Chapter 2, Problem 15RQ

Summary Introduction

To review:

Part I: The compliance of the lungs if a patient generates a negative pleural pressure change of -8 cm H₂O during inspiration, and the lungs accept a new volume of 630 ml.

Part II: The compliance of the lungs of the same patient, 6 hours later, if he generates a pleural pressure of -12 cm H₂O during inspiration, and the lungs accept a new volume of 850 ml.

Part III: Comparing Part II to Part I, is the patient’s lung compliance increasing or decreasing.

Introduction:

The curve between the pressure and volume, which describes the elastic strength of the lungs, allowing the inhaling of air, is called lung compliance (${\text{C}}_{\text{L}}$). ${\text{C}}_{\text{L}}$ is described as the alteration in the ration in the volume of the lung ($\text{ΔV}$) for per unit change in the pressure ($\text{ΔP}$). It is mathematically expressed in milliliters per centimeter of pressure of water (m$\text{L}/\text{cm}{\text{H}}_{\text{2}}\text{O}$).