Standardizing Predicted Body Weight Equations for Mechanical Ventilation Tidal Volume Settings.

Area of Science:

• Critical Care Medicine
• Pulmonary Medicine
• Biomedical Engineering

Background:

• Lung protective mechanical ventilation guidelines recommend a tidal volume of 6 mL/kg predicted body weight (PBW).
• Discrepancies among various PBW equations can lead to significant variations in delivered tidal volumes.
• This variability may impact research findings and patient care.

Purpose of the Study:

• To compare the differences between commonly used PBW equations (NIH ARDS Network, Actuarial, Stewart).
• To quantify the impact of these differences on tidal volume calculations across diverse patient demographics.
• To recommend a standardized PBW equation for clinical trials and practice.

Main Methods:

• Utilized three-dimensional and two-dimensional surface analysis to compare NIH ARDS Network (ARDSNet), Actuarial (ACTUARIAL), and Stewart (STEWART) PBW equations.
• Input variables included height, age, and sex across physiologic ranges.
• Quantified PBW equation differences using actual clinical trial subject data.

Main Results:

• Significant mathematical differences were observed between PBW equations, exceeding 30% in women and 24% in men for ACTUARIAL vs. ARDSNet.
• The largest discrepancies occurred in older, shorter individuals, particularly women.
• Actual tidal volume differences in clinical trial subjects reached up to 24% for women and 15% for men.

Conclusions:

• PBW equation variability is a substantial source of interstudy variation in mechanical ventilation research.
• Adopting a standard PBW equation is crucial for consistency.
• The NIH National Heart, Lung, and Blood Institute ARDS Network PBW equation is recommended due to its association with the 6 mL/kg PBW target discovery.