Association with Preamble Studies
When patients were in the state of mechanical ventilation, their diaphragm could shrink and thin in 48 hours, which made the patients dependent on ventilators. ICU-acquired weakness (ICU-AW) occurred in 25%~60% of the cases. However, the incidence of ICU-AW among patients with long-term mechanical ventilation was even as high as 67%   , which greatly increased the incidence of ventilator-associated pneumonia in patients, and made it difficult to withdraw of ventilation. Pulmonary rehabilitation (or respiratory rehabilitation) is a comprehensive intervention based on comprehensive patient assessment, aiming at treatment for patients, including but not limited to sports training, education and behavior changes, so as to improve the physical and mental health of patients with chronic respiratory diseases, and promote patients' long-term adherence to healthy behaviors . Pulmonary rehabilitation technic is not only effective in COPD patients, but also can be applied to other respiratory diseases, such as lung transplantation  , lung cancer , interstitial lung disease , bronchiectasis , etc. It can reduce the length of hospitalization, reduce the number of hospitalizations, reduce the symptoms of dyspnea, enhance peripheral muscle strength and endurance, improve the amount of exercise and also patients' quality of life, and can even ameliorate patients' anxiety and depression. Pulmonary rehabilitation conducted at home can further strengthen patients' self-management consciousness  . In addition to assessing the improvement of patients' function, this study focused more on the effect of pulmonary rehabilitation on the prognosis of patients in ICU.
The patients included in this study were all patients with invasive positive pressure mechanical ventilation after extubation proved by spontaneous breathing test (SBT) and leak test. There was no significant difference in the assessment of basic vital signs. Diaphragm mobility, diaphragm thickness, and thickness variation rate in all patients were significantly lower than those in normal adults. In addition, 76% of the enrolled patients developed ICU-AW, and 92% could not take care of themselves. It could be due to the massive application of sedation and hormones drugs as well as braking during endotracheal intubation. The patients had a state of exercise intolerance and limited activity level, which is also consistent with previous studies . However, compared with the control group, after the pulmonary rehabilitation treatment was performed, various indicators were significantly improved in the experimental group, and patients' respiratory and limb dysfunction basically got ameliorated. Pulmonary ventilation was closely related to the patient's position. The patients in the experimental group were trained in the sitting position and the standing position at an early stage. The change in position promoted the downward movement of the diaphragm and improved lung ventilation, thereby improving oxygenation and reducing breathing difficulties . Respiratory function and physical activity’s mutual promotion ameliorates the patients' dysfunction. In addition, compared with the control group, the experimental group's patients took significantly less time to get out of bed for the first time. On the one hand, the patients in the experimental group received rehabilitation treatment, the concept of which is early mobility, so these patients had relatively good campaign at the early stage, being able to actively carry out suitable physical activities; on the other hand, early use of electric total lift bed for standing training would not only assist the recovery of patients' cognitive function and improve their level of cooperation, but also promote the recovery of patients' lower limb muscle strength, shortening the time it took to get out of bed by the patients themselves  .
The main point of this study is to analyze the prognosis of patients. We found that compared with the control group, the incidence of non-invasive ventilator re-use was significantly reduced in the experimental group. At present, High-Flow instrument, as a means of respiratory support, is more and more used in the sequential treatment of patients with extubation. Yet, non-invasive support is stronger than that of High-Flow instrument. If phenomena like respiratory muscle fatigue appeared in the enrolled patients, the doctor would choose whether to perform non-invasive ventilation or tracheal intubation , which proved that the patient was in an unstable breathing state at the time, and it might be caused by weakness of the diaphragm. After extubation, the patients in the experimental group received pulmonary rehabilitation treatment, which improved the diaphragm function and reduced the use of non-invasive ventilator. Similarly, there was a significant difference between the two groups in the re-intubation rate after correction. There were 4 patients in the control group who needed emergency intubation, but due to the wishes of their families, invasive ventilation has not been performed, and the actual number of intubation patients in the control group was 11, which made the results statistically different. The diaphragmatic ultrasound and oxygenation index of the experimental group improved significantly, that means, during the pulmonary rehabilitation treatment, the occurrence of respiratory muscle fatigue was avoided, thereby reducing the rate of re-intubation. However, there was no significant difference in the mortality rate between the two groups. The mortality rate was affected by the function of the patient's heart, kidney and other organs as well as the primary disease. Pulmonary rehabilitation could only ameliorate the patient's dysfunction, but could not cure fundamentally, and it had no obvious effect on improving the functions of other organs, so it could not affect the mortality of patients. This is also consistent with previous research results. In addition, the patients in the experimental group enjoyed early mobility, such as sitting training, standing training, etc., which reduced the complications such as pressure sore, aspiration and thrombus caused by braking .
Significance of the Findings
The study found that pulmonary rehabilitation can improve the prognosis of patients with extubation. Yet for the elderly patients, pulmonary rehabilitation is a long-lasting process, which takes a long time of treatment to produce significant results, whereas ICU patients are generally subject to a quick referral, so there is no significant impact on their ICU hospital stay, but it can reduce the patient's length of hospital stay and save medical costs. In essence, pulmonary rehabilitation is of great significance to patients.
Strengths and Limitations
Pulmonary rehabilitation can reduce patient's symptoms, improving limb muscle function, exercise ability, quality of life, etc., but its essence is long-term sustained behavior. If the pulmonary rehabilitation program got stopped immediately after the completion of the initial phase, these aforementioned benefits would then begin to decline in the next 6 to 12 months . Long-term follow-up is needed, but this study did not carry out family follow-up, and thus there is a lack of knowledge and supervision of the patient's rehabilitation at home, and a failure of tracking and analyzing the patient's long-term status. We look forward to adding long-term follow-up mechanism for discharged ICU patients into our next trials.