Factors That Increase or Decrease the Rate of Increase of Alveolar Anesthetic Concentration (Fa(A))/Inspired Anesthetic Concentration (Fi(I))

Increase	Decrease
Low blood solubility	High blood solubility	The lower the blood:gas solubility, the faster the increase in F_A/F_I.
Low cardiac output	High cardiac output	The lower the cardiac output, the faster the increase in the F_A/F_I.
High minute ventilation	Low minute ventilation	The higher the minute ventilation, the faster the increase in F_A/F_I.
High pulmonary arterial to venous partial pressure	Low pulmonary arterial to venous partial pressure	At the beginning of induction, the pulmonary to venous blood partial pressure gradient is zero, but it increases rapidly, and F_A/F_I increases rapidly. Later during induction and maintenance, the pulmonary venous blood partial pressure increases more slowly, so F_A/F_I increases more slowly.