Pressure-supported ventilation is widely used in critically ill patients, and the patient's effort in spontaneous breathing is an important predictor of the success rate of weaning, but this index is difficult to measure accurately under clinical conditions. It has been demonstrated that the absolute value of diaphragm excursion is influenced by multiple factors and cannot be used as a predictor of weaning from mechanical ventilation. This study aims to reveal the characteristics of diaphragm excursion changes (respiratory excursion) at different levels of pressure support, and explore whether it can predict the weaning from mechanical ventilation.
Prospective cohort study.
Patients admitted to the ICU who were mechanically ventilated and had met the criteria to perform an autonomic breathing test were enrolled. Patients with tracheal obstruction or after thoracic/gastric/esophageal surgery were excluded.
Different levels of pressure support (20,15,10,5 and 0 cm H2O) were applied in pressure-assisted ventilation mode, and the effort of each patient's inspiratory muscles at different support levels was observed by B- and M-mode ultrasonography to assess right side diaphragm mobility.
Measurements and Main Results
Respiratory mechanics parameters under deep/calm breathing, dynamic changes in diaphragm movement, diaphragm excursion inflection points and whether the patients were successfully deconditioned were recorded. Forty-one patients were enrolled, and the results showed that 78.6% (22/28) of patients with a deep breathing inflection point of 10 cmH2O (nadir of 5 cmH2O) and 33.3% (4/12) of patients with a deep breathing inflection point of 15 cmH2O (nadir of 10 cmH2O) successfully weaned from mechanical ventilation, with the former having a significantly higher rate than the latter. The success rate was statistically significant (Chi-square=7.556 P=0.006); 77.8% (21/27) of patients with calm breathing inflection point of 10 cmH2O (lowest point of 5 cmH2O) and 38.5% (5/13) of patients with calm breathing inflection point of 15 cmH2O (lowest point of 10 cmH2O). 13), the former had a statistically significant higher off-boarding success rate than the latter (Chi-square=5.962 P=0.0146).
In the process of weaning from mechanical ventilation patients, when performing a spontaneous breathing test, the right diaphragm excursion inflection point during deep/calm breathing can be measured by ultrasound to assess the patient's spontaneous breathing effort component, and this study found that the weaning success rate was lower in the group with an inflection point of 15 cm H2O than in the group with an inflection point of 10 cm H2O, so the diaphragm excursion inflection point may be a reliable indicator to predict the deconditioning success.