Precautions for Using Non-Invasive Ventilators

Non-invasive ventilator therapy refers to artificial ventilation that does not require an artificial airway. Instead, it connects the ventilator to the patient through a mask, such as a nasal mask or face mask, providing positive pressure support to assist ventilation. Early intervention with non-invasive ventilators has not only helped many patients improve their condition and saved costs, but also avoided the pain of intubation and reduced complications such as ventilator-associated pneumonia.

However, in clinical practice, many people still lack the correct understanding of non-invasive ventilator usage procedures and make common mistakes without realizing it, which not only affects treatment effectiveness but may even lead to treatment failure.

Non-invasive ventilator Usage Process

Step 1: Assessment
Before using a non-invasive ventilator, it is necessary to first assess the patient's condition to determine whether they have indications and contraindications for its use.

Noninvasive ventilators are indicated for patients with COPD complicated by acute respiratory failure, acute left heart failure, and pulmonary encephalopathy. They are also suitable for patients in the early stages of acute respiratory failure, acute severe asthma, sleep apnea, severe myasthenia gravis, and neurological respiratory failure. Furthermore, patients experiencing respiratory insufficiency after surgery can also be treated with noninvasive ventilators.

Noninvasive ventilators are relatively contraindicated in patients with pneumothorax and pneumomediastinum, as well as hemoptysis.

Patients receiving noninvasive ventilator therapy generally must meet the following criteria:

Stable hemodynamics;

No aspiration, severe gastrointestinal bleeding, excessive airway secretions, or difficulty expectorating;

No facial trauma that would impair the use of an oral/nasal mask;

Able to tolerate an oral/nasal mask.

Generally speaking, patients requiring ventilatory support who do not meet the above criteria are contraindicated for noninvasive ventilators and should consider invasive ventilation or other treatment options after a physician's evaluation.

Step 2: Verification
Prepare all necessary supplies and bring them to the bedside. Verify the patient's information and select the appropriate mask based on the patient's facial condition.

Step 3: Explanation
Explain to the patient the purpose and importance of noninvasive ventilator therapy, the possible discomfort during treatment, and the requirements for patient cooperation. Reassure the patient's anxiety and gain understanding and cooperation, which are the foundation for successful noninvasive ventilator use and improved efficacy.

Step 4: Clearance
Oral debris and oral and nasal secretions can increase resistance or dead space, potentially even being blown into the lower respiratory tract and causing secondary infection. Excessive sputum in the airways or atelectasis caused by sputum plugs can impair airway patency, increase resistance, and reduce ventilation efficiency, compromising treatment effectiveness and even posing a risk of suffocation.

Therefore, before initiating noninvasive ventilator therapy, it is important to pay attention to the following factors: timely removal of food debris, oral and nasal secretions, sputum, and the presence of atelectasis.

Step 5: Positioning
We all know that airway patency is crucial during cardiopulmonary resuscitation. In fact, airway patency is also crucial when using noninvasive ventilators. Improper positioning can not only affect lung mobility and ventilation, but can also increase resistance.

Therefore, the correct approach is to place the patient in a sitting or semi-recumbent position, with the head of the bed elevated at least 30 degrees. The head can be tilted slightly back, but care should be taken to prevent aspiration.

Step 6: Installing the Humidifier
Install the humidifier and fill it with humidifying fluid, typically sterile distilled water.

Step 7: Installing the Ventilator Tubing
After installing the humidifier, install the ventilator tubing.

Step 8: Connecting the Oxygen Source
Noninvasive ventilators used in hospitals connect to a central oxygen supply, while home-use noninvasive ventilators connect to an external oxygen concentrator or tank.

Step 9: Connecting the Power Supply and Turning On the Ventilator
Plug in the ventilator, press the on/off button to turn it on, and then adjust the humidification temperature setting to the appropriate level.

Step 10: Select Mode and Adjust Parameters
Choosing a breathing mode and setting parameters are not one-size-fits-all; they must be tailored to the patient's condition. Therefore, this step is crucial and essential for any doctor using a ventilator.

Let's first review the common modes of noninvasive ventilators:
S/T Mode (Spontaneous/Timed Mode)
In this mode, the ventilator delivers a higher pressure (IPAP) during inspiration and a lower pressure (EPAP) during expiration. This mode prioritizes spontaneous breathing. If the patient fails to initiate a breath within the set rate interval, the ventilator will trigger a mandatory breath according to the set inspiratory time.

This is the most widely used mode in clinical practice and is suitable for patients with relatively stable spontaneous breathing but who are at risk of respiratory arrest or respiratory failure.

CPAP (Continuous Positive Airway Pressure) Mode
This mode requires the patient to have strong spontaneous breathing, with the patient performing the entire work of breathing. There are no triggers or switching steps during CPAP operation, but rather a constant pressure during inspiration and expiration (i.e., CPAP = IPAP = EPAP), helping to reduce airway resistance and maintain upper airway patency.
This mode offers the advantages of free breathing and comfort, but also has the disadvantages of imprecise tidal volumes and virtually no additional ventilation support. This mode is suitable for type I respiratory failure, acute and chronic heart failure (especially cardiogenic pulmonary edema due to relative volume overload), and obstructive sleep apnea syndrome.

Common Diseases, Breathing Modes, and Parameter Settings
Acute Exacerbation/Stable Phase of COPD:
S/T mode is generally preferred, with IPAP: 12-20 cmH2O, EPAP: 4-6 cmH2O, and inspiratory time: 0.8-1.2 seconds. It's important to avoid the misconception of only using it during the day and not at night. In fact, continuous nighttime use is more important and helps correct nocturnal hypoxia and hypoventilation.

Obstructive Sleep Apnea:
If possible, patients with this condition should select a breathing mode and adjust treatment parameters based on polysomnography (PSG) results and clinical presentation. CPAP mode is generally preferred, but ST mode is also an option.

In CPAP mode, pressure is typically started at 4-5 cmH2O and then gradually increased based on obstructive apnea, hypoventilation, respiratory effort-related arousals, and snoring. As pressure increases, apnea, hypoventilation, respiratory effort-related arousals, and snoring gradually disappear. In S/T mode, the initial pressure settings are typically: IPAP: 8-12 cmH2O, EPAP: 4-6 cmH2O, and a respiratory rate of 12-18 breaths/minute. EPAP pressure should be increased in the event of obstructive apnea. For obstructive hypopnea, effort-related arousals, and snoring, only IPAP pressure should be increased, with the pressure difference being ≥ 6 cmH2O. If the IPAP-EPAP pressure difference increases, EPAP pressure should be increased to maintain upper airway patency.

Step 11: Select the ventilator's "Standby" button.

After setting the ventilator mode and parameters, click the "Standby" button. Do not start the ventilator yet.

Step 12: Wear and Secure the Mask.

Apply the mask (or nasal mask) to the patient and secure it, paying attention to the tightness of the headband.

Step 13: Connect the breathing tube to the mask and immediately start the ventilator.

The correct approach is to put the mask on first, connect the ventilator tubing, and then start the ventilator immediately when the non-invasive ventilator is in standby mode.

Step 14: Observation and Adjustment
When the patient is first placed on the ventilator, do not leave the patient; observe them at the bedside and adjust the parameters based on their tolerance, blood oxygen level, heart rate, and other conditions.

Summary
The process for using a noninvasive ventilator is: Assess → Verify → Explain → Clear → Position the patient → Place the humidifier → Install the breathing tube → Connect the oxygen source → Connect the power supply and turn on the ventilator → Select the mode and adjust the parameters → Select the "Standby" mode on the ventilator → Put on the mask and secure it → Connect the breathing tube and mask and immediately start the ventilator → Observe and adjust.

During treatment, monitor vital signs including consciousness, blood oxygen level, carbon dioxide, patient-ventilator coordination, tidal volume, ventilator operation, and adverse reactions.