Abstract Rationale The physiological impact of lung recruitment during noninvasive face mask ventilation remains unclear. Methods We prospectively enrolled 33 pneumonia patients receiving noninvasive ventilation via a face mask. Initially, ventilator parameters were set as follows: positive-end expiratory pressure (PEEP) at 5 cmH2O, with support pressure titrated to maintain a pressure difference 5 cmH2O. The fraction of inspired oxygen (FiO2) was adjusted to keep peripheral oxygen saturation (SpO2) between 88% and 92%. Subsequently, PEEP was sequentially increased to 10, 15, 20, 25, and 30 cmH2O. Each PEEP level was maintained for 10 minutes until vital signs stabilized, at which point esophageal pressure, electrical impedance tomography, and diaphragmatic ultrasound measurements were recorded. Results Four patients were unable to tolerate a PEEP of 25 cmH2O, and 12 patients were unable to tolerate a PEEP of 30 cmH2O. Under PEEP levels of 5, 10, 15, 20, 25, and 30 cmH2O, SpO2 values were 90.6±1.6%, 92.4±1.7%, 94.3±2.3%, 95.0±3.1%, 95.0±4.2%, and 96.0±3.3%, respectively. The corresponding pressure-time products were 115±73, 93±59, 75±54, 81±56, 73±83, and 80±70 cmH2O·s/min. The fraction of diaphragmatic thickening was 32.9±16.3%, 28.3±13.2%, 26.6±11.9%, 24.9±13.3%, 20.8±12.3%, and 21.0±12.3%, while diaphragmatic excursion was 1.68±0.56, 1.55±0.46, 1.40±0.39, 1.37±0.48, 1.32±0.48, and 1.20±0.37 cm, respectively. Tidal impedance variation values were 200±75, 199±65, 184±66, 150±54, 142±60, and 106±46 arbitrary units (AU), respectively. Conclusion Lung recruitment during face mask ventilation is feasible. Oxygenation improved with increasing PEEP levels. However, the fraction of diaphragmatic thickening and diaphragmatic excursion decreased, while the work of breathing initially decreased and then remained stable. This abstract is funded by: None
Duan et al. (Fri,) studied this question.