With the development of perinatal medicine, more and more newborns with respiratory failure can be treated due to the use of respiratory support technology. However, long-term invasive mechanical ventilation treatment can lead to a series of complications such as ventilator-associated pneumonia, atelectasis and air leakage syndrome, and increase the risk of bronchopulmonary dysplasia and neurodevelopmental lag of premature infants. It also leads to longer hospital stays and higher hospital costs. To shorten the invasive mechanical ventilation time and improve the success rate of withdrawal through various ways is the development direction of neonatal mechanical ventilation therapy. Respiratory muscle atrophy is common and rapid in children receiving invasive mechanical ventilation, and is an important cause of ventilator dependence and withdrawal failure. The diaphragm of newborns is the main respiratory muscle, of which the diaphragm type 1 endurance fiber accounts for only about 30%, far lower than the proportion of about 55% in adults, so the diaphragm of newborns is more prone to fatigue. Previous animal experiments and clinical studies in children and adults have confirmed that diaphragmatic pacing therapy applied to patients with long-term invasive mechanical ventilation can prevent diaphragmatic atrophy, reverse diaphragmatic injury, significantly improve diaphragmatic thickness, improve diaphragmatic anti-fatigue ability, thereby increasing lung ventilation, relieving dyspnea, and achieving the effect of assisted extubation. The neonatology Department of the Children's Hospital Affiliated to Chongqing Medical University started neonatal external diaphragm pacemaker treatment in 2022, and has completed 1383 cases so far, initially showing the effectiveness and safety of external diaphragm pacemaker treatment in neonatal population. But so far, there is no systematic evaluation of clinical intervention effect of external diaphragm pacemaker treatment on neonatal respiratory failure patients at home and abroad. Based on this, the project team intends to conduct a prospective randomized controlled study to systematically evaluate the safety of external diaphragm pacemaker in preterm infants requiring invasive mechanical ventilation for ≥7 days at 28 to 35 weeks of gestation, and to evaluate the efficacy of external diaphragm pacemaker in adjuvant extubation.