From the Guidelines
Normal lung compliance values are approximately 1.2 to 2.0 ml/cm H2O per kilogram body weight. This range is based on the most recent and highest quality study available, which was published in the American Journal of Respiratory and Critical Care Medicine in 2003 1. The study discusses the care of children with chronic lung disease of infancy and childhood, and it provides valuable insights into lung compliance in this population.
Key Points to Consider
- Lung compliance is dependent on lung volume, and results are often expressed as "specific compliance" to account for this relationship.
- The study found that dynamic specific compliance in infants with chronic lung disease of infancy (CLDI) is 30 to 50% of control values for infants 2 to 4 months of age.
- Static compliance of the respiratory system in young infants with CLDI is also reduced, with values reported as 60% of control values.
- As infants with CLDI grow, their specific compliance improves to 80 to 90% of control subjects between the ages of 2 and 3 years.
Clinical Implications
Understanding normal lung compliance values is crucial in clinical settings, as decreased compliance is characteristic of restrictive lung diseases, while increased compliance is seen in conditions like emphysema. Measuring compliance helps clinicians assess lung function, guide ventilator settings, and monitor disease progression or treatment effectiveness. The values of 1.2 to 2.0 ml/cm H2O per kilogram body weight serve as a reference point for evaluating lung compliance in patients and making informed decisions about their care.
From the Research
Normal Lung Compliance Values
- Normal lung compliance values are typically measured in terms of dynamic and static pulmonary compliance.
- A study published in 2007 2 found that the mean values for dynamic compliance (Cdyn) and static compliance (Cstat) in healthy men were 2.91 +/- 1.08 L/kPa and 3.34 +/- 1.04 L/kPa, respectively.
- The same study also reported that specific dynamic compliance (Cdyn/ITGV) and specific static compliance (Cstat/ITGV) were 0.71 +/- 0.30 kPa (-1) and 0.82 +/- 0.31 kPa (-1), respectively.
- Another study published in 2007 3 used static pulmonary compliance (Cst) values to evaluate the prognosis of mechanically ventilated patients, with a cutoff value of 0.025 L/cm H2O used to distinguish between patients with good and poor prognosis.
Factors Affecting Lung Compliance
- Age and height have been found to be correlated with lung compliance, with older age and taller height associated with lower lung compliance 2.
- However, the predictability of lung compliance based on anthropometric variables such as age and height is low, suggesting that other factors also play a role in determining lung compliance.
Clinical Applications of Lung Compliance
- Lung compliance is an important parameter in the diagnosis and management of respiratory diseases such as chronic obstructive pulmonary disease (COPD) and asthma 4, 5, 6.
- Impulse oscillometry has been found to be a useful tool for detecting small airway dysfunction and predicting acute exacerbations in patients with COPD and asthma-COPD overlap 6.