Non-invasive ventilator is usually applied in the acute exacerbation of COPD, or late carbon dioxide has been at a relatively high level. The following complications may occur after using a non-invasive ventilator: 1. Patients who are especially thin apply the ventilator, they will face the inappropriate size of the mask, which will produce gas leakage. After air leakage, the patient will suck the gas into the stomach, which will cause gastric distension, discomfort and even reflux, especially after a full meal, too much nutritional fluid will reflux, which will lead to misaspiration. This risk is relatively high, and once misaspiration occurs, it can be life-threatening. When doing non-invasive ventilator, you must actively communicate with the patient and speak to the medical staff whenever you feel uncomfortable, and the medical staff will basically accompany you. 2. Because of the poor heart function and fast heart rate, if you use the ventilator after half an hour or even 20-30 minutes, you will feel uncomfortable and fatigued. Do not take too long at a time, you can do it several times, once fatigue, but aggravate the heart function; 3, some patients apply non-invasive ventilator for a long time, and even sleep at night with continuous application of non-invasive ventilator. Patients who appear apnea with ventilator are prone to accidental disconnecting of ventilator at night when they sleep, or improper setting of ventilator parameters, which will instead aggravate lung damage, poor removal of carbon dioxide, or even higher carbon dioxide, which in turn will increase side effects if not properly applied.