From the Guidelines
Normal lung compliance values in infants 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 highlights that lung compliance is dependent on lung volume, and therefore, specific compliance is often expressed as a corrected value for body weight, lung volume at functional residual capacity (FRC), or body length.
The provided evidence suggests that infants with chronic lung disease of infancy and childhood (CLDI) have significantly lower compliance values, ranging from 30 to 50% of control values for infants 2 to 4 months of age 1. However, as infants grow and their lungs mature, specific compliance improves to values of 80 to 90% of control subjects between the ages of 2 and 3 years 1.
Key points to consider when evaluating lung compliance in infants include:
- Lung compliance is lower in infants due to smaller lung size and less developed elastic tissue
- Premature infants have even lower compliance values due to surfactant deficiency and immature lung development
- Compliance values increase as infants grow and their lungs mature
- Respiratory system compliance may have predictive value for the development of CLDI and can be used to assess respiratory function and determine appropriate ventilator settings 1.
In clinical practice, it is essential to consider these normal ranges when assessing respiratory function and determining appropriate ventilator settings for infants. By understanding the normal lung compliance values in infants and how they change with growth and development, clinicians can provide more effective respiratory support and improve outcomes for their patients.
From the Research
Normal Lung Compliance Values in Infants
- The normal lung compliance values in infants can be determined through various studies, including those that measure dynamic lung compliance (Cdyn) and total respiratory system compliance (Crs) 2.
- A study published in 1987 measured lung compliance and pulmonary conductance in 40 normal infants and children ranging in age from the newborn period to 5 years, and found that specific compliance was around 75 +/- 13 ml/cm H2O/L-FRC 3.
- Another study published in 1982 determined the compliance of the respiratory system in 82 newborns and found that respiratory compliance was correlated with the severity of the disease in infants with respiratory distress 4.
- However, it is essential to note that lung compliance values can vary depending on factors such as gestational age, birth weight, and the presence of respiratory disease 2, 5, 6.
- The measurement of lung compliance can be challenging, especially in sick intubated preterm infants, where oesophageal pressure and hence Cdyn cannot be reliably measured 2.
- Despite these challenges, measuring lung compliance can be useful in predicting the course and outcome of respiratory disease in infants, as well as in classifying the severity of the disease 4.