Respiratory System
Respiratory Tract Embryology Stages {EPCSA}
- Embryonic
- Pseudoglandular
- Canalicular
- Saccular
- Alveolar
Lung Volumes and Measurements
| Indices | Methods |
|---|---|
| IRV TV ERV | Spirometry |
| RV | Helium dilution method Plethysmography |
Perfusion and Diffusion Limited Pulmonary Circulation
Ventilation/Perfusion (V/Q) Ratio
| Ratio | Conditions |
|---|---|
| 0 | Shunt |
| Low | Lung base |
| High | Lung apex |
| ∞ | Dead space |
Dead Space
| Parameter | VD = VT × (PaCO2 - PECO2) ÷ PaCO2 |
|---|---|
| VD | Dead space |
| VT | Tidal volume |
| PaCO2 | Arterial CO2 pressure (mmHg) |
| PECO2 | Expired Air CO2 pressure (mmHg) |
Diffusion Rate
| Parameter | G × A ÷ T |
|---|---|
| G | A-a gradient |
| A | Area |
| T | Thickness |
Alveolar Gas Equation
| Parameter | PAO2 = PIO2 - PaCO2 ÷ RQ |
|---|---|
| PAO2 | Alveolar O2 pressure (mmHg) |
| PIO2 | Inspired Air O2 pressure (mmHg) |
| PaCO2 | Arterial CO2 pressure (mmHg) |
| RQ | Respiratory quotient |