Question

Intravenous sodium bicarbonate (NaHCO₃, same as baking soda) is a common treatment for metabolic acidosis. Explain how this treatment works. Do you think sodium bicarbonate treatment will affect the ability of hemoglobin to transport and deliver oxygen to body tissues? Why? Would this treatment help someone with carbon monoxide poisoning?

Answer 1

Metabolic acidiosis is caused due to three reasons- increased acid production, loss of bicarbonate or a reduction in the amount of acidic ions excreted by the kidneys.

Sodium bicarbonate helps to treat acidiosis caused due to loss of base which reduces the blood pH levels. Sodium bicarbonate is a base. As it is injected intravenously, it works to neutralize the excess acid by releasing basic ions [bicarbonate ions] in the blood which combine with the free hydrogen ions and increase the blood pH to normal levels.

In the blood, bicarbonate ions help to neutralize acid which are produced by other metabolic processes. The hydrogen ions dissociate from hemoglobin and combine with bicarbonates to form carbonic acid with the help of carbonic anhydrase. Further reactions facilitated by carbonic hydrase helps to convert carbonic acid back to CO2 and water.

CO2 is more soluble in blood than O2 which is mainly transported in the blood as oxyhemoglobin. So, bicarbonate ions can indirectly help the hemoglobin to transport O2 to body tissues.

It is believed that acidiosis may increase tissue oxygen availability. Carbon monoxide is dangerous because it binds with the hemoglobin and drastically reduces its ability to transport oxygen to the tissues. The oxygen starved brain cells and cells of other vital organs can get damaged irreparably, cusing death or a comatose condition. If these facts are taken into consideration then it seems that injecting bicarbonated might not help in curing carbon monoxide poisoning. Oxygen therapy is the best treatment for CO poisoning.