Mean Airway Pressure Calculator
Calculate mean airway pressure (Paw) for mechanical ventilation assessment
Medical Disclaimer
This calculator is for educational and informational purposes only. Mean airway pressure calculations should only be used by qualified medical professionals. Always consult with healthcare providers for patient care decisions and ventilator management.
Calculate Mean Airway Pressure
Total time for one complete respiratory cycle (inspiration + expiration)
Duration of inspiration phase (typically ~1.9s at 12/min)
Typical range: 4-8 cmH₂O (prevents alveolar collapse)
Typical range: 15-25 cmH₂O (highest pressure during inspiration)
Waveform pattern affects the mean pressure calculation
Mean Airway Pressure Results
Calculation Details
Formula: Paw = K × (Ti/Ttot) × (PIP-PEEP) + PEEP
K value: 1.00 (rectangular)
Ti/Ttot ratio: 0.0%
I:E ratio: 0:0
Clinical Assessment
Enter values to see assessment
Example Calculation
Standard Mechanical Ventilation
Respiratory Rate: 12 breaths/min
Total Cycle Time: 5.0s
Inspiratory Time: 1.9s
PIP: 20 cmH₂O
PEEP: 5 cmH₂O
Waveform: Rectangular (K=1)
Calculation Steps
1. Ti/Ttot = 1.9s / 5.0s = 0.38
2. PIP - PEEP = 20 - 5 = 15 cmH₂O
3. Paw = 1.0 × 0.38 × 15 + 5
4. Paw = 10.7 cmH₂O
Normal Values Reference
Mean Airway Pressure
Normal: 10-15 cmH₂O (13.6-20.4 mmHg)
Two-lung ventilation typical range
PEEP
Normal: 4-8 cmH₂O
Prevents alveolar collapse
PIP
Normal: ~20 cmH₂O
Range: 15-25 cmH₂O for preterm neonates
Inspiratory Time
Typical: ~1.9s
At respiratory rate of 12/min
Pressure Waveforms
Rectangular (K=1.0)
Square wave - constant pressure during inspiration
Triangular (K=0.5)
Linear increase to peak, then linear decrease
Sine-like (K≈0.64)
Smooth sinusoidal pressure pattern
Clinical Significance
Correlates with alveolar pressure
Helps assess potential lung trauma
Evaluates oxygenation efficiency
High values may reduce cardiac output
Used for ventilator optimization
Understanding Mean Airway Pressure
What is Mean Airway Pressure?
Mean airway pressure (Paw) is the average pressure applied to the lungs during mechanical ventilation throughout both inspiration and expiration phases. It represents the time-averaged pressure that acts on the alveoli during the respiratory cycle.
Clinical Importance
- •Correlates closely with alveolar pressure
- •Helps assess risk of barotrauma
- •Influences arterial oxygenation
- •Affects hemodynamic status
Formula Components
Paw = K × (Ti/Ttot) × (PIP - PEEP) + PEEP
- Paw: Mean airway pressure (cmH₂O)
- K: Waveform constant (1.0, 0.5, or 0.64)
- Ti: Inspiratory time (seconds)
- Ttot: Total respiratory cycle time (seconds)
- PIP: Peak inspiratory pressure (cmH₂O)
- PEEP: Positive end-expiratory pressure (cmH₂O)
Note: High mean airway pressure may compromise venous return and cardiac output, requiring careful monitoring of hemodynamic parameters.
Normal Range
Typical mean airway pressure ranges from 10-15 cmH₂O (13.6-20.4 mmHg) in two-lung ventilation. Values may vary based on patient height, age, and underlying pathology.
High Paw Effects
Elevated mean airway pressure can reduce cardiac index and cardiac output by impeding venous return. This may lead to hemodynamic instability requiring intervention.
Optimization
Optimal mean airway pressure balances adequate oxygenation with minimal cardiovascular compromise. Adjust PEEP, PIP, and I:E ratio to achieve therapeutic goals.