Simulation of Respiratory Regulation of Blood Gases in the Critically Ill Patient

In the regulation of arterial blood gases, the relative importance of metabolic exchange, respiratory capability, and level of ventilatory control sensitivity to blood O₂, CO₂ and pH was investigated. The study was based on a dynamic computer simulation of a multi-compartment elastic lung and its interactions with the cardiorespiratory system, and the regulation of acid/base balance. The model was evaluated with clinical data from control and critically ill patients. This study suggests that increases in metabolic demand and reduced ventilatory capability are major factors in influencing the regulation of arterial gas tensions and pH in patients with severe sepsis, rather than changes in the level of sensitivity to arterial CO₂ and O₂.