Work of breathing during successful spontaneous breathing trial

J Crit Care. 2009 Dec;24(4):508-14. doi: 10.1016/j.jcrc.2008.10.013. Epub 2009 Feb 13.


Objective: The aim of this study was to evaluate the work of breathing (WOB) behavior during a 120-minute successful spontaneous breathing trial (SBT) with T-tube trial, and its predictive value for extubation outcome.

Design: A prospective cohort study.

Setting: 2 medical-surgical intensive care units.

Patients: Fifty-one consecutive patients mechanically ventilated for more than 48 hours after a successful SBT were extubated based on the institutional protocol and followed for the occurrence of postextubation respiratory distress during 48 hours.

Measurements and main results: All cases were serially monitored during 120 minutes of SBT using the respiratory monitoring system Ventrak 1500 (Medical Novametrix Systems, Wallingford, CT). Successful extubation occurred in 38 (74.5%) of 51 of the sample. Respiratory and hemodynamic parameters, APACHE II score, sex, days on mechanical ventilation, and cause of respiratory failure were unable to predict extubation outcome. The WOB significantly increased during SBT in extubation failure patients (WOB at 1st minute 0.24 +/- 0.06 J/L vs WOB at 120th minute = 0.39 +/- 0.07 J/L; P < .01) when compared to successfully extubated patients (WOB at 1st minute 0.21 +/- 0.08 J/L vs WOB at 120th minute = 0.24 +/- 0.11 J/L; P = .12). The WOB variation was able to predict extubation outcome only after the 90th minute of SBT (extubation failure = 0.35 +/- 0.08 J/L vs extubation success = 0.22 +/- 0.11 J/L; P = .01).

Conclusion: An increase in the WOB could predict extubation failure during a T-tube trial of 120 minutes.

MeSH terms

  • Aged
  • Female
  • Hemodynamics
  • Humans
  • Male
  • Middle Aged
  • Prospective Studies
  • Respiration*
  • Respiration, Artificial*
  • Respiratory Insufficiency
  • Respiratory Mechanics / physiology*
  • Sex Factors
  • Time Factors
  • Ventilator Weaning / methods*