Dead Space Calculator
Calculate physiological dead space using the Bohr equation for respiratory assessment
Calculate Physiological Dead Space
Medical Disclaimer
This calculator is for educational purposes only and should not replace professional medical consultation. Always consult with healthcare professionals for medical diagnosis and treatment decisions.
Normal range: 35-45 mmHg (4.7-6.0 kPa)
Mixed expiratory CO₂ concentration
Normal range: 400-600 ml (0.4-0.6 L) for healthy adults
Dead Space Results
Formula used: pDS = ((alCO₂ - exCO₂) / alCO₂) × TV
Input values: Alveolar CO₂: 0.0 mmHg, Expiratory CO₂: 0.0 mmHg, Tidal Volume: 0 ml
Normal range: 150-200 ml for healthy adults
Example Calculation
Healthy Adult Example
Alveolar CO₂ concentration: 40 mmHg
Expiratory CO₂ concentration: 30 mmHg
Tidal volume: 500 ml (0.5 L)
Calculation Steps
pDS = ((40 - 30) / 40) × 500
pDS = (10 / 40) × 500
pDS = 0.25 × 500
pDS = 125 ml
VD/VT ratio = 125/500 = 25%
Types of Dead Space
Anatomical
Airways that conduct air but don't exchange gases
Nose, mouth, trachea, bronchi
Functional
Total dead space including alveolar
Anatomical + Alveolar dead space
Physiological
Same as functional dead space
What this calculator measures
Normal Values
Note: Values can vary with age, disease, and ventilation conditions.
Understanding Dead Space
What is Dead Space?
Dead space refers to the volume of inhaled air that doesn't participate in gas exchange. It includes all parts of the respiratory system where air moves but no oxygen and carbon dioxide exchange occurs with the blood.
Clinical Significance
- •Assesses respiratory efficiency
- •Evaluates lung disease severity
- •Guides ventilator management
- •Monitors treatment response
The Bohr Equation
pDS = ((alCO₂ - exCO₂) / alCO₂) × TV
- pDS: Physiological dead space (ml)
- alCO₂: Alveolar CO₂ concentration (mmHg)
- exCO₂: Mixed expiratory CO₂ concentration (mmHg)
- TV: Tidal volume (ml)
Important: This calculator provides estimates for educational purposes. Clinical measurements require specialized equipment and professional interpretation.
Factors Affecting Dead Space
Increased Dead Space
- • Pulmonary embolism
- • COPD
- • Pulmonary fibrosis
- • Mechanical ventilation
- • Advanced age
- • Smoking
Normal Variations
- • Body position
- • Breathing pattern
- • Exercise level
- • Pregnancy
- • Altitude
- • Individual anatomy
Measurement Considerations
- • Equipment accuracy
- • Steady-state conditions
- • Patient cooperation
- • Temperature and pressure
- • Timing of measurements
- • Clinical context