A novel biometric approach to estimating tidal volume

Area of Science:

• Critical Care Medicine
• Pulmonary Medicine
• Biomedical Engineering

Background:

• Low tidal volume ventilation (LTVV) is recommended for acute respiratory distress syndrome and controlled ventilation.
• Poor adherence to LTVV is linked to challenges in measuring ideal body weight (IBW).
• A novel biometric tool using demispan was developed to estimate tidal volume (V_T).

Purpose of the Study:

• To validate a novel biometric approach for estimating V_T in mechanically ventilated patients.
• To demonstrate the accuracy of demispan-derived V_T as an alternative to IBW calculated from height.
• To assess the potential for improved adherence to LTVV guidelines.

Main Methods:

• Developed a computer program and paper tape for direct V_T estimation using demispan.
• Conducted an observational validation study on post-cardiac surgery patients.
• Compared V_T derived from demispan with V_T calculated from measured height.

Main Results:

• Demispan-derived V_T correlated well (r=0.8) with height-derived V_T, showing no statistical difference.
• Compliance with V_T ≤ 6.5 mL/kg IBW improved from 62% (height) to 80% (demispan).
• Bland-Altman analysis showed acceptable limits of agreement for the demispan method.

Conclusions:

• The demispan-based biometric tool accurately estimates V_T in ventilated patients.
• The tool's simplicity and accuracy can enhance adherence to recommended V_T restriction.
• This approach offers a practical solution to improve LTVV delivery.