title: The Ratio of Inspiratory Pressure Over Electrical Activity of the Diaphragm Remains Stable During ICU Stay and is not Related to Clinical Outcome.
abstract: BACKGROUND
  We previously described an index, defined as the ratio between the inspiratory muscle pressure (Pmus) and the electrical activity of the diaphragm (EA(di)) (Pmus/EA(di) index). In the present work, we describe the trend of Pmus/EA(di) index over time, investigating whether it could be an indicator of muscular efficiency associated with risk factors for diaphragmatic injury and/or clinical outcomes.
  
  
  METHODS
  This work is a retrospective analysis of subjects with measurements of Pmus/EA(di) index obtained, on different days, during assisted ventilation. Effects of Pmus/EA(di) index absolute value on clinical outcomes were investigated dividing subjects into those with Pmus/EA(di) index higher or lower than the median. Effects of Pmus/EA(di) index trend over time were analyzed, distinguishing between subjects with Pmus/EA(di) index increasing or decreasing.
  
  
  RESULTS
  Mean Pmus/EA(di) index was 1.04 ± 0.67, and the median (interquartile range) was 1.00 (0.59-1.34), without a systematic trend over the days. Demographic, ventilator, or outcome data did not significantly differ between subjects with Pmus/EA(di) index higher or lower than the median. Similarly, we did not find relevant differences in subjects with Pmus/EA(di) index increasing or decreasing over time.
  
  
  CONCLUSIONS
  The Pmus/EA(di) index value remained constant in each subject over time, although the inter-individual variability was high. Neither the Pmus/EA(di) index nor its trends appeared to be associated with ventilatory variables or clinical outcome.
authors.affiliation: Department of Health Science, University of Milan-Bicocca, Monza, Italy. Department of Emergency and Intensive Care, San Gerardo Hospital, Monza, Italy. giacomo.bellani1@unimib.it.
authors.forename: Giacomo
authors.initials: G
authors.lastname: Bellani
authors.affiliation: Department of Emergency and Intensive care, A. Manzoni Hospital, Lecco, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Coppadoro
authors.affiliation: Department of Health Science, University of Milan-Bicocca, Monza, Italy. Department of Emergency and Intensive Care, San Gerardo Hospital, Monza, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Pozzi
authors.affiliation: Department of Health Science, University of Milan-Bicocca, Monza, Italy. Department of Emergency and Intensive Care, San Gerardo Hospital, Monza, Italy.
authors.forename: Alfio
authors.initials: A
authors.lastname: Bronco
authors.affiliation: Humanitas Research Hospital, Rozzano, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Albiero
authors.affiliation: Department of Health Science, University of Milan-Bicocca, Monza, Italy. Department of Emergency and Intensive Care, San Gerardo Hospital, Monza, Italy.
authors.forename: Nilde
authors.initials: N
authors.lastname: Eronia
authors.affiliation: Department of Health Science, University of Milan-Bicocca, Monza, Italy.
authors.forename: Valeria
authors.initials: V
authors.lastname: Meroni
authors.affiliation: Department of Emergency and Intensive Care, San Gerardo Hospital, Monza, Italy.
authors.forename: Giacomo
authors.initials: G
authors.lastname: Grasselli
authors.affiliation: Department of Health Science, University of Milan-Bicocca, Monza, Italy. Department of Emergency and Intensive Care, San Gerardo Hospital, Monza, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Pesenti
mesh_terms: D000368:Aged; D003964:Diaphragm / Q000503:physiopathology*; D004576:Electromyography / Q000706:statistics & numerical data; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D007362:Intensive Care Units; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D000072277:Maximal Respiratory Pressures / Q000706:statistics & numerical data*; D008875:Middle Aged; D012121:Respiration, Artificial / Q000379:methods / Q000706:statistics & numerical data*; D012132:Respiratory Muscles / Q000502:physiology; D012189:Retrospective Studies; D016896:Treatment Outcome
keywords: diaphragm; electromyography; muscle pressure; neutrally adjusted ventilator assist; pressure support; weaning