The COPD patient group had a lower risk of failure than the pneumonia group when withdrawing from the NAVA machine, the difference was statistically significant; p <0.05 Patients with SOFA score > 4; SAPS II score > 33.5; APACHE II scores > 14.5 have a higher risk of failure, with a statistically significant difference; p <0.05 The changes of pH, PaO2, PaO2/FiO2, and PaCO2 were stable during the process of stopping the machine breathing NAVA, there was no difference between the two groups of success and failure; p> 0.05 Heart rate in the successful group was lower than that of the failed group during the procedure of mechanical ventilation with NAVA method, but the difference was not statistically significant.