Med-Surg Respiratory System, part 13: Mechanical Ventilation
by Cathy Parkes August 27, 2021 Updated: January 03, 2022 6 min read
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.
When you see this Cool Chicken, that indicates one of Cathy's silly mnemonics to help you remember. The Cool Chicken hints in these articles are just a taste of what's available across our Level Up RN Flashcards for nursing students!
A mechanical ventilator is a machine that helps a patient breathe (ventilate) when they cannot breathe on their own, often when they are having surgery or during a critical illness (ARF, severe hypoxia, respiratory fatigue, etc.). The patient is connected to the ventilator with a hollow tube that serves as an artificial airway. This tube extends through the mouth down into the main airway or trachea.
Mechanical ventilation improves gas exchange and decreases the work of breathing until the cause of respiratory failure can be identified and corrected.
Mechanical ventilator have two types of alarms: low pressure alarms and high pressure alarms.
Low pressure alarms
Low pressure alarms are due to leaks, which may be caused by disconnection, a cuff leak, or tube displacement.
Low pressure alarm = Leak.
High pressure alarms
High pressure alarms are due to an increase in pressure and may be caused by a variety of things, including pulmonary edema (excess fluid in the lungs), pneumothorax, bronchospasm (a tightening of the airway smooth muscle marked by a wheezing cough), biting (the tube), secretions blocking the airflow, coughing, and possible kinks in the tube.
The Cool Chicken pneumonic to help remember this long set of possible causes of a high pressure alarm is:
2 PB sandwiches can make you SiCK.
A mechanical ventilator has many settings. If you plan to work in the ICU, training is key to ensure you are comfortable with operating a ventilator.
Respiratory rate (f)
Respiratory rate is the number of breaths per minute that are delivered to the patient (the “f” stands for “frequency”). The most usual setting is between 6 and 20 breaths/minute.
Tidal volume (VT)
Tidal volume is the volume of gas that is delivered with each breath (usually 6 - 10 ml/kg).
Inspiratory flow rate/time
Inspiratory flow rate/time is the speed of VT delivery (usually between 40 - 80 L/min, 0.8 - 1.2 sec).
Pressure limit is the maximum pressure of VT delivery, usually 10 - 20 cm H2O above peak inspiratory pressure.
Fi₂O (fraction of inspired oxygen)
FiO2 is the O2 concentration of the air being delivered to the patient. This can vary between 21% ("room air" or the typical concentration of the oxygen we breathe) and 100%.
I:E ratio is the duration of inspiration to expiration (inhaling and exhaling). That ratio is typically 1:2 or 1:1.5, that is, the expiratory time is about twice as long as the inspiratory time.
Positive end expiratory pressure (PEEP)
PEEP (positive end-expiratory pressure): This is the pressure that is applied at the end of ventilator-assisted expiration to distend the alveoli and prevent collapse (usually 5 cm H2O).
These are some best practices for nursing care of a patient who is mechanically ventilated:
- Keep a manual resuscitation bag (bag-valve mask) and reintubation equipment (two different tube sizes) at bedside.
- Regularly assess the patient's level of consciousness, their vital signs, breath sounds, pulse oximetry, and ABGs.
- Suction any oral and tracheal secretions as needed.
- Reposition the ET tube every 24 hours (or more frequently). This is to prevent skin breakdown — a tube simply resting against the mucosa can cause damage (e.g., a pressure injury).
- Provide the patient with frequent oral care in order to reduce bacterial overgrowth.
- Monitor for complications such as ventilator-associated pneumonia (also called VAP). Other complications include volutrauma (overdistension of the alveoli due to PEEP), and cardiac compromise (for example, hypotension, or low blood pressure).
- After extubation, encourage the patient to take deep breaths, cough, reposition themselves, and make use of an incentive spirometer.
Hi. I'm Cathy with Level Up RN. In this video, we are going to talk about mechanical ventilation, and at the end of the video, I'm going to give you guys a little straightforward quiz to test your knowledge of some of the facts I'll be covering in this video. So mechanical ventilation improves gas exchange and decreases the work of breathing until the cause of respiratory failure can be identified and corrected. So we're going to go through the different types of alarms that you will hear with mechanical ventilators, and then we're going to talk about the settings, and then nursing care with mechanical ventilation.
So we have low pressure alarms and high pressure alarms. Low pressure alarms are due to leaks. So low pressure, leaks; both start with L. Causes include disconnection, cuff leak, as well as tube displacement. Then we have our high pressure alarms, which is due to an increase in pressure, which makes sense. So there are a variety of causes of a high pressure alarm, and they can be hard to remember, so luckily for you guys, there's a member of the Level Up RN community who provided this little saying to help you remember them all. So she wrote in: "Two PB sandwiches can make you sick." So two peanut butter sandwiches can make you sick. So we have our two PB. So two Ps include pulmonary edema and pneumothorax. The two Bs include bronchospasm and biting. And then with sick, S-C-K, we have secretions for the S, cough for the C, and kink for the K. So, "Two PB sandwiches can make you sick" will help you remember the first letter of all of the key causes of a high pressure alarm.
Next, let's talk about some of the settings that we'll see with a mechanical ventilator. And obviously, if you're going to be working in the ICU, you should get training and precepting so that you're very comfortable with operating a ventilator. So I'm going to go through some of the settings here on the flash card, but not every single one. So we have respiratory rate. This is the number of breaths per minute that are delivered to the patient. Then we have the tidal volume, or VT, as it's abbreviated, and this is the volume of gas that is delivered with each breath. Then we have our FiO2, which is the fraction of inspired oxygen, and this is the O2 concentration of the air that is being delivered to the patient, and it can vary between 21% and 100%. Then we have our I:E ratio. This is the duration of inspiration to expiration, and that ratio is typically 1:2 or 1:1.5. Then we have our PEEP, which is the positive end-expiratory pressure. This is the pressure that is applied at the end of expiration to distend the alveoli and prevent collapse.
All right. Now let's talk about best practices for nursing care of a patient who is mechanically ventilated. So at the bedside, we want to have a manual resuscitation bag as well as reintubation equipment, which includes two different tube sizes that are readily available. Then we want to regularly assess our patient's level of consciousness, their vital signs, their breath sounds, as well as their pulse oximetry and their ABGs. We want to suction their oral and tracheal secretions as needed. And then we need to reposition their ET tube every 24 hours or more frequently to prevent skin breakdown, because if that tube just rest there against the mucosa, it can cause damage and a pressure injury, and then that would be a hospital-acquired pressure injury. We want to provide our patient with frequent oral care, and we want to monitor for complications such as ventilator-associated pneumonia. And then after extubation, we want to encourage our patient to take deep breaths, cough, and use their incentive spirometer.
All right. Time for a quiz. I have three questions for you regarding mechanical ventilation. First question, excess secretions will cause what type of alarm? If you said a high pressure alarm, you're correct. Question number two, what should be kept at the bedside for a patient who is on a mechanical ventilator? The answer is a manual resuscitation bag as well as reintubation equipment. Question number three, a cuff leak will cause what type of alarm? The answer is a low pressure alarm. All right. That is it for this video, and that is it for the respiratory system. So I hope this video series has been super helpful for you guys. If so, be sure to subscribe to our channel, share a link to your classmates and friends in nursing school, and leave me a comment and let me know what you liked best about these videos. Thank you so much for watching.
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