Fifty Years of Research in ARDS.Vt Selection in Acute Respiratory Distress Syndrome

Abstract

Mechanical ventilation (MV) is critical in the management of many patients with acute respiratory distress syndrome (ARDS). However, MV can also cause ventilator-induced lung injury (VILI). The selection of an appropriate Vt is an essential part of a lung-protective MV strategy. Since the publication of a large randomized clinical trial demonstrating the benefit of lower Vts, the use of Vts of 6 ml/kg predicted body weight (based on sex and height) has been recommended in clinical practice guidelines. However, the predicted body weight approach is imperfect in patients with ARDS because the amount of aerated lung varies considerably due to differences in inflammation, consolidation, flooding, and atelectasis. Better approaches to setting Vt may include limits on end-inspiratory transpulmonary pressure, lung strain, and driving pressure. The limits of lowering Vt have not yet been established, and some patients may benefit from Vts that are lower than those in current use. However, lowering Vts may result in respiratory acidosis. Tactics to reduce respiratory acidosis include reductions in ventilation circuit dead space, increases in respiratory rate, higher positive end-expiratory pressures in patients who recruit lung in response to positive end-expiratory pressure, recruitment maneuvers, and prone positioning. Mechanical adjuncts such as extracorporeal carbon dioxide removal may be useful to normalize pH and carbon dioxide levels, but further studies will be necessary to demonstrate benefit with this technology.

Feasibility and safety of extracorporeal CO2 removal to enhance protective ventilation in acute respiratory distress syndrome: the SUPERNOVA study

“…Adverse events occurred in the first 24 h of ECCO 2 R in 26 patients ( Table 3). Duration of invasive mechanical ventilation was 17 [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] days. A total of 69 patients (73%) were alive at day 28.…”

“…Recent data have demonstrated that there is no safe upper limit for P PLAT or ΔP [13,23]. For example, the mortality rate in ARDS patients with ΔP values ≤ 14 cmH 2 O is still as high as 20% [13,23]. Patient outcomes may therefore be improved by aggressively lowering ventilatory variables such as V T , P PLAT , or ΔP as facilitated by ECCO 2 R devices that remove CO 2 .…”

Volume Guarantee High-Frequency Oscillatory Ventilation in Preterm Infants With RDS: Tidal Volume and DCO2 Levels for Optimal Ventilation Using Open-Lung Strategies

“…However, a weak but significant correlation between MAPhf and optimal VThf levels in this study may indicate the need for higher VThf levels in infants with more severe lung disease or inadequate lung recruitment. Patients who responded well to recruitment probably needed lower MAPhf and VThf levels due to decreased physiologic dead space and shunt, similar to ARDS patients (23). However, there is no strong evidence to support this assumption.…”

Outcomes of Patients Presenting with Mild Acute Respiratory Distress Syndrome

“…Tidal volumes and PEEP are potentially modifiable factors in the management of patients with ARDS. [42][43][44][45] In accordance with the observational study design, no recommendations regarding ventilator settings were given to investigators, and mean tidal volumes around 8 ml/kg predicted body weight used in this study were higher than the 6 ml/kg usually recommended. 42,46 Modes of ventilation allowing spontaneous breathing were used for more than 40% of patients on the day of ARDS onset.…”