title: Patient-ventilator interaction in ARDS patients with extremely low compliance undergoing ECMO: a novel approach based on diaphragm electrical activity.
abstract: OBJECTIVE
  Patients 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.
  
  
  METHODS
  We 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.
  
  
  RESULTS
  AI(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).
  
  
  CONCLUSIONS
  EAdi 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.
authors.affiliation: Department of Perioperative Medicine and Intensive Care, San Gerardo Hospital, Via Pergolesi 33, 20900 Monza, Italy.
authors.forename: Tommaso
authors.initials: T
authors.lastname: Mauri
authors.forename: Giacomo
authors.initials: G
authors.lastname: Bellani
authors.forename: Giacomo
authors.initials: G
authors.lastname: Grasselli
authors.forename: Andrea
authors.initials: A
authors.lastname: Confalonieri
authors.forename: Roberto
authors.initials: R
authors.lastname: Rona
authors.forename: Nicolo'
authors.initials: N
authors.lastname: Patroniti
authors.forename: Antonio
authors.initials: A
authors.lastname: Pesenti
mesh_terms: D000328:Adult; D000368:Aged; D003964:Diaphragm / Q000503:physiopathology; D055724:Electrophysiological Phenomena; D015199:Extracorporeal Membrane Oxygenation; D005260:Female; D006801:Humans; D059725:Interactive Ventilatory Support; D008170:Lung Compliance; D008297:Male; D008875:Middle Aged; D012128:Respiratory Distress Syndrome / Q000503:physiopathology / Q000628:therapy*; D055815:Young Adult