Diaphragm ultrasound as a predictor of successful extubation from mechanical ventilation

Thorax. 2014 May;69(5):423-7. doi: 10.1136/thoraxjnl-2013-204111. Epub 2013 Dec 23.


Introduction: The purpose of this study was to evaluate if ultrasound derived measures of diaphragm thickening, rather than diaphragm motion, can be used to predict extubation success or failure.

Methods: Sixty-three mechanically ventilated patients were prospectively recruited. Diaphragm thickness (tdi) was measured in the zone of apposition of the diaphragm to the rib cage using a 7-10 MHz ultrasound transducer. The percent change in tdi between end-expiration and end-inspiration (Δtdi%) was calculated during either spontaneous breathing (SB) or pressure support (PS) weaning trials. A successful extubation was defined as SB for >48 h following endotracheal tube removal.

Results: Of the 63 subjects studied, 27 patients were weaned with SB and 36 were weaned with PS. The combined sensitivity and specificity of Δtdi%≥30% for extubation success was 88% and 71%, respectively. The positive predictive value and negative predictive value were 91% and 63%, respectively. The area under the receiver operating characteristic curve was 0.79 for Δtdi%.

Conclusions: Ultrasound measures of diaphragm thickening in the zone of apposition may be useful to predict extubation success or failure during SB or PS trials.

Keywords: Respiratory Muscles.

Publication types

  • Multicenter Study
  • Randomized Controlled Trial

MeSH terms

  • Aged
  • Airway Extubation / methods
  • Airway Extubation / standards*
  • Critical Illness / therapy*
  • Diaphragm / diagnostic imaging*
  • Female
  • Follow-Up Studies
  • Humans
  • Male
  • Prospective Studies
  • ROC Curve
  • Respiration*
  • Respiration, Artificial*
  • Ultrasonography
  • Ventilator Weaning / methods*