• Tommaso Mauri, Giacomo Bellani, Giacomo Grasselli, Andrea Confalonieri, Roberto Rona, Nicolo' Patroniti, and Antonio Pesenti.
• Department of Perioperative Medicine and Intensive Care, San Gerardo Hospital, Via Pergolesi 33, 20900 Monza, Italy.
• Intensive Care Med. 2013 Feb 1; 39 (2): 282-91.

PurposePatients with acute respiratory distress syndrome (ARDS) requiring extracorporeal membrane oxygenation (ECMO) usually present very low respiratory system compliance (Cst(rs)) values (i.e., severe restrictive respiratory syndrome patients). As a consequence, they are at high risk of experiencing poor patient-ventilator interaction during assisted breathing. We hypothesized that monitoring of diaphragm electrical activity (EAdi) may enhance asynchrony assessment and that neurally adjusted ventilatory assist (NAVA) may reduce asynchrony, especially in more severely restricted patients.MethodsWe enrolled ten consecutive ARDS patients with very low Cst(rs) values undergoing ECMO after switching from controlled to pressure support ventilation (PSV). We randomly tested (30 min) while recording EAdi: (1) PSV30 (PSV with an expiratory trigger at 30 % of flow peak value); (2) PSV1 (PSV with expiratory trigger at 1 %); (3) NAVA. During each step, we measured the EAdi-based asynchrony index (AI(EAdi)) = flow-, pressure- and EAdi-based asynchrony events/EAdi-based respiratory rate × 100.ResultsAI(EAdi) was high during all ventilation modes, and the most represented asynchrony pattern was specific for this population (i.e., premature cycling). NAVA was associated with significantly decreased, although suboptimal, AI(EAdi) values in comparison to PSV30 and PSV1 (p < 0.01 for both). The PSV30-NAVA and PSV1-NAVA differences in AI(EAdi) values were inversely correlated with patients' Cst(rs) (R (2) = 0.545, p = 0.01 and R (2) = 0.425, p < 0.05; respectively).ConclusionsEAdi allows accurate analysis of asynchrony patterns and magnitude in ARDS patients with very low Cst(rs) undergoing ECMO. In these patients, NAVA is associated with reduced asynchrony.

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