[Study of timing of invasive and noninvasive sequential ventilation in patients with acute respiratory distress syndrome].

OBJECTIVE: To investigate the timing and value of noninvasive ventilation (NIV) as a weaning tool immediately after early extubation in patients with acute respiratory distress syndrome (ARDS).

METHODS: A prospective randomized controlled trial was conducted. The ARDS patients with surgical diseases admitted to Department of Respiratory Intensive Care Unit (RICU) of the First Affiliated Hospital of Xinjiang Medical University were enrolled. The patients were randomly divided into sequential group and control group. All patients underwent endotracheal intubation and were mechanically ventilated. Every 12 hours during the first 3 days, the lung recruitment maneuver was performed during pressure control ventilation (PCV). After lung recruitment, all patients were ventilated with synchronized intermittent mandatory ventilation (SIMV) + pressure support ventilation (PSV) + positive end-expiratory pressure (PEEP) or assistant/control ventilation (A/C). The objects in sequential group who met the following criteria including those with oxygen index (PaO2/FiO2) reaching 200-250 mmHg (1 mmHg=0.133 kPa) under PEEP of 8 cmH2O (1 cmH2O=0.098 kPa), and pressure support of 12 cmH2O, and most acute infiltrating lesions having resolved on chest imaging, received noninvasive ventilation (NIV) immediately after extubation, and patients in control group continued to have invasive mechanical ventilation via intubation or tracheostomy with an endotracheal tube. The baseline data in both groups and the number of re-intubation in the sequential group were recorded. The duration of invasive mechanical ventilation and total duration of mechanical ventilation, ICU length of stay, the incidence of ventilator-associated pneumonia (VAP), and mortality rate were compared between the two groups.

RESULTS: 53 consecutive adult patients were enrolled, including 26 in sequential group and 27 cases in control group. The period of endotracheal intubation was 7.0 (6.8, 9.5) days, and 7.7% (2/26) patients underwent re-intubation in sequential group. There were significant difference in respiratory and circulatory indicators before extubation spontaneous breathing trial (SBT) ≤10 minutes in sequential group, indicating that the patients were still in the early stage of extubation sequential NIV. There was no significant difference in indices reflecting respiratory function and circulation between the two groups, except that respiratory rate at 1 hour was slightly increased in sequential group as compared with that of control group, indicating that sequential NIV could maintain invasive ventilation function. There was significant difference in duration of invasive mechanical ventilation [7.0 (6.8, 9.5) days vs. 21.0 (17.0, 25.0) days, Z=-6.048, P=0.000], duration of total mechanical ventilation (18.0±4.1 days vs. 22.0±7.3 days, t=-2.805, P=0.008), and length of ICU stay (21.0±4.1 days vs. 28.0±8.1 days, t=-4.012, P=0.000) between sequential group and control group, but there was no significant differences in the incidence of VAP [15.4% (4/26) vs. 29.6 (8/27), χ(2)=1.535, P=0.215] and mortality rate [7.7% (2/26) vs. 18.5% (5/27), P=0.420].

CONCLUSIONS: When PaO2/FiO2 reached 200-250 mmHg under the condition of low ventilation, sequential NIV facilitates the early discontinuation of mechanical ventilation in ARDS patients with surgical diseases, with shortening of duration of invasive mechanical ventilation, total mechanical ventilation, and the length of ICU stay.