Wednesday, July 28, 2010

Wednesday July 28, 2010
Involuntary Cough Strength and Extubation Outcomes for Patients in an ICU

Background: Removing the artificial airway is the last step in the mechanical ventilation withdrawal process. In order to assess cough effectiveness, a critical component of this process, we evaluated the involuntary cough peak flow (CPFi) to predict the extubation outcome for patients weaned from mechanical ventilation in ICUs.

Methods: One hundred fifty patients were weaned from ventilators, passed a spontaneous breathing trial (SBT), and were judged by their physician to be ready for extubation in the Tri-Service General Hospital ICUs from February 2003 to July 2003. CPFi was induced by 2 mL of normal saline solution at the end of inspiration and measured using a hand-held respiratory mechanics monitor. All patients were then extubated.


Results: Of 150 enrolled patients for this study, 118 (78.7%) had successful extubation and 32 (21.3%) failed.

In the univariate analysis, in the extubation failures compared with the extubation successes - there were


  • higher Acute Physiology and Chronic Health Evaluation (APACHE) II scores (16.0 vs 18.5, P = .018),
  • less negative maximum inspiratory pressure (−45.0 vs −39.0, P = .010),
  • lower cough peak flows (CPFs) (74.0 vs 42.0 L/min, P less than .001),
  • longer postextubation hospital stays (15.0 vs 31.5 days, P less than .001), and
  • longer postextubation ICU stays (1.0 vs 9.5 days, P less than .001)

In the multivariate analysis, increasing risk of extubation failure were noted in

  • a higher APACHE II score and
  • a lower CPF

The receiver operator characteristic curve cutoff point for CPF was 58.5 L/min, with a sensitivity of 78.8% and specificity of 78.1%


Conclusions: CPFi as an indication of cough reflex has the potential to predict successful extubation in patients who pass an SBT.