory Pressure- This is pressure that is used to keep the alveolar sacs from completely collapsing as the patient exhales. Remember how we want that for our patients experiencing ARDS? It's normally set between 5-10.
  • Respiratory Rate- Well, you should probably be able to figure this one out. This is the rate of breaths per minute that the patient takes. On a ventilator we may be controlling all of the breaths of the patient, therefore, we're controlling how many times the patient breaths per minute. Sometimes the patients can over breathe the vent, sometimes they can't. This setting is the MINIMUM amount of breaths a patient will take in a minute. The patient can't under-breathe this setting. Is that a word? I'm making it a word if it's not.
  • FiO2- is the amount of oxygen that the ventilator delivers. Remember that room air is 21% (think back to the percentages of our atmospheric gases). If your patient is in really bad shape, the higher the percentage of oxygen will be. For instance my patient with ARDS the other day had been on 80-85% and was weaned down to 40-50%.
  • Volume Control- is when the vent is set to deliver a certain preset amount of oxygen (Tidal Volume). Tidal Volume can be set anywhere between 400-800. 
  • Pressure Control- is when the vent is set at a peak inspiratory pressure (PIP) to be delivered with each breath vs a set amount of volume. I don't really see this often. It's used with infants. I don't work with infants. I just wanted you to know that there are two types of control- Volume, and Pressure. Pressure control guarantees a set amount of pressure but allows the Tidal Volume to fluctuate. In Pressure control you can have air-trapping and there is no clinical trials shown to support its use in adults. 

Ok. Now that we kind of know the basics of everything let's move on. 

When do we intubate?

Well, I've read several sources and so far the thing I like most is the 50/50 rule. When a patient's PaO2 is below 50 and the PaCO2 is above 50. This is just a general guideline, but I liked it. 

There is an art to ventilators. Nothing is really set in stone. Each patient is different. So we might intubate based on the 50/50 rule. We might intubate when the patient is breathing more than 35 breaths a minute, when the pH is acidic (below 7.25-ish range). 

Good news is that you won't really be making that decision. Yay. But certainly if your patient is showing signs of respiratory distress you need to call the physician, or a rapid, whatever. Your patient has to breathe, yo. 

I'm drinking soda... sorry. I get a little wonky.

Modes of Ventilation

For the sake of not overwhelming you- or me- I'm only going to talk about the more common modes that I see used. 

  • Assist Control Ventilation (AC or ACV)
  • Controlled Mandatory Ventilation (CMV)
  • Synchronized Intermittent Mandatory Ventilation (SIMV)
  • Intermittent Mandatory Ventilation (IMV)

Assist Control Ventilation

A set tidal volume and respiratory rate. The patient is able to over breathe the vent. When the patient over breathes the vent it senses it and delivers a fixed amount of tidal volume. If the patient is too weak to take spontaneous breaths, the vent will deliver a set amount of respirations.

You'll see this setting when patients are working on being weaned from the vent. Or weak patients. It's a common setting for the vent initially. 

Pros- It doesn't result in atrophy of the respiratory muscles like other settings can produce. It lets the patient change their rate of breaths when their body is detecting changes in CO2. Our bodies are so cool.

Cons- Can cause hyperventilation, and can decrease cardiac output. Look out for Respiratory Alkalosis.

Controlled Mandatory Ventilation

Delivers a set tidal volume and respiratory rate. The ventilator does ALL the work. Patient needs to be sedated or paralyzed. 

Pros- If the patient is apneic, the vent does all the work.

Cons- Doesn't permit normal spontaneous breathing, cannot adjust to PaCO2 demands (if it increases patient isn't able to increase the rate of respirations), and can cause respiratory muscles to atrophy.

Synchronized Intermittent Mandatory Ventilation

A set tidal volume is delivered at a set rate in synchronization of the patient's on initiated spontaneous breath. If the patient under breathes the vent- it will initiate a breath. If the patient over-breathes the vent it will not supplement the breaths with a set amount of volume. 

Pros- less stacking of breaths than IMV. Patient can exercise respiratory muscles. May improve cardiac output. 

Cons- May fatigue the patient's respiratory muscles. Respiratory Acidosis may occur. 

Intermittent Mandatory Ventilation

Delivers a set tidal volume at a set rate that is set at the lowest setting to support and maintain appropriate ABGs. The set tidal volume will be delivered regardless of the patient's efforts or timing of the patient's respiratory cycle.

Pros- Allows patient to do some of the breathing. Having some control can reduce anxiety which will lesson the need for sedation. Less likely to produce barotrauma from increased pressure. 

Cons- Ventilator peak inspiratory pressure (PIP) must be set <10 cm above the patient's PIP to prevent stacked breaths. Stacked breaths refers to when the patient breathes and the ventilator also breathes on top of each other. This could produce barotrauma if not set appropriately. 


Ok. That was a doozy of a post.
This was just a "quick" overview. By no means is this anywhere near detailed what it could be, but this is meant to help nurses understand the gist of ventilators. I'll try to post some common problems with ventilators later- such as ventilator assisted pneumonia.  

Respiratory therapists and physicians will handle the majority of the ventilator care, however I think it's always best to know as much as you can. Let's be honest, who's the one talking and explaining stuff to the patients and families? The nurses. So the more you know, the better you'll be at speaking to them and explaining the disease processes of the patient. 

The more informed people are the less anxiety they have. Anxiety manifests from fear of the unknown.


You might also want to check out my ebook for $3.99 Easy Guide to Interpret Acid-Base Imbalances. If your patient is on a ventilator, then you'll be drawing ABGs every 6 hours or more. This is a quick guide to teach you once and for all how to interpret those lab values. It took me four different teachers, in four different classes before I FINALLY had all the pieces and had that "Aha!" moment. It's cheaper than your lunch, and you don't even have to have a kindle to read it! 

Do you see other ventilator settings commonly used on your units? What are they? Leave me a comment below!!




  1. Thank you! have an exam soon and this helped me.

  2. ( accelerated BSN student at Villanova)

  3. Nursing school is very challenging and even more so in an accelerated program. Kudos to you! :)

  4. Ventilators are type of machine that helps people breathe or breathes for them by removing the carbon dioxide from the lungs and replacing it oxygen. It can be used during surgery, during treatment for a lung disease, or for short- and long-term life support. Nurses, doctors, respiratory therapists, home care nurses, and nurses at long-term care facilities, among others, should know how to use a ventilator. Taking ventilator training classes is a good way to learn how to use this piece of equipment.

  5. I was an oncology nurse for almost two years, I recently took a job in the SICU. I was confident in my old job- chemo certified, research chemo drugs, blood administrations every single day, critical lab values that were 'normal' to us, neutropenic precautions/studies- and confident enough to ask for help when I needed --and that I could comprehend what the answer meant!! My new job?! I wanted to cry!! I wrote all these numbers and abbreviations down, recapped my notes, asked what they meant (obviously it was not broken down like this, they basically just clarified what the settings were on) THANK YOU for saving my sanity!!! Your article was the exact words that were going through my head!!

    1. Anon, I understand how you feel. I was incredibly overwhelmed as a student nurse in the MICU. And of course, you ask questions but no one really breaks it down. And they often make you feel like you're one inch tall for not knowing something that is pretty complicated. I'm sure a respiratory therapist could explain all of these things even further. I know this was a simplified article, but still I think it's somewhat helpful. I am so glad that you enjoyed it. Good luck to you in your new job as you transition! Which, btw, I know NOTHING about chemo, giving chemo, or accessing ports. So go you! Medicine and nursing has become so specific and departmentalized. You'll have that confidence back in no time! Thanks for reading. :)

    2. It is good to hear someone elses's experience. I was also confident in my old job and went to an ICU and a year later I am still unsure and feel like an idiot! but becoming a smarter idiot if that makes any sense. Thanks for the lesson. Trying to understand vents better. Jodi

  6. When you go overseas and work in this area, YOU will be very necessary in the ventilated person care, no respiratory therapists, although the intensivist will be competent with ventilators, mor junior medicos will look to you for guidance.

  7. Call the rt to explain to the family they are trained extensively in the area of mechanical ventilation.

    1. Oh I agree 100%. But I do know that in the settings I've been in sometimes respiratory or the doctors aren't easily accessible to go speak to the patient and their families so the poor nurse is being bombarded with tons of questions. Sometimes I tell those families, "I've said as much as I feel comfortable speaking about. I don't want to say something wrong, or confuse anyone, so I've asked the doctor, practitioner, etc. to come speak to you as soon as possible." That usually does the trick. I try to know as much as possible so that I can answer the questions my patients' families have, but I am FAR from being an expert.

  8. This comment has been removed by a blog administrator.

  9. "there is no clinical trials shown to support its use in adults."

    Please, read the post above. References would be most helpful here and have your work peer checked before publishing. I'm no expert (i.e. RT) but sounds like some more discovery is necessary. Good luck.

  10. Thank you for this, Just sat in a 2 hour class on this and was still so lost. This helped break it down a bit more. Also I tired to click on the link " Respiratory Problems in Intensive Care" and it took it to an unknown site. Just wondering if there is another way of accessing it?

    1. Oh bummer. I wrote this about a year ago. I didn't realize that site no longer existed. Thanks for letting me know and thanks for reading. I know this is kind of basic ventilator stuff but I thought it helped me organize my thoughts and process things better. So why not share it with others? :P I'll search around and see if I can find some other websites since that link is now broken. Have a great day! :)

  11. I will be starting nursing school in January and I am looking for any and all help I can get. I currently work in An ICU as a patient care tech and it's nice to know what the nurses and docs are talking about when assessing our vent patients. We do tend to see quite a bit of pressure support settings though. Very interesting. Thank you!!!!!

    1. Congratulations on starting nursing school!!! You are already going to know so much and will continue to learn so much by being a tech in the ICU. My last clinical rotation was in an ICU and I learned so so so much. I'm no longer on an ICU but I am thankful for how much that experience taught me. Check out these posts for some helpful tips:

      Good luck to you!!

  12. Info is wrong and /or outdated. We set vTe for adults lower than 400cc regularly. Doesn't mention pressure support mode at all, difference between AC and SIMV etc.

  13. Info is outdated. There is no mode that locks the patient out from breathing (what you call controlled mandatory ventilation). There are no hard and fast rules on when to use a certain setting. Mostly physician preference. Tidal volume is usually 5-10 ml/kg, based on ideal body weight. I am an RT.

    1. Agreed. I'm an RT. Always ask an RT before touching the settings as well, THEY'RE HAPPY TO HELP. We would much rather help then be paged to a code blue. Adjusting things without knowing the in's and out's of mechanical ventilation can very well be life and death. I assure you, you will not be bothering anyone if you ask for help. If they are bothered they probably shouldn't be in the healthcare field.

  14. My friend went into cardiac arrest 7 weeks ago and I preformed CPR but he coded 3 more times by the time he arrived at hospital, he's a quadriplegic, he was diagnosed with double phenomenon and his only kidney he has left failed, he's on hemodialysis but he's not yet been able to be weaned off the ventilator , he's been trying to talk through the trachea tube, he will have to go to a rehabilitation center for his lungs and his kidney. How does it look to you, is he going to pull through, thank you, very concerned

  15. Please read my questions above

  16. I am an RRT and work with vent patients daily. There is a lot of inaccurate information here. Please consult an RT or pulmonologist/intensivist before giving incomplete/inaccurate information to other nurses.

  17. I am an RRT and This article is COMPLETELY INACCURATE!!!!!

  18. This article is dangerous and innaccurate. Nurses beware. Many of the explanation are just simply wrong. The writer should have had her article proof read and corrected by a
    Respiratory Therapist. Nurses if you want a ventilator class or explanations this is not it!

  19. Another Respiratory Therapist here to chime in. I agree with my fellow therapist there are many inaccuracies in your article. As such I would recommend that your fellow nurses get their information regarding ventilators from a pulmonologist or a respiratory therapist. While you are well intentioned, you are not as well educated in the use of ventilators as Respiratory Therapists are and they can give a more detailed and accurate explanation of the different modes of ventilation and when they are most often used.

  20. I am a RT and have been for quite some time. I mangage 25 weekers and end of lifers with just about chronic everything. There is some great info in this article, but 90% of what I have read makes me cringe. There is a lot and I me A LOT of false info in this article. They call me the RT GURU where I work. If you are unsure of something, your next step should be finding the most seasoned staff member that still does
    Patient care, and pick their brain. Us RTs love to teach.

  21. Ouch, this info is very outdated.