Degree of convexity calculated from expiratory flow-volume curves for identifying airway obstruction in nonsedated and nonparalyzed ventilated patients

https://doi.org/10.1016/j.resp.2021.103739Get rights and content
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Highlights

  • The degree of convexity from EFV curves significantly correlated with FEV1% predicted in nonsedated and nonparalyzed patients receiving MV.

  • A degree of convexity > 16.75 at a tidal volume of 12 mL/kg IBW effectively differentiated COPD from non-COPD.

  • We demonstrated the potential of using the convexity in EFV curves to detect airway obstruction in the nonsedated and nonparalyzed patients.

Abstract

The predictive performance of applying the degree of convexity in expiratory flow-volume (EFV) curves to detect airway obstruction in ventilated patients has yet to be investigated. We enrolled 33 nonsedated and nonparalyzed mechanically ventilated patients and found that the degree of convexity had a significant negative correlation with FEV1% predicted. The mean degree of convexity in EFV curves in the chronic obstructive pulmonary disease (COPD) group (n = 18) was significantly higher than that in the non-COPD group (n = 15; 26.37 % ± 11.94 % vs. 17.24 % ± 10.98 %, p = 0.030) at a tidal volume of 12 mL/kg IBW. A degree of convexity in the EFV curve > 16.75 at a tidal volume of 12 mL/kg IBW effectively differentiated COPD from non-COPD (AUC = 0.700, sensitivity = 77.8 %, specificity = 53.3 %, p = 0.051). The degree of convexity calculated from EFV curves may help physicians to identify ventilated patients with airway obstruction.

Keywords

Mechanical ventilation
Expiratory flow-volume curves
Degree of convexity

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