Dead Space (Vd/Vt)

Dead space represents the portion of tidal volume that does not participate in gas exchange. The Bohr equation calculates the dead space-to-tidal volume ratio.

Disclaimer

This calculator is for educational purposes only. Always verify with clinical judgment.

Bohr Equation Calculator

PaCO2 (mmHg)

PeCO2 (mixed expired CO2, mmHg)

Tidal Volume (mL, optional for Vd volume)

Body Weight (kg, for anatomic Vd estimate)

Formulas

Vd/Vt = (PaCO2 - PeCO2) / PaCO2 (Bohr equation)

Anatomic Vd ≈ 2.2 mL/kg body weight

References

West JB. Respiratory Physiology: The Essentials, 10th Edition.
Hess DR, Kacmarek RM. Essentials of Mechanical Ventilation, 4th Edition.