Under normal circumstances, 70% to

Under normal circumstances, 70% to 75% of patients can quickly remove the catheter after aspiration again, but there are still 20% to 25% of patients who have difficulty removing the catheter or even the catheter. At present, the most commonly used export method is the natural breath test (sbt), which includes t tube test, low-level psv and continuous positive pressure inhalation, as well as synchronized intermittent mandatory ventilation and bilevel positive pressure ventilation and other exit methods. There are many pathophysiological factors that affect extubation. Failure of extubation may mean re-extubation. Causes include re-extubation, high secretion, reduced airway protection, heart failure or airway obstruction, coronary artery disease, and abnormal nervous system (brain Department of disease, vision or coma), respiratory dysfunction (decreased self-function, respiratory overload), other (digestive tract bleeding, sepsis, surgical treatment, etc.). Other factors that may increase the risk of reintubation: 70 years old; long mechanical ventilation time; anemia (30%); severe pathological state at the time of extubation; long-term continuous use of sedatives, etc. Due to the lack of systematic knowledge of withdrawal from the ventilator, many hospitals mainly Rely on the doctor's clinical experience and subjective judgment to guide the patient off-line mechanical ventilation. However, many clinical studies have shown that the traditional empirical withdrawal method has a poor prognosis. Due to conservative reasons, clinicians often cannot withdraw from the machine in time, which makes the patient's mechanical ventilation time too long, and it is not suitable to extend the mechanical ventilation time. This will lead to a series of complications, affect the prognosis, and increase hospital costs. There are few reference indicators for routine extubation, and the patient's spontaneous breathing function cannot be fully evaluated. The failure rate of extubation is close to 20%. With the continuous deepening of clinical research, it is found that the evaluation of sbt before sbt patients discontinues has a higher success rate, and sbt can predict the success rate of discontinuation to a certain extent. However, many patients still pass sbt in clinical practice, but they still have not stopped the drug. Because the contraction process of the ventilator will cause a series of changes in the patient’s respiratory mechanics, the intrathoracic pressure changes from positive pressure to negative pressure, which promotes changes and increases in venous blood volume, so that the left ventricular end-diastolic volume is forced to increase, and the cardiac discharge capacity When it increases, before and after the heart load increases, the lung capacity increases, and the resistance increases, which leads to the enhancement of the fluidity and ventilation function of the lung outside the pulmonary vessels, which affects the success of the filling machine. Therefore, for patients with basic cardiac insufficiency, special attention should be paid to whether their heart can withstand the sudden increase in load before and after drug withdrawal, which is related to the success or failure of the drug withdrawal machine.