Abstract
Understanding the basic concepts and the dynamics of the equation of motion will help the anaesthesiologist and the intensive care physician in gaining an insight into the basics of modern mechanical ventilation. An equation of the type V(t) = V(0) × (1-e(-kt)) is often encountered while studying the concepts of mechanical ventilation. This leaves one wondering about the meaning of 'e'. It is explained as the base of a natural logarithm, and the base e as an irrational constant approximately equal to 2. 7182. In medical literature, various physiological mechanisms are explained by using the exponential function e. However, the explanations do not sufficiently help the learner to demystify the enigmatic term e. In this article, an effort is made to explain this function with the help of simple analogies and relevant mathematical concepts. The process of volume build-up in the lungs during mechanical ventilation is used as a model for the explanations.