To model the ventilatory effects of propofol, we will develop a mathematical model of human respiratory control. We will base this on the respiratory model proposed by Ursino (Ursino Model)19-21 which is a three compartment model comprising the lung, brain and tissues for gas exchange. We will enhance the model to include ventilatory regulation, along with pharmacokinetic and pharmacodynamic models of propofol including a respiratory effect site. The identification of suitable parameters for the model will include non-linear fitting of the clinical data (age, weight, BSA, ventilatory volumes, CO2 excretion, respiratory rate, and entropy).