[Threshold value of f/Vt index for predicting successful weaning from mechanical ventilation in active smokers].

Background: Mechanical ventilation (MV) is used in 60-70 % of patients admitted to the intensive care unit (ICU). An f/Vt threshold value of 105 is a predictor of successful weaning from mechanical ventilation (WMV) in patients with asthma, cardiac surgery, pneumonia, sepsis, neurocritical, etc. However, there are no reports about the usefulness of the f/Vt value to predict successful WMV in patients with active smoking (AS). The purpose of this paper is to identify a threshold value for f/Vt to predict successful WMV in patients with AS.

Methods: Prospectively, 85 patients with AS and MV >24 hours admitted to de ICU were included. Demographic and clinical data were registered. The f/Vt value was measured with a Wright's spirometer, and the sensibility, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated to predict a successful WMV. A p value <0.05 was considered statistically significant.

Results: The average of f/Vt was 68.69. Successful WMV was of 75.3 %. An f/Vt threshold value of 79.5 had sensibility of 76 %, specificity of 61 %, PPV of 85 %, and NPV of 46 % to predict successful WMV in this group of patients.

Conclusions: An f/Vt threshold value of 79.5 is useful to predict successful WMV in patients with AS.