Noninvasive Ventilation Clinical Guide
Traditional oxygen therapy is delivered using a nasal cannula or loose-fitting oxygen mask. However, the rate of airflow through these devices is limited, which limits the amount of oxygen that can be delivered to the patient over a given period of time.
On the other hand, the noninvasive ventilation (NIV) interface (usually a face mask, but sometimes a nasal mask or even a helmet) is tight-fitting, which means that there is less leakage of oxygen from the mask. The air pressure delivered by NIV is also higher, meaning that more oxygen can be delivered to the patient over a given period of time.
So, NIV can be used to deliver high levels of oxygen to your patients in respiratory distress or failure without requiring the use of mechanical ventilation (an endotracheal tube and ventilator, which is much more invasive, painful and uncomfortable for the patient).
This Clinical Guide covers the basics of NIV: What is it? How does it work? Who can benefit from NIV? Who should not receive NIV? Check out the articles below!
An overview of noninvasive ventilation
There are two main methods of noninvasive ventilation (NIV)—continuous positive airway pressure (CPAP) and bilevel positive airway pressure (we'll call it BPAP, but sometimes it's also called BiPAP). Both systems use the same equipment, and both deliver oxygen at a positive pressure. However, as the name suggests, CPAP provides one continuous positive pressure, which is the same when the patient breathes in as when the patient breathes out. In contrast, BPAP provides a higher pressure when the patient breathes in and a lower pressure when the patient breathes out. In both cases, the rate of respiration (the number of times the patient breathes in and out in a minute) is determined by the patient, not by the machine. In contrast, when mechanical ventilation with an endotracheal tube and ventilator is used, the patient’s breathing rate is generally determined by the machine.
Physiologic effects of noninvasive ventilation
In a normal, healthy patient, breathing usually occurs under negative pressure. However, the positive air pressure delivered with noninvasive ventilation (NIV) results in some physiological changes in both the respiratory system and circulatory system, which makes it a useful therapy for treating some specific diseases and conditions. As you probably know, NIV results in improved oxygenation and ventilation for the patient. But did you also know that NIV enhances pulmonary physiology, and reduces both afterload and preload?
Traditional indications for noninvasive ventilation
Noninvasive ventilation (NIV) is traditionally used to treat pulmonary edema (fluid in the lungs), acute exacerbations of chronic obstructive pulmonary disease (AECOPD), and obstructive sleep apnea (which is often treated at home with bedside devices).
Controversial uses of noninvasive ventilation
In addition to the more traditional applications of noninvasive ventilation, or NIV, (e.g., obstructive sleep apnea [OSA], pulmonary edema, and chronic obstructive pulmonary disease [COPD]), NIV may also be useful in treating some patients with pneumonia, asthma, acute respiratory distress syndrome (ARDS), and even altered mental status.
Other, special uses of noninvasive ventilation
Short term use of noninvasive ventilation (NIV) may also be useful to increase oxygen levels before inserting an endotracheal tube (a process known as preoxygenation), to help prevent a patient who has recently had an endotracheal tube removed from needing to be reintubated, and to help relieve breathing difficulties in patients who are receiving palliative (end-of-life) care.
Tips and tricks for using noninvasive ventilation
Even though noninvasive ventilation (NIV) is, as its name suggests, not as invasive as other forms of respiratory support (e.g., mechanical ventilation), not all patients adjust well to its use. But, there are some tips and tricks you can use—about mask selection, initiation, and titration—to get even the most NIV-averse patient to comply, so they can reap the benefits.
Using a high-flow nasal cannula (nasal high flow)
High-flow nasal cannula (HFNC, or nasal high flow [NHF]) is not technically a form of noninvasive ventilation (NIV), but it does share some similarities to NIV and can be used as an alternative therapy in some situations. This procedure provides a high flow of oxygen through a specialized nasal cannula without the use of positive air pressure.