[Clinical study of optimal positive end-expiratory pressure titration guided by lung stretch index in patients with acute respiratory distress syndrome].

OBJECTIVE: To investigate the clinical practicability of positive end-expiratory pressure (PEEP) titrated by lung stretch index (SI) in patients with acute respiratory distress syndrome (ARDS).

METHODS: A parallel randomized controlled trial was conducted. Patients with moderate to severe ARDS who required mechanical ventilation admitted to the department of critical care medicine of General Hospital of the Yangtze River Shipping from August 2022 to February 2023 were enrolled. They were randomly divide into SI guided PEEP titration group (SI group) and pressure-volume curve (P-V curve) inspiratory low inflection point (LIP) guided PEEP titration group (LIP group). All patients were ventilated in a supine position after admission, with the head of the bed raised by 30 degree angle. The primary disease was actively treated, prone position ventilation for 12 h/d, and lung protective ventilation strategies such as controlled lung expansion were used for lung recruitment. On this basis, mechanical ventilation parameters were titrated with SI in the SI group; the LIP group titrated mechanical ventilation parameters with P-V curve inspiratory LIP+2 cmH2 O (1 cmH2 O≈0.098 kPa). The oxygenation index (PaO2 /FiO2 ), and respiratory mechanics indicators such as lung dynamic compliance (Cdyn), peak airway pressure (Pip) were monitored before recruitment maneuver and after 1, 3, and 5 days of treatment. The therapeutic effect of the two groups was compared.

RESULTS: There were 41 patients in the SI group and 40 patients in the LIP group. There was no significant difference in general information such as gender, age, and disease type between the two groups. The mechanical ventilation time and the length of intensive care unit (ICU) stay in the SI group were significantly shorter than those in the LIP group (days: 9.47±3.36 vs. 14.68±5.52, 22.27±4.68 vs. 27.57±9.52, both P < 0.05). Although the 28-day mortality of the SI group was lower than that of the LIP group, the difference was not statistically significant [19.5% (8/41) vs. 35.0% (14/40), P > 0.05]. On the fifth day, the PaO2 /FiO2 was higher in SI group [mmHg (1 mmHg≈0.133 kPa): 225.57±47.85 vs. 198.32±31.59, P < 0.05], the Cdyn was higher in SI group (mL/cmH2 O: 47.39±6.71 vs. 35.88±5.35, P < 0.01), the Pip was lower in SI group (mmHg: 35.85±5.77 vs. 43.87±6.68, P < 0.05). The Kaplan-Meier survival curve showed no statistically significant difference in the 28 days cumulative survival rate between the two groups (Log-Rank: χ 2 = 2.348, P = 0.125).

CONCLUSIONS: The application of SI titration with PEEP in the treatment of ARDS patients may improve their prognosis.