title: Patterns of diaphragm function in critically ill patients receiving prolonged mechanical ventilation: a prospective longitudinal study.
abstract: BACKGROUND
  In intensive care unit (ICU) patients, diaphragmatic dysfunction (DD) can occur on admission or during the subsequent stay. The respective incidence of these two phenomena has not been previously studied in humans. The study was designed to describe temporal trends in diaphragm function in mechanically ventilated (MV) patients.
  
  
  METHODS
  Ancillary study of a prospective, 6-month, observational cohort study conducted in two ICUs. MV patients were studied within 24 h following intubation (day-1) and every 48-72 h thereafter. Diaphragm function was assessed by twitch tracheal pressure (Ptr,stim) in response to bilateral anterior magnetic phrenic nerve stimulation. Diaphragm dysfunction was defined as Ptr,stim < 11 cmH2O. Patients who received MV for at least 5 days were retained, and the first and the last measures were analysed.
  
  
  RESULTS
  Forty-three patients were included. Overall, 79 % of patients developed DD at some point during their ICU stay: 23 (53 %) patients presented DD on initiation of mechanical ventilation, 14 (33 %) of whom had persistent DD, while diaphragm function improved in 9 (21 %). Among the remaining 20 (47 %) patients who did not present DD on initiation of MV, 11 (26 %) developed DD during the ICU stay, while 9 (21 %) did not. Mortality was higher in patients with DD either on initiation of mechanical ventilation or during the subsequent ICU stay than in those who never developed DD (35 vs. 0 %, p = 0.04). Duration of MV was higher in patients with DD on initiation of MV that subsequently persisted than in patients who never exhibited diaphragm dysfunction (18 vs. 5 days, p = 0.04). Factors associated with a change in Ptr,stim were: age [linear coefficient regression (Coeff.) -0.097, standard error (SD) 0.047, p = 0.046], PaO2/FiO2 ratio (Coeff. 0.014, SD 0.006, p = 0.0211) and the proportion of the time under MV with sedation (per 10 %, Coeff. -5.359, SD 2.451, p = 0.035).
  
  
  CONCLUSIONS
  DD is observed in a large majority of MV patients ≥5 days at some point of their ICU stay. Various patterns of DD are observed, including DD on initiation of mechanical ventilation and ICU-acquired DD. Trial registration clinicaltrials.gov Identifier # NCT00786526.
authors: INSERM, UMRS1158 Neurophysiologie respiratoire expérimentale et clinique, Sorbonne Universités, UPMC Univ Paris 06, Paris, France. alexandre.demoule@aphp.fr.|Intensive Care Unit and Respiratory Division (Département "R3S"), Groupe Hospitalier Pitié-Salpêtrière Charles Foix, AP-HP, 75013, Paris, France. alexandre.demoule@aphp.fr.|Service de Pneumologie et Réanimation Médicale, Groupe Hospitalier Pitié-Salpêtrière, 47-83 boulevard de l'Hôpital, 75651, Paris Cedex 13, France. alexandre.demoule@aphp.fr.
authors: Alexandre
authors: A
authors: Demoule
authors: Department of Medical Information, Hôpital Arnaud de Villeneuve, IMAG U5149, University of Montpellier, Montpellier, France.
authors: Nicolas
authors: N
authors: Molinari
authors: INSERM U1046, CNRS UMR 9214, Montpellier School of Medicine, University of Montpellier, Montpellier, France.|Intensive Care and Anesthesiology Department, Saint Eloi Hospital, Montpellier, France.
authors: Boris
authors: B
authors: Jung
authors: Intensive Care Unit and Respiratory Division (Département "R3S"), Groupe Hospitalier Pitié-Salpêtrière Charles Foix, AP-HP, 75013, Paris, France.
authors: Hélène
authors: H
authors: Prodanovic
authors: INSERM U1046, CNRS UMR 9214, Montpellier School of Medicine, University of Montpellier, Montpellier, France.|Intensive Care and Anesthesiology Department, Saint Eloi Hospital, Montpellier, France.
authors: Gerald
authors: G
authors: Chanques
authors: Physiology and Experimental Medecine, Heart-Muscle UMR CNRS 9214 - INSERM U1046, Montpellier University, Montpellier, France.
authors: Stefan
authors: S
authors: Matecki
authors: Intensive Care Unit and Respiratory Division (Département "R3S"), Groupe Hospitalier Pitié-Salpêtrière Charles Foix, AP-HP, 75013, Paris, France.
authors: Julien
authors: J
authors: Mayaux
authors: INSERM, UMRS1158 Neurophysiologie respiratoire expérimentale et clinique, Sorbonne Universités, UPMC Univ Paris 06, Paris, France.|Intensive Care Unit and Respiratory Division (Département "R3S"), Groupe Hospitalier Pitié-Salpêtrière Charles Foix, AP-HP, 75013, Paris, France.
authors: Thomas
authors: T
authors: Similowski
authors: INSERM U1046, CNRS UMR 9214, Montpellier School of Medicine, University of Montpellier, Montpellier, France.|Intensive Care and Anesthesiology Department, Saint Eloi Hospital, Montpellier, France.
authors: Samir
authors: S
authors: Jaber
keywords: Diaphragm Respiratory muscles function; Intensive care unit; Mechanical ventilation; Outcome; Phrenic nerve stimulation; Sepsis