Comp+ breathing
- 1. COMPLIANCE & WORK OF BREATHING Presentor: Arthi . P.R
- 2. COMPLIANCE Compliance - Change in Lung volume for the given change in atmospheric pressure It is the reciprocal of Elastance Compliance of the respiratory system = CRS Change in Lung Volume Change in Airway Pressure V P =
- 3. Compliance RS - Interaction of the compliance of lungs and compliance of chest wall Reciprocal of Compliance is the sum of reciprocal of Lung and Chest wall CL = Alveolar Presssure - Intrapleural Pressure CW= Intrapleural Pressure - Ambient Pressure Intrapleural Pressure is difficult to measure - Esophageal Pressure from Ballon Manometry is commonly used as an approximation of intrapleural pressure 1 CRS 1 CL 1 CW +=
- 4. Factors Affecting Compliance (CL) 1. Lung Volume - Compliance is related to Normal FRC 2. Surface Tension of Alveoli - Surfactant the major factor determining the Lung Recoil Without Surfactant Lung will normally behave like an air bubble following Laplace Equation P = 2T/R Normally- when radius of bubble decreases without change is surface tension the pressure increases But in Lung - When the radius decreases the surface tension also decreases and this opposes the collapse of smaller lung unit. P- Gas Pressure T- Surface Tension R- Radius
- 5. Other Factors Affecting Compliance (CL) 3. Pulmonary Blood Volume 4. Interstitial Edema Factors Affecting Chest Wall Compliance (CCW) 1. Posture 2. Obesity 3. Ossification of Costal Cartilages 4. Scaring of Skin
- 6. DYNAMIC COMPLIANCE Normal Healthy person- As the respiratory system inflates to 60% of the TLC - the chest wall is aiding the Muscle of respiration to inflate. Above this level the muscles of Inspiration should work to distend both the Lungs and the Chest wall - Dynamic Compliance P = Peak Airway Pressure - PEEP DC - Also include Effect of Airway resistance & Normal Hysteresis of Lung Parenchyma(Resistance to Change of Shape both during Stretch & Contraction) DC- Affected by frequency of Respiration & Velocity of Gas Flow
- 7. STATIC COMPLIANCE It is measured at a point of No gas flow and when the pressure gradient is allowed to Equilibrate to the entire airway. (Eg)In Anesthetised & Paralysed Patient during ventilation in VCV mode with a fixed inspiratory flow and using an end expiratory pause P = Plateau Airway Pressure - PEEP SC - refers to Actual Distending pressure in the patients alveoli Difference between Static & Dynamic Compliance reflects Airway resistance