nproduced by normal respiration . When oxygen delivery I D 02 ) to the mucosa is reduced below metabolic demand ( ie , anaerobiasis ) , acidosis ensues . Th ie hydrogen ions that are produced are titrated with bicarbonate , and ( by mass action : H + + HCO3 - OILCO.eCo2 + H2O ) even more CO2 will accumulate than would be expected by a reduction in blood flow . By assuming that arterial ( art ) bicarbonate equals mucosal bicarbonate , intramucosal pH ( pHi ) can be calculated using the Henderson - Hasselbalch equation :