title: Ultrasonographic Evaluation of Diaphragm Thickness During Mechanical Ventilation in Intensive Care Patients.
abstract: BACKGROUND
  Mechanical ventilation is associated with atrophy and weakness of the diaphragm. Ultrasound is an easy noninvasive way to track changes in thickness of the diaphragm.
  
  
  OBJECTIVE
  To validate ultrasound as a means of tracking thickness of the diaphragm in patients undergoing mechanical ventilation by evaluating interobserver and interoperator reliability and to collect initial data on the relationship of mode of ventilation to changes in the diaphragm.
  
  
  METHODS
  Daily ultrasound images of the quadriceps and the right side of the diaphragm were acquired in 8 critically ill patients receiving various modes of mechanical ventilation. Thickness of the diaphragm and the quadriceps was measured, and changes with time were noted. Interoperator and interobserver reliability were measured.
  
  
  RESULTS
  Intraclass correlation coefficients between operators and between observers for thickness of the diaphragm and quadriceps were greater than 0.95, indicating excellent interoperator and interobserver reliability. Patients receiving assist-control ventilation (n = 4) showed a mean decline in diaphragm thickness of 4.7% per day. Patients receiving pressure support ventilation (n = 8) showed a mean increase in diaphragm thickness of 1.5% per day. Quadriceps thickness declined in all participants (n = 8) at a mean rate of 2.0% per day.
  
  
  CONCLUSIONS
  Use of ultrasound to measure thickness of the diaphragm in 8 intensive care patients undergoing various modes of mechanical ventilation was feasible and yielded reproducible results. Ultrasound tracking of changes in thickness of the diaphragm in this small sample indicated that the thickness decreased during assist-control mode and increased during pressure support mode.
authors.affiliation: Colin Anthony Francis is a doctoral student in the Department of Experimental Medicine, University of British Columbia, Vancouver, Canada. Joaquín Andrés Hoffer is a professor in the Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada. Steven Reynolds is a critical care physician in the Department of Critical Care, Royal Columbian Hospital, Fraser Health Authority, New Westminster, BC, Canada.
authors.forename: Colin Anthony
authors.initials: CA
authors.lastname: Francis
authors.affiliation: Colin Anthony Francis is a doctoral student in the Department of Experimental Medicine, University of British Columbia, Vancouver, Canada. Joaquín Andrés Hoffer is a professor in the Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada. Steven Reynolds is a critical care physician in the Department of Critical Care, Royal Columbian Hospital, Fraser Health Authority, New Westminster, BC, Canada.
authors.forename: Joaquín Andrés
authors.initials: JA
authors.lastname: Hoffer
authors.affiliation: Colin Anthony Francis is a doctoral student in the Department of Experimental Medicine, University of British Columbia, Vancouver, Canada. Joaquín Andrés Hoffer is a professor in the Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada. Steven Reynolds is a critical care physician in the Department of Critical Care, Royal Columbian Hospital, Fraser Health Authority, New Westminster, BC, Canada. sreynolds.md@gmail.com.
authors.forename: Steven
authors.initials: S
authors.lastname: Reynolds
mesh_terms: D001284:Atrophy / Q000000981:diagnostic imaging / Q000209:etiology; D003422:Critical Care; D003964:Diaphragm / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D015588:Observer Variation; D052097:Quadriceps Muscle / Q000000981:diagnostic imaging* / Q000473:pathology; D015203:Reproducibility of Results; D012121:Respiration, Artificial / Q000009:adverse effects* / Q000379:methods; D013997:Time Factors; D014463:Ultrasonography