Comparison of two different recruitment maneuver patterns in ARDS patients

Background: The differential effects of the two most commonly investigated recruitment maneuvers (RMs), i.e., sigh recruitment and sustained inflation, have not been fully investigated yet. This study aimed to compare the effects of these two RMs on respiratory mechanics, gas exchange, and electrical impedance tomography (EIT)-derived lung volumes on mechanically ventilated ARDS patients. Results: This is a two-period two-sequence randomized crossover study. Two RMs were tested in randomized sequence: a sigh recruitment (one minute with a PEEP of 5 cmH2O, a driving pressure of 40 cmH2O at a respiratory rate of 10 bpm) and a sustained inflation maneuver (constant airway pressure of 40 cmH2O for 30 s). Following the application of the first RM, respiratory mechanics, hemodynamics and EIT-derived lung volumes were measured every 5 min for the following 30 min, while gas exchange was monitored every 15 min. After a 30-min washout period, intended to allow the lung to return to pre-recruitment steady-state conditions, the second RM was applied, and the same measurements were obtained. Twenty-three ARDS patients were enrolled; 13 patients underwent sigh recruitment as first RM and sustained inflation as the second RM, 10 patients underwent the opposite sequence. Patients who underwent both sigh recruitment or sustained inflation as first maneuver showed similar respiratory mechanics, hemodynamics, gas exchange and EIT-derived lung volumes before the RMs compared to patients who underwent sigh recruitment or sustained inflation as the second maneuver after the 30-min washout period. Independently from the order, after the application of each RMs, respiratory system, lung and chest wall mechanics, arterial oxygenation and EIT-derived lung volumes remained similar to baseline at all measurement timepoints from 5 to 30 min. Nine and 13% of patients increased PaO2/FiO2 over 20% from baseline 5 min after sigh recruitment and sustained inflation, respectively; a similar percentage was found after 30 min. Conclusion: Neither a sigh recruitment nor a sustained inflation maneuvers had clinically significant effect on respiratory mechanics, gas exchange, hemodynamics or EIT-derived lung volume distribution within the first 30 min after their application.