From the Guidelines
Pulmonary compliance is the change in lung volume for a given change in transpulmonary pressure, typically measured as the volume change per unit of pressure change (mL/cmH2O), and it is a critical parameter in assessing lung function and guiding mechanical ventilation settings. According to the study published in Intensive Care Medicine 1, lung compliance is decreased in patients with Acute Lung Injury (ALI) or Acute Respiratory Distress Syndrome (ARDS), with compliance approaching 20 ml/cmH2O, or less than one-fourth that of normal.
Key Factors Affecting Pulmonary Compliance
- Elastic recoil of lung tissue
- Surface tension at the air-liquid interface in alveoli, which is reduced by surfactant produced by type II pneumocytes
- Conditions such as pulmonary fibrosis, ARDS, and pulmonary edema, which decrease compliance
- Conditions such as emphysema and aging, which increase compliance
Clinical Significance of Pulmonary Compliance
- Guides mechanical ventilation settings
- Assesses disease progression
- Evaluates response to treatments in respiratory conditions
- Helps in early detection of pulmonary pathologies, as changes in compliance can precede clinical symptoms. In clinical practice, understanding pulmonary compliance is essential for managing patients with respiratory diseases, particularly those requiring mechanical ventilation, as it directly impacts morbidity, mortality, and quality of life.
From the Research
Definition of Pulmonary Compliance
Pulmonary compliance refers to the ability of the lung to expand with changes in pressure. It is one of the earliest physiological measurements to be altered in patients with parenchymal lung disease 2.
Factors Affecting Pulmonary Compliance
Several factors can affect pulmonary compliance, including:
- Lung volume and pressure changes
- Presence of lung disease, such as idiopathic pulmonary fibrosis (IPF) or chronic obstructive pulmonary disease (COPD)
- Level of positive end-expiratory pressure (PEEP) applied during mechanical ventilation
Measurement of Pulmonary Compliance
Pulmonary compliance can be measured using various techniques, including:
- Dynamic lung compliance imaging from 4DCT-derived volume change estimation 2
- Electrical impedance tomography (EIT) to guide PEEP titration and optimize lung recruitment and homogeneity of ventilation 3, 4, 5
- Pressure-volume curve analysis to select optimal PEEP levels 5
Clinical Significance of Pulmonary Compliance
Pulmonary compliance is an important parameter in the management of patients with respiratory diseases. Monitoring changes in pulmonary compliance can help identify patients at risk for disease progression and guide therapeutic interventions, such as adjustments to PEEP levels during mechanical ventilation 2, 3, 4, 5.