title: Respiratory weakness after mechanical ventilation is associated with one-year mortality - a prospective study.
abstract: Diaphragm dysfunction in mechanically ventilated patients is associated with poor outcome. Maximal inspiratory pressure (MIP) can be used to evaluate inspiratory muscle function. However, it is unclear whether respiratory weakness is independently associated with long-term mortality. The aim of this study was to determine if low MIP is independently associated with one-year mortality.
  
  
  
  We conducted a prospective observational cohort study in an 18-bed ICU. Adults requiring at least 24 hours of mechanical ventilation with scheduled extubation and no evidence of pre-existing muscle weakness underwent MIP evaluation just before extubation. Patients were divided into two groups: low MIP (MIP ≤30 cmH2O) and high MIP (MIP >30 cmH2O). Mortality was recorded for one year after extubation. For the survival analysis, the effect of low MIP was assessed using the log-rank test. The independent effect of low MIP on post mechanical ventilation mortality was analyzed using a multivariable Cox regression model.
  
  
  
  One hundred and twenty-four patients underwent MIP evaluation (median age 66 years (25(th)-75(th) percentile 56-74), Simplified Acute Physiology Score (SAPS) 2 = 45 (33-57), duration of mechanical ventilation 7 days (4-10)). Fifty-four percent of patients had low MIP. One-year mortality was 31 % (95 % CI 0.21, 0.43) in the low MIP group and 7 % (95 % CI 0.02, 0.16) in the high MIP group. After adjustment for SAPS 2 score, body mass index and duration of mechanical ventilation, low MIP was independently associated with one-year mortality (hazard ratio 4.41, 95 % CI 1.5, 12.9, p = 0.007). Extubation failure was also associated with low MIP (relative risk 3.0, 95 % CI 1, -9.6; p = 0.03) but tracheostomy and ICU length of stay were not.
  
  
  
  Low MIP is frequent in patients on mechanical ventilation and is an independent risk factor for long-term mortality in ICU patients requiring mechanical ventilation. MIP is easily evaluated at the patient's bedside.
  
  
  
  This study was retrospectively registered in www.clinicaltrials.gov (NCT02363231) in February 2015.
authors.affiliation: Intensive Care Unit Department, Groupe Hospitalier du Havre, Avenue Pierre Mendes France, 76290, Montivilliers, France. medrinal.clement.mk@gmail.com.|Groupe de Recherche sur le Handicap Ventilatoire, UPRES EA 3830, Haute-Normandie Institute of Biomedical Research and Innovation, Rouen University, Rouen, France. medrinal.clement.mk@gmail.com.
authors.forename: Clément
authors.initials: C
authors.lastname: Medrinal
authors.affiliation: Intensive Care Unit Department, Groupe Hospitalier du Havre, Avenue Pierre Mendes France, 76290, Montivilliers, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Prieur
authors.affiliation: Intensive Care Unit Department, Groupe Hospitalier du Havre, Avenue Pierre Mendes France, 76290, Montivilliers, France.
authors.forename: Éric
authors.initials: É
authors.lastname: Frenoy
authors.affiliation: Intensive Care Unit Department, Groupe Hospitalier du Havre, Avenue Pierre Mendes France, 76290, Montivilliers, France.
authors.forename: Aurora
authors.initials: A
authors.lastname: Robledo Quesada
authors.affiliation: Department of Health and Community Medicine, University Hospitals and University of Geneva, Geneva, Switzerland.
authors.forename: Antoine
authors.initials: A
authors.lastname: Poncet
authors.affiliation: ADIR Association, Bois Guillaume, France.
authors.forename: Tristan
authors.initials: T
authors.lastname: Bonnevie
authors.affiliation: ADIR Association, Bois Guillaume, France.
authors.forename: Francis-Edouard
authors.initials: FE
authors.lastname: Gravier
authors.affiliation: Intensive Care Unit Department, Groupe Hospitalier du Havre, Avenue Pierre Mendes France, 76290, Montivilliers, France.|Groupe de Recherche sur le Handicap Ventilatoire, UPRES EA 3830, Haute-Normandie Institute of Biomedical Research and Innovation, Rouen University, Rouen, France.
authors.forename: Bouchra
authors.initials: B
authors.lastname: Lamia
authors.affiliation: University of Applied Sciences and Arts Western Switzerland (HES-SO), Lausanne, Switzerland.
authors.forename: Olivier
authors.initials: O
authors.lastname: Contal
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005602:France / Q000453:epidemiology; D017052:Hospital Mortality; D006801:Humans; D007362:Intensive Care Units / Q000458:organization & administration / Q000706:statistics & numerical data; D007902:Length of Stay; D008297:Male; D000072277:Maximal Respiratory Pressures; D008875:Middle Aged; D018908:Muscle Weakness / Q000453:epidemiology / Q000209:etiology* / Q000503:physiopathology; D011446:Prospective Studies; D012372:ROC Curve; D012121:Respiration, Artificial / Q000009:adverse effects* / Q000706:statistics & numerical data; D012132:Respiratory Muscles / Q000002:abnormalities / Q000378:metabolism / Q000503:physiopathology*; D012189:Retrospective Studies; D012307:Risk Factors; D015300:Ventilator Weaning / Q000401:mortality
keywords: Diaphragm; ICU; Maximal inspiratory pressure; Mechanical ventilation; Mortality