RESUMO
OBJECTIVES: To validate a mathematical model using porous media theory for alveolar CO2 determination in ventilated patients. DESIGN: Mathematical modeling study with prospective clinical validation to simulate CO2 exchange from bloodstream to airway entrance. SETTING: ICU. PATIENTS: Thirteen critically ill patients without chronic or acute lung disease. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Model outcomes compared with patient data showed correlations for end-tidal CO2 (EtCO 2 ), area under the CO2 curve, and Pa CO2 of 0.918, 0.954, and 0.995. Determination coefficients ( R2 ) were 0.843, 0.910, and 0.990, indicating precision and predictive power. CONCLUSIONS: The mathematical model shows potential in pulmonary critical care. Although promising, practical application demands further validation, clinician training, and patient-specific adjustments. The path to clinical use will be iterative, involving validation and education.