Med-Surg Respiratory System, part 3: Oxygen Delivery Devices, Hypoxemia/Hypoxia, Sleep Apnea
by Cathy Parkes August 18, 2021 Updated: August 09, 2023 6 min read
In this article, we'll explain the different oxygen delivery systems you will encounter as a nurse, and we'll cover what happens when you get too little oxygen (hypoxemia and hypoxia) or too much oxygen (oxygen toxicity). We'll also begin our coverage of respiratory system disorders with an overview on sleep apnea.
The Med-Surg Nursing video series follows along with our Medical-Surgical Nursing Flashcards, which are intended to help RN and PN nursing students study for nursing school exams, including the ATI, HESI, and NCLEX.
Oxygen delivery systems
Oxygen delivery devices are devices that deliver oxygen to a patient when, for a variety of reasons, they may not be able to breathe in enough oxygen on their own. Here, we'll cover the nasal cannula, simple face mask, partial rebreather mask, non-rebreather mask, Venturi mask, and an aerosol mask/face tent.
We'll list the approximate liters per minute that can be delivered using each device. Please be aware that depending on the textbook or the online source that you are using, these ranges can differ slightly.
A nasal cannula is an oxygen delivery device that consists of a small tube placed under the nose, and it's something you will see being used all the time in the hospital. Nasal cannulas deliver 1 - 6 L of oxygen per minute.
If your patient is getting over 4 liters per minute, it can be drying to the nostrils. Patients can be given a water-based lubricant inside the nose, and you can also attach some water to the device to humidify the air they receive.
Simple face mask
A simple face mask is an oxygen delivery device that consists of a clear mask that sits over the nose and mouth and has a tube attached to supply oxygen. A simple face mask delivers 6 - 10 L of oxygen per minute.
A face mask, of course, impairs the patient's ability to eat, drink, and makes it difficult for them to talk.
Partial rebreather mask
A partial rebreather mask is an oxygen delivery device that looks like a simple face mask but with a bag attached. The valve attached to the bag allows the patient to rebreathe some of their own air.
When you have a patient with a partial rebreather mask, you will inflate the bag that's attached to the mask about 2/3 full, and adjust the flow rate so the bag stays inflated at that amount. Do not let the bag deflate, because that places the patient at risk for suffocation.
A partial rebreather delivers 10 - 12 L of oxygen per minute.
A non-rebreather mask is an oxygen delivery device with a one-way valve so the patient does not inhale the same air they exhale.
A non-rebreather mask works similarly to a partial rebreather mask in terms of how you will operate it. Inflate the bag that's attached to the mask about 2/3 full, and adjust the flow rate so the bag stays inflated at that amount. Again, do not let the bag deflate, because that places the patient at risk for suffocation!
flow rate, with a non-rebreather, we're looking at about 10 to 15 liters per minute.
A venturi mask (also called a venturi device) looks similar to a simple face mask but has a special regulating tube attached. A venturi device provides the most precise oxygen delivery without intubation. It also provides high humidification.
A venturi device (referring to the special valve) can be applied to other masks. The flow rate when using a venturi device will depend on what mask it is applied to, but it's usually between 4 - 12 L of oxygen per minute.
Aerosol mask/face tent
An aerosol mask or face tent is a mask that is similar to a simple face mask, but it is projected outward so that it does not sit on top of the face, but hovers above the nose and mouth (it may touch the face on the cheeks and sides of face). A face tent is the best device for patients who have facial trauma because it does not touch the face. It provides high humidification.
A face tent has a high flow rate, usually over 15 L per minute.
Hypoxemia is insufficient oxygen in the arterial blood, less than 80 mmHg. And the way we would need to diagnose hypoxemia is through an arterial blood gas test. Low SaO₂ levels may indicate hypoxemia.
If you'd like to learn more about interpreting ABG results, check out our Arterial Blood Gas Interpretation Flashcards for Nursing Students.
Hypoxia is insufficient tissue oxygenation.
Arterial blood flow is what delivers oxygen to body tissue, so hypoxemia (low oxygen in arterial blood) can lead to hypoxia (low oxygen in the tissues). As a nurse, it is important to know the early vs. late signs of hypoxia.
Early signs and symptoms of hypoxia
Early signs of hypoxia can include restlessness, irritability, abnormal breathing, such as the use of the accessory muscles, nasal flaring, or adventitious lung sounds. The patient may also have tachycardia, tachypnea, hypertension, and pallor.
Late signs and symptoms hypoxia
If hypoxia continues, the late signs can include a decreased level of consciousness, increased lactic acid levels, which is lactic acidosis. The patient may also have dysrhythmias, bradypnea, bradycardia, hypotension, and cyanosis.
Oxygen toxicity is a condition resulting from receiving too much supplemental oxygen. Oxygen toxicity is a human-made issue, meaning that it would have to be from supplemental oxygen, like in a healthcare setting or oxygen used for underwater diving. You can't get oxygen toxicity if you are just walking around breathing normally!
If a patient is receiving assistance from an oxygen delivery device for their hypoxia, it's important to use the lowest oxygen flow rate possible. Using too high of an oxygen flow rate in this situation could lead to oxygen toxicity.
Signs and symptoms of oxygen toxicity
Signs and symptoms of oxygen toxicity include a nonproductive cough, nasal congestion, substernal pain, headache, nausea and vomiting, fatigue, and a sore throat.
Sleep apnea is a breathing disruption that occurs during sleep that lasts at least 10 seconds and occurs 5 or more times per hour. Sleep apnea can be obstructive or central.
The word apnea means the temporary cessation of breathing.
Obstructive sleep apnea
Obstructive sleep apnea is when sleep apnea is caused by an obstruction—the upper airways become blocked by overly relaxed airway muscles or by the tongue or soft palate.
Central sleep apnea
With central sleep apnea, the brain doesn't send the proper signals to the muscles that control breathing.
Sleep apnea risk factors
Risk factors associated with sleep apnea include obesity, large tonsils, and neuromuscular or endocrine disorders.
If you'd like to learn more about endocrine disorders, check out the Endocrine system section of this Medical-Surgical video series! These videos are made to follow along with our Medical-Surgical Nursing Flashcards
Sleep apnea signs and symptoms
Signs and symptoms of sleep apnea may include persistent daytime sleepiness or irritability.
In the video, Cathy shares an example of how her daughter had sleep apnea due to large tonsils, and she was very irritable during the day. She had her tonsils removed, and her mood greatly improved because she could sleep through the night!
Sleep apnea diagnostics
In order for sleep apnea to be diagnosed, the patient will usually need to undergo a sleep study, also called polysomnography. A sleep study is an overnight exam wherein a provider monitors a patient's sleep, with the assistance of other measurement methods like an EKG. They may count how many times a patient experiences an apnea.
The word polysomnography is easy to remember when you break it down into its parts. Poly- means multiple, -somno- means sleep, and -graphy means writing or recording. During polysomnography, multiple factors about sleep are observed and recorded!
Sleep apnea treatment
Treatment options for sleep apnea include continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BiPAP) — these are devices that a patient wears while sleeping that provide pressure to keep airways open. In addition, the patient may need to have their adenoids (tonsils) removed via a tonsillectomy.
Hi, I'm Cathy with Level Up RN. In this video, we are going to talk about oxygen delivery devices as well as hypoxemia and hypoxia. We're going to talk about oxygen toxicity, and then we'll start getting into our respiratory disorders, starting with sleep apnea. And at the end of the video, I'll give you guys a quiz and test your knowledge about some of the facts I'm going to be covering in this video.
Let's first talk about our oxygen delivery devices. For each of these devices, I'll share a rough liters per minute that can be delivered using that device. Just know that depending on your textbook or the source online that you're using, those ranges will vary across sources.
So first of all, a nasal cannula is something you see being used all the time in the hospital. It delivers between 1 and 6 liters per minute. If your patient is getting over 4 liters per minute, then it can be rather drying in the nares. So you can provide the patient a water-based lubricant using their nares, and you can also attach some water to humidify the air that the patient is receiving.
Then we have a simple face mask which delivers between 6 to 10 liters per minute. A face mask, of course, kind of impairs the patient's ability to eat, drink, and makes it difficult for them to talk.
And then we have our partial rebreather and our non-rebreather masks.
So the difference between these is that with a non-rebreather, there is a one-way valve such that the patient is not rebreathing the air that they exhale.
So with either of these devices, we're going to want to inflate the bag that's attached to the mask about two-thirds full, and we're going to want to adjust the flow rate such that that bag stays inflated about two-thirds full. We do not want to let that bag deflate because then that places the patient at risk for suffocation.
In terms of the flow rate, with a non-rebreather, we're looking at about 10 to 15 liters per minute.
With a partial rebreather, we're looking at between 10 and 12 liters per minute.
Then we have our Venturi device, and our Venturi device provides the most precise oxygen delivery without intubation. It also provides high humidification. In terms of the flow rate, it will depend on what mask that Venturi device is applied to. So it usually varies between 4 and 12 liters per minute.
And then finally, we have our face tent, which is good for patients who have facial trauma. It provides high humidification, and the flow rate will be pretty high, usually over 15 liters per minute.
Next, let's talk about hypoxemia and hypoxia.
Hypoxemia is where we have insufficient oxygen in the arterial blood. So it will be less than 80 mmHg. And the way we would need to diagnose hypoxemia is through an ABG, or arterial blood gas.
Hypoxia is insufficient tissue oxygenation. And as a nurse, it's going to be important for you to know the early signs of hypoxia versus the late signs of hypoxia.
Early signs can include restlessness, irritability, abnormal breathing, such as the use of the accessory muscles, nasal flaring, or adventitious lung sounds. The patient may also have tachycardia, tachypnea, hypertension, as well as pallor.
Now, if hypoxia continues to the point where we have the late signs of hypoxia, these late signs can include a decreased level of consciousness, increased lactic acid levels, so lactic acidosis. The patient may also have dysrhythmias, bradypnea, bradycardia, hypotension, and cyanosis.
So when we're giving oxygen to a patient, we always want to use the lowest oxygen flow rate in order to manage the patient's hypoxia.
We don't want to give them too much oxygen, or else, they can have oxygen toxicity. Signs and symptoms of oxygen toxicity include a nonproductive cough, nasal congestion, substernal pain, headache, nausea and vomiting, fatigue, and a sore throat.
All right. Now, we're going to transition to talking about respiratory system disorders, starting with sleep apnea.
Sleep apnea is defined as a breathing disruption that occurs during sleep that last at least 10 seconds and occurs 5 or more times per hour.
So the causes of sleep apnea include obstructive causes and central causes.
With obstructive sleep apnea, the upper airways become blocked by overly relaxed airway muscles or by the tongue or soft palate.
With central sleep apnea, the brain doesn't send the proper signals to the muscles that control breathing.
So risk factors associated with sleep apnea include obesity, large tonsils, and neuromuscular or endocrine disorders.
Signs and symptoms may include persistent daytime sleepiness or irritability. So my daughter had huge tonsils, just massive, and she was very irritable during the day. We ended up taking them out, and as soon as she was recovered, she was a brand-new person. She was getting sleep, and it wasn't really impairing her airway during the night.
So in terms of how we diagnose sleep apnea, we would do so with a sleep study.
And then treatment options include a CPAP, which is continuous positive airway pressure, or BiPAP, which is bilevel positive airway pressure. In addition, the patient may need to get their adenoids out or their tonsils out through a tonsillectomy, which is what we had to do for my daughter.
Okay. Time for a quiz. I have three questions for you. First question. Which oxygen delivery system provides the most precise oxygen delivery without intubation? If you said a Venturi device, you're correct. Question number two is a fill-in-the-blank question. Restlessness and irritability are blank signs of hypoxia. The answer is early. These are early signs of hypoxia. Question number three. With sleep apnea, the patient has a disruption in sleep that last at least blank seconds and occurs more than blank times per hour. If you said 10 and 5, you're correct. I hope this video has been helpful. If so, be sure to like the video and leave me a comment. Take care.
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