Neonatal Nurse Practitioner Practice Exam

What is the formula for calculating the time constant in neonatal respiratory physiology?

1. Compliance x resistance

2. Resistance x compliance

3. Volume/pressure

4. Frequency x gas flow

The correct answer is: Resistance x compliance

The time constant in neonatal respiratory physiology is an important measurement that reflects the time it takes for the lung to fill or empty as influenced by its compliance and resistance. The correct formula for calculating the time constant is derived from the relationship between these two factors: the time constant equals resistance multiplied by compliance. This relationship highlights that both the resistance of the airways and the compliance of the lung tissue play crucial roles in determining how quickly air can move in and out of the lungs. High resistance or low compliance will increase the time constant, indicating slower lung inflation and deflation. Conversely, low resistance or high compliance decreases the time constant, allowing for more efficient ventilation. Understanding this concept is essential for neonatal care, where the mechanics of breathing can differ significantly from those in older populations. Conditions that affect either compliance, such as respiratory distress syndrome, or resistance, such as airway obstruction, can significantly impact the time constant and respiratory efficacy in neonates. Thus, the time constant is a key factor in assessing and managing respiratory function in this vulnerable population.