Pulse Packet Stochastic Model for Gastric Emptying in the Fasted State: A Physiological Approach

Fasted-state gastrointestinal (GI) fluid transit is typically represented as a first-order, deterministic process (averaged and viewed as a continuous approximation). It is, however, most likely a discrete process involving fluid packets interrupted by variable time periods of little to no fluid emptying. In this report we present a physiologically based pulsed-packet gastric fluid emptying model and evaluate it with respect to recent gastrointestinal fluid volume emptying results, published gastric emptying of various dosage forms, and gastric fluid emptying as a function of GI motility. We develop the mathematical model for gastric emptying of discrete volumes emptied during intermittent pulse times of variable lengths, defined as a function of gastric motility utilizing a Poisson point process with motility-dependent intensity. We compare the simulations with observed gastric emptying results. The discrete pulse packet gastric volumetric emptying model is a more physiologically realistic mathematical model for gastric emptying, and it accounts well for the average observed emptying rates and, importantly, encompasses the variability of of observed volume and dosage form emptying rates.