Reservoir Masks – Low-flow Oxygen Delivery (Nursing)

by Rhonda Lawes, PhD, RN

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    00:00 Okay, now we got some mask with some accoutrement. So look at that. You can see in the picture we've got a mask, it's got a strap that goes around the back of the patient's head. It's got that tubing, that's the one that we would connect to an oxygen tank or to a wall outlet. And then it's got this rectangle at the bottom. That's actually a bag or what we call the reservoir.

    00:22 So these are how this work. They can either be a partial rebreather or a non-rebreather.

    00:28 These are both considered reservoir masks and what makes a reservoir mask a reservoir mask is, you got it, the reservoir, the bag on the bottom. The simple face mask, remember that, had no accoutrement, they had no reservoir. So, that's what makes a reservoir mask have that name. Kind of ever run that into that ground but I don't want you to forget it. Now, both masks resemble the simple face mask except they just have that extra bag. This mask delivers a higher concentration of oxygen for people who have some pretty serious respiratory complications. Okay, so if I'm lining this up in my mind, I'm going to start with a nasal cannula, the next highest would be a simple face mask, the next highest concentration of oxygen delivery would be a reservoir mask. You got it. That's critically important that you don't speed past that because nurses need to know which device provides the most concentration of oxygen. Why would I use one over the other? And you could base it on the variables that you see with that particular patient. Okay, so you got the feel for it. Nasal cannula, simple mask without accoutrement or reservoir. Now, we're going to talk about the 2 types of masks that have reservoirs. Okay, so a non-rebreather delivers the highest concentration of oxygen. Let's pause for just a moment, pay a little respect to the non-rebreather. So if I've got somebody who is able to breathe on their own but still needs a really high concentration of oxygen, this is my #1 choice because 100% oxygen can only be delivered with a ventilator or a super tight-fitting mask. So this one gives us a high concentration but it's not really going to be actually delivering 100% oxygen. A ventilator can do that because we have a tube in your mouth right down into your trachea and we can specifically deliver volumes and the external air is not messing us up. But with a mask that's kind of loose fitting, you'll have lots of gaps around that with a patient, you're not going to be able to deliver a pure 100% oxygen because of the mixing. Now, reservoir masks have one way valves. Okay, that's to stop the outside air from mixing. That's why they can deliver the highest concentration. Now I want you to take a look at this mask. You already recognized the tubing; you already recognized the bag, the reservoir; I want you to look at the mask. Remember we talked about the simple face mask, it had those exhalation holes on the side. Right? So when they breathe in, you also have air coming in the hole sometimes. Right? But then when you breathe out, the air went out the side. Now look at this mask. You see that the color is different. That's because the holes are there, that's so you can still exhale but there's a little cover. Now let me explain how that works. The cover is over those holes. If I breathe in, that cover is flat against those holes and all I'm going to be breathing in is air from that bag. So when I inhale, that's a very thin kind of rubbery plastic, it will close tight against those holes and the air I'm breathing is going to come straight out of that reservoir. But what's supplying the air in that bag? That tubing, the oxygen tubing. So by wearing this mask and having that special one-way valve on the side over those holes, when I breathe in these valves, they'll close tight and so the only place I'm getting air is from the reservoir. Okay? So I want you to slow down and make sure you have that concept. A one-way valve doesn't look very special, it's simple but it is functional. Same holes as in a simple mask, but you put a one-way valve over those holes. When you breathe in, they close; when I breathe out, they kind of flap and allow me to exhale out the side. That's why non-rebreather masking delivers such a high concentration of oxygen. Not perfect, but it's definitely better than a simple mask. So the non-rebreather, that's why it's a low-flow oxygen device with a very high FiO₂. Remember, it's that reservoir bag and that one-way valve that's the killer combo. The reservoir bag facilitates higher concentrations of oxygen and the one-way valve prevents the patient from inhaling expired air. Remember, you've got those valves on both sides of the mask. When the patient breathes in, those valves close and so the only air the patient's breathing is the air from the reservoir. When you exhale, they open and air goes out those holes. Non-rebreather, reservoir, and one-way valve. That's what allows you to have a low-flow oxygen device and a high FiO₂. Now we can set up between 10 and 15 liters per minute. Now again some people might debate this, but usually you want a flow of at least 10 liters a minute to fill that bag with enough volume to be inhaled. So we're going to do it about 10-15 liters which should be about 80%-95%. Remember, you can't get a perfect 100%. Why? Right, because this isn't a super tight-fitting mask. Now if you're the patient wearing it, you're going feel like it's pretty snug but there's going to be gaps around because it's just a universal mask, it's not fit particularly for that patient. Try not to keep patients on 15 liters for longer than you absolutely think is necessary because if we're overoxygenating a patient for prolonged periods of time, it can be harmful to them. Oxygen should be treated like a drug, has specific orders for it, and do your best if you walk in to a patient, start taking care of them, and whatever they're on be on the same page with the healthcare provider.

    06:47 Are we titrating up or down, don't just let things hang out for no reason. Always ask why is my patient receiving this treatment, is it appropriate, should we be weaning, should we be increasing? Remember that flow has to be as sufficient enough to keep that reservoir bag from deflating when the patient takes a breathe in. That's why I usually recommend a minimum of 10 liters.

    07:13 So, patients who are severely hypoxic, this is a good choice. But they have to be able to breathe on their own. So, hypoxic means low oxygen in their blood but they have be able to breathe on their own. This isn't going to help somebody who has had an opioid overdose. Right? At least not before we give them naloxone or the Narcan. So I have to be able to breathe on my own, but for some reason I have low arterial oxygen. Okay, let's walk through this one more time because I really want to make sure you have it. See how the tubing fills the reservoir bag so the oxygen delivers through the tubing into the reservoir of the bag. On inhale, that one-way valve is going to suck to the side of the mask and it's only going to allow the patient to get air from the reservoir, the concentrated oxygen delivered by the tubing. When I exhale, the one- way valve in between the mask and the bag will close. The one-way valve on the sides of the mask will open up and you expire air through that way. So we've got more than 1 one-way valve. Right? On the mask and in between the mask and the bag, they work at opposite times because when I go to exhale it's going to close in between the mask and the bag preventing my expired air from going into the bag and forcing my expired air to go out of the sides of the mask. It's really simple, but really ingenious. Okay, so let's compare the tubes, a partial rebreather and a non-rebreather. Now let's look at the parts that are the same. They both have mask, check check. They both have a connection between the mask in the bag, check check. They both have bags, check check. Now you can't see it here, but they both would have elastic straps so it help keep the mask on the patient's face. So, what's the difference between the two? It's all about the valves. Look at the non-rebreather. They have one-way valves on the mask and in between the mask and the reservoir. So, the partial rebreather allows for mixing of inspired and delivered oxygen, right. So because there's no one-way valve there, you can see that it goes both ways. So when the patient breathes in, they get air both from the bag and kind of mixing up in the air and when they breathe out some of that air will also down in the rebreather in the bag. So you've got the partial rebreather. The non-rebreather has a lot more control. It has the valves up here on the top and the valve in the tubing between the mask and the bag. So when you breathe in, these valves close so no air from the room comes in, this valve is open and I only get air the oxygen that's 100% oxygen from the reservoir bag and when I breathe out the valve in the middle closes so none of my expired air goes down in to the bag, it only goes out the one-way valves in my mask. So that's the difference. The difference between a partial rebreather and a non-rebreather are one-way valves, both on the mask and in the piece in between the mask and the reservoir.

    About the Lecture

    The lecture Reservoir Masks – Low-flow Oxygen Delivery (Nursing) by Rhonda Lawes, PhD, RN is from the course Supplemental Oxygen (Nursing).

    Included Quiz Questions

    1. People with serious respiratory conditions in need of higher concentrations of oxygen
    2. Clients who are not cooperative with receiving a nasal cannula
    3. Clients in need of low flow concentrations of oxygen
    4. Clients with non-labored breathing and clear lung sounds
    1. Ventilator
    2. Tight-fitting non-rebreather masks
    3. Nasal cannula
    4. Simple mask
    5. Room air with a pulse oximeter reading of 100%
    1. One-way valves
    2. Two-way valves
    3. Two prongs that deliver oxygen to the nose
    4. An extra oxygen port
    1. They can be set between 10 and 15 liters per minute.
    2. Prolonged periods of overoxygenating at 15 liters per minute can be harmful.
    3. Flow must be sufficient to keep the reservoir bag from deflating upon inspiration.
    4. They can be used for clients who are severely hypoxic but can ventilate well.
    5. They deliver an oxygen concentration of 40–60%.
    1. They lack a one-way valve to prevent expired air from returning to the client.
    2. A partial rebreather mask can deliver 100% oxygen.
    3. They are meant for delivering nebulizer treatments.
    4. Only a ventilated client will receive 100% oxygen concentration.

    Author of lecture Reservoir Masks – Low-flow Oxygen Delivery (Nursing)

     Rhonda Lawes, PhD, RN

    Rhonda Lawes, PhD, RN

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    By Mahziar K. on 05. February 2022 for Reservoir Masks – Low-flow Oxygen Delivery (Nursing)

    I am an MD and never learned the rebreather mask. This lecture helped me to know the oxygen delivery methods better.