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Thursday, 25 October 2018

Moderate and Severe Acute Respiratory Distress Syndrome: Hemodynamic and Cardiac Effects of an Open Lung Strategy With Recruitment Maneuver Analyzed Using Echocardiography*

 by Mercado, Pablo; Maizel, Julien; Kontar, Loay; Nalos, Marek; Huang, Stephen; Orde, Sam; McLean, Anthony; Slama, Michel  

Objectives: Open lung ventilation with a recruitment maneuver could be beneficial for acute respiratory distress syndrome patients. However, the increased airway pressures resulting from the recruitment maneuver may induce cardiac dysfunction, limiting the benefit of this maneuver. We analyzed the effect of a recruitment maneuver and decremental positive end-expiratory pressure titration on cardiac function.
Settings: Medical ICU Amiens, France.
Patients: Twenty patients with moderate to severe acute respiratory distress syndrome Interventions: Patients underwent a stepwise recruitment maneuver with respiratory evaluation and echocardiography assessment of cardiac function including longitudinal strain at baseline, peak positive end-expiratory pressure of recruitment maneuver (positive end-expiratory pressure 40 cm H2O), and at “optimal” positive end-expiratory pressure. The patients were divided into two groups based on change on the PaO2/FIO2 ratio (nonresponders < 50%; responders ≥ 50%). 
Measurements and Main Results: At peak positive end-expiratory pressure during the recruitment maneuver, the arterial pressure, cardiac output, left ventricular size decreased and right ventricular size increased. The left ventricular ejection fraction decreased from 60% ± 13% to 48% ± 18% (p = 0.05). Both left and right ventricular global longitudinal strain were impaired (–15.8% ± 4.5% to –11% ± 4.7% and –19% ± 5% to –14% ± 6% [p = 0.05] respectively). Fifty percent of patients were nonresponders and demonstrated a lower hemodynamic tolerance to the recruitment maneuver than responders. Optimal positive end-expiratory pressure was 14 ± 5 cm H2O (vs 11 ± 4 cm H2O at baseline), and PaO2/FIO2 ratio increased from 111 ± 25 to 197 ± 89 mm Hg (p < 0.0001). All hemodynamic variables returned to their baseline value after the recruitment maneuver despite a higher positive end-expiratory pressure.
Conclusions: An open lung strategy with a stepwise recruitment maneuver permitted a higher positive end-expiratory pressure and improved oxygenation without any cardiac impairment. The recruitment maneuver was associated with mild and transient, cardiac dysfunction, with nonresponders demonstrating poorer tolerance.

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