title: Maximum inspiratory pressure, a surrogate parameter for the assessment of ICU-acquired weakness.
abstract: BACKGROUND
  Physical examination has been advocated as a primary determinant of ICU-acquired weakness (ICU-AW). The purpose of the study is to investigate ICU-AW development by using Maximum Inspiratory Pressure (MIP) as a surrogate parameter of the standardized method to evaluate patients' peripheral muscle strength.
  
  
  METHODS
  Seventy-four patients were recruited in the study and prospectively evaluated in a multidisciplinary university ICU towards the appearance of ICU-AW. APACHE II admission score was 16 ± 6 and ICU stay 26 ± 18 days. ICU-AW was diagnosed with the Medical Research Council (MRC) scale for the clinical evaluation of muscle strength. MIP was measured using the unidirectional valve method, independently of the patients' ability to cooperate.
  
  
  RESULTS
  A significant correlation was found between MIP and MRC (r = 0.68, p < 0.001). Patients that developed ICU-AW (MRC<48) had a longer weaning period compared to non ICU-AW patients (12 ± 14 versus 2 ± 3 days, p < 0.01). A cut-off point of 36 cmH2O for MIP was defined by ROC curve analysis for ICU-AW diagnosis (88% sensitivity,76% specificity). Patients with MIP below the cut-off point of 36 cmH2O had a significant greater weaning period (10 ± 14 versus 3 ± 3 days, p = 0.004) also shown by Kaplan-Meier analysis (log-rank:8.2;p = 0.004).
  
  
  CONCLUSIONS
  MIP estimated using the unidirectional valve method may be a potential surrogate parameter for the assessment of muscle strength compromise, useful for the early detection of ICU-AW.
authors.affiliation: First Critical Care Department, Evangelismos Hospital, National and Kapodestrian University of Athens, Athens, Greece. a-icu@med.uoa.gr.
authors.forename: Georgios
authors.initials: G
authors.lastname: Tzanis
authors.forename: Ioannis
authors.initials: I
authors.lastname: Vasileiadis
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Zervakis
authors.forename: Eleftherios
authors.initials: E
authors.lastname: Karatzanos
authors.forename: Stavros
authors.initials: S
authors.lastname: Dimopoulos
authors.forename: Theodore
authors.initials: T
authors.lastname: Pitsolis
authors.forename: Elli
authors.initials: E
authors.lastname: Tripodaki
authors.forename: Vasiliki
authors.initials: V
authors.lastname: Gerovasili
authors.forename: Christina
authors.initials: C
authors.lastname: Routsi
authors.forename: Serafim
authors.initials: S
authors.lastname: Nanas