GapCO2 and Respiratory Rate in Patients Under Volume Mechanical Ventilation

As an approximate of the difference between venous-to-arterial CO2 tension (∆PCO2), ∆PCO2 is proportional to CO2 production and inversely related to cardiac output (Fick equation). Anaerobic CO2 production is thought to occur when tissue hypoxia is present, mostly because of buffering of bicarbonate ions by the protons produced in excess secondary to the hydrolysis of adenosine triphosphate. Therefore ∆PCO2 has been proposed as a marker of tissue hypoxia.