title: Early type II fiber atrophy in intensive care unit patients with nonexcitable muscle membrane.
abstract: OBJECTIVE
  Intensive care unit-acquired weakness indicates increased morbidity and mortality. Nonexcitable muscle membrane after direct muscle stimulation develops early and predicts intensive care unit-acquired weakness in sedated, mechanically ventilated patients. A comparison of muscle histology at an early stage in intensive care unit-acquired weakness has not been done. We investigated whether nonexcitable muscle membrane indicates fast-twitch myofiber atrophy during the early course of critical illness.
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  Two intensive care units at Charité University Medicine, Berlin.
  
  
  METHODS
  Patients at increased risk for development of intensive care unit-acquired weakness, indicated by Sepsis-related Organ Failure Assessment scores ≥8 on 3 of 5 consecutive days within their first week in the intensive care unit.
  
  
  METHODS
  None.
  
  
  RESULTS
  Electrophysiological compound muscle action potentials after direct muscle stimulation and muscle biopsies were obtained at median days 7 and 5, respectively. Patients with nonexcitable muscle membranes (n = 15) showed smaller median type II cross-sectional areas (p < .05), whereas type I muscle fibers did not compared with patients with preserved muscle membrane excitability (compound muscle action potentials after direct muscle stimulation ≥3.0 mV; n = 9). We also observed decreased mRNA transcription levels of myosin heavy chain isoform IIa and a lower densitometric ratio of fast-to-slow myosin heavy chain protein content.
  
  
  CONCLUSIONS
  We suggest that electrophysiological nonexcitable muscle membrane predicts preferential type II fiber atrophy in intensive care unit patients during early critical illness.
authors.affiliation: Department of Anesthesiology and Operative Intensive Care Medicine, Campus Virchow-Klinikum & Campus Mitte, Charité University Medicine, Berlin, Germany.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Bierbrauer
authors.forename: Susanne
authors.initials: S
authors.lastname: Koch
authors.forename: Claudio
authors.initials: C
authors.lastname: Olbricht
authors.forename: Jida
authors.initials: J
authors.lastname: Hamati
authors.forename: Dörte
authors.initials: D
authors.lastname: Lodka
authors.forename: Joanna
authors.initials: J
authors.lastname: Schneider
authors.forename: Anja
authors.initials: A
authors.lastname: Luther-Schröder
authors.forename: Christian
authors.initials: C
authors.lastname: Kleber
authors.forename: Katharina
authors.initials: K
authors.lastname: Faust
authors.forename: Solveigh
authors.initials: S
authors.lastname: Wiesener
authors.forename: Claudia D
authors.initials: CD
authors.lastname: Spies
authors.forename: Joachim
authors.initials: J
authors.lastname: Spranger
authors.forename: Simone
authors.initials: S
authors.lastname: Spuler
authors.forename: Jens
authors.initials: J
authors.lastname: Fielitz
authors.forename: Steffen
authors.initials: S
authors.lastname: Weber-Carstens
mesh_terms: D000200:Action Potentials; D000328:Adult; D000368:Aged; D001284:Atrophy / Q000453:epidemiology / Q000473:pathology; D015331:Cohort Studies; D003422:Critical Care / Q000379:methods; D016638:Critical Illness; D004576:Electromyography / Q000379:methods; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008566:Membranes; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000473:pathology*; D018908:Muscle Weakness / Q000175:diagnosis* / Q000453:epidemiology; D011237:Predictive Value of Tests; D011446:Prospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric; D013997:Time Factors