Document Detail

Neurally adjusted ventilatory assist increases respiratory variability and complexity in acute respiratory failure.
MedLine Citation:
PMID:  20179505     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Neurally adjusted ventilatory assist (NAVA) is a partial ventilatory support mode where positive pressure is provided in relation to diaphragmatic electrical activity (EAdi). Central inspiratory activity is normally not monotonous, but it demonstrates short-term variability and complexity. The authors reasoned that NAVA should produce a more "natural" or variable breathing pattern than other modes. This study compared respiratory variability and complexity during pressure support ventilation (PSV) and NAVA. METHODS: Flow and EAdi were recorded during routine PSV (tidal volume approximately 6-8 ml/kg) and four NAVA levels (1-4 cm H2O/microVEAdi) in 12 intubated patients. Breath-by-breath variability of flow and EAdi-related variables was quantified by the coefficient of variation (CV) and autocorrelation analysis. Complexity of flow and EAdi was described using noise titration, largest Lyapunov exponent, Kolmogorov-Sinai entropy, and three-dimensional phase portraits. RESULTS: Switching from PSV to NAVA increased the CV and decreased the autocorrelation for most flow-related variables in a dose-dependent manner (P < 0.05, partial eta for the CV of mean inspiratory flow 0.642). The changes were less marked for EAdi. A positive noise limit was consistently found for flow and EAdi. Largest Lyapunov exponent and Kolmogorov-Sinai entropy for flow were greater during NAVA than PSV and increased with NAVA level (P < 0.05, partial eta 0.334 and 0.312, respectively). Largest Lyapunov exponent and Kolmogorov-Sinai entropy for EAdi were not influenced by ventilator mode. CONCLUSIONS: Compared with PSV, NAVA increases the breathing pattern variability and complexity of flow, whereas the complexity of EAdi is unchanged. Whether this improves clinical outcomes remains to be determined.
Matthieu Schmidt; Alexandre Demoule; Christophe Cracco; Alexandre Gharbi; Marie-No?lle Fiamma; Christian Straus; Alexandre Duguet; Stewart B Gottfried; Thomas Similowski
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Anesthesiology     Volume:  112     ISSN:  1528-1175     ISO Abbreviation:  Anesthesiology     Publication Date:  2010 Mar 
Date Detail:
Created Date:  2010-02-24     Completed Date:  2010-03-30     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  1300217     Medline TA:  Anesthesiology     Country:  United States    
Other Details:
Languages:  eng     Pagination:  670-81     Citation Subset:  AIM; IM    
Assistance Publique-H?pitaux de Paris, Service de Pneumologie et R?animation, Groupe Hospitalier Piti?-Salp?tri?re, and Universit? Paris 6-Pierre et Marie Curie, Paris, France.
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MeSH Terms
Aged, 80 and over
Air Pressure
Blood Gas Analysis
Data Interpretation, Statistical
Diaphragm / physiology
Dose-Response Relationship, Drug
Esophagus / innervation,  physiology
Intensive Care
Middle Aged
Respiration, Artificial*
Respiratory Distress Syndrome, Adult / physiopathology*,  therapy*
Respiratory Mechanics / physiology*
Ventilator Weaning

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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