OBJECTIVE:Acute respiratory distress syndrome is characterized by collapse of gravitationally dependent lung regions that usually diverts tidal ventilation toward nondependent regions. We hypothesized that higher positive end-expiratory pressure and enhanced spontaneous breathing may increase the proportion of tidal ventilation reaching dependent lung regions in patients with acute respiratory distress syndrome undergoing pressure support ventilation. DESIGN: Prospective, randomized, cross-over study. SETTING:General and neurosurgical ICUs of a single university-affiliated hospital. PATIENTS: We enrolled ten intubated patients recovering from acute respiratory distress syndrome, after clinical switch from controlled ventilation to pressure support ventilation. INTERVENTIONS: We compared, at the same pressure support ventilation level, a lower positive end-expiratory pressure (i.e., clinical positive end-expiratory pressure = 7 ± 2 cm H2O) with a higher one, obtained by adding 5 cm H2O (12 ± 2 cm H2O). Furthermore, a pressure support ventilation level associated with increased respiratory drive (3 ± 2 cm H2O) was tested against resting pressure support ventilation (12 ± 3 cm H2O), at clinical positive end-expiratory pressure. MEASUREMENTS AND MAIN RESULTS: During all study phases, we measured, by electrical impedance tomography, the proportion of tidal ventilation reaching dependent and nondependent lung regions (Vt%dep and Vt%(nondep)), regional tidal volumes (Vt(dep) and Vt(nondep)), and antero-posterior ventilation homogeneity (Vt%nondep/Vt%dep). We also collected ventilation variables and arterial blood gases. Application of higher positive end-expiratory pressure levels increased Vt%dep and Vtdep values and decreased Vt%nondep/Vt%dep ratio, as compared with lower positive end-expiratory pressure (p < 0.01). Similarly, during lower pressure support ventilation, Vt%dep increased, Vtnondep decreased, and Vtdep did not change, likely indicating a higher efficiency of posterior diaphragm that led to decreased Vt%nondep/Vt%dep (p < 0.01). Finally, PaO2/FIO2 ratios correlated with Vt%dep during all study phases (p < 0.05). CONCLUSIONS: In patients with acute respiratory distress syndrome undergoing pressure support ventilation, higher positive end-expiratory pressure and lower support levels increase the fraction of tidal ventilation reaching dependent lung regions, yielding more homogeneous ventilation and, possibly, better ventilation/perfusion coupling.
RCT Entities:
OBJECTIVE:Acute respiratory distress syndrome is characterized by collapse of gravitationally dependent lung regions that usually diverts tidal ventilation toward nondependent regions. We hypothesized that higher positive end-expiratory pressure and enhanced spontaneous breathing may increase the proportion of tidal ventilation reaching dependent lung regions in patients with acute respiratory distress syndrome undergoing pressure support ventilation. DESIGN: Prospective, randomized, cross-over study. SETTING: General and neurosurgical ICUs of a single university-affiliated hospital. PATIENTS: We enrolled ten intubated patients recovering from acute respiratory distress syndrome, after clinical switch from controlled ventilation to pressure support ventilation. INTERVENTIONS: We compared, at the same pressure support ventilation level, a lower positive end-expiratory pressure (i.e., clinical positive end-expiratory pressure = 7 ± 2 cm H2O) with a higher one, obtained by adding 5 cm H2O (12 ± 2 cm H2O). Furthermore, a pressure support ventilation level associated with increased respiratory drive (3 ± 2 cm H2O) was tested against resting pressure support ventilation (12 ± 3 cm H2O), at clinical positive end-expiratory pressure. MEASUREMENTS AND MAIN RESULTS: During all study phases, we measured, by electrical impedance tomography, the proportion of tidal ventilation reaching dependent and nondependent lung regions (Vt%dep and Vt%(nondep)), regional tidal volumes (Vt(dep) and Vt(nondep)), and antero-posterior ventilation homogeneity (Vt%nondep/Vt%dep). We also collected ventilation variables and arterial blood gases. Application of higher positive end-expiratory pressure levels increased Vt%dep and Vtdep values and decreased Vt%nondep/Vt%dep ratio, as compared with lower positive end-expiratory pressure (p < 0.01). Similarly, during lower pressure support ventilation, Vt%dep increased, Vtnondep decreased, and Vtdep did not change, likely indicating a higher efficiency of posterior diaphragm that led to decreased Vt%nondep/Vt%dep (p < 0.01). Finally, PaO2/FIO2 ratios correlated with Vt%dep during all study phases (p < 0.05). CONCLUSIONS: In patients with acute respiratory distress syndrome undergoing pressure support ventilation, higher positive end-expiratory pressure and lower support levels increase the fraction of tidal ventilation reaching dependent lung regions, yielding more homogeneous ventilation and, possibly, better ventilation/perfusion coupling.
Authors: Antonio Pesenti; Guido Musch; Daniel Lichtenstein; Francesco Mojoli; Marcelo B P Amato; Gilda Cinnella; Luciano Gattinoni; Michael Quintel Journal: Intensive Care Med Date: 2016-03-31 Impact factor: 17.440
Authors: Tommaso Mauri; Nilde Eronia; Cecilia Turrini; Marta Battistini; Giacomo Grasselli; Roberto Rona; Carlo Alberto Volta; Giacomo Bellani; Antonio Pesenti Journal: Intensive Care Med Date: 2016-08-12 Impact factor: 17.440
Authors: Ewan C Goligher; Martin Dres; Bhakti K Patel; Sarina K Sahetya; Jeremy R Beitler; Irene Telias; Takeshi Yoshida; Katerina Vaporidi; Domenico Luca Grieco; Tom Schepens; Giacomo Grasselli; Savino Spadaro; Jose Dianti; Marcelo Amato; Giacomo Bellani; Alexandre Demoule; Eddy Fan; Niall D Ferguson; Dimitrios Georgopoulos; Claude Guérin; Robinder G Khemani; Franco Laghi; Alain Mercat; Francesco Mojoli; Coen A C Ottenheijm; Samir Jaber; Leo Heunks; Jordi Mancebo; Tommaso Mauri; Antonio Pesenti; Laurent Brochard Journal: Am J Respir Crit Care Med Date: 2020-10-01 Impact factor: 30.528